xref: /linux/drivers/tty/serial/serial_core.c (revision 78964fcac47fc1525ecb4c37cd5fbc873c28320b)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Driver core for serial ports
4  *
5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6  *
7  *  Copyright 1999 ARM Limited
8  *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
9  */
10 #include <linux/module.h>
11 #include <linux/tty.h>
12 #include <linux/tty_flip.h>
13 #include <linux/slab.h>
14 #include <linux/sched/signal.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/gpio/consumer.h>
18 #include <linux/kernel.h>
19 #include <linux/of.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/proc_fs.h>
22 #include <linux/seq_file.h>
23 #include <linux/device.h>
24 #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
25 #include <linux/serial_core.h>
26 #include <linux/sysrq.h>
27 #include <linux/delay.h>
28 #include <linux/mutex.h>
29 #include <linux/math64.h>
30 #include <linux/security.h>
31 
32 #include <linux/irq.h>
33 #include <linux/uaccess.h>
34 
35 #include "serial_base.h"
36 
37 /*
38  * This is used to lock changes in serial line configuration.
39  */
40 static DEFINE_MUTEX(port_mutex);
41 
42 /*
43  * lockdep: port->lock is initialized in two places, but we
44  *          want only one lock-class:
45  */
46 static struct lock_class_key port_lock_key;
47 
48 #define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)
49 
50 /*
51  * Max time with active RTS before/after data is sent.
52  */
53 #define RS485_MAX_RTS_DELAY	100 /* msecs */
54 
55 static void uart_change_pm(struct uart_state *state,
56 			   enum uart_pm_state pm_state);
57 
58 static void uart_port_shutdown(struct tty_port *port);
59 
60 static int uart_dcd_enabled(struct uart_port *uport)
61 {
62 	return !!(uport->status & UPSTAT_DCD_ENABLE);
63 }
64 
65 static inline struct uart_port *uart_port_ref(struct uart_state *state)
66 {
67 	if (atomic_add_unless(&state->refcount, 1, 0))
68 		return state->uart_port;
69 	return NULL;
70 }
71 
72 static inline void uart_port_deref(struct uart_port *uport)
73 {
74 	if (atomic_dec_and_test(&uport->state->refcount))
75 		wake_up(&uport->state->remove_wait);
76 }
77 
78 #define uart_port_lock(state, flags)					\
79 	({								\
80 		struct uart_port *__uport = uart_port_ref(state);	\
81 		if (__uport)						\
82 			spin_lock_irqsave(&__uport->lock, flags);	\
83 		__uport;						\
84 	})
85 
86 #define uart_port_unlock(uport, flags)					\
87 	({								\
88 		struct uart_port *__uport = uport;			\
89 		if (__uport) {						\
90 			spin_unlock_irqrestore(&__uport->lock, flags);	\
91 			uart_port_deref(__uport);			\
92 		}							\
93 	})
94 
95 static inline struct uart_port *uart_port_check(struct uart_state *state)
96 {
97 	lockdep_assert_held(&state->port.mutex);
98 	return state->uart_port;
99 }
100 
101 /**
102  * uart_write_wakeup - schedule write processing
103  * @port: port to be processed
104  *
105  * This routine is used by the interrupt handler to schedule processing in the
106  * software interrupt portion of the driver. A driver is expected to call this
107  * function when the number of characters in the transmit buffer have dropped
108  * below a threshold.
109  *
110  * Locking: @port->lock should be held
111  */
112 void uart_write_wakeup(struct uart_port *port)
113 {
114 	struct uart_state *state = port->state;
115 	/*
116 	 * This means you called this function _after_ the port was
117 	 * closed.  No cookie for you.
118 	 */
119 	BUG_ON(!state);
120 	tty_port_tty_wakeup(&state->port);
121 }
122 EXPORT_SYMBOL(uart_write_wakeup);
123 
124 static void uart_stop(struct tty_struct *tty)
125 {
126 	struct uart_state *state = tty->driver_data;
127 	struct uart_port *port;
128 	unsigned long flags;
129 
130 	port = uart_port_lock(state, flags);
131 	if (port)
132 		port->ops->stop_tx(port);
133 	uart_port_unlock(port, flags);
134 }
135 
136 static void __uart_start(struct uart_state *state)
137 {
138 	struct uart_port *port = state->uart_port;
139 	struct serial_port_device *port_dev;
140 	int err;
141 
142 	if (!port || port->flags & UPF_DEAD || uart_tx_stopped(port))
143 		return;
144 
145 	port_dev = port->port_dev;
146 
147 	/* Increment the runtime PM usage count for the active check below */
148 	err = pm_runtime_get(&port_dev->dev);
149 	if (err < 0) {
150 		pm_runtime_put_noidle(&port_dev->dev);
151 		return;
152 	}
153 
154 	/*
155 	 * Start TX if enabled, and kick runtime PM. If the device is not
156 	 * enabled, serial_port_runtime_resume() calls start_tx() again
157 	 * after enabling the device.
158 	 */
159 	if (!pm_runtime_enabled(port->dev) || pm_runtime_active(port->dev))
160 		port->ops->start_tx(port);
161 	pm_runtime_mark_last_busy(&port_dev->dev);
162 	pm_runtime_put_autosuspend(&port_dev->dev);
163 }
164 
165 static void uart_start(struct tty_struct *tty)
166 {
167 	struct uart_state *state = tty->driver_data;
168 	struct uart_port *port;
169 	unsigned long flags;
170 
171 	port = uart_port_lock(state, flags);
172 	__uart_start(state);
173 	uart_port_unlock(port, flags);
174 }
175 
176 static void
177 uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
178 {
179 	unsigned long flags;
180 	unsigned int old;
181 
182 	spin_lock_irqsave(&port->lock, flags);
183 	old = port->mctrl;
184 	port->mctrl = (old & ~clear) | set;
185 	if (old != port->mctrl && !(port->rs485.flags & SER_RS485_ENABLED))
186 		port->ops->set_mctrl(port, port->mctrl);
187 	spin_unlock_irqrestore(&port->lock, flags);
188 }
189 
190 #define uart_set_mctrl(port, set)	uart_update_mctrl(port, set, 0)
191 #define uart_clear_mctrl(port, clear)	uart_update_mctrl(port, 0, clear)
192 
193 static void uart_port_dtr_rts(struct uart_port *uport, bool active)
194 {
195 	if (active)
196 		uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
197 	else
198 		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
199 }
200 
201 /* Caller holds port mutex */
202 static void uart_change_line_settings(struct tty_struct *tty, struct uart_state *state,
203 				      const struct ktermios *old_termios)
204 {
205 	struct uart_port *uport = uart_port_check(state);
206 	struct ktermios *termios;
207 	bool old_hw_stopped;
208 
209 	/*
210 	 * If we have no tty, termios, or the port does not exist,
211 	 * then we can't set the parameters for this port.
212 	 */
213 	if (!tty || uport->type == PORT_UNKNOWN)
214 		return;
215 
216 	termios = &tty->termios;
217 	uport->ops->set_termios(uport, termios, old_termios);
218 
219 	/*
220 	 * Set modem status enables based on termios cflag
221 	 */
222 	spin_lock_irq(&uport->lock);
223 	if (termios->c_cflag & CRTSCTS)
224 		uport->status |= UPSTAT_CTS_ENABLE;
225 	else
226 		uport->status &= ~UPSTAT_CTS_ENABLE;
227 
228 	if (termios->c_cflag & CLOCAL)
229 		uport->status &= ~UPSTAT_DCD_ENABLE;
230 	else
231 		uport->status |= UPSTAT_DCD_ENABLE;
232 
233 	/* reset sw-assisted CTS flow control based on (possibly) new mode */
234 	old_hw_stopped = uport->hw_stopped;
235 	uport->hw_stopped = uart_softcts_mode(uport) &&
236 			    !(uport->ops->get_mctrl(uport) & TIOCM_CTS);
237 	if (uport->hw_stopped != old_hw_stopped) {
238 		if (!old_hw_stopped)
239 			uport->ops->stop_tx(uport);
240 		else
241 			__uart_start(state);
242 	}
243 	spin_unlock_irq(&uport->lock);
244 }
245 
246 /*
247  * Startup the port.  This will be called once per open.  All calls
248  * will be serialised by the per-port mutex.
249  */
250 static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
251 			     bool init_hw)
252 {
253 	struct uart_port *uport = uart_port_check(state);
254 	unsigned long flags;
255 	unsigned long page;
256 	int retval = 0;
257 
258 	if (uport->type == PORT_UNKNOWN)
259 		return 1;
260 
261 	/*
262 	 * Make sure the device is in D0 state.
263 	 */
264 	uart_change_pm(state, UART_PM_STATE_ON);
265 
266 	/*
267 	 * Initialise and allocate the transmit and temporary
268 	 * buffer.
269 	 */
270 	page = get_zeroed_page(GFP_KERNEL);
271 	if (!page)
272 		return -ENOMEM;
273 
274 	uart_port_lock(state, flags);
275 	if (!state->xmit.buf) {
276 		state->xmit.buf = (unsigned char *) page;
277 		uart_circ_clear(&state->xmit);
278 		uart_port_unlock(uport, flags);
279 	} else {
280 		uart_port_unlock(uport, flags);
281 		/*
282 		 * Do not free() the page under the port lock, see
283 		 * uart_shutdown().
284 		 */
285 		free_page(page);
286 	}
287 
288 	retval = uport->ops->startup(uport);
289 	if (retval == 0) {
290 		if (uart_console(uport) && uport->cons->cflag) {
291 			tty->termios.c_cflag = uport->cons->cflag;
292 			tty->termios.c_ispeed = uport->cons->ispeed;
293 			tty->termios.c_ospeed = uport->cons->ospeed;
294 			uport->cons->cflag = 0;
295 			uport->cons->ispeed = 0;
296 			uport->cons->ospeed = 0;
297 		}
298 		/*
299 		 * Initialise the hardware port settings.
300 		 */
301 		uart_change_line_settings(tty, state, NULL);
302 
303 		/*
304 		 * Setup the RTS and DTR signals once the
305 		 * port is open and ready to respond.
306 		 */
307 		if (init_hw && C_BAUD(tty))
308 			uart_port_dtr_rts(uport, true);
309 	}
310 
311 	/*
312 	 * This is to allow setserial on this port. People may want to set
313 	 * port/irq/type and then reconfigure the port properly if it failed
314 	 * now.
315 	 */
316 	if (retval && capable(CAP_SYS_ADMIN))
317 		return 1;
318 
319 	return retval;
320 }
321 
322 static int uart_startup(struct tty_struct *tty, struct uart_state *state,
323 			bool init_hw)
324 {
325 	struct tty_port *port = &state->port;
326 	int retval;
327 
328 	if (tty_port_initialized(port))
329 		return 0;
330 
331 	retval = uart_port_startup(tty, state, init_hw);
332 	if (retval)
333 		set_bit(TTY_IO_ERROR, &tty->flags);
334 
335 	return retval;
336 }
337 
338 /*
339  * This routine will shutdown a serial port; interrupts are disabled, and
340  * DTR is dropped if the hangup on close termio flag is on.  Calls to
341  * uart_shutdown are serialised by the per-port semaphore.
342  *
343  * uport == NULL if uart_port has already been removed
344  */
345 static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
346 {
347 	struct uart_port *uport = uart_port_check(state);
348 	struct tty_port *port = &state->port;
349 	unsigned long flags;
350 	char *xmit_buf = NULL;
351 
352 	/*
353 	 * Set the TTY IO error marker
354 	 */
355 	if (tty)
356 		set_bit(TTY_IO_ERROR, &tty->flags);
357 
358 	if (tty_port_initialized(port)) {
359 		tty_port_set_initialized(port, false);
360 
361 		/*
362 		 * Turn off DTR and RTS early.
363 		 */
364 		if (uport && uart_console(uport) && tty) {
365 			uport->cons->cflag = tty->termios.c_cflag;
366 			uport->cons->ispeed = tty->termios.c_ispeed;
367 			uport->cons->ospeed = tty->termios.c_ospeed;
368 		}
369 
370 		if (!tty || C_HUPCL(tty))
371 			uart_port_dtr_rts(uport, false);
372 
373 		uart_port_shutdown(port);
374 	}
375 
376 	/*
377 	 * It's possible for shutdown to be called after suspend if we get
378 	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
379 	 * we don't try to resume a port that has been shutdown.
380 	 */
381 	tty_port_set_suspended(port, false);
382 
383 	/*
384 	 * Do not free() the transmit buffer page under the port lock since
385 	 * this can create various circular locking scenarios. For instance,
386 	 * console driver may need to allocate/free a debug object, which
387 	 * can endup in printk() recursion.
388 	 */
389 	uart_port_lock(state, flags);
390 	xmit_buf = state->xmit.buf;
391 	state->xmit.buf = NULL;
392 	uart_port_unlock(uport, flags);
393 
394 	free_page((unsigned long)xmit_buf);
395 }
396 
397 /**
398  * uart_update_timeout - update per-port frame timing information
399  * @port: uart_port structure describing the port
400  * @cflag: termios cflag value
401  * @baud: speed of the port
402  *
403  * Set the @port frame timing information from which the FIFO timeout value is
404  * derived. The @cflag value should reflect the actual hardware settings as
405  * number of bits, parity, stop bits and baud rate is taken into account here.
406  *
407  * Locking: caller is expected to take @port->lock
408  */
409 void
410 uart_update_timeout(struct uart_port *port, unsigned int cflag,
411 		    unsigned int baud)
412 {
413 	unsigned int size = tty_get_frame_size(cflag);
414 	u64 frame_time;
415 
416 	frame_time = (u64)size * NSEC_PER_SEC;
417 	port->frame_time = DIV64_U64_ROUND_UP(frame_time, baud);
418 }
419 EXPORT_SYMBOL(uart_update_timeout);
420 
421 /**
422  * uart_get_baud_rate - return baud rate for a particular port
423  * @port: uart_port structure describing the port in question.
424  * @termios: desired termios settings
425  * @old: old termios (or %NULL)
426  * @min: minimum acceptable baud rate
427  * @max: maximum acceptable baud rate
428  *
429  * Decode the termios structure into a numeric baud rate, taking account of the
430  * magic 38400 baud rate (with spd_* flags), and mapping the %B0 rate to 9600
431  * baud.
432  *
433  * If the new baud rate is invalid, try the @old termios setting. If it's still
434  * invalid, we try 9600 baud.
435  *
436  * The @termios structure is updated to reflect the baud rate we're actually
437  * going to be using. Don't do this for the case where B0 is requested ("hang
438  * up").
439  *
440  * Locking: caller dependent
441  */
442 unsigned int
443 uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
444 		   const struct ktermios *old, unsigned int min, unsigned int max)
445 {
446 	unsigned int try;
447 	unsigned int baud;
448 	unsigned int altbaud;
449 	int hung_up = 0;
450 	upf_t flags = port->flags & UPF_SPD_MASK;
451 
452 	switch (flags) {
453 	case UPF_SPD_HI:
454 		altbaud = 57600;
455 		break;
456 	case UPF_SPD_VHI:
457 		altbaud = 115200;
458 		break;
459 	case UPF_SPD_SHI:
460 		altbaud = 230400;
461 		break;
462 	case UPF_SPD_WARP:
463 		altbaud = 460800;
464 		break;
465 	default:
466 		altbaud = 38400;
467 		break;
468 	}
469 
470 	for (try = 0; try < 2; try++) {
471 		baud = tty_termios_baud_rate(termios);
472 
473 		/*
474 		 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
475 		 * Die! Die! Die!
476 		 */
477 		if (try == 0 && baud == 38400)
478 			baud = altbaud;
479 
480 		/*
481 		 * Special case: B0 rate.
482 		 */
483 		if (baud == 0) {
484 			hung_up = 1;
485 			baud = 9600;
486 		}
487 
488 		if (baud >= min && baud <= max)
489 			return baud;
490 
491 		/*
492 		 * Oops, the quotient was zero.  Try again with
493 		 * the old baud rate if possible.
494 		 */
495 		termios->c_cflag &= ~CBAUD;
496 		if (old) {
497 			baud = tty_termios_baud_rate(old);
498 			if (!hung_up)
499 				tty_termios_encode_baud_rate(termios,
500 								baud, baud);
501 			old = NULL;
502 			continue;
503 		}
504 
505 		/*
506 		 * As a last resort, if the range cannot be met then clip to
507 		 * the nearest chip supported rate.
508 		 */
509 		if (!hung_up) {
510 			if (baud <= min)
511 				tty_termios_encode_baud_rate(termios,
512 							min + 1, min + 1);
513 			else
514 				tty_termios_encode_baud_rate(termios,
515 							max - 1, max - 1);
516 		}
517 	}
518 	/* Should never happen */
519 	WARN_ON(1);
520 	return 0;
521 }
522 EXPORT_SYMBOL(uart_get_baud_rate);
523 
524 /**
525  * uart_get_divisor - return uart clock divisor
526  * @port: uart_port structure describing the port
527  * @baud: desired baud rate
528  *
529  * Calculate the divisor (baud_base / baud) for the specified @baud,
530  * appropriately rounded.
531  *
532  * If 38400 baud and custom divisor is selected, return the custom divisor
533  * instead.
534  *
535  * Locking: caller dependent
536  */
537 unsigned int
538 uart_get_divisor(struct uart_port *port, unsigned int baud)
539 {
540 	unsigned int quot;
541 
542 	/*
543 	 * Old custom speed handling.
544 	 */
545 	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
546 		quot = port->custom_divisor;
547 	else
548 		quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);
549 
550 	return quot;
551 }
552 EXPORT_SYMBOL(uart_get_divisor);
553 
554 static int uart_put_char(struct tty_struct *tty, u8 c)
555 {
556 	struct uart_state *state = tty->driver_data;
557 	struct uart_port *port;
558 	struct circ_buf *circ;
559 	unsigned long flags;
560 	int ret = 0;
561 
562 	circ = &state->xmit;
563 	port = uart_port_lock(state, flags);
564 	if (!circ->buf) {
565 		uart_port_unlock(port, flags);
566 		return 0;
567 	}
568 
569 	if (port && uart_circ_chars_free(circ) != 0) {
570 		circ->buf[circ->head] = c;
571 		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
572 		ret = 1;
573 	}
574 	uart_port_unlock(port, flags);
575 	return ret;
576 }
577 
578 static void uart_flush_chars(struct tty_struct *tty)
579 {
580 	uart_start(tty);
581 }
582 
583 static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
584 {
585 	struct uart_state *state = tty->driver_data;
586 	struct uart_port *port;
587 	struct circ_buf *circ;
588 	unsigned long flags;
589 	int c, ret = 0;
590 
591 	/*
592 	 * This means you called this function _after_ the port was
593 	 * closed.  No cookie for you.
594 	 */
595 	if (WARN_ON(!state))
596 		return -EL3HLT;
597 
598 	port = uart_port_lock(state, flags);
599 	circ = &state->xmit;
600 	if (!circ->buf) {
601 		uart_port_unlock(port, flags);
602 		return 0;
603 	}
604 
605 	while (port) {
606 		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
607 		if (count < c)
608 			c = count;
609 		if (c <= 0)
610 			break;
611 		memcpy(circ->buf + circ->head, buf, c);
612 		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
613 		buf += c;
614 		count -= c;
615 		ret += c;
616 	}
617 
618 	__uart_start(state);
619 	uart_port_unlock(port, flags);
620 	return ret;
621 }
622 
623 static unsigned int uart_write_room(struct tty_struct *tty)
624 {
625 	struct uart_state *state = tty->driver_data;
626 	struct uart_port *port;
627 	unsigned long flags;
628 	unsigned int ret;
629 
630 	port = uart_port_lock(state, flags);
631 	ret = uart_circ_chars_free(&state->xmit);
632 	uart_port_unlock(port, flags);
633 	return ret;
634 }
635 
636 static unsigned int uart_chars_in_buffer(struct tty_struct *tty)
637 {
638 	struct uart_state *state = tty->driver_data;
639 	struct uart_port *port;
640 	unsigned long flags;
641 	unsigned int ret;
642 
643 	port = uart_port_lock(state, flags);
644 	ret = uart_circ_chars_pending(&state->xmit);
645 	uart_port_unlock(port, flags);
646 	return ret;
647 }
648 
649 static void uart_flush_buffer(struct tty_struct *tty)
650 {
651 	struct uart_state *state = tty->driver_data;
652 	struct uart_port *port;
653 	unsigned long flags;
654 
655 	/*
656 	 * This means you called this function _after_ the port was
657 	 * closed.  No cookie for you.
658 	 */
659 	if (WARN_ON(!state))
660 		return;
661 
662 	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
663 
664 	port = uart_port_lock(state, flags);
665 	if (!port)
666 		return;
667 	uart_circ_clear(&state->xmit);
668 	if (port->ops->flush_buffer)
669 		port->ops->flush_buffer(port);
670 	uart_port_unlock(port, flags);
671 	tty_port_tty_wakeup(&state->port);
672 }
673 
674 /*
675  * This function performs low-level write of high-priority XON/XOFF
676  * character and accounting for it.
677  *
678  * Requires uart_port to implement .serial_out().
679  */
680 void uart_xchar_out(struct uart_port *uport, int offset)
681 {
682 	serial_port_out(uport, offset, uport->x_char);
683 	uport->icount.tx++;
684 	uport->x_char = 0;
685 }
686 EXPORT_SYMBOL_GPL(uart_xchar_out);
687 
688 /*
689  * This function is used to send a high-priority XON/XOFF character to
690  * the device
691  */
692 static void uart_send_xchar(struct tty_struct *tty, char ch)
693 {
694 	struct uart_state *state = tty->driver_data;
695 	struct uart_port *port;
696 	unsigned long flags;
697 
698 	port = uart_port_ref(state);
699 	if (!port)
700 		return;
701 
702 	if (port->ops->send_xchar)
703 		port->ops->send_xchar(port, ch);
704 	else {
705 		spin_lock_irqsave(&port->lock, flags);
706 		port->x_char = ch;
707 		if (ch)
708 			port->ops->start_tx(port);
709 		spin_unlock_irqrestore(&port->lock, flags);
710 	}
711 	uart_port_deref(port);
712 }
713 
714 static void uart_throttle(struct tty_struct *tty)
715 {
716 	struct uart_state *state = tty->driver_data;
717 	upstat_t mask = UPSTAT_SYNC_FIFO;
718 	struct uart_port *port;
719 
720 	port = uart_port_ref(state);
721 	if (!port)
722 		return;
723 
724 	if (I_IXOFF(tty))
725 		mask |= UPSTAT_AUTOXOFF;
726 	if (C_CRTSCTS(tty))
727 		mask |= UPSTAT_AUTORTS;
728 
729 	if (port->status & mask) {
730 		port->ops->throttle(port);
731 		mask &= ~port->status;
732 	}
733 
734 	if (mask & UPSTAT_AUTORTS)
735 		uart_clear_mctrl(port, TIOCM_RTS);
736 
737 	if (mask & UPSTAT_AUTOXOFF)
738 		uart_send_xchar(tty, STOP_CHAR(tty));
739 
740 	uart_port_deref(port);
741 }
742 
743 static void uart_unthrottle(struct tty_struct *tty)
744 {
745 	struct uart_state *state = tty->driver_data;
746 	upstat_t mask = UPSTAT_SYNC_FIFO;
747 	struct uart_port *port;
748 
749 	port = uart_port_ref(state);
750 	if (!port)
751 		return;
752 
753 	if (I_IXOFF(tty))
754 		mask |= UPSTAT_AUTOXOFF;
755 	if (C_CRTSCTS(tty))
756 		mask |= UPSTAT_AUTORTS;
757 
758 	if (port->status & mask) {
759 		port->ops->unthrottle(port);
760 		mask &= ~port->status;
761 	}
762 
763 	if (mask & UPSTAT_AUTORTS)
764 		uart_set_mctrl(port, TIOCM_RTS);
765 
766 	if (mask & UPSTAT_AUTOXOFF)
767 		uart_send_xchar(tty, START_CHAR(tty));
768 
769 	uart_port_deref(port);
770 }
771 
772 static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
773 {
774 	struct uart_state *state = container_of(port, struct uart_state, port);
775 	struct uart_port *uport;
776 	int ret = -ENODEV;
777 
778 	/*
779 	 * Ensure the state we copy is consistent and no hardware changes
780 	 * occur as we go
781 	 */
782 	mutex_lock(&port->mutex);
783 	uport = uart_port_check(state);
784 	if (!uport)
785 		goto out;
786 
787 	retinfo->type	    = uport->type;
788 	retinfo->line	    = uport->line;
789 	retinfo->port	    = uport->iobase;
790 	if (HIGH_BITS_OFFSET)
791 		retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
792 	retinfo->irq		    = uport->irq;
793 	retinfo->flags	    = (__force int)uport->flags;
794 	retinfo->xmit_fifo_size  = uport->fifosize;
795 	retinfo->baud_base	    = uport->uartclk / 16;
796 	retinfo->close_delay	    = jiffies_to_msecs(port->close_delay) / 10;
797 	retinfo->closing_wait    = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
798 				ASYNC_CLOSING_WAIT_NONE :
799 				jiffies_to_msecs(port->closing_wait) / 10;
800 	retinfo->custom_divisor  = uport->custom_divisor;
801 	retinfo->hub6	    = uport->hub6;
802 	retinfo->io_type         = uport->iotype;
803 	retinfo->iomem_reg_shift = uport->regshift;
804 	retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;
805 
806 	ret = 0;
807 out:
808 	mutex_unlock(&port->mutex);
809 	return ret;
810 }
811 
812 static int uart_get_info_user(struct tty_struct *tty,
813 			 struct serial_struct *ss)
814 {
815 	struct uart_state *state = tty->driver_data;
816 	struct tty_port *port = &state->port;
817 
818 	return uart_get_info(port, ss) < 0 ? -EIO : 0;
819 }
820 
821 static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
822 			 struct uart_state *state,
823 			 struct serial_struct *new_info)
824 {
825 	struct uart_port *uport = uart_port_check(state);
826 	unsigned long new_port;
827 	unsigned int change_irq, change_port, closing_wait;
828 	unsigned int old_custom_divisor, close_delay;
829 	upf_t old_flags, new_flags;
830 	int retval = 0;
831 
832 	if (!uport)
833 		return -EIO;
834 
835 	new_port = new_info->port;
836 	if (HIGH_BITS_OFFSET)
837 		new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
838 
839 	new_info->irq = irq_canonicalize(new_info->irq);
840 	close_delay = msecs_to_jiffies(new_info->close_delay * 10);
841 	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
842 			ASYNC_CLOSING_WAIT_NONE :
843 			msecs_to_jiffies(new_info->closing_wait * 10);
844 
845 
846 	change_irq  = !(uport->flags & UPF_FIXED_PORT)
847 		&& new_info->irq != uport->irq;
848 
849 	/*
850 	 * Since changing the 'type' of the port changes its resource
851 	 * allocations, we should treat type changes the same as
852 	 * IO port changes.
853 	 */
854 	change_port = !(uport->flags & UPF_FIXED_PORT)
855 		&& (new_port != uport->iobase ||
856 		    (unsigned long)new_info->iomem_base != uport->mapbase ||
857 		    new_info->hub6 != uport->hub6 ||
858 		    new_info->io_type != uport->iotype ||
859 		    new_info->iomem_reg_shift != uport->regshift ||
860 		    new_info->type != uport->type);
861 
862 	old_flags = uport->flags;
863 	new_flags = (__force upf_t)new_info->flags;
864 	old_custom_divisor = uport->custom_divisor;
865 
866 	if (!capable(CAP_SYS_ADMIN)) {
867 		retval = -EPERM;
868 		if (change_irq || change_port ||
869 		    (new_info->baud_base != uport->uartclk / 16) ||
870 		    (close_delay != port->close_delay) ||
871 		    (closing_wait != port->closing_wait) ||
872 		    (new_info->xmit_fifo_size &&
873 		     new_info->xmit_fifo_size != uport->fifosize) ||
874 		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
875 			goto exit;
876 		uport->flags = ((uport->flags & ~UPF_USR_MASK) |
877 			       (new_flags & UPF_USR_MASK));
878 		uport->custom_divisor = new_info->custom_divisor;
879 		goto check_and_exit;
880 	}
881 
882 	if (change_irq || change_port) {
883 		retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
884 		if (retval)
885 			goto exit;
886 	}
887 
888 	/*
889 	 * Ask the low level driver to verify the settings.
890 	 */
891 	if (uport->ops->verify_port)
892 		retval = uport->ops->verify_port(uport, new_info);
893 
894 	if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
895 	    (new_info->baud_base < 9600))
896 		retval = -EINVAL;
897 
898 	if (retval)
899 		goto exit;
900 
901 	if (change_port || change_irq) {
902 		retval = -EBUSY;
903 
904 		/*
905 		 * Make sure that we are the sole user of this port.
906 		 */
907 		if (tty_port_users(port) > 1)
908 			goto exit;
909 
910 		/*
911 		 * We need to shutdown the serial port at the old
912 		 * port/type/irq combination.
913 		 */
914 		uart_shutdown(tty, state);
915 	}
916 
917 	if (change_port) {
918 		unsigned long old_iobase, old_mapbase;
919 		unsigned int old_type, old_iotype, old_hub6, old_shift;
920 
921 		old_iobase = uport->iobase;
922 		old_mapbase = uport->mapbase;
923 		old_type = uport->type;
924 		old_hub6 = uport->hub6;
925 		old_iotype = uport->iotype;
926 		old_shift = uport->regshift;
927 
928 		/*
929 		 * Free and release old regions
930 		 */
931 		if (old_type != PORT_UNKNOWN && uport->ops->release_port)
932 			uport->ops->release_port(uport);
933 
934 		uport->iobase = new_port;
935 		uport->type = new_info->type;
936 		uport->hub6 = new_info->hub6;
937 		uport->iotype = new_info->io_type;
938 		uport->regshift = new_info->iomem_reg_shift;
939 		uport->mapbase = (unsigned long)new_info->iomem_base;
940 
941 		/*
942 		 * Claim and map the new regions
943 		 */
944 		if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
945 			retval = uport->ops->request_port(uport);
946 		} else {
947 			/* Always success - Jean II */
948 			retval = 0;
949 		}
950 
951 		/*
952 		 * If we fail to request resources for the
953 		 * new port, try to restore the old settings.
954 		 */
955 		if (retval) {
956 			uport->iobase = old_iobase;
957 			uport->type = old_type;
958 			uport->hub6 = old_hub6;
959 			uport->iotype = old_iotype;
960 			uport->regshift = old_shift;
961 			uport->mapbase = old_mapbase;
962 
963 			if (old_type != PORT_UNKNOWN) {
964 				retval = uport->ops->request_port(uport);
965 				/*
966 				 * If we failed to restore the old settings,
967 				 * we fail like this.
968 				 */
969 				if (retval)
970 					uport->type = PORT_UNKNOWN;
971 
972 				/*
973 				 * We failed anyway.
974 				 */
975 				retval = -EBUSY;
976 			}
977 
978 			/* Added to return the correct error -Ram Gupta */
979 			goto exit;
980 		}
981 	}
982 
983 	if (change_irq)
984 		uport->irq      = new_info->irq;
985 	if (!(uport->flags & UPF_FIXED_PORT))
986 		uport->uartclk  = new_info->baud_base * 16;
987 	uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |
988 				 (new_flags & UPF_CHANGE_MASK);
989 	uport->custom_divisor   = new_info->custom_divisor;
990 	port->close_delay     = close_delay;
991 	port->closing_wait    = closing_wait;
992 	if (new_info->xmit_fifo_size)
993 		uport->fifosize = new_info->xmit_fifo_size;
994 
995  check_and_exit:
996 	retval = 0;
997 	if (uport->type == PORT_UNKNOWN)
998 		goto exit;
999 	if (tty_port_initialized(port)) {
1000 		if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
1001 		    old_custom_divisor != uport->custom_divisor) {
1002 			/*
1003 			 * If they're setting up a custom divisor or speed,
1004 			 * instead of clearing it, then bitch about it.
1005 			 */
1006 			if (uport->flags & UPF_SPD_MASK) {
1007 				dev_notice_ratelimited(uport->dev,
1008 				       "%s sets custom speed on %s. This is deprecated.\n",
1009 				      current->comm,
1010 				      tty_name(port->tty));
1011 			}
1012 			uart_change_line_settings(tty, state, NULL);
1013 		}
1014 	} else {
1015 		retval = uart_startup(tty, state, true);
1016 		if (retval == 0)
1017 			tty_port_set_initialized(port, true);
1018 		if (retval > 0)
1019 			retval = 0;
1020 	}
1021  exit:
1022 	return retval;
1023 }
1024 
1025 static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
1026 {
1027 	struct uart_state *state = tty->driver_data;
1028 	struct tty_port *port = &state->port;
1029 	int retval;
1030 
1031 	down_write(&tty->termios_rwsem);
1032 	/*
1033 	 * This semaphore protects port->count.  It is also
1034 	 * very useful to prevent opens.  Also, take the
1035 	 * port configuration semaphore to make sure that a
1036 	 * module insertion/removal doesn't change anything
1037 	 * under us.
1038 	 */
1039 	mutex_lock(&port->mutex);
1040 	retval = uart_set_info(tty, port, state, ss);
1041 	mutex_unlock(&port->mutex);
1042 	up_write(&tty->termios_rwsem);
1043 	return retval;
1044 }
1045 
1046 /**
1047  * uart_get_lsr_info - get line status register info
1048  * @tty: tty associated with the UART
1049  * @state: UART being queried
1050  * @value: returned modem value
1051  */
1052 static int uart_get_lsr_info(struct tty_struct *tty,
1053 			struct uart_state *state, unsigned int __user *value)
1054 {
1055 	struct uart_port *uport = uart_port_check(state);
1056 	unsigned int result;
1057 
1058 	result = uport->ops->tx_empty(uport);
1059 
1060 	/*
1061 	 * If we're about to load something into the transmit
1062 	 * register, we'll pretend the transmitter isn't empty to
1063 	 * avoid a race condition (depending on when the transmit
1064 	 * interrupt happens).
1065 	 */
1066 	if (uport->x_char ||
1067 	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
1068 	     !uart_tx_stopped(uport)))
1069 		result &= ~TIOCSER_TEMT;
1070 
1071 	return put_user(result, value);
1072 }
1073 
1074 static int uart_tiocmget(struct tty_struct *tty)
1075 {
1076 	struct uart_state *state = tty->driver_data;
1077 	struct tty_port *port = &state->port;
1078 	struct uart_port *uport;
1079 	int result = -EIO;
1080 
1081 	mutex_lock(&port->mutex);
1082 	uport = uart_port_check(state);
1083 	if (!uport)
1084 		goto out;
1085 
1086 	if (!tty_io_error(tty)) {
1087 		result = uport->mctrl;
1088 		spin_lock_irq(&uport->lock);
1089 		result |= uport->ops->get_mctrl(uport);
1090 		spin_unlock_irq(&uport->lock);
1091 	}
1092 out:
1093 	mutex_unlock(&port->mutex);
1094 	return result;
1095 }
1096 
1097 static int
1098 uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
1099 {
1100 	struct uart_state *state = tty->driver_data;
1101 	struct tty_port *port = &state->port;
1102 	struct uart_port *uport;
1103 	int ret = -EIO;
1104 
1105 	mutex_lock(&port->mutex);
1106 	uport = uart_port_check(state);
1107 	if (!uport)
1108 		goto out;
1109 
1110 	if (!tty_io_error(tty)) {
1111 		uart_update_mctrl(uport, set, clear);
1112 		ret = 0;
1113 	}
1114 out:
1115 	mutex_unlock(&port->mutex);
1116 	return ret;
1117 }
1118 
1119 static int uart_break_ctl(struct tty_struct *tty, int break_state)
1120 {
1121 	struct uart_state *state = tty->driver_data;
1122 	struct tty_port *port = &state->port;
1123 	struct uart_port *uport;
1124 	int ret = -EIO;
1125 
1126 	mutex_lock(&port->mutex);
1127 	uport = uart_port_check(state);
1128 	if (!uport)
1129 		goto out;
1130 
1131 	if (uport->type != PORT_UNKNOWN && uport->ops->break_ctl)
1132 		uport->ops->break_ctl(uport, break_state);
1133 	ret = 0;
1134 out:
1135 	mutex_unlock(&port->mutex);
1136 	return ret;
1137 }
1138 
1139 static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state)
1140 {
1141 	struct tty_port *port = &state->port;
1142 	struct uart_port *uport;
1143 	int flags, ret;
1144 
1145 	if (!capable(CAP_SYS_ADMIN))
1146 		return -EPERM;
1147 
1148 	/*
1149 	 * Take the per-port semaphore.  This prevents count from
1150 	 * changing, and hence any extra opens of the port while
1151 	 * we're auto-configuring.
1152 	 */
1153 	if (mutex_lock_interruptible(&port->mutex))
1154 		return -ERESTARTSYS;
1155 
1156 	uport = uart_port_check(state);
1157 	if (!uport) {
1158 		ret = -EIO;
1159 		goto out;
1160 	}
1161 
1162 	ret = -EBUSY;
1163 	if (tty_port_users(port) == 1) {
1164 		uart_shutdown(tty, state);
1165 
1166 		/*
1167 		 * If we already have a port type configured,
1168 		 * we must release its resources.
1169 		 */
1170 		if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
1171 			uport->ops->release_port(uport);
1172 
1173 		flags = UART_CONFIG_TYPE;
1174 		if (uport->flags & UPF_AUTO_IRQ)
1175 			flags |= UART_CONFIG_IRQ;
1176 
1177 		/*
1178 		 * This will claim the ports resources if
1179 		 * a port is found.
1180 		 */
1181 		uport->ops->config_port(uport, flags);
1182 
1183 		ret = uart_startup(tty, state, true);
1184 		if (ret == 0)
1185 			tty_port_set_initialized(port, true);
1186 		if (ret > 0)
1187 			ret = 0;
1188 	}
1189 out:
1190 	mutex_unlock(&port->mutex);
1191 	return ret;
1192 }
1193 
1194 static void uart_enable_ms(struct uart_port *uport)
1195 {
1196 	/*
1197 	 * Force modem status interrupts on
1198 	 */
1199 	if (uport->ops->enable_ms)
1200 		uport->ops->enable_ms(uport);
1201 }
1202 
1203 /*
1204  * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
1205  * - mask passed in arg for lines of interest
1206  *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
1207  * Caller should use TIOCGICOUNT to see which one it was
1208  *
1209  * FIXME: This wants extracting into a common all driver implementation
1210  * of TIOCMWAIT using tty_port.
1211  */
1212 static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
1213 {
1214 	struct uart_port *uport;
1215 	struct tty_port *port = &state->port;
1216 	DECLARE_WAITQUEUE(wait, current);
1217 	struct uart_icount cprev, cnow;
1218 	int ret;
1219 
1220 	/*
1221 	 * note the counters on entry
1222 	 */
1223 	uport = uart_port_ref(state);
1224 	if (!uport)
1225 		return -EIO;
1226 	spin_lock_irq(&uport->lock);
1227 	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
1228 	uart_enable_ms(uport);
1229 	spin_unlock_irq(&uport->lock);
1230 
1231 	add_wait_queue(&port->delta_msr_wait, &wait);
1232 	for (;;) {
1233 		spin_lock_irq(&uport->lock);
1234 		memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1235 		spin_unlock_irq(&uport->lock);
1236 
1237 		set_current_state(TASK_INTERRUPTIBLE);
1238 
1239 		if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
1240 		    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
1241 		    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
1242 		    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
1243 			ret = 0;
1244 			break;
1245 		}
1246 
1247 		schedule();
1248 
1249 		/* see if a signal did it */
1250 		if (signal_pending(current)) {
1251 			ret = -ERESTARTSYS;
1252 			break;
1253 		}
1254 
1255 		cprev = cnow;
1256 	}
1257 	__set_current_state(TASK_RUNNING);
1258 	remove_wait_queue(&port->delta_msr_wait, &wait);
1259 	uart_port_deref(uport);
1260 
1261 	return ret;
1262 }
1263 
1264 /*
1265  * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
1266  * Return: write counters to the user passed counter struct
1267  * NB: both 1->0 and 0->1 transitions are counted except for
1268  *     RI where only 0->1 is counted.
1269  */
1270 static int uart_get_icount(struct tty_struct *tty,
1271 			  struct serial_icounter_struct *icount)
1272 {
1273 	struct uart_state *state = tty->driver_data;
1274 	struct uart_icount cnow;
1275 	struct uart_port *uport;
1276 
1277 	uport = uart_port_ref(state);
1278 	if (!uport)
1279 		return -EIO;
1280 	spin_lock_irq(&uport->lock);
1281 	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1282 	spin_unlock_irq(&uport->lock);
1283 	uart_port_deref(uport);
1284 
1285 	icount->cts         = cnow.cts;
1286 	icount->dsr         = cnow.dsr;
1287 	icount->rng         = cnow.rng;
1288 	icount->dcd         = cnow.dcd;
1289 	icount->rx          = cnow.rx;
1290 	icount->tx          = cnow.tx;
1291 	icount->frame       = cnow.frame;
1292 	icount->overrun     = cnow.overrun;
1293 	icount->parity      = cnow.parity;
1294 	icount->brk         = cnow.brk;
1295 	icount->buf_overrun = cnow.buf_overrun;
1296 
1297 	return 0;
1298 }
1299 
1300 #define SER_RS485_LEGACY_FLAGS	(SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
1301 				 SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
1302 				 SER_RS485_TERMINATE_BUS)
1303 
1304 static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
1305 {
1306 	u32 flags = rs485->flags;
1307 
1308 	/* Don't return -EINVAL for unsupported legacy flags */
1309 	flags &= ~SER_RS485_LEGACY_FLAGS;
1310 
1311 	/*
1312 	 * For any bit outside of the legacy ones that is not supported by
1313 	 * the driver, return -EINVAL.
1314 	 */
1315 	if (flags & ~port->rs485_supported.flags)
1316 		return -EINVAL;
1317 
1318 	/* Asking for address w/o addressing mode? */
1319 	if (!(rs485->flags & SER_RS485_ADDRB) &&
1320 	    (rs485->flags & (SER_RS485_ADDR_RECV|SER_RS485_ADDR_DEST)))
1321 		return -EINVAL;
1322 
1323 	/* Address given but not enabled? */
1324 	if (!(rs485->flags & SER_RS485_ADDR_RECV) && rs485->addr_recv)
1325 		return -EINVAL;
1326 	if (!(rs485->flags & SER_RS485_ADDR_DEST) && rs485->addr_dest)
1327 		return -EINVAL;
1328 
1329 	return 0;
1330 }
1331 
1332 static void uart_sanitize_serial_rs485_delays(struct uart_port *port,
1333 					      struct serial_rs485 *rs485)
1334 {
1335 	if (!port->rs485_supported.delay_rts_before_send) {
1336 		if (rs485->delay_rts_before_send) {
1337 			dev_warn_ratelimited(port->dev,
1338 				"%s (%d): RTS delay before sending not supported\n",
1339 				port->name, port->line);
1340 		}
1341 		rs485->delay_rts_before_send = 0;
1342 	} else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
1343 		rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY;
1344 		dev_warn_ratelimited(port->dev,
1345 			"%s (%d): RTS delay before sending clamped to %u ms\n",
1346 			port->name, port->line, rs485->delay_rts_before_send);
1347 	}
1348 
1349 	if (!port->rs485_supported.delay_rts_after_send) {
1350 		if (rs485->delay_rts_after_send) {
1351 			dev_warn_ratelimited(port->dev,
1352 				"%s (%d): RTS delay after sending not supported\n",
1353 				port->name, port->line);
1354 		}
1355 		rs485->delay_rts_after_send = 0;
1356 	} else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
1357 		rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY;
1358 		dev_warn_ratelimited(port->dev,
1359 			"%s (%d): RTS delay after sending clamped to %u ms\n",
1360 			port->name, port->line, rs485->delay_rts_after_send);
1361 	}
1362 }
1363 
1364 static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
1365 {
1366 	u32 supported_flags = port->rs485_supported.flags;
1367 
1368 	if (!(rs485->flags & SER_RS485_ENABLED)) {
1369 		memset(rs485, 0, sizeof(*rs485));
1370 		return;
1371 	}
1372 
1373 	/* Pick sane settings if the user hasn't */
1374 	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
1375 	    !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
1376 	    !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
1377 		dev_warn_ratelimited(port->dev,
1378 			"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
1379 			port->name, port->line);
1380 		rs485->flags |= SER_RS485_RTS_ON_SEND;
1381 		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
1382 		supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
1383 	}
1384 
1385 	rs485->flags &= supported_flags;
1386 
1387 	uart_sanitize_serial_rs485_delays(port, rs485);
1388 
1389 	/* Return clean padding area to userspace */
1390 	memset(rs485->padding0, 0, sizeof(rs485->padding0));
1391 	memset(rs485->padding1, 0, sizeof(rs485->padding1));
1392 }
1393 
1394 static void uart_set_rs485_termination(struct uart_port *port,
1395 				       const struct serial_rs485 *rs485)
1396 {
1397 	if (!(rs485->flags & SER_RS485_ENABLED))
1398 		return;
1399 
1400 	gpiod_set_value_cansleep(port->rs485_term_gpio,
1401 				 !!(rs485->flags & SER_RS485_TERMINATE_BUS));
1402 }
1403 
1404 static int uart_rs485_config(struct uart_port *port)
1405 {
1406 	struct serial_rs485 *rs485 = &port->rs485;
1407 	unsigned long flags;
1408 	int ret;
1409 
1410 	if (!(rs485->flags & SER_RS485_ENABLED))
1411 		return 0;
1412 
1413 	uart_sanitize_serial_rs485(port, rs485);
1414 	uart_set_rs485_termination(port, rs485);
1415 
1416 	spin_lock_irqsave(&port->lock, flags);
1417 	ret = port->rs485_config(port, NULL, rs485);
1418 	spin_unlock_irqrestore(&port->lock, flags);
1419 	if (ret)
1420 		memset(rs485, 0, sizeof(*rs485));
1421 
1422 	return ret;
1423 }
1424 
1425 static int uart_get_rs485_config(struct uart_port *port,
1426 			 struct serial_rs485 __user *rs485)
1427 {
1428 	unsigned long flags;
1429 	struct serial_rs485 aux;
1430 
1431 	spin_lock_irqsave(&port->lock, flags);
1432 	aux = port->rs485;
1433 	spin_unlock_irqrestore(&port->lock, flags);
1434 
1435 	if (copy_to_user(rs485, &aux, sizeof(aux)))
1436 		return -EFAULT;
1437 
1438 	return 0;
1439 }
1440 
1441 static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
1442 			 struct serial_rs485 __user *rs485_user)
1443 {
1444 	struct serial_rs485 rs485;
1445 	int ret;
1446 	unsigned long flags;
1447 
1448 	if (!port->rs485_config)
1449 		return -ENOTTY;
1450 
1451 	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
1452 		return -EFAULT;
1453 
1454 	ret = uart_check_rs485_flags(port, &rs485);
1455 	if (ret)
1456 		return ret;
1457 	uart_sanitize_serial_rs485(port, &rs485);
1458 	uart_set_rs485_termination(port, &rs485);
1459 
1460 	spin_lock_irqsave(&port->lock, flags);
1461 	ret = port->rs485_config(port, &tty->termios, &rs485);
1462 	if (!ret) {
1463 		port->rs485 = rs485;
1464 
1465 		/* Reset RTS and other mctrl lines when disabling RS485 */
1466 		if (!(rs485.flags & SER_RS485_ENABLED))
1467 			port->ops->set_mctrl(port, port->mctrl);
1468 	}
1469 	spin_unlock_irqrestore(&port->lock, flags);
1470 	if (ret)
1471 		return ret;
1472 
1473 	if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
1474 		return -EFAULT;
1475 
1476 	return 0;
1477 }
1478 
1479 static int uart_get_iso7816_config(struct uart_port *port,
1480 				   struct serial_iso7816 __user *iso7816)
1481 {
1482 	unsigned long flags;
1483 	struct serial_iso7816 aux;
1484 
1485 	if (!port->iso7816_config)
1486 		return -ENOTTY;
1487 
1488 	spin_lock_irqsave(&port->lock, flags);
1489 	aux = port->iso7816;
1490 	spin_unlock_irqrestore(&port->lock, flags);
1491 
1492 	if (copy_to_user(iso7816, &aux, sizeof(aux)))
1493 		return -EFAULT;
1494 
1495 	return 0;
1496 }
1497 
1498 static int uart_set_iso7816_config(struct uart_port *port,
1499 				   struct serial_iso7816 __user *iso7816_user)
1500 {
1501 	struct serial_iso7816 iso7816;
1502 	int i, ret;
1503 	unsigned long flags;
1504 
1505 	if (!port->iso7816_config)
1506 		return -ENOTTY;
1507 
1508 	if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
1509 		return -EFAULT;
1510 
1511 	/*
1512 	 * There are 5 words reserved for future use. Check that userspace
1513 	 * doesn't put stuff in there to prevent breakages in the future.
1514 	 */
1515 	for (i = 0; i < ARRAY_SIZE(iso7816.reserved); i++)
1516 		if (iso7816.reserved[i])
1517 			return -EINVAL;
1518 
1519 	spin_lock_irqsave(&port->lock, flags);
1520 	ret = port->iso7816_config(port, &iso7816);
1521 	spin_unlock_irqrestore(&port->lock, flags);
1522 	if (ret)
1523 		return ret;
1524 
1525 	if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
1526 		return -EFAULT;
1527 
1528 	return 0;
1529 }
1530 
1531 /*
1532  * Called via sys_ioctl.  We can use spin_lock_irq() here.
1533  */
1534 static int
1535 uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
1536 {
1537 	struct uart_state *state = tty->driver_data;
1538 	struct tty_port *port = &state->port;
1539 	struct uart_port *uport;
1540 	void __user *uarg = (void __user *)arg;
1541 	int ret = -ENOIOCTLCMD;
1542 
1543 
1544 	/*
1545 	 * These ioctls don't rely on the hardware to be present.
1546 	 */
1547 	switch (cmd) {
1548 	case TIOCSERCONFIG:
1549 		down_write(&tty->termios_rwsem);
1550 		ret = uart_do_autoconfig(tty, state);
1551 		up_write(&tty->termios_rwsem);
1552 		break;
1553 	}
1554 
1555 	if (ret != -ENOIOCTLCMD)
1556 		goto out;
1557 
1558 	if (tty_io_error(tty)) {
1559 		ret = -EIO;
1560 		goto out;
1561 	}
1562 
1563 	/*
1564 	 * The following should only be used when hardware is present.
1565 	 */
1566 	switch (cmd) {
1567 	case TIOCMIWAIT:
1568 		ret = uart_wait_modem_status(state, arg);
1569 		break;
1570 	}
1571 
1572 	if (ret != -ENOIOCTLCMD)
1573 		goto out;
1574 
1575 	/* rs485_config requires more locking than others */
1576 	if (cmd == TIOCSRS485)
1577 		down_write(&tty->termios_rwsem);
1578 
1579 	mutex_lock(&port->mutex);
1580 	uport = uart_port_check(state);
1581 
1582 	if (!uport || tty_io_error(tty)) {
1583 		ret = -EIO;
1584 		goto out_up;
1585 	}
1586 
1587 	/*
1588 	 * All these rely on hardware being present and need to be
1589 	 * protected against the tty being hung up.
1590 	 */
1591 
1592 	switch (cmd) {
1593 	case TIOCSERGETLSR: /* Get line status register */
1594 		ret = uart_get_lsr_info(tty, state, uarg);
1595 		break;
1596 
1597 	case TIOCGRS485:
1598 		ret = uart_get_rs485_config(uport, uarg);
1599 		break;
1600 
1601 	case TIOCSRS485:
1602 		ret = uart_set_rs485_config(tty, uport, uarg);
1603 		break;
1604 
1605 	case TIOCSISO7816:
1606 		ret = uart_set_iso7816_config(state->uart_port, uarg);
1607 		break;
1608 
1609 	case TIOCGISO7816:
1610 		ret = uart_get_iso7816_config(state->uart_port, uarg);
1611 		break;
1612 	default:
1613 		if (uport->ops->ioctl)
1614 			ret = uport->ops->ioctl(uport, cmd, arg);
1615 		break;
1616 	}
1617 out_up:
1618 	mutex_unlock(&port->mutex);
1619 	if (cmd == TIOCSRS485)
1620 		up_write(&tty->termios_rwsem);
1621 out:
1622 	return ret;
1623 }
1624 
1625 static void uart_set_ldisc(struct tty_struct *tty)
1626 {
1627 	struct uart_state *state = tty->driver_data;
1628 	struct uart_port *uport;
1629 	struct tty_port *port = &state->port;
1630 
1631 	if (!tty_port_initialized(port))
1632 		return;
1633 
1634 	mutex_lock(&state->port.mutex);
1635 	uport = uart_port_check(state);
1636 	if (uport && uport->ops->set_ldisc)
1637 		uport->ops->set_ldisc(uport, &tty->termios);
1638 	mutex_unlock(&state->port.mutex);
1639 }
1640 
1641 static void uart_set_termios(struct tty_struct *tty,
1642 			     const struct ktermios *old_termios)
1643 {
1644 	struct uart_state *state = tty->driver_data;
1645 	struct uart_port *uport;
1646 	unsigned int cflag = tty->termios.c_cflag;
1647 	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
1648 	bool sw_changed = false;
1649 
1650 	mutex_lock(&state->port.mutex);
1651 	uport = uart_port_check(state);
1652 	if (!uport)
1653 		goto out;
1654 
1655 	/*
1656 	 * Drivers doing software flow control also need to know
1657 	 * about changes to these input settings.
1658 	 */
1659 	if (uport->flags & UPF_SOFT_FLOW) {
1660 		iflag_mask |= IXANY|IXON|IXOFF;
1661 		sw_changed =
1662 		   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
1663 		   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
1664 	}
1665 
1666 	/*
1667 	 * These are the bits that are used to setup various
1668 	 * flags in the low level driver. We can ignore the Bfoo
1669 	 * bits in c_cflag; c_[io]speed will always be set
1670 	 * appropriately by set_termios() in tty_ioctl.c
1671 	 */
1672 	if ((cflag ^ old_termios->c_cflag) == 0 &&
1673 	    tty->termios.c_ospeed == old_termios->c_ospeed &&
1674 	    tty->termios.c_ispeed == old_termios->c_ispeed &&
1675 	    ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
1676 	    !sw_changed) {
1677 		goto out;
1678 	}
1679 
1680 	uart_change_line_settings(tty, state, old_termios);
1681 	/* reload cflag from termios; port driver may have overridden flags */
1682 	cflag = tty->termios.c_cflag;
1683 
1684 	/* Handle transition to B0 status */
1685 	if (((old_termios->c_cflag & CBAUD) != B0) && ((cflag & CBAUD) == B0))
1686 		uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
1687 	/* Handle transition away from B0 status */
1688 	else if (((old_termios->c_cflag & CBAUD) == B0) && ((cflag & CBAUD) != B0)) {
1689 		unsigned int mask = TIOCM_DTR;
1690 
1691 		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
1692 			mask |= TIOCM_RTS;
1693 		uart_set_mctrl(uport, mask);
1694 	}
1695 out:
1696 	mutex_unlock(&state->port.mutex);
1697 }
1698 
1699 /*
1700  * Calls to uart_close() are serialised via the tty_lock in
1701  *   drivers/tty/tty_io.c:tty_release()
1702  *   drivers/tty/tty_io.c:do_tty_hangup()
1703  */
1704 static void uart_close(struct tty_struct *tty, struct file *filp)
1705 {
1706 	struct uart_state *state = tty->driver_data;
1707 
1708 	if (!state) {
1709 		struct uart_driver *drv = tty->driver->driver_state;
1710 		struct tty_port *port;
1711 
1712 		state = drv->state + tty->index;
1713 		port = &state->port;
1714 		spin_lock_irq(&port->lock);
1715 		--port->count;
1716 		spin_unlock_irq(&port->lock);
1717 		return;
1718 	}
1719 
1720 	pr_debug("uart_close(%d) called\n", tty->index);
1721 
1722 	tty_port_close(tty->port, tty, filp);
1723 }
1724 
1725 static void uart_tty_port_shutdown(struct tty_port *port)
1726 {
1727 	struct uart_state *state = container_of(port, struct uart_state, port);
1728 	struct uart_port *uport = uart_port_check(state);
1729 	char *buf;
1730 
1731 	/*
1732 	 * At this point, we stop accepting input.  To do this, we
1733 	 * disable the receive line status interrupts.
1734 	 */
1735 	if (WARN(!uport, "detached port still initialized!\n"))
1736 		return;
1737 
1738 	spin_lock_irq(&uport->lock);
1739 	uport->ops->stop_rx(uport);
1740 	spin_unlock_irq(&uport->lock);
1741 
1742 	uart_port_shutdown(port);
1743 
1744 	/*
1745 	 * It's possible for shutdown to be called after suspend if we get
1746 	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
1747 	 * we don't try to resume a port that has been shutdown.
1748 	 */
1749 	tty_port_set_suspended(port, false);
1750 
1751 	/*
1752 	 * Free the transmit buffer.
1753 	 */
1754 	spin_lock_irq(&uport->lock);
1755 	buf = state->xmit.buf;
1756 	state->xmit.buf = NULL;
1757 	spin_unlock_irq(&uport->lock);
1758 
1759 	free_page((unsigned long)buf);
1760 
1761 	uart_change_pm(state, UART_PM_STATE_OFF);
1762 }
1763 
1764 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1765 {
1766 	struct uart_state *state = tty->driver_data;
1767 	struct uart_port *port;
1768 	unsigned long char_time, expire, fifo_timeout;
1769 
1770 	port = uart_port_ref(state);
1771 	if (!port)
1772 		return;
1773 
1774 	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
1775 		uart_port_deref(port);
1776 		return;
1777 	}
1778 
1779 	/*
1780 	 * Set the check interval to be 1/5 of the estimated time to
1781 	 * send a single character, and make it at least 1.  The check
1782 	 * interval should also be less than the timeout.
1783 	 *
1784 	 * Note: we have to use pretty tight timings here to satisfy
1785 	 * the NIST-PCTS.
1786 	 */
1787 	char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);
1788 
1789 	if (timeout && timeout < char_time)
1790 		char_time = timeout;
1791 
1792 	if (!uart_cts_enabled(port)) {
1793 		/*
1794 		 * If the transmitter hasn't cleared in twice the approximate
1795 		 * amount of time to send the entire FIFO, it probably won't
1796 		 * ever clear.  This assumes the UART isn't doing flow
1797 		 * control, which is currently the case.  Hence, if it ever
1798 		 * takes longer than FIFO timeout, this is probably due to a
1799 		 * UART bug of some kind.  So, we clamp the timeout parameter at
1800 		 * 2 * FIFO timeout.
1801 		 */
1802 		fifo_timeout = uart_fifo_timeout(port);
1803 		if (timeout == 0 || timeout > 2 * fifo_timeout)
1804 			timeout = 2 * fifo_timeout;
1805 	}
1806 
1807 	expire = jiffies + timeout;
1808 
1809 	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
1810 		port->line, jiffies, expire);
1811 
1812 	/*
1813 	 * Check whether the transmitter is empty every 'char_time'.
1814 	 * 'timeout' / 'expire' give us the maximum amount of time
1815 	 * we wait.
1816 	 */
1817 	while (!port->ops->tx_empty(port)) {
1818 		msleep_interruptible(jiffies_to_msecs(char_time));
1819 		if (signal_pending(current))
1820 			break;
1821 		if (timeout && time_after(jiffies, expire))
1822 			break;
1823 	}
1824 	uart_port_deref(port);
1825 }
1826 
1827 /*
1828  * Calls to uart_hangup() are serialised by the tty_lock in
1829  *   drivers/tty/tty_io.c:do_tty_hangup()
1830  * This runs from a workqueue and can sleep for a _short_ time only.
1831  */
1832 static void uart_hangup(struct tty_struct *tty)
1833 {
1834 	struct uart_state *state = tty->driver_data;
1835 	struct tty_port *port = &state->port;
1836 	struct uart_port *uport;
1837 	unsigned long flags;
1838 
1839 	pr_debug("uart_hangup(%d)\n", tty->index);
1840 
1841 	mutex_lock(&port->mutex);
1842 	uport = uart_port_check(state);
1843 	WARN(!uport, "hangup of detached port!\n");
1844 
1845 	if (tty_port_active(port)) {
1846 		uart_flush_buffer(tty);
1847 		uart_shutdown(tty, state);
1848 		spin_lock_irqsave(&port->lock, flags);
1849 		port->count = 0;
1850 		spin_unlock_irqrestore(&port->lock, flags);
1851 		tty_port_set_active(port, false);
1852 		tty_port_tty_set(port, NULL);
1853 		if (uport && !uart_console(uport))
1854 			uart_change_pm(state, UART_PM_STATE_OFF);
1855 		wake_up_interruptible(&port->open_wait);
1856 		wake_up_interruptible(&port->delta_msr_wait);
1857 	}
1858 	mutex_unlock(&port->mutex);
1859 }
1860 
1861 /* uport == NULL if uart_port has already been removed */
1862 static void uart_port_shutdown(struct tty_port *port)
1863 {
1864 	struct uart_state *state = container_of(port, struct uart_state, port);
1865 	struct uart_port *uport = uart_port_check(state);
1866 
1867 	/*
1868 	 * clear delta_msr_wait queue to avoid mem leaks: we may free
1869 	 * the irq here so the queue might never be woken up.  Note
1870 	 * that we won't end up waiting on delta_msr_wait again since
1871 	 * any outstanding file descriptors should be pointing at
1872 	 * hung_up_tty_fops now.
1873 	 */
1874 	wake_up_interruptible(&port->delta_msr_wait);
1875 
1876 	if (uport) {
1877 		/* Free the IRQ and disable the port. */
1878 		uport->ops->shutdown(uport);
1879 
1880 		/* Ensure that the IRQ handler isn't running on another CPU. */
1881 		synchronize_irq(uport->irq);
1882 	}
1883 }
1884 
1885 static bool uart_carrier_raised(struct tty_port *port)
1886 {
1887 	struct uart_state *state = container_of(port, struct uart_state, port);
1888 	struct uart_port *uport;
1889 	int mctrl;
1890 
1891 	uport = uart_port_ref(state);
1892 	/*
1893 	 * Should never observe uport == NULL since checks for hangup should
1894 	 * abort the tty_port_block_til_ready() loop before checking for carrier
1895 	 * raised -- but report carrier raised if it does anyway so open will
1896 	 * continue and not sleep
1897 	 */
1898 	if (WARN_ON(!uport))
1899 		return true;
1900 	spin_lock_irq(&uport->lock);
1901 	uart_enable_ms(uport);
1902 	mctrl = uport->ops->get_mctrl(uport);
1903 	spin_unlock_irq(&uport->lock);
1904 	uart_port_deref(uport);
1905 
1906 	return mctrl & TIOCM_CAR;
1907 }
1908 
1909 static void uart_dtr_rts(struct tty_port *port, bool active)
1910 {
1911 	struct uart_state *state = container_of(port, struct uart_state, port);
1912 	struct uart_port *uport;
1913 
1914 	uport = uart_port_ref(state);
1915 	if (!uport)
1916 		return;
1917 	uart_port_dtr_rts(uport, active);
1918 	uart_port_deref(uport);
1919 }
1920 
1921 static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
1922 {
1923 	struct uart_driver *drv = driver->driver_state;
1924 	struct uart_state *state = drv->state + tty->index;
1925 
1926 	tty->driver_data = state;
1927 
1928 	return tty_standard_install(driver, tty);
1929 }
1930 
1931 /*
1932  * Calls to uart_open are serialised by the tty_lock in
1933  *   drivers/tty/tty_io.c:tty_open()
1934  * Note that if this fails, then uart_close() _will_ be called.
1935  *
1936  * In time, we want to scrap the "opening nonpresent ports"
1937  * behaviour and implement an alternative way for setserial
1938  * to set base addresses/ports/types.  This will allow us to
1939  * get rid of a certain amount of extra tests.
1940  */
1941 static int uart_open(struct tty_struct *tty, struct file *filp)
1942 {
1943 	struct uart_state *state = tty->driver_data;
1944 	int retval;
1945 
1946 	retval = tty_port_open(&state->port, tty, filp);
1947 	if (retval > 0)
1948 		retval = 0;
1949 
1950 	return retval;
1951 }
1952 
1953 static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
1954 {
1955 	struct uart_state *state = container_of(port, struct uart_state, port);
1956 	struct uart_port *uport;
1957 	int ret;
1958 
1959 	uport = uart_port_check(state);
1960 	if (!uport || uport->flags & UPF_DEAD)
1961 		return -ENXIO;
1962 
1963 	/*
1964 	 * Start up the serial port.
1965 	 */
1966 	ret = uart_startup(tty, state, false);
1967 	if (ret > 0)
1968 		tty_port_set_active(port, true);
1969 
1970 	return ret;
1971 }
1972 
1973 static const char *uart_type(struct uart_port *port)
1974 {
1975 	const char *str = NULL;
1976 
1977 	if (port->ops->type)
1978 		str = port->ops->type(port);
1979 
1980 	if (!str)
1981 		str = "unknown";
1982 
1983 	return str;
1984 }
1985 
1986 #ifdef CONFIG_PROC_FS
1987 
1988 static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
1989 {
1990 	struct uart_state *state = drv->state + i;
1991 	struct tty_port *port = &state->port;
1992 	enum uart_pm_state pm_state;
1993 	struct uart_port *uport;
1994 	char stat_buf[32];
1995 	unsigned int status;
1996 	int mmio;
1997 
1998 	mutex_lock(&port->mutex);
1999 	uport = uart_port_check(state);
2000 	if (!uport)
2001 		goto out;
2002 
2003 	mmio = uport->iotype >= UPIO_MEM;
2004 	seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
2005 			uport->line, uart_type(uport),
2006 			mmio ? "mmio:0x" : "port:",
2007 			mmio ? (unsigned long long)uport->mapbase
2008 			     : (unsigned long long)uport->iobase,
2009 			uport->irq);
2010 
2011 	if (uport->type == PORT_UNKNOWN) {
2012 		seq_putc(m, '\n');
2013 		goto out;
2014 	}
2015 
2016 	if (capable(CAP_SYS_ADMIN)) {
2017 		pm_state = state->pm_state;
2018 		if (pm_state != UART_PM_STATE_ON)
2019 			uart_change_pm(state, UART_PM_STATE_ON);
2020 		spin_lock_irq(&uport->lock);
2021 		status = uport->ops->get_mctrl(uport);
2022 		spin_unlock_irq(&uport->lock);
2023 		if (pm_state != UART_PM_STATE_ON)
2024 			uart_change_pm(state, pm_state);
2025 
2026 		seq_printf(m, " tx:%d rx:%d",
2027 				uport->icount.tx, uport->icount.rx);
2028 		if (uport->icount.frame)
2029 			seq_printf(m, " fe:%d",	uport->icount.frame);
2030 		if (uport->icount.parity)
2031 			seq_printf(m, " pe:%d",	uport->icount.parity);
2032 		if (uport->icount.brk)
2033 			seq_printf(m, " brk:%d", uport->icount.brk);
2034 		if (uport->icount.overrun)
2035 			seq_printf(m, " oe:%d", uport->icount.overrun);
2036 		if (uport->icount.buf_overrun)
2037 			seq_printf(m, " bo:%d", uport->icount.buf_overrun);
2038 
2039 #define INFOBIT(bit, str) \
2040 	if (uport->mctrl & (bit)) \
2041 		strncat(stat_buf, (str), sizeof(stat_buf) - \
2042 			strlen(stat_buf) - 2)
2043 #define STATBIT(bit, str) \
2044 	if (status & (bit)) \
2045 		strncat(stat_buf, (str), sizeof(stat_buf) - \
2046 		       strlen(stat_buf) - 2)
2047 
2048 		stat_buf[0] = '\0';
2049 		stat_buf[1] = '\0';
2050 		INFOBIT(TIOCM_RTS, "|RTS");
2051 		STATBIT(TIOCM_CTS, "|CTS");
2052 		INFOBIT(TIOCM_DTR, "|DTR");
2053 		STATBIT(TIOCM_DSR, "|DSR");
2054 		STATBIT(TIOCM_CAR, "|CD");
2055 		STATBIT(TIOCM_RNG, "|RI");
2056 		if (stat_buf[0])
2057 			stat_buf[0] = ' ';
2058 
2059 		seq_puts(m, stat_buf);
2060 	}
2061 	seq_putc(m, '\n');
2062 #undef STATBIT
2063 #undef INFOBIT
2064 out:
2065 	mutex_unlock(&port->mutex);
2066 }
2067 
2068 static int uart_proc_show(struct seq_file *m, void *v)
2069 {
2070 	struct tty_driver *ttydrv = m->private;
2071 	struct uart_driver *drv = ttydrv->driver_state;
2072 	int i;
2073 
2074 	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
2075 	for (i = 0; i < drv->nr; i++)
2076 		uart_line_info(m, drv, i);
2077 	return 0;
2078 }
2079 #endif
2080 
2081 static void uart_port_spin_lock_init(struct uart_port *port)
2082 {
2083 	spin_lock_init(&port->lock);
2084 	lockdep_set_class(&port->lock, &port_lock_key);
2085 }
2086 
2087 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
2088 /**
2089  * uart_console_write - write a console message to a serial port
2090  * @port: the port to write the message
2091  * @s: array of characters
2092  * @count: number of characters in string to write
2093  * @putchar: function to write character to port
2094  */
2095 void uart_console_write(struct uart_port *port, const char *s,
2096 			unsigned int count,
2097 			void (*putchar)(struct uart_port *, unsigned char))
2098 {
2099 	unsigned int i;
2100 
2101 	for (i = 0; i < count; i++, s++) {
2102 		if (*s == '\n')
2103 			putchar(port, '\r');
2104 		putchar(port, *s);
2105 	}
2106 }
2107 EXPORT_SYMBOL_GPL(uart_console_write);
2108 
2109 /**
2110  * uart_get_console - get uart port for console
2111  * @ports: ports to search in
2112  * @nr: number of @ports
2113  * @co: console to search for
2114  * Returns: uart_port for the console @co
2115  *
2116  * Check whether an invalid uart number has been specified (as @co->index), and
2117  * if so, search for the first available port that does have console support.
2118  */
2119 struct uart_port * __init
2120 uart_get_console(struct uart_port *ports, int nr, struct console *co)
2121 {
2122 	int idx = co->index;
2123 
2124 	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
2125 				     ports[idx].membase == NULL))
2126 		for (idx = 0; idx < nr; idx++)
2127 			if (ports[idx].iobase != 0 ||
2128 			    ports[idx].membase != NULL)
2129 				break;
2130 
2131 	co->index = idx;
2132 
2133 	return ports + idx;
2134 }
2135 
2136 /**
2137  * uart_parse_earlycon - Parse earlycon options
2138  * @p:	     ptr to 2nd field (ie., just beyond '<name>,')
2139  * @iotype:  ptr for decoded iotype (out)
2140  * @addr:    ptr for decoded mapbase/iobase (out)
2141  * @options: ptr for <options> field; %NULL if not present (out)
2142  *
2143  * Decodes earlycon kernel command line parameters of the form:
2144  *  * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2145  *  * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2146  *
2147  * The optional form:
2148  *  * earlycon=<name>,0x<addr>,<options>
2149  *  * console=<name>,0x<addr>,<options>
2150  *
2151  * is also accepted; the returned @iotype will be %UPIO_MEM.
2152  *
2153  * Returns: 0 on success or -%EINVAL on failure
2154  */
2155 int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
2156 			char **options)
2157 {
2158 	if (strncmp(p, "mmio,", 5) == 0) {
2159 		*iotype = UPIO_MEM;
2160 		p += 5;
2161 	} else if (strncmp(p, "mmio16,", 7) == 0) {
2162 		*iotype = UPIO_MEM16;
2163 		p += 7;
2164 	} else if (strncmp(p, "mmio32,", 7) == 0) {
2165 		*iotype = UPIO_MEM32;
2166 		p += 7;
2167 	} else if (strncmp(p, "mmio32be,", 9) == 0) {
2168 		*iotype = UPIO_MEM32BE;
2169 		p += 9;
2170 	} else if (strncmp(p, "mmio32native,", 13) == 0) {
2171 		*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
2172 			UPIO_MEM32BE : UPIO_MEM32;
2173 		p += 13;
2174 	} else if (strncmp(p, "io,", 3) == 0) {
2175 		*iotype = UPIO_PORT;
2176 		p += 3;
2177 	} else if (strncmp(p, "0x", 2) == 0) {
2178 		*iotype = UPIO_MEM;
2179 	} else {
2180 		return -EINVAL;
2181 	}
2182 
2183 	/*
2184 	 * Before you replace it with kstrtoull(), think about options separator
2185 	 * (',') it will not tolerate
2186 	 */
2187 	*addr = simple_strtoull(p, NULL, 0);
2188 	p = strchr(p, ',');
2189 	if (p)
2190 		p++;
2191 
2192 	*options = p;
2193 	return 0;
2194 }
2195 EXPORT_SYMBOL_GPL(uart_parse_earlycon);
2196 
2197 /**
2198  * uart_parse_options - Parse serial port baud/parity/bits/flow control.
2199  * @options: pointer to option string
2200  * @baud: pointer to an 'int' variable for the baud rate.
2201  * @parity: pointer to an 'int' variable for the parity.
2202  * @bits: pointer to an 'int' variable for the number of data bits.
2203  * @flow: pointer to an 'int' variable for the flow control character.
2204  *
2205  * uart_parse_options() decodes a string containing the serial console
2206  * options. The format of the string is <baud><parity><bits><flow>,
2207  * eg: 115200n8r
2208  */
2209 void
2210 uart_parse_options(const char *options, int *baud, int *parity,
2211 		   int *bits, int *flow)
2212 {
2213 	const char *s = options;
2214 
2215 	*baud = simple_strtoul(s, NULL, 10);
2216 	while (*s >= '0' && *s <= '9')
2217 		s++;
2218 	if (*s)
2219 		*parity = *s++;
2220 	if (*s)
2221 		*bits = *s++ - '0';
2222 	if (*s)
2223 		*flow = *s;
2224 }
2225 EXPORT_SYMBOL_GPL(uart_parse_options);
2226 
2227 /**
2228  * uart_set_options - setup the serial console parameters
2229  * @port: pointer to the serial ports uart_port structure
2230  * @co: console pointer
2231  * @baud: baud rate
2232  * @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
2233  * @bits: number of data bits
2234  * @flow: flow control character - 'r' (rts)
2235  *
2236  * Locking: Caller must hold console_list_lock in order to serialize
2237  * early initialization of the serial-console lock.
2238  */
2239 int
2240 uart_set_options(struct uart_port *port, struct console *co,
2241 		 int baud, int parity, int bits, int flow)
2242 {
2243 	struct ktermios termios;
2244 	static struct ktermios dummy;
2245 
2246 	/*
2247 	 * Ensure that the serial-console lock is initialised early.
2248 	 *
2249 	 * Note that the console-registered check is needed because
2250 	 * kgdboc can call uart_set_options() for an already registered
2251 	 * console via tty_find_polling_driver() and uart_poll_init().
2252 	 */
2253 	if (!uart_console_registered_locked(port) && !port->console_reinit)
2254 		uart_port_spin_lock_init(port);
2255 
2256 	memset(&termios, 0, sizeof(struct ktermios));
2257 
2258 	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
2259 	tty_termios_encode_baud_rate(&termios, baud, baud);
2260 
2261 	if (bits == 7)
2262 		termios.c_cflag |= CS7;
2263 	else
2264 		termios.c_cflag |= CS8;
2265 
2266 	switch (parity) {
2267 	case 'o': case 'O':
2268 		termios.c_cflag |= PARODD;
2269 		fallthrough;
2270 	case 'e': case 'E':
2271 		termios.c_cflag |= PARENB;
2272 		break;
2273 	}
2274 
2275 	if (flow == 'r')
2276 		termios.c_cflag |= CRTSCTS;
2277 
2278 	/*
2279 	 * some uarts on other side don't support no flow control.
2280 	 * So we set * DTR in host uart to make them happy
2281 	 */
2282 	port->mctrl |= TIOCM_DTR;
2283 
2284 	port->ops->set_termios(port, &termios, &dummy);
2285 	/*
2286 	 * Allow the setting of the UART parameters with a NULL console
2287 	 * too:
2288 	 */
2289 	if (co) {
2290 		co->cflag = termios.c_cflag;
2291 		co->ispeed = termios.c_ispeed;
2292 		co->ospeed = termios.c_ospeed;
2293 	}
2294 
2295 	return 0;
2296 }
2297 EXPORT_SYMBOL_GPL(uart_set_options);
2298 #endif /* CONFIG_SERIAL_CORE_CONSOLE */
2299 
2300 /**
2301  * uart_change_pm - set power state of the port
2302  *
2303  * @state: port descriptor
2304  * @pm_state: new state
2305  *
2306  * Locking: port->mutex has to be held
2307  */
2308 static void uart_change_pm(struct uart_state *state,
2309 			   enum uart_pm_state pm_state)
2310 {
2311 	struct uart_port *port = uart_port_check(state);
2312 
2313 	if (state->pm_state != pm_state) {
2314 		if (port && port->ops->pm)
2315 			port->ops->pm(port, pm_state, state->pm_state);
2316 		state->pm_state = pm_state;
2317 	}
2318 }
2319 
2320 struct uart_match {
2321 	struct uart_port *port;
2322 	struct uart_driver *driver;
2323 };
2324 
2325 static int serial_match_port(struct device *dev, void *data)
2326 {
2327 	struct uart_match *match = data;
2328 	struct tty_driver *tty_drv = match->driver->tty_driver;
2329 	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2330 		match->port->line;
2331 
2332 	return dev->devt == devt; /* Actually, only one tty per port */
2333 }
2334 
2335 int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
2336 {
2337 	struct uart_state *state = drv->state + uport->line;
2338 	struct tty_port *port = &state->port;
2339 	struct device *tty_dev;
2340 	struct uart_match match = {uport, drv};
2341 
2342 	mutex_lock(&port->mutex);
2343 
2344 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2345 	if (tty_dev && device_may_wakeup(tty_dev)) {
2346 		enable_irq_wake(uport->irq);
2347 		put_device(tty_dev);
2348 		mutex_unlock(&port->mutex);
2349 		return 0;
2350 	}
2351 	put_device(tty_dev);
2352 
2353 	/*
2354 	 * Nothing to do if the console is not suspending
2355 	 * except stop_rx to prevent any asynchronous data
2356 	 * over RX line. However ensure that we will be
2357 	 * able to Re-start_rx later.
2358 	 */
2359 	if (!console_suspend_enabled && uart_console(uport)) {
2360 		if (uport->ops->start_rx) {
2361 			spin_lock_irq(&uport->lock);
2362 			uport->ops->stop_rx(uport);
2363 			spin_unlock_irq(&uport->lock);
2364 		}
2365 		goto unlock;
2366 	}
2367 
2368 	uport->suspended = 1;
2369 
2370 	if (tty_port_initialized(port)) {
2371 		const struct uart_ops *ops = uport->ops;
2372 		int tries;
2373 		unsigned int mctrl;
2374 
2375 		tty_port_set_suspended(port, true);
2376 		tty_port_set_initialized(port, false);
2377 
2378 		spin_lock_irq(&uport->lock);
2379 		ops->stop_tx(uport);
2380 		if (!(uport->rs485.flags & SER_RS485_ENABLED))
2381 			ops->set_mctrl(uport, 0);
2382 		/* save mctrl so it can be restored on resume */
2383 		mctrl = uport->mctrl;
2384 		uport->mctrl = 0;
2385 		ops->stop_rx(uport);
2386 		spin_unlock_irq(&uport->lock);
2387 
2388 		/*
2389 		 * Wait for the transmitter to empty.
2390 		 */
2391 		for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
2392 			msleep(10);
2393 		if (!tries)
2394 			dev_err(uport->dev, "%s: Unable to drain transmitter\n",
2395 				uport->name);
2396 
2397 		ops->shutdown(uport);
2398 		uport->mctrl = mctrl;
2399 	}
2400 
2401 	/*
2402 	 * Disable the console device before suspending.
2403 	 */
2404 	if (uart_console(uport))
2405 		console_stop(uport->cons);
2406 
2407 	uart_change_pm(state, UART_PM_STATE_OFF);
2408 unlock:
2409 	mutex_unlock(&port->mutex);
2410 
2411 	return 0;
2412 }
2413 EXPORT_SYMBOL(uart_suspend_port);
2414 
2415 int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
2416 {
2417 	struct uart_state *state = drv->state + uport->line;
2418 	struct tty_port *port = &state->port;
2419 	struct device *tty_dev;
2420 	struct uart_match match = {uport, drv};
2421 	struct ktermios termios;
2422 
2423 	mutex_lock(&port->mutex);
2424 
2425 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2426 	if (!uport->suspended && device_may_wakeup(tty_dev)) {
2427 		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
2428 			disable_irq_wake(uport->irq);
2429 		put_device(tty_dev);
2430 		mutex_unlock(&port->mutex);
2431 		return 0;
2432 	}
2433 	put_device(tty_dev);
2434 	uport->suspended = 0;
2435 
2436 	/*
2437 	 * Re-enable the console device after suspending.
2438 	 */
2439 	if (uart_console(uport)) {
2440 		/*
2441 		 * First try to use the console cflag setting.
2442 		 */
2443 		memset(&termios, 0, sizeof(struct ktermios));
2444 		termios.c_cflag = uport->cons->cflag;
2445 		termios.c_ispeed = uport->cons->ispeed;
2446 		termios.c_ospeed = uport->cons->ospeed;
2447 
2448 		/*
2449 		 * If that's unset, use the tty termios setting.
2450 		 */
2451 		if (port->tty && termios.c_cflag == 0)
2452 			termios = port->tty->termios;
2453 
2454 		if (console_suspend_enabled)
2455 			uart_change_pm(state, UART_PM_STATE_ON);
2456 		uport->ops->set_termios(uport, &termios, NULL);
2457 		if (!console_suspend_enabled && uport->ops->start_rx) {
2458 			spin_lock_irq(&uport->lock);
2459 			uport->ops->start_rx(uport);
2460 			spin_unlock_irq(&uport->lock);
2461 		}
2462 		if (console_suspend_enabled)
2463 			console_start(uport->cons);
2464 	}
2465 
2466 	if (tty_port_suspended(port)) {
2467 		const struct uart_ops *ops = uport->ops;
2468 		int ret;
2469 
2470 		uart_change_pm(state, UART_PM_STATE_ON);
2471 		spin_lock_irq(&uport->lock);
2472 		if (!(uport->rs485.flags & SER_RS485_ENABLED))
2473 			ops->set_mctrl(uport, 0);
2474 		spin_unlock_irq(&uport->lock);
2475 		if (console_suspend_enabled || !uart_console(uport)) {
2476 			/* Protected by port mutex for now */
2477 			struct tty_struct *tty = port->tty;
2478 
2479 			ret = ops->startup(uport);
2480 			if (ret == 0) {
2481 				if (tty)
2482 					uart_change_line_settings(tty, state, NULL);
2483 				uart_rs485_config(uport);
2484 				spin_lock_irq(&uport->lock);
2485 				if (!(uport->rs485.flags & SER_RS485_ENABLED))
2486 					ops->set_mctrl(uport, uport->mctrl);
2487 				ops->start_tx(uport);
2488 				spin_unlock_irq(&uport->lock);
2489 				tty_port_set_initialized(port, true);
2490 			} else {
2491 				/*
2492 				 * Failed to resume - maybe hardware went away?
2493 				 * Clear the "initialized" flag so we won't try
2494 				 * to call the low level drivers shutdown method.
2495 				 */
2496 				uart_shutdown(tty, state);
2497 			}
2498 		}
2499 
2500 		tty_port_set_suspended(port, false);
2501 	}
2502 
2503 	mutex_unlock(&port->mutex);
2504 
2505 	return 0;
2506 }
2507 EXPORT_SYMBOL(uart_resume_port);
2508 
2509 static inline void
2510 uart_report_port(struct uart_driver *drv, struct uart_port *port)
2511 {
2512 	char address[64];
2513 
2514 	switch (port->iotype) {
2515 	case UPIO_PORT:
2516 		snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
2517 		break;
2518 	case UPIO_HUB6:
2519 		snprintf(address, sizeof(address),
2520 			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
2521 		break;
2522 	case UPIO_MEM:
2523 	case UPIO_MEM16:
2524 	case UPIO_MEM32:
2525 	case UPIO_MEM32BE:
2526 	case UPIO_AU:
2527 	case UPIO_TSI:
2528 		snprintf(address, sizeof(address),
2529 			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
2530 		break;
2531 	default:
2532 		strscpy(address, "*unknown*", sizeof(address));
2533 		break;
2534 	}
2535 
2536 	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
2537 	       port->dev ? dev_name(port->dev) : "",
2538 	       port->dev ? ": " : "",
2539 	       port->name,
2540 	       address, port->irq, port->uartclk / 16, uart_type(port));
2541 
2542 	/* The magic multiplier feature is a bit obscure, so report it too.  */
2543 	if (port->flags & UPF_MAGIC_MULTIPLIER)
2544 		pr_info("%s%s%s extra baud rates supported: %d, %d",
2545 			port->dev ? dev_name(port->dev) : "",
2546 			port->dev ? ": " : "",
2547 			port->name,
2548 			port->uartclk / 8, port->uartclk / 4);
2549 }
2550 
2551 static void
2552 uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2553 		    struct uart_port *port)
2554 {
2555 	unsigned int flags;
2556 
2557 	/*
2558 	 * If there isn't a port here, don't do anything further.
2559 	 */
2560 	if (!port->iobase && !port->mapbase && !port->membase)
2561 		return;
2562 
2563 	/*
2564 	 * Now do the auto configuration stuff.  Note that config_port
2565 	 * is expected to claim the resources and map the port for us.
2566 	 */
2567 	flags = 0;
2568 	if (port->flags & UPF_AUTO_IRQ)
2569 		flags |= UART_CONFIG_IRQ;
2570 	if (port->flags & UPF_BOOT_AUTOCONF) {
2571 		if (!(port->flags & UPF_FIXED_TYPE)) {
2572 			port->type = PORT_UNKNOWN;
2573 			flags |= UART_CONFIG_TYPE;
2574 		}
2575 		port->ops->config_port(port, flags);
2576 	}
2577 
2578 	if (port->type != PORT_UNKNOWN) {
2579 		unsigned long flags;
2580 
2581 		uart_report_port(drv, port);
2582 
2583 		/* Power up port for set_mctrl() */
2584 		uart_change_pm(state, UART_PM_STATE_ON);
2585 
2586 		/*
2587 		 * Ensure that the modem control lines are de-activated.
2588 		 * keep the DTR setting that is set in uart_set_options()
2589 		 * We probably don't need a spinlock around this, but
2590 		 */
2591 		spin_lock_irqsave(&port->lock, flags);
2592 		port->mctrl &= TIOCM_DTR;
2593 		if (!(port->rs485.flags & SER_RS485_ENABLED))
2594 			port->ops->set_mctrl(port, port->mctrl);
2595 		spin_unlock_irqrestore(&port->lock, flags);
2596 
2597 		uart_rs485_config(port);
2598 
2599 		/*
2600 		 * If this driver supports console, and it hasn't been
2601 		 * successfully registered yet, try to re-register it.
2602 		 * It may be that the port was not available.
2603 		 */
2604 		if (port->cons && !console_is_registered(port->cons))
2605 			register_console(port->cons);
2606 
2607 		/*
2608 		 * Power down all ports by default, except the
2609 		 * console if we have one.
2610 		 */
2611 		if (!uart_console(port))
2612 			uart_change_pm(state, UART_PM_STATE_OFF);
2613 	}
2614 }
2615 
2616 #ifdef CONFIG_CONSOLE_POLL
2617 
2618 static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2619 {
2620 	struct uart_driver *drv = driver->driver_state;
2621 	struct uart_state *state = drv->state + line;
2622 	enum uart_pm_state pm_state;
2623 	struct tty_port *tport;
2624 	struct uart_port *port;
2625 	int baud = 9600;
2626 	int bits = 8;
2627 	int parity = 'n';
2628 	int flow = 'n';
2629 	int ret = 0;
2630 
2631 	tport = &state->port;
2632 	mutex_lock(&tport->mutex);
2633 
2634 	port = uart_port_check(state);
2635 	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
2636 		ret = -1;
2637 		goto out;
2638 	}
2639 
2640 	pm_state = state->pm_state;
2641 	uart_change_pm(state, UART_PM_STATE_ON);
2642 
2643 	if (port->ops->poll_init) {
2644 		/*
2645 		 * We don't set initialized as we only initialized the hw,
2646 		 * e.g. state->xmit is still uninitialized.
2647 		 */
2648 		if (!tty_port_initialized(tport))
2649 			ret = port->ops->poll_init(port);
2650 	}
2651 
2652 	if (!ret && options) {
2653 		uart_parse_options(options, &baud, &parity, &bits, &flow);
2654 		console_list_lock();
2655 		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
2656 		console_list_unlock();
2657 	}
2658 out:
2659 	if (ret)
2660 		uart_change_pm(state, pm_state);
2661 	mutex_unlock(&tport->mutex);
2662 	return ret;
2663 }
2664 
2665 static int uart_poll_get_char(struct tty_driver *driver, int line)
2666 {
2667 	struct uart_driver *drv = driver->driver_state;
2668 	struct uart_state *state = drv->state + line;
2669 	struct uart_port *port;
2670 	int ret = -1;
2671 
2672 	port = uart_port_ref(state);
2673 	if (port) {
2674 		ret = port->ops->poll_get_char(port);
2675 		uart_port_deref(port);
2676 	}
2677 
2678 	return ret;
2679 }
2680 
2681 static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2682 {
2683 	struct uart_driver *drv = driver->driver_state;
2684 	struct uart_state *state = drv->state + line;
2685 	struct uart_port *port;
2686 
2687 	port = uart_port_ref(state);
2688 	if (!port)
2689 		return;
2690 
2691 	if (ch == '\n')
2692 		port->ops->poll_put_char(port, '\r');
2693 	port->ops->poll_put_char(port, ch);
2694 	uart_port_deref(port);
2695 }
2696 #endif
2697 
2698 static const struct tty_operations uart_ops = {
2699 	.install	= uart_install,
2700 	.open		= uart_open,
2701 	.close		= uart_close,
2702 	.write		= uart_write,
2703 	.put_char	= uart_put_char,
2704 	.flush_chars	= uart_flush_chars,
2705 	.write_room	= uart_write_room,
2706 	.chars_in_buffer= uart_chars_in_buffer,
2707 	.flush_buffer	= uart_flush_buffer,
2708 	.ioctl		= uart_ioctl,
2709 	.throttle	= uart_throttle,
2710 	.unthrottle	= uart_unthrottle,
2711 	.send_xchar	= uart_send_xchar,
2712 	.set_termios	= uart_set_termios,
2713 	.set_ldisc	= uart_set_ldisc,
2714 	.stop		= uart_stop,
2715 	.start		= uart_start,
2716 	.hangup		= uart_hangup,
2717 	.break_ctl	= uart_break_ctl,
2718 	.wait_until_sent= uart_wait_until_sent,
2719 #ifdef CONFIG_PROC_FS
2720 	.proc_show	= uart_proc_show,
2721 #endif
2722 	.tiocmget	= uart_tiocmget,
2723 	.tiocmset	= uart_tiocmset,
2724 	.set_serial	= uart_set_info_user,
2725 	.get_serial	= uart_get_info_user,
2726 	.get_icount	= uart_get_icount,
2727 #ifdef CONFIG_CONSOLE_POLL
2728 	.poll_init	= uart_poll_init,
2729 	.poll_get_char	= uart_poll_get_char,
2730 	.poll_put_char	= uart_poll_put_char,
2731 #endif
2732 };
2733 
2734 static const struct tty_port_operations uart_port_ops = {
2735 	.carrier_raised = uart_carrier_raised,
2736 	.dtr_rts	= uart_dtr_rts,
2737 	.activate	= uart_port_activate,
2738 	.shutdown	= uart_tty_port_shutdown,
2739 };
2740 
2741 /**
2742  * uart_register_driver - register a driver with the uart core layer
2743  * @drv: low level driver structure
2744  *
2745  * Register a uart driver with the core driver. We in turn register with the
2746  * tty layer, and initialise the core driver per-port state.
2747  *
2748  * We have a proc file in /proc/tty/driver which is named after the normal
2749  * driver.
2750  *
2751  * @drv->port should be %NULL, and the per-port structures should be registered
2752  * using uart_add_one_port() after this call has succeeded.
2753  *
2754  * Locking: none, Interrupts: enabled
2755  */
2756 int uart_register_driver(struct uart_driver *drv)
2757 {
2758 	struct tty_driver *normal;
2759 	int i, retval = -ENOMEM;
2760 
2761 	BUG_ON(drv->state);
2762 
2763 	/*
2764 	 * Maybe we should be using a slab cache for this, especially if
2765 	 * we have a large number of ports to handle.
2766 	 */
2767 	drv->state = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
2768 	if (!drv->state)
2769 		goto out;
2770 
2771 	normal = tty_alloc_driver(drv->nr, TTY_DRIVER_REAL_RAW |
2772 			TTY_DRIVER_DYNAMIC_DEV);
2773 	if (IS_ERR(normal)) {
2774 		retval = PTR_ERR(normal);
2775 		goto out_kfree;
2776 	}
2777 
2778 	drv->tty_driver = normal;
2779 
2780 	normal->driver_name	= drv->driver_name;
2781 	normal->name		= drv->dev_name;
2782 	normal->major		= drv->major;
2783 	normal->minor_start	= drv->minor;
2784 	normal->type		= TTY_DRIVER_TYPE_SERIAL;
2785 	normal->subtype		= SERIAL_TYPE_NORMAL;
2786 	normal->init_termios	= tty_std_termios;
2787 	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2788 	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2789 	normal->driver_state    = drv;
2790 	tty_set_operations(normal, &uart_ops);
2791 
2792 	/*
2793 	 * Initialise the UART state(s).
2794 	 */
2795 	for (i = 0; i < drv->nr; i++) {
2796 		struct uart_state *state = drv->state + i;
2797 		struct tty_port *port = &state->port;
2798 
2799 		tty_port_init(port);
2800 		port->ops = &uart_port_ops;
2801 	}
2802 
2803 	retval = tty_register_driver(normal);
2804 	if (retval >= 0)
2805 		return retval;
2806 
2807 	for (i = 0; i < drv->nr; i++)
2808 		tty_port_destroy(&drv->state[i].port);
2809 	tty_driver_kref_put(normal);
2810 out_kfree:
2811 	kfree(drv->state);
2812 out:
2813 	return retval;
2814 }
2815 EXPORT_SYMBOL(uart_register_driver);
2816 
2817 /**
2818  * uart_unregister_driver - remove a driver from the uart core layer
2819  * @drv: low level driver structure
2820  *
2821  * Remove all references to a driver from the core driver. The low level
2822  * driver must have removed all its ports via the uart_remove_one_port() if it
2823  * registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
2824  *
2825  * Locking: none, Interrupts: enabled
2826  */
2827 void uart_unregister_driver(struct uart_driver *drv)
2828 {
2829 	struct tty_driver *p = drv->tty_driver;
2830 	unsigned int i;
2831 
2832 	tty_unregister_driver(p);
2833 	tty_driver_kref_put(p);
2834 	for (i = 0; i < drv->nr; i++)
2835 		tty_port_destroy(&drv->state[i].port);
2836 	kfree(drv->state);
2837 	drv->state = NULL;
2838 	drv->tty_driver = NULL;
2839 }
2840 EXPORT_SYMBOL(uart_unregister_driver);
2841 
2842 struct tty_driver *uart_console_device(struct console *co, int *index)
2843 {
2844 	struct uart_driver *p = co->data;
2845 	*index = co->index;
2846 	return p->tty_driver;
2847 }
2848 EXPORT_SYMBOL_GPL(uart_console_device);
2849 
2850 static ssize_t uartclk_show(struct device *dev,
2851 	struct device_attribute *attr, char *buf)
2852 {
2853 	struct serial_struct tmp;
2854 	struct tty_port *port = dev_get_drvdata(dev);
2855 
2856 	uart_get_info(port, &tmp);
2857 	return sprintf(buf, "%d\n", tmp.baud_base * 16);
2858 }
2859 
2860 static ssize_t type_show(struct device *dev,
2861 	struct device_attribute *attr, char *buf)
2862 {
2863 	struct serial_struct tmp;
2864 	struct tty_port *port = dev_get_drvdata(dev);
2865 
2866 	uart_get_info(port, &tmp);
2867 	return sprintf(buf, "%d\n", tmp.type);
2868 }
2869 
2870 static ssize_t line_show(struct device *dev,
2871 	struct device_attribute *attr, char *buf)
2872 {
2873 	struct serial_struct tmp;
2874 	struct tty_port *port = dev_get_drvdata(dev);
2875 
2876 	uart_get_info(port, &tmp);
2877 	return sprintf(buf, "%d\n", tmp.line);
2878 }
2879 
2880 static ssize_t port_show(struct device *dev,
2881 	struct device_attribute *attr, char *buf)
2882 {
2883 	struct serial_struct tmp;
2884 	struct tty_port *port = dev_get_drvdata(dev);
2885 	unsigned long ioaddr;
2886 
2887 	uart_get_info(port, &tmp);
2888 	ioaddr = tmp.port;
2889 	if (HIGH_BITS_OFFSET)
2890 		ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
2891 	return sprintf(buf, "0x%lX\n", ioaddr);
2892 }
2893 
2894 static ssize_t irq_show(struct device *dev,
2895 	struct device_attribute *attr, char *buf)
2896 {
2897 	struct serial_struct tmp;
2898 	struct tty_port *port = dev_get_drvdata(dev);
2899 
2900 	uart_get_info(port, &tmp);
2901 	return sprintf(buf, "%d\n", tmp.irq);
2902 }
2903 
2904 static ssize_t flags_show(struct device *dev,
2905 	struct device_attribute *attr, char *buf)
2906 {
2907 	struct serial_struct tmp;
2908 	struct tty_port *port = dev_get_drvdata(dev);
2909 
2910 	uart_get_info(port, &tmp);
2911 	return sprintf(buf, "0x%X\n", tmp.flags);
2912 }
2913 
2914 static ssize_t xmit_fifo_size_show(struct device *dev,
2915 	struct device_attribute *attr, char *buf)
2916 {
2917 	struct serial_struct tmp;
2918 	struct tty_port *port = dev_get_drvdata(dev);
2919 
2920 	uart_get_info(port, &tmp);
2921 	return sprintf(buf, "%d\n", tmp.xmit_fifo_size);
2922 }
2923 
2924 static ssize_t close_delay_show(struct device *dev,
2925 	struct device_attribute *attr, char *buf)
2926 {
2927 	struct serial_struct tmp;
2928 	struct tty_port *port = dev_get_drvdata(dev);
2929 
2930 	uart_get_info(port, &tmp);
2931 	return sprintf(buf, "%d\n", tmp.close_delay);
2932 }
2933 
2934 static ssize_t closing_wait_show(struct device *dev,
2935 	struct device_attribute *attr, char *buf)
2936 {
2937 	struct serial_struct tmp;
2938 	struct tty_port *port = dev_get_drvdata(dev);
2939 
2940 	uart_get_info(port, &tmp);
2941 	return sprintf(buf, "%d\n", tmp.closing_wait);
2942 }
2943 
2944 static ssize_t custom_divisor_show(struct device *dev,
2945 	struct device_attribute *attr, char *buf)
2946 {
2947 	struct serial_struct tmp;
2948 	struct tty_port *port = dev_get_drvdata(dev);
2949 
2950 	uart_get_info(port, &tmp);
2951 	return sprintf(buf, "%d\n", tmp.custom_divisor);
2952 }
2953 
2954 static ssize_t io_type_show(struct device *dev,
2955 	struct device_attribute *attr, char *buf)
2956 {
2957 	struct serial_struct tmp;
2958 	struct tty_port *port = dev_get_drvdata(dev);
2959 
2960 	uart_get_info(port, &tmp);
2961 	return sprintf(buf, "%d\n", tmp.io_type);
2962 }
2963 
2964 static ssize_t iomem_base_show(struct device *dev,
2965 	struct device_attribute *attr, char *buf)
2966 {
2967 	struct serial_struct tmp;
2968 	struct tty_port *port = dev_get_drvdata(dev);
2969 
2970 	uart_get_info(port, &tmp);
2971 	return sprintf(buf, "0x%lX\n", (unsigned long)tmp.iomem_base);
2972 }
2973 
2974 static ssize_t iomem_reg_shift_show(struct device *dev,
2975 	struct device_attribute *attr, char *buf)
2976 {
2977 	struct serial_struct tmp;
2978 	struct tty_port *port = dev_get_drvdata(dev);
2979 
2980 	uart_get_info(port, &tmp);
2981 	return sprintf(buf, "%d\n", tmp.iomem_reg_shift);
2982 }
2983 
2984 static ssize_t console_show(struct device *dev,
2985 	struct device_attribute *attr, char *buf)
2986 {
2987 	struct tty_port *port = dev_get_drvdata(dev);
2988 	struct uart_state *state = container_of(port, struct uart_state, port);
2989 	struct uart_port *uport;
2990 	bool console = false;
2991 
2992 	mutex_lock(&port->mutex);
2993 	uport = uart_port_check(state);
2994 	if (uport)
2995 		console = uart_console_registered(uport);
2996 	mutex_unlock(&port->mutex);
2997 
2998 	return sprintf(buf, "%c\n", console ? 'Y' : 'N');
2999 }
3000 
3001 static ssize_t console_store(struct device *dev,
3002 	struct device_attribute *attr, const char *buf, size_t count)
3003 {
3004 	struct tty_port *port = dev_get_drvdata(dev);
3005 	struct uart_state *state = container_of(port, struct uart_state, port);
3006 	struct uart_port *uport;
3007 	bool oldconsole, newconsole;
3008 	int ret;
3009 
3010 	ret = kstrtobool(buf, &newconsole);
3011 	if (ret)
3012 		return ret;
3013 
3014 	mutex_lock(&port->mutex);
3015 	uport = uart_port_check(state);
3016 	if (uport) {
3017 		oldconsole = uart_console_registered(uport);
3018 		if (oldconsole && !newconsole) {
3019 			ret = unregister_console(uport->cons);
3020 		} else if (!oldconsole && newconsole) {
3021 			if (uart_console(uport)) {
3022 				uport->console_reinit = 1;
3023 				register_console(uport->cons);
3024 			} else {
3025 				ret = -ENOENT;
3026 			}
3027 		}
3028 	} else {
3029 		ret = -ENXIO;
3030 	}
3031 	mutex_unlock(&port->mutex);
3032 
3033 	return ret < 0 ? ret : count;
3034 }
3035 
3036 static DEVICE_ATTR_RO(uartclk);
3037 static DEVICE_ATTR_RO(type);
3038 static DEVICE_ATTR_RO(line);
3039 static DEVICE_ATTR_RO(port);
3040 static DEVICE_ATTR_RO(irq);
3041 static DEVICE_ATTR_RO(flags);
3042 static DEVICE_ATTR_RO(xmit_fifo_size);
3043 static DEVICE_ATTR_RO(close_delay);
3044 static DEVICE_ATTR_RO(closing_wait);
3045 static DEVICE_ATTR_RO(custom_divisor);
3046 static DEVICE_ATTR_RO(io_type);
3047 static DEVICE_ATTR_RO(iomem_base);
3048 static DEVICE_ATTR_RO(iomem_reg_shift);
3049 static DEVICE_ATTR_RW(console);
3050 
3051 static struct attribute *tty_dev_attrs[] = {
3052 	&dev_attr_uartclk.attr,
3053 	&dev_attr_type.attr,
3054 	&dev_attr_line.attr,
3055 	&dev_attr_port.attr,
3056 	&dev_attr_irq.attr,
3057 	&dev_attr_flags.attr,
3058 	&dev_attr_xmit_fifo_size.attr,
3059 	&dev_attr_close_delay.attr,
3060 	&dev_attr_closing_wait.attr,
3061 	&dev_attr_custom_divisor.attr,
3062 	&dev_attr_io_type.attr,
3063 	&dev_attr_iomem_base.attr,
3064 	&dev_attr_iomem_reg_shift.attr,
3065 	&dev_attr_console.attr,
3066 	NULL
3067 };
3068 
3069 static const struct attribute_group tty_dev_attr_group = {
3070 	.attrs = tty_dev_attrs,
3071 };
3072 
3073 /**
3074  * serial_core_add_one_port - attach a driver-defined port structure
3075  * @drv: pointer to the uart low level driver structure for this port
3076  * @uport: uart port structure to use for this port.
3077  *
3078  * Context: task context, might sleep
3079  *
3080  * This allows the driver @drv to register its own uart_port structure with the
3081  * core driver. The main purpose is to allow the low level uart drivers to
3082  * expand uart_port, rather than having yet more levels of structures.
3083  * Caller must hold port_mutex.
3084  */
3085 static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *uport)
3086 {
3087 	struct uart_state *state;
3088 	struct tty_port *port;
3089 	int ret = 0;
3090 	struct device *tty_dev;
3091 	int num_groups;
3092 
3093 	if (uport->line >= drv->nr)
3094 		return -EINVAL;
3095 
3096 	state = drv->state + uport->line;
3097 	port = &state->port;
3098 
3099 	mutex_lock(&port->mutex);
3100 	if (state->uart_port) {
3101 		ret = -EINVAL;
3102 		goto out;
3103 	}
3104 
3105 	/* Link the port to the driver state table and vice versa */
3106 	atomic_set(&state->refcount, 1);
3107 	init_waitqueue_head(&state->remove_wait);
3108 	state->uart_port = uport;
3109 	uport->state = state;
3110 
3111 	state->pm_state = UART_PM_STATE_UNDEFINED;
3112 	uport->cons = drv->cons;
3113 	uport->minor = drv->tty_driver->minor_start + uport->line;
3114 	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
3115 				drv->tty_driver->name_base + uport->line);
3116 	if (!uport->name) {
3117 		ret = -ENOMEM;
3118 		goto out;
3119 	}
3120 
3121 	/*
3122 	 * If this port is in use as a console then the spinlock is already
3123 	 * initialised.
3124 	 */
3125 	if (!uart_console_registered(uport))
3126 		uart_port_spin_lock_init(uport);
3127 
3128 	if (uport->cons && uport->dev)
3129 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
3130 
3131 	tty_port_link_device(port, drv->tty_driver, uport->line);
3132 	uart_configure_port(drv, state, uport);
3133 
3134 	port->console = uart_console(uport);
3135 
3136 	num_groups = 2;
3137 	if (uport->attr_group)
3138 		num_groups++;
3139 
3140 	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
3141 				    GFP_KERNEL);
3142 	if (!uport->tty_groups) {
3143 		ret = -ENOMEM;
3144 		goto out;
3145 	}
3146 	uport->tty_groups[0] = &tty_dev_attr_group;
3147 	if (uport->attr_group)
3148 		uport->tty_groups[1] = uport->attr_group;
3149 
3150 	/*
3151 	 * Register the port whether it's detected or not.  This allows
3152 	 * setserial to be used to alter this port's parameters.
3153 	 */
3154 	tty_dev = tty_port_register_device_attr_serdev(port, drv->tty_driver,
3155 			uport->line, uport->dev, port, uport->tty_groups);
3156 	if (!IS_ERR(tty_dev)) {
3157 		device_set_wakeup_capable(tty_dev, 1);
3158 	} else {
3159 		dev_err(uport->dev, "Cannot register tty device on line %d\n",
3160 		       uport->line);
3161 	}
3162 
3163  out:
3164 	mutex_unlock(&port->mutex);
3165 
3166 	return ret;
3167 }
3168 
3169 /**
3170  * serial_core_remove_one_port - detach a driver defined port structure
3171  * @drv: pointer to the uart low level driver structure for this port
3172  * @uport: uart port structure for this port
3173  *
3174  * Context: task context, might sleep
3175  *
3176  * This unhooks (and hangs up) the specified port structure from the core
3177  * driver. No further calls will be made to the low-level code for this port.
3178  * Caller must hold port_mutex.
3179  */
3180 static void serial_core_remove_one_port(struct uart_driver *drv,
3181 					struct uart_port *uport)
3182 {
3183 	struct uart_state *state = drv->state + uport->line;
3184 	struct tty_port *port = &state->port;
3185 	struct uart_port *uart_port;
3186 	struct tty_struct *tty;
3187 
3188 	mutex_lock(&port->mutex);
3189 	uart_port = uart_port_check(state);
3190 	if (uart_port != uport)
3191 		dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
3192 			  uart_port, uport);
3193 
3194 	if (!uart_port) {
3195 		mutex_unlock(&port->mutex);
3196 		return;
3197 	}
3198 	mutex_unlock(&port->mutex);
3199 
3200 	/*
3201 	 * Remove the devices from the tty layer
3202 	 */
3203 	tty_port_unregister_device(port, drv->tty_driver, uport->line);
3204 
3205 	tty = tty_port_tty_get(port);
3206 	if (tty) {
3207 		tty_vhangup(port->tty);
3208 		tty_kref_put(tty);
3209 	}
3210 
3211 	/*
3212 	 * If the port is used as a console, unregister it
3213 	 */
3214 	if (uart_console(uport))
3215 		unregister_console(uport->cons);
3216 
3217 	/*
3218 	 * Free the port IO and memory resources, if any.
3219 	 */
3220 	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
3221 		uport->ops->release_port(uport);
3222 	kfree(uport->tty_groups);
3223 	kfree(uport->name);
3224 
3225 	/*
3226 	 * Indicate that there isn't a port here anymore.
3227 	 */
3228 	uport->type = PORT_UNKNOWN;
3229 	uport->port_dev = NULL;
3230 
3231 	mutex_lock(&port->mutex);
3232 	WARN_ON(atomic_dec_return(&state->refcount) < 0);
3233 	wait_event(state->remove_wait, !atomic_read(&state->refcount));
3234 	state->uart_port = NULL;
3235 	mutex_unlock(&port->mutex);
3236 }
3237 
3238 /**
3239  * uart_match_port - are the two ports equivalent?
3240  * @port1: first port
3241  * @port2: second port
3242  *
3243  * This utility function can be used to determine whether two uart_port
3244  * structures describe the same port.
3245  */
3246 bool uart_match_port(const struct uart_port *port1,
3247 		const struct uart_port *port2)
3248 {
3249 	if (port1->iotype != port2->iotype)
3250 		return false;
3251 
3252 	switch (port1->iotype) {
3253 	case UPIO_PORT:
3254 		return port1->iobase == port2->iobase;
3255 	case UPIO_HUB6:
3256 		return port1->iobase == port2->iobase &&
3257 		       port1->hub6   == port2->hub6;
3258 	case UPIO_MEM:
3259 	case UPIO_MEM16:
3260 	case UPIO_MEM32:
3261 	case UPIO_MEM32BE:
3262 	case UPIO_AU:
3263 	case UPIO_TSI:
3264 		return port1->mapbase == port2->mapbase;
3265 	}
3266 
3267 	return false;
3268 }
3269 EXPORT_SYMBOL(uart_match_port);
3270 
3271 static struct serial_ctrl_device *
3272 serial_core_get_ctrl_dev(struct serial_port_device *port_dev)
3273 {
3274 	struct device *dev = &port_dev->dev;
3275 
3276 	return to_serial_base_ctrl_device(dev->parent);
3277 }
3278 
3279 /*
3280  * Find a registered serial core controller device if one exists. Returns
3281  * the first device matching the ctrl_id. Caller must hold port_mutex.
3282  */
3283 static struct serial_ctrl_device *serial_core_ctrl_find(struct uart_driver *drv,
3284 							struct device *phys_dev,
3285 							int ctrl_id)
3286 {
3287 	struct uart_state *state;
3288 	int i;
3289 
3290 	lockdep_assert_held(&port_mutex);
3291 
3292 	for (i = 0; i < drv->nr; i++) {
3293 		state = drv->state + i;
3294 		if (!state->uart_port || !state->uart_port->port_dev)
3295 			continue;
3296 
3297 		if (state->uart_port->dev == phys_dev &&
3298 		    state->uart_port->ctrl_id == ctrl_id)
3299 			return serial_core_get_ctrl_dev(state->uart_port->port_dev);
3300 	}
3301 
3302 	return NULL;
3303 }
3304 
3305 static struct serial_ctrl_device *serial_core_ctrl_device_add(struct uart_port *port)
3306 {
3307 	return serial_base_ctrl_add(port, port->dev);
3308 }
3309 
3310 static int serial_core_port_device_add(struct serial_ctrl_device *ctrl_dev,
3311 				       struct uart_port *port)
3312 {
3313 	struct serial_port_device *port_dev;
3314 
3315 	port_dev = serial_base_port_add(port, ctrl_dev);
3316 	if (IS_ERR(port_dev))
3317 		return PTR_ERR(port_dev);
3318 
3319 	port->port_dev = port_dev;
3320 
3321 	return 0;
3322 }
3323 
3324 /*
3325  * Initialize a serial core port device, and a controller device if needed.
3326  */
3327 int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
3328 {
3329 	struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
3330 	int ret;
3331 
3332 	mutex_lock(&port_mutex);
3333 
3334 	/*
3335 	 * Prevent serial_port_runtime_resume() from trying to use the port
3336 	 * until serial_core_add_one_port() has completed
3337 	 */
3338 	port->flags |= UPF_DEAD;
3339 
3340 	/* Inititalize a serial core controller device if needed */
3341 	ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
3342 	if (!ctrl_dev) {
3343 		new_ctrl_dev = serial_core_ctrl_device_add(port);
3344 		if (IS_ERR(new_ctrl_dev)) {
3345 			ret = PTR_ERR(new_ctrl_dev);
3346 			goto err_unlock;
3347 		}
3348 		ctrl_dev = new_ctrl_dev;
3349 	}
3350 
3351 	/*
3352 	 * Initialize a serial core port device. Tag the port dead to prevent
3353 	 * serial_port_runtime_resume() trying to do anything until port has
3354 	 * been registered. It gets cleared by serial_core_add_one_port().
3355 	 */
3356 	ret = serial_core_port_device_add(ctrl_dev, port);
3357 	if (ret)
3358 		goto err_unregister_ctrl_dev;
3359 
3360 	ret = serial_core_add_one_port(drv, port);
3361 	if (ret)
3362 		goto err_unregister_port_dev;
3363 
3364 	port->flags &= ~UPF_DEAD;
3365 
3366 	mutex_unlock(&port_mutex);
3367 
3368 	return 0;
3369 
3370 err_unregister_port_dev:
3371 	serial_base_port_device_remove(port->port_dev);
3372 
3373 err_unregister_ctrl_dev:
3374 	serial_base_ctrl_device_remove(new_ctrl_dev);
3375 
3376 err_unlock:
3377 	mutex_unlock(&port_mutex);
3378 
3379 	return ret;
3380 }
3381 
3382 /*
3383  * Removes a serial core port device, and the related serial core controller
3384  * device if the last instance.
3385  */
3386 void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port)
3387 {
3388 	struct device *phys_dev = port->dev;
3389 	struct serial_port_device *port_dev = port->port_dev;
3390 	struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
3391 	int ctrl_id = port->ctrl_id;
3392 
3393 	mutex_lock(&port_mutex);
3394 
3395 	port->flags |= UPF_DEAD;
3396 
3397 	serial_core_remove_one_port(drv, port);
3398 
3399 	/* Note that struct uart_port *port is no longer valid at this point */
3400 	serial_base_port_device_remove(port_dev);
3401 
3402 	/* Drop the serial core controller device if no ports are using it */
3403 	if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
3404 		serial_base_ctrl_device_remove(ctrl_dev);
3405 
3406 	mutex_unlock(&port_mutex);
3407 }
3408 
3409 /**
3410  * uart_handle_dcd_change - handle a change of carrier detect state
3411  * @uport: uart_port structure for the open port
3412  * @active: new carrier detect status
3413  *
3414  * Caller must hold uport->lock.
3415  */
3416 void uart_handle_dcd_change(struct uart_port *uport, bool active)
3417 {
3418 	struct tty_port *port = &uport->state->port;
3419 	struct tty_struct *tty = port->tty;
3420 	struct tty_ldisc *ld;
3421 
3422 	lockdep_assert_held_once(&uport->lock);
3423 
3424 	if (tty) {
3425 		ld = tty_ldisc_ref(tty);
3426 		if (ld) {
3427 			if (ld->ops->dcd_change)
3428 				ld->ops->dcd_change(tty, active);
3429 			tty_ldisc_deref(ld);
3430 		}
3431 	}
3432 
3433 	uport->icount.dcd++;
3434 
3435 	if (uart_dcd_enabled(uport)) {
3436 		if (active)
3437 			wake_up_interruptible(&port->open_wait);
3438 		else if (tty)
3439 			tty_hangup(tty);
3440 	}
3441 }
3442 EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
3443 
3444 /**
3445  * uart_handle_cts_change - handle a change of clear-to-send state
3446  * @uport: uart_port structure for the open port
3447  * @active: new clear-to-send status
3448  *
3449  * Caller must hold uport->lock.
3450  */
3451 void uart_handle_cts_change(struct uart_port *uport, bool active)
3452 {
3453 	lockdep_assert_held_once(&uport->lock);
3454 
3455 	uport->icount.cts++;
3456 
3457 	if (uart_softcts_mode(uport)) {
3458 		if (uport->hw_stopped) {
3459 			if (active) {
3460 				uport->hw_stopped = false;
3461 				uport->ops->start_tx(uport);
3462 				uart_write_wakeup(uport);
3463 			}
3464 		} else {
3465 			if (!active) {
3466 				uport->hw_stopped = true;
3467 				uport->ops->stop_tx(uport);
3468 			}
3469 		}
3470 
3471 	}
3472 }
3473 EXPORT_SYMBOL_GPL(uart_handle_cts_change);
3474 
3475 /**
3476  * uart_insert_char - push a char to the uart layer
3477  *
3478  * User is responsible to call tty_flip_buffer_push when they are done with
3479  * insertion.
3480  *
3481  * @port: corresponding port
3482  * @status: state of the serial port RX buffer (LSR for 8250)
3483  * @overrun: mask of overrun bits in @status
3484  * @ch: character to push
3485  * @flag: flag for the character (see TTY_NORMAL and friends)
3486  */
3487 void uart_insert_char(struct uart_port *port, unsigned int status,
3488 		      unsigned int overrun, u8 ch, u8 flag)
3489 {
3490 	struct tty_port *tport = &port->state->port;
3491 
3492 	if ((status & port->ignore_status_mask & ~overrun) == 0)
3493 		if (tty_insert_flip_char(tport, ch, flag) == 0)
3494 			++port->icount.buf_overrun;
3495 
3496 	/*
3497 	 * Overrun is special.  Since it's reported immediately,
3498 	 * it doesn't affect the current character.
3499 	 */
3500 	if (status & ~port->ignore_status_mask & overrun)
3501 		if (tty_insert_flip_char(tport, 0, TTY_OVERRUN) == 0)
3502 			++port->icount.buf_overrun;
3503 }
3504 EXPORT_SYMBOL_GPL(uart_insert_char);
3505 
3506 #ifdef CONFIG_MAGIC_SYSRQ_SERIAL
3507 static const u8 sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
3508 
3509 static void uart_sysrq_on(struct work_struct *w)
3510 {
3511 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3512 
3513 	sysrq_toggle_support(1);
3514 	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
3515 		sysrq_toggle_seq_len, sysrq_toggle_seq);
3516 }
3517 static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
3518 
3519 /**
3520  * uart_try_toggle_sysrq - Enables SysRq from serial line
3521  * @port: uart_port structure where char(s) after BREAK met
3522  * @ch: new character in the sequence after received BREAK
3523  *
3524  * Enables magic SysRq when the required sequence is met on port
3525  * (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
3526  *
3527  * Returns: %false if @ch is out of enabling sequence and should be
3528  * handled some other way, %true if @ch was consumed.
3529  */
3530 bool uart_try_toggle_sysrq(struct uart_port *port, u8 ch)
3531 {
3532 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3533 
3534 	if (!sysrq_toggle_seq_len)
3535 		return false;
3536 
3537 	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
3538 	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
3539 		port->sysrq_seq = 0;
3540 		return false;
3541 	}
3542 
3543 	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
3544 		port->sysrq = jiffies + SYSRQ_TIMEOUT;
3545 		return true;
3546 	}
3547 
3548 	schedule_work(&sysrq_enable_work);
3549 
3550 	port->sysrq = 0;
3551 	return true;
3552 }
3553 EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
3554 #endif
3555 
3556 /**
3557  * uart_get_rs485_mode() - retrieve rs485 properties for given uart
3558  * @port: uart device's target port
3559  *
3560  * This function implements the device tree binding described in
3561  * Documentation/devicetree/bindings/serial/rs485.txt.
3562  */
3563 int uart_get_rs485_mode(struct uart_port *port)
3564 {
3565 	struct serial_rs485 *rs485conf = &port->rs485;
3566 	struct device *dev = port->dev;
3567 	u32 rs485_delay[2];
3568 	int ret;
3569 	int rx_during_tx_gpio_flag;
3570 
3571 	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
3572 					     rs485_delay, 2);
3573 	if (!ret) {
3574 		rs485conf->delay_rts_before_send = rs485_delay[0];
3575 		rs485conf->delay_rts_after_send = rs485_delay[1];
3576 	} else {
3577 		rs485conf->delay_rts_before_send = 0;
3578 		rs485conf->delay_rts_after_send = 0;
3579 	}
3580 
3581 	uart_sanitize_serial_rs485_delays(port, rs485conf);
3582 
3583 	/*
3584 	 * Clear full-duplex and enabled flags, set RTS polarity to active high
3585 	 * to get to a defined state with the following properties:
3586 	 */
3587 	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
3588 			      SER_RS485_TERMINATE_BUS |
3589 			      SER_RS485_RTS_AFTER_SEND);
3590 	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
3591 
3592 	if (device_property_read_bool(dev, "rs485-rx-during-tx"))
3593 		rs485conf->flags |= SER_RS485_RX_DURING_TX;
3594 
3595 	if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
3596 		rs485conf->flags |= SER_RS485_ENABLED;
3597 
3598 	if (device_property_read_bool(dev, "rs485-rts-active-low")) {
3599 		rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
3600 		rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
3601 	}
3602 
3603 	/*
3604 	 * Disabling termination by default is the safe choice:  Else if many
3605 	 * bus participants enable it, no communication is possible at all.
3606 	 * Works fine for short cables and users may enable for longer cables.
3607 	 */
3608 	port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
3609 							GPIOD_OUT_LOW);
3610 	if (IS_ERR(port->rs485_term_gpio)) {
3611 		ret = PTR_ERR(port->rs485_term_gpio);
3612 		port->rs485_term_gpio = NULL;
3613 		return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n");
3614 	}
3615 	if (port->rs485_term_gpio)
3616 		port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;
3617 
3618 	rx_during_tx_gpio_flag = (rs485conf->flags & SER_RS485_RX_DURING_TX) ?
3619 				 GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
3620 	port->rs485_rx_during_tx_gpio = devm_gpiod_get_optional(dev,
3621 								"rs485-rx-during-tx",
3622 								rx_during_tx_gpio_flag);
3623 	if (IS_ERR(port->rs485_rx_during_tx_gpio)) {
3624 		ret = PTR_ERR(port->rs485_rx_during_tx_gpio);
3625 		port->rs485_rx_during_tx_gpio = NULL;
3626 		return dev_err_probe(dev, ret, "Cannot get rs485-rx-during-tx-gpios\n");
3627 	}
3628 
3629 	return 0;
3630 }
3631 EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
3632 
3633 /* Compile-time assertions for serial_rs485 layout */
3634 static_assert(offsetof(struct serial_rs485, padding) ==
3635               (offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
3636 static_assert(offsetof(struct serial_rs485, padding1) ==
3637 	      offsetof(struct serial_rs485, padding[1]));
3638 static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
3639 	      sizeof(struct serial_rs485));
3640 
3641 MODULE_DESCRIPTION("Serial driver core");
3642 MODULE_LICENSE("GPL");
3643