xref: /linux/drivers/tty/serial/serial_core.c (revision 55ec81f7517fad09135f65552cea0a3ee84fff30)
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_active(&port_dev->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 	int ret;
1408 
1409 	uart_sanitize_serial_rs485(port, rs485);
1410 	uart_set_rs485_termination(port, rs485);
1411 
1412 	ret = port->rs485_config(port, NULL, rs485);
1413 	if (ret)
1414 		memset(rs485, 0, sizeof(*rs485));
1415 
1416 	return ret;
1417 }
1418 
1419 static int uart_get_rs485_config(struct uart_port *port,
1420 			 struct serial_rs485 __user *rs485)
1421 {
1422 	unsigned long flags;
1423 	struct serial_rs485 aux;
1424 
1425 	spin_lock_irqsave(&port->lock, flags);
1426 	aux = port->rs485;
1427 	spin_unlock_irqrestore(&port->lock, flags);
1428 
1429 	if (copy_to_user(rs485, &aux, sizeof(aux)))
1430 		return -EFAULT;
1431 
1432 	return 0;
1433 }
1434 
1435 static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
1436 			 struct serial_rs485 __user *rs485_user)
1437 {
1438 	struct serial_rs485 rs485;
1439 	int ret;
1440 	unsigned long flags;
1441 
1442 	if (!port->rs485_config)
1443 		return -ENOTTY;
1444 
1445 	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
1446 		return -EFAULT;
1447 
1448 	ret = uart_check_rs485_flags(port, &rs485);
1449 	if (ret)
1450 		return ret;
1451 	uart_sanitize_serial_rs485(port, &rs485);
1452 	uart_set_rs485_termination(port, &rs485);
1453 
1454 	spin_lock_irqsave(&port->lock, flags);
1455 	ret = port->rs485_config(port, &tty->termios, &rs485);
1456 	if (!ret) {
1457 		port->rs485 = rs485;
1458 
1459 		/* Reset RTS and other mctrl lines when disabling RS485 */
1460 		if (!(rs485.flags & SER_RS485_ENABLED))
1461 			port->ops->set_mctrl(port, port->mctrl);
1462 	}
1463 	spin_unlock_irqrestore(&port->lock, flags);
1464 	if (ret)
1465 		return ret;
1466 
1467 	if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
1468 		return -EFAULT;
1469 
1470 	return 0;
1471 }
1472 
1473 static int uart_get_iso7816_config(struct uart_port *port,
1474 				   struct serial_iso7816 __user *iso7816)
1475 {
1476 	unsigned long flags;
1477 	struct serial_iso7816 aux;
1478 
1479 	if (!port->iso7816_config)
1480 		return -ENOTTY;
1481 
1482 	spin_lock_irqsave(&port->lock, flags);
1483 	aux = port->iso7816;
1484 	spin_unlock_irqrestore(&port->lock, flags);
1485 
1486 	if (copy_to_user(iso7816, &aux, sizeof(aux)))
1487 		return -EFAULT;
1488 
1489 	return 0;
1490 }
1491 
1492 static int uart_set_iso7816_config(struct uart_port *port,
1493 				   struct serial_iso7816 __user *iso7816_user)
1494 {
1495 	struct serial_iso7816 iso7816;
1496 	int i, ret;
1497 	unsigned long flags;
1498 
1499 	if (!port->iso7816_config)
1500 		return -ENOTTY;
1501 
1502 	if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
1503 		return -EFAULT;
1504 
1505 	/*
1506 	 * There are 5 words reserved for future use. Check that userspace
1507 	 * doesn't put stuff in there to prevent breakages in the future.
1508 	 */
1509 	for (i = 0; i < ARRAY_SIZE(iso7816.reserved); i++)
1510 		if (iso7816.reserved[i])
1511 			return -EINVAL;
1512 
1513 	spin_lock_irqsave(&port->lock, flags);
1514 	ret = port->iso7816_config(port, &iso7816);
1515 	spin_unlock_irqrestore(&port->lock, flags);
1516 	if (ret)
1517 		return ret;
1518 
1519 	if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
1520 		return -EFAULT;
1521 
1522 	return 0;
1523 }
1524 
1525 /*
1526  * Called via sys_ioctl.  We can use spin_lock_irq() here.
1527  */
1528 static int
1529 uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
1530 {
1531 	struct uart_state *state = tty->driver_data;
1532 	struct tty_port *port = &state->port;
1533 	struct uart_port *uport;
1534 	void __user *uarg = (void __user *)arg;
1535 	int ret = -ENOIOCTLCMD;
1536 
1537 
1538 	/*
1539 	 * These ioctls don't rely on the hardware to be present.
1540 	 */
1541 	switch (cmd) {
1542 	case TIOCSERCONFIG:
1543 		down_write(&tty->termios_rwsem);
1544 		ret = uart_do_autoconfig(tty, state);
1545 		up_write(&tty->termios_rwsem);
1546 		break;
1547 	}
1548 
1549 	if (ret != -ENOIOCTLCMD)
1550 		goto out;
1551 
1552 	if (tty_io_error(tty)) {
1553 		ret = -EIO;
1554 		goto out;
1555 	}
1556 
1557 	/*
1558 	 * The following should only be used when hardware is present.
1559 	 */
1560 	switch (cmd) {
1561 	case TIOCMIWAIT:
1562 		ret = uart_wait_modem_status(state, arg);
1563 		break;
1564 	}
1565 
1566 	if (ret != -ENOIOCTLCMD)
1567 		goto out;
1568 
1569 	/* rs485_config requires more locking than others */
1570 	if (cmd == TIOCSRS485)
1571 		down_write(&tty->termios_rwsem);
1572 
1573 	mutex_lock(&port->mutex);
1574 	uport = uart_port_check(state);
1575 
1576 	if (!uport || tty_io_error(tty)) {
1577 		ret = -EIO;
1578 		goto out_up;
1579 	}
1580 
1581 	/*
1582 	 * All these rely on hardware being present and need to be
1583 	 * protected against the tty being hung up.
1584 	 */
1585 
1586 	switch (cmd) {
1587 	case TIOCSERGETLSR: /* Get line status register */
1588 		ret = uart_get_lsr_info(tty, state, uarg);
1589 		break;
1590 
1591 	case TIOCGRS485:
1592 		ret = uart_get_rs485_config(uport, uarg);
1593 		break;
1594 
1595 	case TIOCSRS485:
1596 		ret = uart_set_rs485_config(tty, uport, uarg);
1597 		break;
1598 
1599 	case TIOCSISO7816:
1600 		ret = uart_set_iso7816_config(state->uart_port, uarg);
1601 		break;
1602 
1603 	case TIOCGISO7816:
1604 		ret = uart_get_iso7816_config(state->uart_port, uarg);
1605 		break;
1606 	default:
1607 		if (uport->ops->ioctl)
1608 			ret = uport->ops->ioctl(uport, cmd, arg);
1609 		break;
1610 	}
1611 out_up:
1612 	mutex_unlock(&port->mutex);
1613 	if (cmd == TIOCSRS485)
1614 		up_write(&tty->termios_rwsem);
1615 out:
1616 	return ret;
1617 }
1618 
1619 static void uart_set_ldisc(struct tty_struct *tty)
1620 {
1621 	struct uart_state *state = tty->driver_data;
1622 	struct uart_port *uport;
1623 	struct tty_port *port = &state->port;
1624 
1625 	if (!tty_port_initialized(port))
1626 		return;
1627 
1628 	mutex_lock(&state->port.mutex);
1629 	uport = uart_port_check(state);
1630 	if (uport && uport->ops->set_ldisc)
1631 		uport->ops->set_ldisc(uport, &tty->termios);
1632 	mutex_unlock(&state->port.mutex);
1633 }
1634 
1635 static void uart_set_termios(struct tty_struct *tty,
1636 			     const struct ktermios *old_termios)
1637 {
1638 	struct uart_state *state = tty->driver_data;
1639 	struct uart_port *uport;
1640 	unsigned int cflag = tty->termios.c_cflag;
1641 	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
1642 	bool sw_changed = false;
1643 
1644 	mutex_lock(&state->port.mutex);
1645 	uport = uart_port_check(state);
1646 	if (!uport)
1647 		goto out;
1648 
1649 	/*
1650 	 * Drivers doing software flow control also need to know
1651 	 * about changes to these input settings.
1652 	 */
1653 	if (uport->flags & UPF_SOFT_FLOW) {
1654 		iflag_mask |= IXANY|IXON|IXOFF;
1655 		sw_changed =
1656 		   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
1657 		   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
1658 	}
1659 
1660 	/*
1661 	 * These are the bits that are used to setup various
1662 	 * flags in the low level driver. We can ignore the Bfoo
1663 	 * bits in c_cflag; c_[io]speed will always be set
1664 	 * appropriately by set_termios() in tty_ioctl.c
1665 	 */
1666 	if ((cflag ^ old_termios->c_cflag) == 0 &&
1667 	    tty->termios.c_ospeed == old_termios->c_ospeed &&
1668 	    tty->termios.c_ispeed == old_termios->c_ispeed &&
1669 	    ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
1670 	    !sw_changed) {
1671 		goto out;
1672 	}
1673 
1674 	uart_change_line_settings(tty, state, old_termios);
1675 	/* reload cflag from termios; port driver may have overridden flags */
1676 	cflag = tty->termios.c_cflag;
1677 
1678 	/* Handle transition to B0 status */
1679 	if (((old_termios->c_cflag & CBAUD) != B0) && ((cflag & CBAUD) == B0))
1680 		uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
1681 	/* Handle transition away from B0 status */
1682 	else if (((old_termios->c_cflag & CBAUD) == B0) && ((cflag & CBAUD) != B0)) {
1683 		unsigned int mask = TIOCM_DTR;
1684 
1685 		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
1686 			mask |= TIOCM_RTS;
1687 		uart_set_mctrl(uport, mask);
1688 	}
1689 out:
1690 	mutex_unlock(&state->port.mutex);
1691 }
1692 
1693 /*
1694  * Calls to uart_close() are serialised via the tty_lock in
1695  *   drivers/tty/tty_io.c:tty_release()
1696  *   drivers/tty/tty_io.c:do_tty_hangup()
1697  */
1698 static void uart_close(struct tty_struct *tty, struct file *filp)
1699 {
1700 	struct uart_state *state = tty->driver_data;
1701 
1702 	if (!state) {
1703 		struct uart_driver *drv = tty->driver->driver_state;
1704 		struct tty_port *port;
1705 
1706 		state = drv->state + tty->index;
1707 		port = &state->port;
1708 		spin_lock_irq(&port->lock);
1709 		--port->count;
1710 		spin_unlock_irq(&port->lock);
1711 		return;
1712 	}
1713 
1714 	pr_debug("uart_close(%d) called\n", tty->index);
1715 
1716 	tty_port_close(tty->port, tty, filp);
1717 }
1718 
1719 static void uart_tty_port_shutdown(struct tty_port *port)
1720 {
1721 	struct uart_state *state = container_of(port, struct uart_state, port);
1722 	struct uart_port *uport = uart_port_check(state);
1723 	char *buf;
1724 
1725 	/*
1726 	 * At this point, we stop accepting input.  To do this, we
1727 	 * disable the receive line status interrupts.
1728 	 */
1729 	if (WARN(!uport, "detached port still initialized!\n"))
1730 		return;
1731 
1732 	spin_lock_irq(&uport->lock);
1733 	uport->ops->stop_rx(uport);
1734 	spin_unlock_irq(&uport->lock);
1735 
1736 	uart_port_shutdown(port);
1737 
1738 	/*
1739 	 * It's possible for shutdown to be called after suspend if we get
1740 	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
1741 	 * we don't try to resume a port that has been shutdown.
1742 	 */
1743 	tty_port_set_suspended(port, false);
1744 
1745 	/*
1746 	 * Free the transmit buffer.
1747 	 */
1748 	spin_lock_irq(&uport->lock);
1749 	buf = state->xmit.buf;
1750 	state->xmit.buf = NULL;
1751 	spin_unlock_irq(&uport->lock);
1752 
1753 	free_page((unsigned long)buf);
1754 
1755 	uart_change_pm(state, UART_PM_STATE_OFF);
1756 }
1757 
1758 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1759 {
1760 	struct uart_state *state = tty->driver_data;
1761 	struct uart_port *port;
1762 	unsigned long char_time, expire, fifo_timeout;
1763 
1764 	port = uart_port_ref(state);
1765 	if (!port)
1766 		return;
1767 
1768 	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
1769 		uart_port_deref(port);
1770 		return;
1771 	}
1772 
1773 	/*
1774 	 * Set the check interval to be 1/5 of the estimated time to
1775 	 * send a single character, and make it at least 1.  The check
1776 	 * interval should also be less than the timeout.
1777 	 *
1778 	 * Note: we have to use pretty tight timings here to satisfy
1779 	 * the NIST-PCTS.
1780 	 */
1781 	char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);
1782 
1783 	if (timeout && timeout < char_time)
1784 		char_time = timeout;
1785 
1786 	if (!uart_cts_enabled(port)) {
1787 		/*
1788 		 * If the transmitter hasn't cleared in twice the approximate
1789 		 * amount of time to send the entire FIFO, it probably won't
1790 		 * ever clear.  This assumes the UART isn't doing flow
1791 		 * control, which is currently the case.  Hence, if it ever
1792 		 * takes longer than FIFO timeout, this is probably due to a
1793 		 * UART bug of some kind.  So, we clamp the timeout parameter at
1794 		 * 2 * FIFO timeout.
1795 		 */
1796 		fifo_timeout = uart_fifo_timeout(port);
1797 		if (timeout == 0 || timeout > 2 * fifo_timeout)
1798 			timeout = 2 * fifo_timeout;
1799 	}
1800 
1801 	expire = jiffies + timeout;
1802 
1803 	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
1804 		port->line, jiffies, expire);
1805 
1806 	/*
1807 	 * Check whether the transmitter is empty every 'char_time'.
1808 	 * 'timeout' / 'expire' give us the maximum amount of time
1809 	 * we wait.
1810 	 */
1811 	while (!port->ops->tx_empty(port)) {
1812 		msleep_interruptible(jiffies_to_msecs(char_time));
1813 		if (signal_pending(current))
1814 			break;
1815 		if (timeout && time_after(jiffies, expire))
1816 			break;
1817 	}
1818 	uart_port_deref(port);
1819 }
1820 
1821 /*
1822  * Calls to uart_hangup() are serialised by the tty_lock in
1823  *   drivers/tty/tty_io.c:do_tty_hangup()
1824  * This runs from a workqueue and can sleep for a _short_ time only.
1825  */
1826 static void uart_hangup(struct tty_struct *tty)
1827 {
1828 	struct uart_state *state = tty->driver_data;
1829 	struct tty_port *port = &state->port;
1830 	struct uart_port *uport;
1831 	unsigned long flags;
1832 
1833 	pr_debug("uart_hangup(%d)\n", tty->index);
1834 
1835 	mutex_lock(&port->mutex);
1836 	uport = uart_port_check(state);
1837 	WARN(!uport, "hangup of detached port!\n");
1838 
1839 	if (tty_port_active(port)) {
1840 		uart_flush_buffer(tty);
1841 		uart_shutdown(tty, state);
1842 		spin_lock_irqsave(&port->lock, flags);
1843 		port->count = 0;
1844 		spin_unlock_irqrestore(&port->lock, flags);
1845 		tty_port_set_active(port, false);
1846 		tty_port_tty_set(port, NULL);
1847 		if (uport && !uart_console(uport))
1848 			uart_change_pm(state, UART_PM_STATE_OFF);
1849 		wake_up_interruptible(&port->open_wait);
1850 		wake_up_interruptible(&port->delta_msr_wait);
1851 	}
1852 	mutex_unlock(&port->mutex);
1853 }
1854 
1855 /* uport == NULL if uart_port has already been removed */
1856 static void uart_port_shutdown(struct tty_port *port)
1857 {
1858 	struct uart_state *state = container_of(port, struct uart_state, port);
1859 	struct uart_port *uport = uart_port_check(state);
1860 
1861 	/*
1862 	 * clear delta_msr_wait queue to avoid mem leaks: we may free
1863 	 * the irq here so the queue might never be woken up.  Note
1864 	 * that we won't end up waiting on delta_msr_wait again since
1865 	 * any outstanding file descriptors should be pointing at
1866 	 * hung_up_tty_fops now.
1867 	 */
1868 	wake_up_interruptible(&port->delta_msr_wait);
1869 
1870 	if (uport) {
1871 		/* Free the IRQ and disable the port. */
1872 		uport->ops->shutdown(uport);
1873 
1874 		/* Ensure that the IRQ handler isn't running on another CPU. */
1875 		synchronize_irq(uport->irq);
1876 	}
1877 }
1878 
1879 static bool uart_carrier_raised(struct tty_port *port)
1880 {
1881 	struct uart_state *state = container_of(port, struct uart_state, port);
1882 	struct uart_port *uport;
1883 	int mctrl;
1884 
1885 	uport = uart_port_ref(state);
1886 	/*
1887 	 * Should never observe uport == NULL since checks for hangup should
1888 	 * abort the tty_port_block_til_ready() loop before checking for carrier
1889 	 * raised -- but report carrier raised if it does anyway so open will
1890 	 * continue and not sleep
1891 	 */
1892 	if (WARN_ON(!uport))
1893 		return true;
1894 	spin_lock_irq(&uport->lock);
1895 	uart_enable_ms(uport);
1896 	mctrl = uport->ops->get_mctrl(uport);
1897 	spin_unlock_irq(&uport->lock);
1898 	uart_port_deref(uport);
1899 
1900 	return mctrl & TIOCM_CAR;
1901 }
1902 
1903 static void uart_dtr_rts(struct tty_port *port, bool active)
1904 {
1905 	struct uart_state *state = container_of(port, struct uart_state, port);
1906 	struct uart_port *uport;
1907 
1908 	uport = uart_port_ref(state);
1909 	if (!uport)
1910 		return;
1911 	uart_port_dtr_rts(uport, active);
1912 	uart_port_deref(uport);
1913 }
1914 
1915 static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
1916 {
1917 	struct uart_driver *drv = driver->driver_state;
1918 	struct uart_state *state = drv->state + tty->index;
1919 
1920 	tty->driver_data = state;
1921 
1922 	return tty_standard_install(driver, tty);
1923 }
1924 
1925 /*
1926  * Calls to uart_open are serialised by the tty_lock in
1927  *   drivers/tty/tty_io.c:tty_open()
1928  * Note that if this fails, then uart_close() _will_ be called.
1929  *
1930  * In time, we want to scrap the "opening nonpresent ports"
1931  * behaviour and implement an alternative way for setserial
1932  * to set base addresses/ports/types.  This will allow us to
1933  * get rid of a certain amount of extra tests.
1934  */
1935 static int uart_open(struct tty_struct *tty, struct file *filp)
1936 {
1937 	struct uart_state *state = tty->driver_data;
1938 	int retval;
1939 
1940 	retval = tty_port_open(&state->port, tty, filp);
1941 	if (retval > 0)
1942 		retval = 0;
1943 
1944 	return retval;
1945 }
1946 
1947 static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
1948 {
1949 	struct uart_state *state = container_of(port, struct uart_state, port);
1950 	struct uart_port *uport;
1951 	int ret;
1952 
1953 	uport = uart_port_check(state);
1954 	if (!uport || uport->flags & UPF_DEAD)
1955 		return -ENXIO;
1956 
1957 	/*
1958 	 * Start up the serial port.
1959 	 */
1960 	ret = uart_startup(tty, state, false);
1961 	if (ret > 0)
1962 		tty_port_set_active(port, true);
1963 
1964 	return ret;
1965 }
1966 
1967 static const char *uart_type(struct uart_port *port)
1968 {
1969 	const char *str = NULL;
1970 
1971 	if (port->ops->type)
1972 		str = port->ops->type(port);
1973 
1974 	if (!str)
1975 		str = "unknown";
1976 
1977 	return str;
1978 }
1979 
1980 #ifdef CONFIG_PROC_FS
1981 
1982 static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
1983 {
1984 	struct uart_state *state = drv->state + i;
1985 	struct tty_port *port = &state->port;
1986 	enum uart_pm_state pm_state;
1987 	struct uart_port *uport;
1988 	char stat_buf[32];
1989 	unsigned int status;
1990 	int mmio;
1991 
1992 	mutex_lock(&port->mutex);
1993 	uport = uart_port_check(state);
1994 	if (!uport)
1995 		goto out;
1996 
1997 	mmio = uport->iotype >= UPIO_MEM;
1998 	seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
1999 			uport->line, uart_type(uport),
2000 			mmio ? "mmio:0x" : "port:",
2001 			mmio ? (unsigned long long)uport->mapbase
2002 			     : (unsigned long long)uport->iobase,
2003 			uport->irq);
2004 
2005 	if (uport->type == PORT_UNKNOWN) {
2006 		seq_putc(m, '\n');
2007 		goto out;
2008 	}
2009 
2010 	if (capable(CAP_SYS_ADMIN)) {
2011 		pm_state = state->pm_state;
2012 		if (pm_state != UART_PM_STATE_ON)
2013 			uart_change_pm(state, UART_PM_STATE_ON);
2014 		spin_lock_irq(&uport->lock);
2015 		status = uport->ops->get_mctrl(uport);
2016 		spin_unlock_irq(&uport->lock);
2017 		if (pm_state != UART_PM_STATE_ON)
2018 			uart_change_pm(state, pm_state);
2019 
2020 		seq_printf(m, " tx:%d rx:%d",
2021 				uport->icount.tx, uport->icount.rx);
2022 		if (uport->icount.frame)
2023 			seq_printf(m, " fe:%d",	uport->icount.frame);
2024 		if (uport->icount.parity)
2025 			seq_printf(m, " pe:%d",	uport->icount.parity);
2026 		if (uport->icount.brk)
2027 			seq_printf(m, " brk:%d", uport->icount.brk);
2028 		if (uport->icount.overrun)
2029 			seq_printf(m, " oe:%d", uport->icount.overrun);
2030 		if (uport->icount.buf_overrun)
2031 			seq_printf(m, " bo:%d", uport->icount.buf_overrun);
2032 
2033 #define INFOBIT(bit, str) \
2034 	if (uport->mctrl & (bit)) \
2035 		strncat(stat_buf, (str), sizeof(stat_buf) - \
2036 			strlen(stat_buf) - 2)
2037 #define STATBIT(bit, str) \
2038 	if (status & (bit)) \
2039 		strncat(stat_buf, (str), sizeof(stat_buf) - \
2040 		       strlen(stat_buf) - 2)
2041 
2042 		stat_buf[0] = '\0';
2043 		stat_buf[1] = '\0';
2044 		INFOBIT(TIOCM_RTS, "|RTS");
2045 		STATBIT(TIOCM_CTS, "|CTS");
2046 		INFOBIT(TIOCM_DTR, "|DTR");
2047 		STATBIT(TIOCM_DSR, "|DSR");
2048 		STATBIT(TIOCM_CAR, "|CD");
2049 		STATBIT(TIOCM_RNG, "|RI");
2050 		if (stat_buf[0])
2051 			stat_buf[0] = ' ';
2052 
2053 		seq_puts(m, stat_buf);
2054 	}
2055 	seq_putc(m, '\n');
2056 #undef STATBIT
2057 #undef INFOBIT
2058 out:
2059 	mutex_unlock(&port->mutex);
2060 }
2061 
2062 static int uart_proc_show(struct seq_file *m, void *v)
2063 {
2064 	struct tty_driver *ttydrv = m->private;
2065 	struct uart_driver *drv = ttydrv->driver_state;
2066 	int i;
2067 
2068 	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
2069 	for (i = 0; i < drv->nr; i++)
2070 		uart_line_info(m, drv, i);
2071 	return 0;
2072 }
2073 #endif
2074 
2075 static void uart_port_spin_lock_init(struct uart_port *port)
2076 {
2077 	spin_lock_init(&port->lock);
2078 	lockdep_set_class(&port->lock, &port_lock_key);
2079 }
2080 
2081 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
2082 /**
2083  * uart_console_write - write a console message to a serial port
2084  * @port: the port to write the message
2085  * @s: array of characters
2086  * @count: number of characters in string to write
2087  * @putchar: function to write character to port
2088  */
2089 void uart_console_write(struct uart_port *port, const char *s,
2090 			unsigned int count,
2091 			void (*putchar)(struct uart_port *, unsigned char))
2092 {
2093 	unsigned int i;
2094 
2095 	for (i = 0; i < count; i++, s++) {
2096 		if (*s == '\n')
2097 			putchar(port, '\r');
2098 		putchar(port, *s);
2099 	}
2100 }
2101 EXPORT_SYMBOL_GPL(uart_console_write);
2102 
2103 /**
2104  * uart_get_console - get uart port for console
2105  * @ports: ports to search in
2106  * @nr: number of @ports
2107  * @co: console to search for
2108  * Returns: uart_port for the console @co
2109  *
2110  * Check whether an invalid uart number has been specified (as @co->index), and
2111  * if so, search for the first available port that does have console support.
2112  */
2113 struct uart_port * __init
2114 uart_get_console(struct uart_port *ports, int nr, struct console *co)
2115 {
2116 	int idx = co->index;
2117 
2118 	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
2119 				     ports[idx].membase == NULL))
2120 		for (idx = 0; idx < nr; idx++)
2121 			if (ports[idx].iobase != 0 ||
2122 			    ports[idx].membase != NULL)
2123 				break;
2124 
2125 	co->index = idx;
2126 
2127 	return ports + idx;
2128 }
2129 
2130 /**
2131  * uart_parse_earlycon - Parse earlycon options
2132  * @p:	     ptr to 2nd field (ie., just beyond '<name>,')
2133  * @iotype:  ptr for decoded iotype (out)
2134  * @addr:    ptr for decoded mapbase/iobase (out)
2135  * @options: ptr for <options> field; %NULL if not present (out)
2136  *
2137  * Decodes earlycon kernel command line parameters of the form:
2138  *  * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2139  *  * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2140  *
2141  * The optional form:
2142  *  * earlycon=<name>,0x<addr>,<options>
2143  *  * console=<name>,0x<addr>,<options>
2144  *
2145  * is also accepted; the returned @iotype will be %UPIO_MEM.
2146  *
2147  * Returns: 0 on success or -%EINVAL on failure
2148  */
2149 int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
2150 			char **options)
2151 {
2152 	if (strncmp(p, "mmio,", 5) == 0) {
2153 		*iotype = UPIO_MEM;
2154 		p += 5;
2155 	} else if (strncmp(p, "mmio16,", 7) == 0) {
2156 		*iotype = UPIO_MEM16;
2157 		p += 7;
2158 	} else if (strncmp(p, "mmio32,", 7) == 0) {
2159 		*iotype = UPIO_MEM32;
2160 		p += 7;
2161 	} else if (strncmp(p, "mmio32be,", 9) == 0) {
2162 		*iotype = UPIO_MEM32BE;
2163 		p += 9;
2164 	} else if (strncmp(p, "mmio32native,", 13) == 0) {
2165 		*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
2166 			UPIO_MEM32BE : UPIO_MEM32;
2167 		p += 13;
2168 	} else if (strncmp(p, "io,", 3) == 0) {
2169 		*iotype = UPIO_PORT;
2170 		p += 3;
2171 	} else if (strncmp(p, "0x", 2) == 0) {
2172 		*iotype = UPIO_MEM;
2173 	} else {
2174 		return -EINVAL;
2175 	}
2176 
2177 	/*
2178 	 * Before you replace it with kstrtoull(), think about options separator
2179 	 * (',') it will not tolerate
2180 	 */
2181 	*addr = simple_strtoull(p, NULL, 0);
2182 	p = strchr(p, ',');
2183 	if (p)
2184 		p++;
2185 
2186 	*options = p;
2187 	return 0;
2188 }
2189 EXPORT_SYMBOL_GPL(uart_parse_earlycon);
2190 
2191 /**
2192  * uart_parse_options - Parse serial port baud/parity/bits/flow control.
2193  * @options: pointer to option string
2194  * @baud: pointer to an 'int' variable for the baud rate.
2195  * @parity: pointer to an 'int' variable for the parity.
2196  * @bits: pointer to an 'int' variable for the number of data bits.
2197  * @flow: pointer to an 'int' variable for the flow control character.
2198  *
2199  * uart_parse_options() decodes a string containing the serial console
2200  * options. The format of the string is <baud><parity><bits><flow>,
2201  * eg: 115200n8r
2202  */
2203 void
2204 uart_parse_options(const char *options, int *baud, int *parity,
2205 		   int *bits, int *flow)
2206 {
2207 	const char *s = options;
2208 
2209 	*baud = simple_strtoul(s, NULL, 10);
2210 	while (*s >= '0' && *s <= '9')
2211 		s++;
2212 	if (*s)
2213 		*parity = *s++;
2214 	if (*s)
2215 		*bits = *s++ - '0';
2216 	if (*s)
2217 		*flow = *s;
2218 }
2219 EXPORT_SYMBOL_GPL(uart_parse_options);
2220 
2221 /**
2222  * uart_set_options - setup the serial console parameters
2223  * @port: pointer to the serial ports uart_port structure
2224  * @co: console pointer
2225  * @baud: baud rate
2226  * @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
2227  * @bits: number of data bits
2228  * @flow: flow control character - 'r' (rts)
2229  *
2230  * Locking: Caller must hold console_list_lock in order to serialize
2231  * early initialization of the serial-console lock.
2232  */
2233 int
2234 uart_set_options(struct uart_port *port, struct console *co,
2235 		 int baud, int parity, int bits, int flow)
2236 {
2237 	struct ktermios termios;
2238 	static struct ktermios dummy;
2239 
2240 	/*
2241 	 * Ensure that the serial-console lock is initialised early.
2242 	 *
2243 	 * Note that the console-registered check is needed because
2244 	 * kgdboc can call uart_set_options() for an already registered
2245 	 * console via tty_find_polling_driver() and uart_poll_init().
2246 	 */
2247 	if (!uart_console_registered_locked(port) && !port->console_reinit)
2248 		uart_port_spin_lock_init(port);
2249 
2250 	memset(&termios, 0, sizeof(struct ktermios));
2251 
2252 	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
2253 	tty_termios_encode_baud_rate(&termios, baud, baud);
2254 
2255 	if (bits == 7)
2256 		termios.c_cflag |= CS7;
2257 	else
2258 		termios.c_cflag |= CS8;
2259 
2260 	switch (parity) {
2261 	case 'o': case 'O':
2262 		termios.c_cflag |= PARODD;
2263 		fallthrough;
2264 	case 'e': case 'E':
2265 		termios.c_cflag |= PARENB;
2266 		break;
2267 	}
2268 
2269 	if (flow == 'r')
2270 		termios.c_cflag |= CRTSCTS;
2271 
2272 	/*
2273 	 * some uarts on other side don't support no flow control.
2274 	 * So we set * DTR in host uart to make them happy
2275 	 */
2276 	port->mctrl |= TIOCM_DTR;
2277 
2278 	port->ops->set_termios(port, &termios, &dummy);
2279 	/*
2280 	 * Allow the setting of the UART parameters with a NULL console
2281 	 * too:
2282 	 */
2283 	if (co) {
2284 		co->cflag = termios.c_cflag;
2285 		co->ispeed = termios.c_ispeed;
2286 		co->ospeed = termios.c_ospeed;
2287 	}
2288 
2289 	return 0;
2290 }
2291 EXPORT_SYMBOL_GPL(uart_set_options);
2292 #endif /* CONFIG_SERIAL_CORE_CONSOLE */
2293 
2294 /**
2295  * uart_change_pm - set power state of the port
2296  *
2297  * @state: port descriptor
2298  * @pm_state: new state
2299  *
2300  * Locking: port->mutex has to be held
2301  */
2302 static void uart_change_pm(struct uart_state *state,
2303 			   enum uart_pm_state pm_state)
2304 {
2305 	struct uart_port *port = uart_port_check(state);
2306 
2307 	if (state->pm_state != pm_state) {
2308 		if (port && port->ops->pm)
2309 			port->ops->pm(port, pm_state, state->pm_state);
2310 		state->pm_state = pm_state;
2311 	}
2312 }
2313 
2314 struct uart_match {
2315 	struct uart_port *port;
2316 	struct uart_driver *driver;
2317 };
2318 
2319 static int serial_match_port(struct device *dev, void *data)
2320 {
2321 	struct uart_match *match = data;
2322 	struct tty_driver *tty_drv = match->driver->tty_driver;
2323 	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2324 		match->port->line;
2325 
2326 	return dev->devt == devt; /* Actually, only one tty per port */
2327 }
2328 
2329 int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
2330 {
2331 	struct uart_state *state = drv->state + uport->line;
2332 	struct tty_port *port = &state->port;
2333 	struct device *tty_dev;
2334 	struct uart_match match = {uport, drv};
2335 
2336 	mutex_lock(&port->mutex);
2337 
2338 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2339 	if (tty_dev && device_may_wakeup(tty_dev)) {
2340 		enable_irq_wake(uport->irq);
2341 		put_device(tty_dev);
2342 		mutex_unlock(&port->mutex);
2343 		return 0;
2344 	}
2345 	put_device(tty_dev);
2346 
2347 	/*
2348 	 * Nothing to do if the console is not suspending
2349 	 * except stop_rx to prevent any asynchronous data
2350 	 * over RX line. However ensure that we will be
2351 	 * able to Re-start_rx later.
2352 	 */
2353 	if (!console_suspend_enabled && uart_console(uport)) {
2354 		if (uport->ops->start_rx) {
2355 			spin_lock_irq(&uport->lock);
2356 			uport->ops->stop_rx(uport);
2357 			spin_unlock_irq(&uport->lock);
2358 		}
2359 		goto unlock;
2360 	}
2361 
2362 	uport->suspended = 1;
2363 
2364 	if (tty_port_initialized(port)) {
2365 		const struct uart_ops *ops = uport->ops;
2366 		int tries;
2367 		unsigned int mctrl;
2368 
2369 		tty_port_set_suspended(port, true);
2370 		tty_port_set_initialized(port, false);
2371 
2372 		spin_lock_irq(&uport->lock);
2373 		ops->stop_tx(uport);
2374 		if (!(uport->rs485.flags & SER_RS485_ENABLED))
2375 			ops->set_mctrl(uport, 0);
2376 		/* save mctrl so it can be restored on resume */
2377 		mctrl = uport->mctrl;
2378 		uport->mctrl = 0;
2379 		ops->stop_rx(uport);
2380 		spin_unlock_irq(&uport->lock);
2381 
2382 		/*
2383 		 * Wait for the transmitter to empty.
2384 		 */
2385 		for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
2386 			msleep(10);
2387 		if (!tries)
2388 			dev_err(uport->dev, "%s: Unable to drain transmitter\n",
2389 				uport->name);
2390 
2391 		ops->shutdown(uport);
2392 		uport->mctrl = mctrl;
2393 	}
2394 
2395 	/*
2396 	 * Disable the console device before suspending.
2397 	 */
2398 	if (uart_console(uport))
2399 		console_stop(uport->cons);
2400 
2401 	uart_change_pm(state, UART_PM_STATE_OFF);
2402 unlock:
2403 	mutex_unlock(&port->mutex);
2404 
2405 	return 0;
2406 }
2407 EXPORT_SYMBOL(uart_suspend_port);
2408 
2409 int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
2410 {
2411 	struct uart_state *state = drv->state + uport->line;
2412 	struct tty_port *port = &state->port;
2413 	struct device *tty_dev;
2414 	struct uart_match match = {uport, drv};
2415 	struct ktermios termios;
2416 
2417 	mutex_lock(&port->mutex);
2418 
2419 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2420 	if (!uport->suspended && device_may_wakeup(tty_dev)) {
2421 		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
2422 			disable_irq_wake(uport->irq);
2423 		put_device(tty_dev);
2424 		mutex_unlock(&port->mutex);
2425 		return 0;
2426 	}
2427 	put_device(tty_dev);
2428 	uport->suspended = 0;
2429 
2430 	/*
2431 	 * Re-enable the console device after suspending.
2432 	 */
2433 	if (uart_console(uport)) {
2434 		/*
2435 		 * First try to use the console cflag setting.
2436 		 */
2437 		memset(&termios, 0, sizeof(struct ktermios));
2438 		termios.c_cflag = uport->cons->cflag;
2439 		termios.c_ispeed = uport->cons->ispeed;
2440 		termios.c_ospeed = uport->cons->ospeed;
2441 
2442 		/*
2443 		 * If that's unset, use the tty termios setting.
2444 		 */
2445 		if (port->tty && termios.c_cflag == 0)
2446 			termios = port->tty->termios;
2447 
2448 		if (console_suspend_enabled)
2449 			uart_change_pm(state, UART_PM_STATE_ON);
2450 		uport->ops->set_termios(uport, &termios, NULL);
2451 		if (!console_suspend_enabled && uport->ops->start_rx) {
2452 			spin_lock_irq(&uport->lock);
2453 			uport->ops->start_rx(uport);
2454 			spin_unlock_irq(&uport->lock);
2455 		}
2456 		if (console_suspend_enabled)
2457 			console_start(uport->cons);
2458 	}
2459 
2460 	if (tty_port_suspended(port)) {
2461 		const struct uart_ops *ops = uport->ops;
2462 		int ret;
2463 
2464 		uart_change_pm(state, UART_PM_STATE_ON);
2465 		spin_lock_irq(&uport->lock);
2466 		if (!(uport->rs485.flags & SER_RS485_ENABLED))
2467 			ops->set_mctrl(uport, 0);
2468 		spin_unlock_irq(&uport->lock);
2469 		if (console_suspend_enabled || !uart_console(uport)) {
2470 			/* Protected by port mutex for now */
2471 			struct tty_struct *tty = port->tty;
2472 
2473 			ret = ops->startup(uport);
2474 			if (ret == 0) {
2475 				if (tty)
2476 					uart_change_line_settings(tty, state, NULL);
2477 				spin_lock_irq(&uport->lock);
2478 				if (!(uport->rs485.flags & SER_RS485_ENABLED))
2479 					ops->set_mctrl(uport, uport->mctrl);
2480 				else
2481 					uart_rs485_config(uport);
2482 				ops->start_tx(uport);
2483 				spin_unlock_irq(&uport->lock);
2484 				tty_port_set_initialized(port, true);
2485 			} else {
2486 				/*
2487 				 * Failed to resume - maybe hardware went away?
2488 				 * Clear the "initialized" flag so we won't try
2489 				 * to call the low level drivers shutdown method.
2490 				 */
2491 				uart_shutdown(tty, state);
2492 			}
2493 		}
2494 
2495 		tty_port_set_suspended(port, false);
2496 	}
2497 
2498 	mutex_unlock(&port->mutex);
2499 
2500 	return 0;
2501 }
2502 EXPORT_SYMBOL(uart_resume_port);
2503 
2504 static inline void
2505 uart_report_port(struct uart_driver *drv, struct uart_port *port)
2506 {
2507 	char address[64];
2508 
2509 	switch (port->iotype) {
2510 	case UPIO_PORT:
2511 		snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
2512 		break;
2513 	case UPIO_HUB6:
2514 		snprintf(address, sizeof(address),
2515 			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
2516 		break;
2517 	case UPIO_MEM:
2518 	case UPIO_MEM16:
2519 	case UPIO_MEM32:
2520 	case UPIO_MEM32BE:
2521 	case UPIO_AU:
2522 	case UPIO_TSI:
2523 		snprintf(address, sizeof(address),
2524 			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
2525 		break;
2526 	default:
2527 		strscpy(address, "*unknown*", sizeof(address));
2528 		break;
2529 	}
2530 
2531 	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
2532 	       port->dev ? dev_name(port->dev) : "",
2533 	       port->dev ? ": " : "",
2534 	       port->name,
2535 	       address, port->irq, port->uartclk / 16, uart_type(port));
2536 
2537 	/* The magic multiplier feature is a bit obscure, so report it too.  */
2538 	if (port->flags & UPF_MAGIC_MULTIPLIER)
2539 		pr_info("%s%s%s extra baud rates supported: %d, %d",
2540 			port->dev ? dev_name(port->dev) : "",
2541 			port->dev ? ": " : "",
2542 			port->name,
2543 			port->uartclk / 8, port->uartclk / 4);
2544 }
2545 
2546 static void
2547 uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2548 		    struct uart_port *port)
2549 {
2550 	unsigned int flags;
2551 
2552 	/*
2553 	 * If there isn't a port here, don't do anything further.
2554 	 */
2555 	if (!port->iobase && !port->mapbase && !port->membase)
2556 		return;
2557 
2558 	/*
2559 	 * Now do the auto configuration stuff.  Note that config_port
2560 	 * is expected to claim the resources and map the port for us.
2561 	 */
2562 	flags = 0;
2563 	if (port->flags & UPF_AUTO_IRQ)
2564 		flags |= UART_CONFIG_IRQ;
2565 	if (port->flags & UPF_BOOT_AUTOCONF) {
2566 		if (!(port->flags & UPF_FIXED_TYPE)) {
2567 			port->type = PORT_UNKNOWN;
2568 			flags |= UART_CONFIG_TYPE;
2569 		}
2570 		port->ops->config_port(port, flags);
2571 	}
2572 
2573 	if (port->type != PORT_UNKNOWN) {
2574 		unsigned long flags;
2575 
2576 		uart_report_port(drv, port);
2577 
2578 		/* Power up port for set_mctrl() */
2579 		uart_change_pm(state, UART_PM_STATE_ON);
2580 
2581 		/*
2582 		 * Ensure that the modem control lines are de-activated.
2583 		 * keep the DTR setting that is set in uart_set_options()
2584 		 * We probably don't need a spinlock around this, but
2585 		 */
2586 		spin_lock_irqsave(&port->lock, flags);
2587 		port->mctrl &= TIOCM_DTR;
2588 		if (!(port->rs485.flags & SER_RS485_ENABLED))
2589 			port->ops->set_mctrl(port, port->mctrl);
2590 		else
2591 			uart_rs485_config(port);
2592 		spin_unlock_irqrestore(&port->lock, flags);
2593 
2594 		/*
2595 		 * If this driver supports console, and it hasn't been
2596 		 * successfully registered yet, try to re-register it.
2597 		 * It may be that the port was not available.
2598 		 */
2599 		if (port->cons && !console_is_registered(port->cons))
2600 			register_console(port->cons);
2601 
2602 		/*
2603 		 * Power down all ports by default, except the
2604 		 * console if we have one.
2605 		 */
2606 		if (!uart_console(port))
2607 			uart_change_pm(state, UART_PM_STATE_OFF);
2608 	}
2609 }
2610 
2611 #ifdef CONFIG_CONSOLE_POLL
2612 
2613 static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2614 {
2615 	struct uart_driver *drv = driver->driver_state;
2616 	struct uart_state *state = drv->state + line;
2617 	enum uart_pm_state pm_state;
2618 	struct tty_port *tport;
2619 	struct uart_port *port;
2620 	int baud = 9600;
2621 	int bits = 8;
2622 	int parity = 'n';
2623 	int flow = 'n';
2624 	int ret = 0;
2625 
2626 	tport = &state->port;
2627 	mutex_lock(&tport->mutex);
2628 
2629 	port = uart_port_check(state);
2630 	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
2631 		ret = -1;
2632 		goto out;
2633 	}
2634 
2635 	pm_state = state->pm_state;
2636 	uart_change_pm(state, UART_PM_STATE_ON);
2637 
2638 	if (port->ops->poll_init) {
2639 		/*
2640 		 * We don't set initialized as we only initialized the hw,
2641 		 * e.g. state->xmit is still uninitialized.
2642 		 */
2643 		if (!tty_port_initialized(tport))
2644 			ret = port->ops->poll_init(port);
2645 	}
2646 
2647 	if (!ret && options) {
2648 		uart_parse_options(options, &baud, &parity, &bits, &flow);
2649 		console_list_lock();
2650 		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
2651 		console_list_unlock();
2652 	}
2653 out:
2654 	if (ret)
2655 		uart_change_pm(state, pm_state);
2656 	mutex_unlock(&tport->mutex);
2657 	return ret;
2658 }
2659 
2660 static int uart_poll_get_char(struct tty_driver *driver, int line)
2661 {
2662 	struct uart_driver *drv = driver->driver_state;
2663 	struct uart_state *state = drv->state + line;
2664 	struct uart_port *port;
2665 	int ret = -1;
2666 
2667 	port = uart_port_ref(state);
2668 	if (port) {
2669 		ret = port->ops->poll_get_char(port);
2670 		uart_port_deref(port);
2671 	}
2672 
2673 	return ret;
2674 }
2675 
2676 static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2677 {
2678 	struct uart_driver *drv = driver->driver_state;
2679 	struct uart_state *state = drv->state + line;
2680 	struct uart_port *port;
2681 
2682 	port = uart_port_ref(state);
2683 	if (!port)
2684 		return;
2685 
2686 	if (ch == '\n')
2687 		port->ops->poll_put_char(port, '\r');
2688 	port->ops->poll_put_char(port, ch);
2689 	uart_port_deref(port);
2690 }
2691 #endif
2692 
2693 static const struct tty_operations uart_ops = {
2694 	.install	= uart_install,
2695 	.open		= uart_open,
2696 	.close		= uart_close,
2697 	.write		= uart_write,
2698 	.put_char	= uart_put_char,
2699 	.flush_chars	= uart_flush_chars,
2700 	.write_room	= uart_write_room,
2701 	.chars_in_buffer= uart_chars_in_buffer,
2702 	.flush_buffer	= uart_flush_buffer,
2703 	.ioctl		= uart_ioctl,
2704 	.throttle	= uart_throttle,
2705 	.unthrottle	= uart_unthrottle,
2706 	.send_xchar	= uart_send_xchar,
2707 	.set_termios	= uart_set_termios,
2708 	.set_ldisc	= uart_set_ldisc,
2709 	.stop		= uart_stop,
2710 	.start		= uart_start,
2711 	.hangup		= uart_hangup,
2712 	.break_ctl	= uart_break_ctl,
2713 	.wait_until_sent= uart_wait_until_sent,
2714 #ifdef CONFIG_PROC_FS
2715 	.proc_show	= uart_proc_show,
2716 #endif
2717 	.tiocmget	= uart_tiocmget,
2718 	.tiocmset	= uart_tiocmset,
2719 	.set_serial	= uart_set_info_user,
2720 	.get_serial	= uart_get_info_user,
2721 	.get_icount	= uart_get_icount,
2722 #ifdef CONFIG_CONSOLE_POLL
2723 	.poll_init	= uart_poll_init,
2724 	.poll_get_char	= uart_poll_get_char,
2725 	.poll_put_char	= uart_poll_put_char,
2726 #endif
2727 };
2728 
2729 static const struct tty_port_operations uart_port_ops = {
2730 	.carrier_raised = uart_carrier_raised,
2731 	.dtr_rts	= uart_dtr_rts,
2732 	.activate	= uart_port_activate,
2733 	.shutdown	= uart_tty_port_shutdown,
2734 };
2735 
2736 /**
2737  * uart_register_driver - register a driver with the uart core layer
2738  * @drv: low level driver structure
2739  *
2740  * Register a uart driver with the core driver. We in turn register with the
2741  * tty layer, and initialise the core driver per-port state.
2742  *
2743  * We have a proc file in /proc/tty/driver which is named after the normal
2744  * driver.
2745  *
2746  * @drv->port should be %NULL, and the per-port structures should be registered
2747  * using uart_add_one_port() after this call has succeeded.
2748  *
2749  * Locking: none, Interrupts: enabled
2750  */
2751 int uart_register_driver(struct uart_driver *drv)
2752 {
2753 	struct tty_driver *normal;
2754 	int i, retval = -ENOMEM;
2755 
2756 	BUG_ON(drv->state);
2757 
2758 	/*
2759 	 * Maybe we should be using a slab cache for this, especially if
2760 	 * we have a large number of ports to handle.
2761 	 */
2762 	drv->state = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
2763 	if (!drv->state)
2764 		goto out;
2765 
2766 	normal = tty_alloc_driver(drv->nr, TTY_DRIVER_REAL_RAW |
2767 			TTY_DRIVER_DYNAMIC_DEV);
2768 	if (IS_ERR(normal)) {
2769 		retval = PTR_ERR(normal);
2770 		goto out_kfree;
2771 	}
2772 
2773 	drv->tty_driver = normal;
2774 
2775 	normal->driver_name	= drv->driver_name;
2776 	normal->name		= drv->dev_name;
2777 	normal->major		= drv->major;
2778 	normal->minor_start	= drv->minor;
2779 	normal->type		= TTY_DRIVER_TYPE_SERIAL;
2780 	normal->subtype		= SERIAL_TYPE_NORMAL;
2781 	normal->init_termios	= tty_std_termios;
2782 	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2783 	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2784 	normal->driver_state    = drv;
2785 	tty_set_operations(normal, &uart_ops);
2786 
2787 	/*
2788 	 * Initialise the UART state(s).
2789 	 */
2790 	for (i = 0; i < drv->nr; i++) {
2791 		struct uart_state *state = drv->state + i;
2792 		struct tty_port *port = &state->port;
2793 
2794 		tty_port_init(port);
2795 		port->ops = &uart_port_ops;
2796 	}
2797 
2798 	retval = tty_register_driver(normal);
2799 	if (retval >= 0)
2800 		return retval;
2801 
2802 	for (i = 0; i < drv->nr; i++)
2803 		tty_port_destroy(&drv->state[i].port);
2804 	tty_driver_kref_put(normal);
2805 out_kfree:
2806 	kfree(drv->state);
2807 out:
2808 	return retval;
2809 }
2810 EXPORT_SYMBOL(uart_register_driver);
2811 
2812 /**
2813  * uart_unregister_driver - remove a driver from the uart core layer
2814  * @drv: low level driver structure
2815  *
2816  * Remove all references to a driver from the core driver. The low level
2817  * driver must have removed all its ports via the uart_remove_one_port() if it
2818  * registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
2819  *
2820  * Locking: none, Interrupts: enabled
2821  */
2822 void uart_unregister_driver(struct uart_driver *drv)
2823 {
2824 	struct tty_driver *p = drv->tty_driver;
2825 	unsigned int i;
2826 
2827 	tty_unregister_driver(p);
2828 	tty_driver_kref_put(p);
2829 	for (i = 0; i < drv->nr; i++)
2830 		tty_port_destroy(&drv->state[i].port);
2831 	kfree(drv->state);
2832 	drv->state = NULL;
2833 	drv->tty_driver = NULL;
2834 }
2835 EXPORT_SYMBOL(uart_unregister_driver);
2836 
2837 struct tty_driver *uart_console_device(struct console *co, int *index)
2838 {
2839 	struct uart_driver *p = co->data;
2840 	*index = co->index;
2841 	return p->tty_driver;
2842 }
2843 EXPORT_SYMBOL_GPL(uart_console_device);
2844 
2845 static ssize_t uartclk_show(struct device *dev,
2846 	struct device_attribute *attr, char *buf)
2847 {
2848 	struct serial_struct tmp;
2849 	struct tty_port *port = dev_get_drvdata(dev);
2850 
2851 	uart_get_info(port, &tmp);
2852 	return sprintf(buf, "%d\n", tmp.baud_base * 16);
2853 }
2854 
2855 static ssize_t type_show(struct device *dev,
2856 	struct device_attribute *attr, char *buf)
2857 {
2858 	struct serial_struct tmp;
2859 	struct tty_port *port = dev_get_drvdata(dev);
2860 
2861 	uart_get_info(port, &tmp);
2862 	return sprintf(buf, "%d\n", tmp.type);
2863 }
2864 
2865 static ssize_t line_show(struct device *dev,
2866 	struct device_attribute *attr, char *buf)
2867 {
2868 	struct serial_struct tmp;
2869 	struct tty_port *port = dev_get_drvdata(dev);
2870 
2871 	uart_get_info(port, &tmp);
2872 	return sprintf(buf, "%d\n", tmp.line);
2873 }
2874 
2875 static ssize_t port_show(struct device *dev,
2876 	struct device_attribute *attr, char *buf)
2877 {
2878 	struct serial_struct tmp;
2879 	struct tty_port *port = dev_get_drvdata(dev);
2880 	unsigned long ioaddr;
2881 
2882 	uart_get_info(port, &tmp);
2883 	ioaddr = tmp.port;
2884 	if (HIGH_BITS_OFFSET)
2885 		ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
2886 	return sprintf(buf, "0x%lX\n", ioaddr);
2887 }
2888 
2889 static ssize_t irq_show(struct device *dev,
2890 	struct device_attribute *attr, char *buf)
2891 {
2892 	struct serial_struct tmp;
2893 	struct tty_port *port = dev_get_drvdata(dev);
2894 
2895 	uart_get_info(port, &tmp);
2896 	return sprintf(buf, "%d\n", tmp.irq);
2897 }
2898 
2899 static ssize_t flags_show(struct device *dev,
2900 	struct device_attribute *attr, char *buf)
2901 {
2902 	struct serial_struct tmp;
2903 	struct tty_port *port = dev_get_drvdata(dev);
2904 
2905 	uart_get_info(port, &tmp);
2906 	return sprintf(buf, "0x%X\n", tmp.flags);
2907 }
2908 
2909 static ssize_t xmit_fifo_size_show(struct device *dev,
2910 	struct device_attribute *attr, char *buf)
2911 {
2912 	struct serial_struct tmp;
2913 	struct tty_port *port = dev_get_drvdata(dev);
2914 
2915 	uart_get_info(port, &tmp);
2916 	return sprintf(buf, "%d\n", tmp.xmit_fifo_size);
2917 }
2918 
2919 static ssize_t close_delay_show(struct device *dev,
2920 	struct device_attribute *attr, char *buf)
2921 {
2922 	struct serial_struct tmp;
2923 	struct tty_port *port = dev_get_drvdata(dev);
2924 
2925 	uart_get_info(port, &tmp);
2926 	return sprintf(buf, "%d\n", tmp.close_delay);
2927 }
2928 
2929 static ssize_t closing_wait_show(struct device *dev,
2930 	struct device_attribute *attr, char *buf)
2931 {
2932 	struct serial_struct tmp;
2933 	struct tty_port *port = dev_get_drvdata(dev);
2934 
2935 	uart_get_info(port, &tmp);
2936 	return sprintf(buf, "%d\n", tmp.closing_wait);
2937 }
2938 
2939 static ssize_t custom_divisor_show(struct device *dev,
2940 	struct device_attribute *attr, char *buf)
2941 {
2942 	struct serial_struct tmp;
2943 	struct tty_port *port = dev_get_drvdata(dev);
2944 
2945 	uart_get_info(port, &tmp);
2946 	return sprintf(buf, "%d\n", tmp.custom_divisor);
2947 }
2948 
2949 static ssize_t io_type_show(struct device *dev,
2950 	struct device_attribute *attr, char *buf)
2951 {
2952 	struct serial_struct tmp;
2953 	struct tty_port *port = dev_get_drvdata(dev);
2954 
2955 	uart_get_info(port, &tmp);
2956 	return sprintf(buf, "%d\n", tmp.io_type);
2957 }
2958 
2959 static ssize_t iomem_base_show(struct device *dev,
2960 	struct device_attribute *attr, char *buf)
2961 {
2962 	struct serial_struct tmp;
2963 	struct tty_port *port = dev_get_drvdata(dev);
2964 
2965 	uart_get_info(port, &tmp);
2966 	return sprintf(buf, "0x%lX\n", (unsigned long)tmp.iomem_base);
2967 }
2968 
2969 static ssize_t iomem_reg_shift_show(struct device *dev,
2970 	struct device_attribute *attr, char *buf)
2971 {
2972 	struct serial_struct tmp;
2973 	struct tty_port *port = dev_get_drvdata(dev);
2974 
2975 	uart_get_info(port, &tmp);
2976 	return sprintf(buf, "%d\n", tmp.iomem_reg_shift);
2977 }
2978 
2979 static ssize_t console_show(struct device *dev,
2980 	struct device_attribute *attr, char *buf)
2981 {
2982 	struct tty_port *port = dev_get_drvdata(dev);
2983 	struct uart_state *state = container_of(port, struct uart_state, port);
2984 	struct uart_port *uport;
2985 	bool console = false;
2986 
2987 	mutex_lock(&port->mutex);
2988 	uport = uart_port_check(state);
2989 	if (uport)
2990 		console = uart_console_registered(uport);
2991 	mutex_unlock(&port->mutex);
2992 
2993 	return sprintf(buf, "%c\n", console ? 'Y' : 'N');
2994 }
2995 
2996 static ssize_t console_store(struct device *dev,
2997 	struct device_attribute *attr, const char *buf, size_t count)
2998 {
2999 	struct tty_port *port = dev_get_drvdata(dev);
3000 	struct uart_state *state = container_of(port, struct uart_state, port);
3001 	struct uart_port *uport;
3002 	bool oldconsole, newconsole;
3003 	int ret;
3004 
3005 	ret = kstrtobool(buf, &newconsole);
3006 	if (ret)
3007 		return ret;
3008 
3009 	mutex_lock(&port->mutex);
3010 	uport = uart_port_check(state);
3011 	if (uport) {
3012 		oldconsole = uart_console_registered(uport);
3013 		if (oldconsole && !newconsole) {
3014 			ret = unregister_console(uport->cons);
3015 		} else if (!oldconsole && newconsole) {
3016 			if (uart_console(uport)) {
3017 				uport->console_reinit = 1;
3018 				register_console(uport->cons);
3019 			} else {
3020 				ret = -ENOENT;
3021 			}
3022 		}
3023 	} else {
3024 		ret = -ENXIO;
3025 	}
3026 	mutex_unlock(&port->mutex);
3027 
3028 	return ret < 0 ? ret : count;
3029 }
3030 
3031 static DEVICE_ATTR_RO(uartclk);
3032 static DEVICE_ATTR_RO(type);
3033 static DEVICE_ATTR_RO(line);
3034 static DEVICE_ATTR_RO(port);
3035 static DEVICE_ATTR_RO(irq);
3036 static DEVICE_ATTR_RO(flags);
3037 static DEVICE_ATTR_RO(xmit_fifo_size);
3038 static DEVICE_ATTR_RO(close_delay);
3039 static DEVICE_ATTR_RO(closing_wait);
3040 static DEVICE_ATTR_RO(custom_divisor);
3041 static DEVICE_ATTR_RO(io_type);
3042 static DEVICE_ATTR_RO(iomem_base);
3043 static DEVICE_ATTR_RO(iomem_reg_shift);
3044 static DEVICE_ATTR_RW(console);
3045 
3046 static struct attribute *tty_dev_attrs[] = {
3047 	&dev_attr_uartclk.attr,
3048 	&dev_attr_type.attr,
3049 	&dev_attr_line.attr,
3050 	&dev_attr_port.attr,
3051 	&dev_attr_irq.attr,
3052 	&dev_attr_flags.attr,
3053 	&dev_attr_xmit_fifo_size.attr,
3054 	&dev_attr_close_delay.attr,
3055 	&dev_attr_closing_wait.attr,
3056 	&dev_attr_custom_divisor.attr,
3057 	&dev_attr_io_type.attr,
3058 	&dev_attr_iomem_base.attr,
3059 	&dev_attr_iomem_reg_shift.attr,
3060 	&dev_attr_console.attr,
3061 	NULL
3062 };
3063 
3064 static const struct attribute_group tty_dev_attr_group = {
3065 	.attrs = tty_dev_attrs,
3066 };
3067 
3068 /**
3069  * serial_core_add_one_port - attach a driver-defined port structure
3070  * @drv: pointer to the uart low level driver structure for this port
3071  * @uport: uart port structure to use for this port.
3072  *
3073  * Context: task context, might sleep
3074  *
3075  * This allows the driver @drv to register its own uart_port structure with the
3076  * core driver. The main purpose is to allow the low level uart drivers to
3077  * expand uart_port, rather than having yet more levels of structures.
3078  * Caller must hold port_mutex.
3079  */
3080 static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *uport)
3081 {
3082 	struct uart_state *state;
3083 	struct tty_port *port;
3084 	int ret = 0;
3085 	struct device *tty_dev;
3086 	int num_groups;
3087 
3088 	if (uport->line >= drv->nr)
3089 		return -EINVAL;
3090 
3091 	state = drv->state + uport->line;
3092 	port = &state->port;
3093 
3094 	mutex_lock(&port->mutex);
3095 	if (state->uart_port) {
3096 		ret = -EINVAL;
3097 		goto out;
3098 	}
3099 
3100 	/* Link the port to the driver state table and vice versa */
3101 	atomic_set(&state->refcount, 1);
3102 	init_waitqueue_head(&state->remove_wait);
3103 	state->uart_port = uport;
3104 	uport->state = state;
3105 
3106 	state->pm_state = UART_PM_STATE_UNDEFINED;
3107 	uport->cons = drv->cons;
3108 	uport->minor = drv->tty_driver->minor_start + uport->line;
3109 	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
3110 				drv->tty_driver->name_base + uport->line);
3111 	if (!uport->name) {
3112 		ret = -ENOMEM;
3113 		goto out;
3114 	}
3115 
3116 	/*
3117 	 * If this port is in use as a console then the spinlock is already
3118 	 * initialised.
3119 	 */
3120 	if (!uart_console_registered(uport))
3121 		uart_port_spin_lock_init(uport);
3122 
3123 	if (uport->cons && uport->dev)
3124 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
3125 
3126 	tty_port_link_device(port, drv->tty_driver, uport->line);
3127 	uart_configure_port(drv, state, uport);
3128 
3129 	port->console = uart_console(uport);
3130 
3131 	num_groups = 2;
3132 	if (uport->attr_group)
3133 		num_groups++;
3134 
3135 	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
3136 				    GFP_KERNEL);
3137 	if (!uport->tty_groups) {
3138 		ret = -ENOMEM;
3139 		goto out;
3140 	}
3141 	uport->tty_groups[0] = &tty_dev_attr_group;
3142 	if (uport->attr_group)
3143 		uport->tty_groups[1] = uport->attr_group;
3144 
3145 	/*
3146 	 * Register the port whether it's detected or not.  This allows
3147 	 * setserial to be used to alter this port's parameters.
3148 	 */
3149 	tty_dev = tty_port_register_device_attr_serdev(port, drv->tty_driver,
3150 			uport->line, uport->dev, port, uport->tty_groups);
3151 	if (!IS_ERR(tty_dev)) {
3152 		device_set_wakeup_capable(tty_dev, 1);
3153 	} else {
3154 		dev_err(uport->dev, "Cannot register tty device on line %d\n",
3155 		       uport->line);
3156 	}
3157 
3158  out:
3159 	mutex_unlock(&port->mutex);
3160 
3161 	return ret;
3162 }
3163 
3164 /**
3165  * serial_core_remove_one_port - detach a driver defined port structure
3166  * @drv: pointer to the uart low level driver structure for this port
3167  * @uport: uart port structure for this port
3168  *
3169  * Context: task context, might sleep
3170  *
3171  * This unhooks (and hangs up) the specified port structure from the core
3172  * driver. No further calls will be made to the low-level code for this port.
3173  * Caller must hold port_mutex.
3174  */
3175 static void serial_core_remove_one_port(struct uart_driver *drv,
3176 					struct uart_port *uport)
3177 {
3178 	struct uart_state *state = drv->state + uport->line;
3179 	struct tty_port *port = &state->port;
3180 	struct uart_port *uart_port;
3181 	struct tty_struct *tty;
3182 
3183 	mutex_lock(&port->mutex);
3184 	uart_port = uart_port_check(state);
3185 	if (uart_port != uport)
3186 		dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
3187 			  uart_port, uport);
3188 
3189 	if (!uart_port) {
3190 		mutex_unlock(&port->mutex);
3191 		return;
3192 	}
3193 	mutex_unlock(&port->mutex);
3194 
3195 	/*
3196 	 * Remove the devices from the tty layer
3197 	 */
3198 	tty_port_unregister_device(port, drv->tty_driver, uport->line);
3199 
3200 	tty = tty_port_tty_get(port);
3201 	if (tty) {
3202 		tty_vhangup(port->tty);
3203 		tty_kref_put(tty);
3204 	}
3205 
3206 	/*
3207 	 * If the port is used as a console, unregister it
3208 	 */
3209 	if (uart_console(uport))
3210 		unregister_console(uport->cons);
3211 
3212 	/*
3213 	 * Free the port IO and memory resources, if any.
3214 	 */
3215 	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
3216 		uport->ops->release_port(uport);
3217 	kfree(uport->tty_groups);
3218 	kfree(uport->name);
3219 
3220 	/*
3221 	 * Indicate that there isn't a port here anymore.
3222 	 */
3223 	uport->type = PORT_UNKNOWN;
3224 	uport->port_dev = NULL;
3225 
3226 	mutex_lock(&port->mutex);
3227 	WARN_ON(atomic_dec_return(&state->refcount) < 0);
3228 	wait_event(state->remove_wait, !atomic_read(&state->refcount));
3229 	state->uart_port = NULL;
3230 	mutex_unlock(&port->mutex);
3231 }
3232 
3233 /**
3234  * uart_match_port - are the two ports equivalent?
3235  * @port1: first port
3236  * @port2: second port
3237  *
3238  * This utility function can be used to determine whether two uart_port
3239  * structures describe the same port.
3240  */
3241 bool uart_match_port(const struct uart_port *port1,
3242 		const struct uart_port *port2)
3243 {
3244 	if (port1->iotype != port2->iotype)
3245 		return false;
3246 
3247 	switch (port1->iotype) {
3248 	case UPIO_PORT:
3249 		return port1->iobase == port2->iobase;
3250 	case UPIO_HUB6:
3251 		return port1->iobase == port2->iobase &&
3252 		       port1->hub6   == port2->hub6;
3253 	case UPIO_MEM:
3254 	case UPIO_MEM16:
3255 	case UPIO_MEM32:
3256 	case UPIO_MEM32BE:
3257 	case UPIO_AU:
3258 	case UPIO_TSI:
3259 		return port1->mapbase == port2->mapbase;
3260 	}
3261 
3262 	return false;
3263 }
3264 EXPORT_SYMBOL(uart_match_port);
3265 
3266 static struct serial_ctrl_device *
3267 serial_core_get_ctrl_dev(struct serial_port_device *port_dev)
3268 {
3269 	struct device *dev = &port_dev->dev;
3270 
3271 	return to_serial_base_ctrl_device(dev->parent);
3272 }
3273 
3274 /*
3275  * Find a registered serial core controller device if one exists. Returns
3276  * the first device matching the ctrl_id. Caller must hold port_mutex.
3277  */
3278 static struct serial_ctrl_device *serial_core_ctrl_find(struct uart_driver *drv,
3279 							struct device *phys_dev,
3280 							int ctrl_id)
3281 {
3282 	struct uart_state *state;
3283 	int i;
3284 
3285 	lockdep_assert_held(&port_mutex);
3286 
3287 	for (i = 0; i < drv->nr; i++) {
3288 		state = drv->state + i;
3289 		if (!state->uart_port || !state->uart_port->port_dev)
3290 			continue;
3291 
3292 		if (state->uart_port->dev == phys_dev &&
3293 		    state->uart_port->ctrl_id == ctrl_id)
3294 			return serial_core_get_ctrl_dev(state->uart_port->port_dev);
3295 	}
3296 
3297 	return NULL;
3298 }
3299 
3300 static struct serial_ctrl_device *serial_core_ctrl_device_add(struct uart_port *port)
3301 {
3302 	return serial_base_ctrl_add(port, port->dev);
3303 }
3304 
3305 static int serial_core_port_device_add(struct serial_ctrl_device *ctrl_dev,
3306 				       struct uart_port *port)
3307 {
3308 	struct serial_port_device *port_dev;
3309 
3310 	port_dev = serial_base_port_add(port, ctrl_dev);
3311 	if (IS_ERR(port_dev))
3312 		return PTR_ERR(port_dev);
3313 
3314 	port->port_dev = port_dev;
3315 
3316 	return 0;
3317 }
3318 
3319 /*
3320  * Initialize a serial core port device, and a controller device if needed.
3321  */
3322 int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
3323 {
3324 	struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
3325 	int ret;
3326 
3327 	mutex_lock(&port_mutex);
3328 
3329 	/*
3330 	 * Prevent serial_port_runtime_resume() from trying to use the port
3331 	 * until serial_core_add_one_port() has completed
3332 	 */
3333 	port->flags |= UPF_DEAD;
3334 
3335 	/* Inititalize a serial core controller device if needed */
3336 	ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
3337 	if (!ctrl_dev) {
3338 		new_ctrl_dev = serial_core_ctrl_device_add(port);
3339 		if (IS_ERR(new_ctrl_dev)) {
3340 			ret = PTR_ERR(new_ctrl_dev);
3341 			goto err_unlock;
3342 		}
3343 		ctrl_dev = new_ctrl_dev;
3344 	}
3345 
3346 	/*
3347 	 * Initialize a serial core port device. Tag the port dead to prevent
3348 	 * serial_port_runtime_resume() trying to do anything until port has
3349 	 * been registered. It gets cleared by serial_core_add_one_port().
3350 	 */
3351 	ret = serial_core_port_device_add(ctrl_dev, port);
3352 	if (ret)
3353 		goto err_unregister_ctrl_dev;
3354 
3355 	ret = serial_core_add_one_port(drv, port);
3356 	if (ret)
3357 		goto err_unregister_port_dev;
3358 
3359 	port->flags &= ~UPF_DEAD;
3360 
3361 	mutex_unlock(&port_mutex);
3362 
3363 	return 0;
3364 
3365 err_unregister_port_dev:
3366 	serial_base_port_device_remove(port->port_dev);
3367 
3368 err_unregister_ctrl_dev:
3369 	serial_base_ctrl_device_remove(new_ctrl_dev);
3370 
3371 err_unlock:
3372 	mutex_unlock(&port_mutex);
3373 
3374 	return ret;
3375 }
3376 
3377 /*
3378  * Removes a serial core port device, and the related serial core controller
3379  * device if the last instance.
3380  */
3381 void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port)
3382 {
3383 	struct device *phys_dev = port->dev;
3384 	struct serial_port_device *port_dev = port->port_dev;
3385 	struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
3386 	int ctrl_id = port->ctrl_id;
3387 
3388 	mutex_lock(&port_mutex);
3389 
3390 	port->flags |= UPF_DEAD;
3391 
3392 	serial_core_remove_one_port(drv, port);
3393 
3394 	/* Note that struct uart_port *port is no longer valid at this point */
3395 	serial_base_port_device_remove(port_dev);
3396 
3397 	/* Drop the serial core controller device if no ports are using it */
3398 	if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
3399 		serial_base_ctrl_device_remove(ctrl_dev);
3400 
3401 	mutex_unlock(&port_mutex);
3402 }
3403 
3404 /**
3405  * uart_handle_dcd_change - handle a change of carrier detect state
3406  * @uport: uart_port structure for the open port
3407  * @active: new carrier detect status
3408  *
3409  * Caller must hold uport->lock.
3410  */
3411 void uart_handle_dcd_change(struct uart_port *uport, bool active)
3412 {
3413 	struct tty_port *port = &uport->state->port;
3414 	struct tty_struct *tty = port->tty;
3415 	struct tty_ldisc *ld;
3416 
3417 	lockdep_assert_held_once(&uport->lock);
3418 
3419 	if (tty) {
3420 		ld = tty_ldisc_ref(tty);
3421 		if (ld) {
3422 			if (ld->ops->dcd_change)
3423 				ld->ops->dcd_change(tty, active);
3424 			tty_ldisc_deref(ld);
3425 		}
3426 	}
3427 
3428 	uport->icount.dcd++;
3429 
3430 	if (uart_dcd_enabled(uport)) {
3431 		if (active)
3432 			wake_up_interruptible(&port->open_wait);
3433 		else if (tty)
3434 			tty_hangup(tty);
3435 	}
3436 }
3437 EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
3438 
3439 /**
3440  * uart_handle_cts_change - handle a change of clear-to-send state
3441  * @uport: uart_port structure for the open port
3442  * @active: new clear-to-send status
3443  *
3444  * Caller must hold uport->lock.
3445  */
3446 void uart_handle_cts_change(struct uart_port *uport, bool active)
3447 {
3448 	lockdep_assert_held_once(&uport->lock);
3449 
3450 	uport->icount.cts++;
3451 
3452 	if (uart_softcts_mode(uport)) {
3453 		if (uport->hw_stopped) {
3454 			if (active) {
3455 				uport->hw_stopped = false;
3456 				uport->ops->start_tx(uport);
3457 				uart_write_wakeup(uport);
3458 			}
3459 		} else {
3460 			if (!active) {
3461 				uport->hw_stopped = true;
3462 				uport->ops->stop_tx(uport);
3463 			}
3464 		}
3465 
3466 	}
3467 }
3468 EXPORT_SYMBOL_GPL(uart_handle_cts_change);
3469 
3470 /**
3471  * uart_insert_char - push a char to the uart layer
3472  *
3473  * User is responsible to call tty_flip_buffer_push when they are done with
3474  * insertion.
3475  *
3476  * @port: corresponding port
3477  * @status: state of the serial port RX buffer (LSR for 8250)
3478  * @overrun: mask of overrun bits in @status
3479  * @ch: character to push
3480  * @flag: flag for the character (see TTY_NORMAL and friends)
3481  */
3482 void uart_insert_char(struct uart_port *port, unsigned int status,
3483 		      unsigned int overrun, u8 ch, u8 flag)
3484 {
3485 	struct tty_port *tport = &port->state->port;
3486 
3487 	if ((status & port->ignore_status_mask & ~overrun) == 0)
3488 		if (tty_insert_flip_char(tport, ch, flag) == 0)
3489 			++port->icount.buf_overrun;
3490 
3491 	/*
3492 	 * Overrun is special.  Since it's reported immediately,
3493 	 * it doesn't affect the current character.
3494 	 */
3495 	if (status & ~port->ignore_status_mask & overrun)
3496 		if (tty_insert_flip_char(tport, 0, TTY_OVERRUN) == 0)
3497 			++port->icount.buf_overrun;
3498 }
3499 EXPORT_SYMBOL_GPL(uart_insert_char);
3500 
3501 #ifdef CONFIG_MAGIC_SYSRQ_SERIAL
3502 static const u8 sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
3503 
3504 static void uart_sysrq_on(struct work_struct *w)
3505 {
3506 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3507 
3508 	sysrq_toggle_support(1);
3509 	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
3510 		sysrq_toggle_seq_len, sysrq_toggle_seq);
3511 }
3512 static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
3513 
3514 /**
3515  * uart_try_toggle_sysrq - Enables SysRq from serial line
3516  * @port: uart_port structure where char(s) after BREAK met
3517  * @ch: new character in the sequence after received BREAK
3518  *
3519  * Enables magic SysRq when the required sequence is met on port
3520  * (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
3521  *
3522  * Returns: %false if @ch is out of enabling sequence and should be
3523  * handled some other way, %true if @ch was consumed.
3524  */
3525 bool uart_try_toggle_sysrq(struct uart_port *port, u8 ch)
3526 {
3527 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3528 
3529 	if (!sysrq_toggle_seq_len)
3530 		return false;
3531 
3532 	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
3533 	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
3534 		port->sysrq_seq = 0;
3535 		return false;
3536 	}
3537 
3538 	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
3539 		port->sysrq = jiffies + SYSRQ_TIMEOUT;
3540 		return true;
3541 	}
3542 
3543 	schedule_work(&sysrq_enable_work);
3544 
3545 	port->sysrq = 0;
3546 	return true;
3547 }
3548 EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
3549 #endif
3550 
3551 /**
3552  * uart_get_rs485_mode() - retrieve rs485 properties for given uart
3553  * @port: uart device's target port
3554  *
3555  * This function implements the device tree binding described in
3556  * Documentation/devicetree/bindings/serial/rs485.txt.
3557  */
3558 int uart_get_rs485_mode(struct uart_port *port)
3559 {
3560 	struct serial_rs485 *rs485conf = &port->rs485;
3561 	struct device *dev = port->dev;
3562 	u32 rs485_delay[2];
3563 	int ret;
3564 	int rx_during_tx_gpio_flag;
3565 
3566 	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
3567 					     rs485_delay, 2);
3568 	if (!ret) {
3569 		rs485conf->delay_rts_before_send = rs485_delay[0];
3570 		rs485conf->delay_rts_after_send = rs485_delay[1];
3571 	} else {
3572 		rs485conf->delay_rts_before_send = 0;
3573 		rs485conf->delay_rts_after_send = 0;
3574 	}
3575 
3576 	uart_sanitize_serial_rs485_delays(port, rs485conf);
3577 
3578 	/*
3579 	 * Clear full-duplex and enabled flags, set RTS polarity to active high
3580 	 * to get to a defined state with the following properties:
3581 	 */
3582 	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
3583 			      SER_RS485_TERMINATE_BUS |
3584 			      SER_RS485_RTS_AFTER_SEND);
3585 	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
3586 
3587 	if (device_property_read_bool(dev, "rs485-rx-during-tx"))
3588 		rs485conf->flags |= SER_RS485_RX_DURING_TX;
3589 
3590 	if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
3591 		rs485conf->flags |= SER_RS485_ENABLED;
3592 
3593 	if (device_property_read_bool(dev, "rs485-rts-active-low")) {
3594 		rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
3595 		rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
3596 	}
3597 
3598 	/*
3599 	 * Disabling termination by default is the safe choice:  Else if many
3600 	 * bus participants enable it, no communication is possible at all.
3601 	 * Works fine for short cables and users may enable for longer cables.
3602 	 */
3603 	port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
3604 							GPIOD_OUT_LOW);
3605 	if (IS_ERR(port->rs485_term_gpio)) {
3606 		ret = PTR_ERR(port->rs485_term_gpio);
3607 		port->rs485_term_gpio = NULL;
3608 		return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n");
3609 	}
3610 	if (port->rs485_term_gpio)
3611 		port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;
3612 
3613 	rx_during_tx_gpio_flag = (rs485conf->flags & SER_RS485_RX_DURING_TX) ?
3614 				 GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
3615 	port->rs485_rx_during_tx_gpio = devm_gpiod_get_optional(dev,
3616 								"rs485-rx-during-tx",
3617 								rx_during_tx_gpio_flag);
3618 	if (IS_ERR(port->rs485_rx_during_tx_gpio)) {
3619 		ret = PTR_ERR(port->rs485_rx_during_tx_gpio);
3620 		port->rs485_rx_during_tx_gpio = NULL;
3621 		return dev_err_probe(dev, ret, "Cannot get rs485-rx-during-tx-gpios\n");
3622 	}
3623 
3624 	return 0;
3625 }
3626 EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
3627 
3628 /* Compile-time assertions for serial_rs485 layout */
3629 static_assert(offsetof(struct serial_rs485, padding) ==
3630               (offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
3631 static_assert(offsetof(struct serial_rs485, padding1) ==
3632 	      offsetof(struct serial_rs485, padding[1]));
3633 static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
3634 	      sizeof(struct serial_rs485));
3635 
3636 MODULE_DESCRIPTION("Serial driver core");
3637 MODULE_LICENSE("GPL");
3638