xref: /linux/drivers/tty/serial/atmel_serial.c (revision f6154d8babbb8a98f0d3ea325aafae2e33bfd8be)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Driver for Atmel AT91 Serial ports
4  *  Copyright (C) 2003 Rick Bronson
5  *
6  *  Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
7  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
8  *
9  *  DMA support added by Chip Coldwell.
10  */
11 #include <linux/circ_buf.h>
12 #include <linux/tty.h>
13 #include <linux/ioport.h>
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/serial.h>
17 #include <linux/clk.h>
18 #include <linux/clk-provider.h>
19 #include <linux/console.h>
20 #include <linux/sysrq.h>
21 #include <linux/tty_flip.h>
22 #include <linux/platform_device.h>
23 #include <linux/of.h>
24 #include <linux/dma-mapping.h>
25 #include <linux/dmaengine.h>
26 #include <linux/atmel_pdc.h>
27 #include <linux/uaccess.h>
28 #include <linux/platform_data/atmel.h>
29 #include <linux/timer.h>
30 #include <linux/err.h>
31 #include <linux/irq.h>
32 #include <linux/suspend.h>
33 #include <linux/mm.h>
34 #include <linux/io.h>
35 
36 #include <asm/div64.h>
37 #include <asm/ioctls.h>
38 
39 #define PDC_BUFFER_SIZE		512
40 /* Revisit: We should calculate this based on the actual port settings */
41 #define PDC_RX_TIMEOUT		(3 * 10)		/* 3 bytes */
42 
43 /* The minium number of data FIFOs should be able to contain */
44 #define ATMEL_MIN_FIFO_SIZE	8
45 /*
46  * These two offsets are substracted from the RX FIFO size to define the RTS
47  * high and low thresholds
48  */
49 #define ATMEL_RTS_HIGH_OFFSET	16
50 #define ATMEL_RTS_LOW_OFFSET	20
51 
52 #include <linux/serial_core.h>
53 
54 #include "serial_mctrl_gpio.h"
55 #include "atmel_serial.h"
56 
57 static void atmel_start_rx(struct uart_port *port);
58 static void atmel_stop_rx(struct uart_port *port);
59 
60 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
61 
62 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
63  * should coexist with the 8250 driver, such as if we have an external 16C550
64  * UART. */
65 #define SERIAL_ATMEL_MAJOR	204
66 #define MINOR_START		154
67 #define ATMEL_DEVICENAME	"ttyAT"
68 
69 #else
70 
71 /* Use device name ttyS, major 4, minor 64-68.  This is the usual serial port
72  * name, but it is legally reserved for the 8250 driver. */
73 #define SERIAL_ATMEL_MAJOR	TTY_MAJOR
74 #define MINOR_START		64
75 #define ATMEL_DEVICENAME	"ttyS"
76 
77 #endif
78 
79 #define ATMEL_ISR_PASS_LIMIT	256
80 
81 struct atmel_dma_buffer {
82 	unsigned char	*buf;
83 	dma_addr_t	dma_addr;
84 	unsigned int	dma_size;
85 	unsigned int	ofs;
86 };
87 
88 struct atmel_uart_char {
89 	u16		status;
90 	u16		ch;
91 };
92 
93 /*
94  * Be careful, the real size of the ring buffer is
95  * sizeof(atmel_uart_char) * ATMEL_SERIAL_RINGSIZE. It means that ring buffer
96  * can contain up to 1024 characters in PIO mode and up to 4096 characters in
97  * DMA mode.
98  */
99 #define ATMEL_SERIAL_RINGSIZE 1024
100 
101 /*
102  * at91: 6 USARTs and one DBGU port (SAM9260)
103  * samx7: 3 USARTs and 5 UARTs
104  */
105 #define ATMEL_MAX_UART		8
106 
107 /*
108  * We wrap our port structure around the generic uart_port.
109  */
110 struct atmel_uart_port {
111 	struct uart_port	uart;		/* uart */
112 	struct clk		*clk;		/* uart clock */
113 	struct clk		*gclk;		/* uart generic clock */
114 	int			may_wakeup;	/* cached value of device_may_wakeup for times we need to disable it */
115 	u32			backup_imr;	/* IMR saved during suspend */
116 	int			break_active;	/* break being received */
117 
118 	bool			use_dma_rx;	/* enable DMA receiver */
119 	bool			use_pdc_rx;	/* enable PDC receiver */
120 	short			pdc_rx_idx;	/* current PDC RX buffer */
121 	struct atmel_dma_buffer	pdc_rx[2];	/* PDC receier */
122 
123 	bool			use_dma_tx;     /* enable DMA transmitter */
124 	bool			use_pdc_tx;	/* enable PDC transmitter */
125 	struct atmel_dma_buffer	pdc_tx;		/* PDC transmitter */
126 
127 	spinlock_t			lock_tx;	/* port lock */
128 	spinlock_t			lock_rx;	/* port lock */
129 	struct dma_chan			*chan_tx;
130 	struct dma_chan			*chan_rx;
131 	struct dma_async_tx_descriptor	*desc_tx;
132 	struct dma_async_tx_descriptor	*desc_rx;
133 	dma_cookie_t			cookie_tx;
134 	dma_cookie_t			cookie_rx;
135 	struct scatterlist		sg_tx;
136 	struct scatterlist		sg_rx;
137 	struct tasklet_struct	tasklet_rx;
138 	struct tasklet_struct	tasklet_tx;
139 	atomic_t		tasklet_shutdown;
140 	unsigned int		irq_status_prev;
141 	unsigned int		tx_len;
142 
143 	struct circ_buf		rx_ring;
144 
145 	struct mctrl_gpios	*gpios;
146 	u32			backup_mode;	/* MR saved during iso7816 operations */
147 	u32			backup_brgr;	/* BRGR saved during iso7816 operations */
148 	unsigned int		tx_done_mask;
149 	u32			fifo_size;
150 	u32			rts_high;
151 	u32			rts_low;
152 	bool			ms_irq_enabled;
153 	u32			rtor;	/* address of receiver timeout register if it exists */
154 	bool			is_usart;
155 	bool			has_frac_baudrate;
156 	bool			has_hw_timer;
157 	struct timer_list	uart_timer;
158 
159 	bool			tx_stopped;
160 	bool			suspended;
161 	unsigned int		pending;
162 	unsigned int		pending_status;
163 	spinlock_t		lock_suspended;
164 
165 	bool			hd_start_rx;	/* can start RX during half-duplex operation */
166 
167 	/* ISO7816 */
168 	unsigned int		fidi_min;
169 	unsigned int		fidi_max;
170 
171 	struct {
172 		u32		cr;
173 		u32		mr;
174 		u32		imr;
175 		u32		brgr;
176 		u32		rtor;
177 		u32		ttgr;
178 		u32		fmr;
179 		u32		fimr;
180 	} cache;
181 
182 	int (*prepare_rx)(struct uart_port *port);
183 	int (*prepare_tx)(struct uart_port *port);
184 	void (*schedule_rx)(struct uart_port *port);
185 	void (*schedule_tx)(struct uart_port *port);
186 	void (*release_rx)(struct uart_port *port);
187 	void (*release_tx)(struct uart_port *port);
188 };
189 
190 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
191 static DECLARE_BITMAP(atmel_ports_in_use, ATMEL_MAX_UART);
192 
193 #if defined(CONFIG_OF)
194 static const struct of_device_id atmel_serial_dt_ids[] = {
195 	{ .compatible = "atmel,at91rm9200-usart-serial" },
196 	{ /* sentinel */ }
197 };
198 #endif
199 
200 static inline struct atmel_uart_port *
201 to_atmel_uart_port(struct uart_port *uart)
202 {
203 	return container_of(uart, struct atmel_uart_port, uart);
204 }
205 
206 static inline u32 atmel_uart_readl(struct uart_port *port, u32 reg)
207 {
208 	return __raw_readl(port->membase + reg);
209 }
210 
211 static inline void atmel_uart_writel(struct uart_port *port, u32 reg, u32 value)
212 {
213 	__raw_writel(value, port->membase + reg);
214 }
215 
216 static inline u8 atmel_uart_read_char(struct uart_port *port)
217 {
218 	return __raw_readb(port->membase + ATMEL_US_RHR);
219 }
220 
221 static inline void atmel_uart_write_char(struct uart_port *port, u8 value)
222 {
223 	__raw_writeb(value, port->membase + ATMEL_US_THR);
224 }
225 
226 static inline int atmel_uart_is_half_duplex(struct uart_port *port)
227 {
228 	return ((port->rs485.flags & SER_RS485_ENABLED) &&
229 		!(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
230 		(port->iso7816.flags & SER_ISO7816_ENABLED);
231 }
232 
233 static inline int atmel_error_rate(int desired_value, int actual_value)
234 {
235 	return 100 - (desired_value * 100) / actual_value;
236 }
237 
238 #ifdef CONFIG_SERIAL_ATMEL_PDC
239 static bool atmel_use_pdc_rx(struct uart_port *port)
240 {
241 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
242 
243 	return atmel_port->use_pdc_rx;
244 }
245 
246 static bool atmel_use_pdc_tx(struct uart_port *port)
247 {
248 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
249 
250 	return atmel_port->use_pdc_tx;
251 }
252 #else
253 static bool atmel_use_pdc_rx(struct uart_port *port)
254 {
255 	return false;
256 }
257 
258 static bool atmel_use_pdc_tx(struct uart_port *port)
259 {
260 	return false;
261 }
262 #endif
263 
264 static bool atmel_use_dma_tx(struct uart_port *port)
265 {
266 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
267 
268 	return atmel_port->use_dma_tx;
269 }
270 
271 static bool atmel_use_dma_rx(struct uart_port *port)
272 {
273 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
274 
275 	return atmel_port->use_dma_rx;
276 }
277 
278 static bool atmel_use_fifo(struct uart_port *port)
279 {
280 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
281 
282 	return atmel_port->fifo_size;
283 }
284 
285 static void atmel_tasklet_schedule(struct atmel_uart_port *atmel_port,
286 				   struct tasklet_struct *t)
287 {
288 	if (!atomic_read(&atmel_port->tasklet_shutdown))
289 		tasklet_schedule(t);
290 }
291 
292 /* Enable or disable the rs485 support */
293 static int atmel_config_rs485(struct uart_port *port, struct ktermios *termios,
294 			      struct serial_rs485 *rs485conf)
295 {
296 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
297 	unsigned int mode;
298 
299 	/* Disable interrupts */
300 	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
301 
302 	mode = atmel_uart_readl(port, ATMEL_US_MR);
303 
304 	if (rs485conf->flags & SER_RS485_ENABLED) {
305 		dev_dbg(port->dev, "Setting UART to RS485\n");
306 		if (rs485conf->flags & SER_RS485_RX_DURING_TX)
307 			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
308 		else
309 			atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
310 
311 		atmel_uart_writel(port, ATMEL_US_TTGR,
312 				  rs485conf->delay_rts_after_send);
313 		mode &= ~ATMEL_US_USMODE;
314 		mode |= ATMEL_US_USMODE_RS485;
315 	} else {
316 		dev_dbg(port->dev, "Setting UART to RS232\n");
317 		if (atmel_use_pdc_tx(port))
318 			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
319 				ATMEL_US_TXBUFE;
320 		else
321 			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
322 	}
323 	atmel_uart_writel(port, ATMEL_US_MR, mode);
324 
325 	/* Enable interrupts */
326 	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
327 
328 	return 0;
329 }
330 
331 static unsigned int atmel_calc_cd(struct uart_port *port,
332 				  struct serial_iso7816 *iso7816conf)
333 {
334 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
335 	unsigned int cd;
336 	u64 mck_rate;
337 
338 	mck_rate = (u64)clk_get_rate(atmel_port->clk);
339 	do_div(mck_rate, iso7816conf->clk);
340 	cd = mck_rate;
341 	return cd;
342 }
343 
344 static unsigned int atmel_calc_fidi(struct uart_port *port,
345 				    struct serial_iso7816 *iso7816conf)
346 {
347 	u64 fidi = 0;
348 
349 	if (iso7816conf->sc_fi && iso7816conf->sc_di) {
350 		fidi = (u64)iso7816conf->sc_fi;
351 		do_div(fidi, iso7816conf->sc_di);
352 	}
353 	return (u32)fidi;
354 }
355 
356 /* Enable or disable the iso7816 support */
357 /* Called with interrupts disabled */
358 static int atmel_config_iso7816(struct uart_port *port,
359 				struct serial_iso7816 *iso7816conf)
360 {
361 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
362 	unsigned int mode;
363 	unsigned int cd, fidi;
364 	int ret = 0;
365 
366 	/* Disable interrupts */
367 	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
368 
369 	mode = atmel_uart_readl(port, ATMEL_US_MR);
370 
371 	if (iso7816conf->flags & SER_ISO7816_ENABLED) {
372 		mode &= ~ATMEL_US_USMODE;
373 
374 		if (iso7816conf->tg > 255) {
375 			dev_err(port->dev, "ISO7816: Timeguard exceeding 255\n");
376 			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
377 			ret = -EINVAL;
378 			goto err_out;
379 		}
380 
381 		if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
382 		    == SER_ISO7816_T(0)) {
383 			mode |= ATMEL_US_USMODE_ISO7816_T0 | ATMEL_US_DSNACK;
384 		} else if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
385 			   == SER_ISO7816_T(1)) {
386 			mode |= ATMEL_US_USMODE_ISO7816_T1 | ATMEL_US_INACK;
387 		} else {
388 			dev_err(port->dev, "ISO7816: Type not supported\n");
389 			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
390 			ret = -EINVAL;
391 			goto err_out;
392 		}
393 
394 		mode &= ~(ATMEL_US_USCLKS | ATMEL_US_NBSTOP | ATMEL_US_PAR);
395 
396 		/* select mck clock, and output  */
397 		mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
398 		/* set parity for normal/inverse mode + max iterations */
399 		mode |= ATMEL_US_PAR_EVEN | ATMEL_US_NBSTOP_1 | ATMEL_US_MAX_ITER(3);
400 
401 		cd = atmel_calc_cd(port, iso7816conf);
402 		fidi = atmel_calc_fidi(port, iso7816conf);
403 		if (fidi == 0) {
404 			dev_warn(port->dev, "ISO7816 fidi = 0, Generator generates no signal\n");
405 		} else if (fidi < atmel_port->fidi_min
406 			   || fidi > atmel_port->fidi_max) {
407 			dev_err(port->dev, "ISO7816 fidi = %u, value not supported\n", fidi);
408 			memset(iso7816conf, 0, sizeof(struct serial_iso7816));
409 			ret = -EINVAL;
410 			goto err_out;
411 		}
412 
413 		if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) {
414 			/* port not yet in iso7816 mode: store configuration */
415 			atmel_port->backup_mode = atmel_uart_readl(port, ATMEL_US_MR);
416 			atmel_port->backup_brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
417 		}
418 
419 		atmel_uart_writel(port, ATMEL_US_TTGR, iso7816conf->tg);
420 		atmel_uart_writel(port, ATMEL_US_BRGR, cd);
421 		atmel_uart_writel(port, ATMEL_US_FIDI, fidi);
422 
423 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXEN);
424 		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY | ATMEL_US_NACK | ATMEL_US_ITERATION;
425 	} else {
426 		dev_dbg(port->dev, "Setting UART back to RS232\n");
427 		/* back to last RS232 settings */
428 		mode = atmel_port->backup_mode;
429 		memset(iso7816conf, 0, sizeof(struct serial_iso7816));
430 		atmel_uart_writel(port, ATMEL_US_TTGR, 0);
431 		atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->backup_brgr);
432 		atmel_uart_writel(port, ATMEL_US_FIDI, 0x174);
433 
434 		if (atmel_use_pdc_tx(port))
435 			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
436 						   ATMEL_US_TXBUFE;
437 		else
438 			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
439 	}
440 
441 	port->iso7816 = *iso7816conf;
442 
443 	atmel_uart_writel(port, ATMEL_US_MR, mode);
444 
445 err_out:
446 	/* Enable interrupts */
447 	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
448 
449 	return ret;
450 }
451 
452 /*
453  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
454  */
455 static u_int atmel_tx_empty(struct uart_port *port)
456 {
457 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
458 
459 	if (atmel_port->tx_stopped)
460 		return TIOCSER_TEMT;
461 	return (atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXEMPTY) ?
462 		TIOCSER_TEMT :
463 		0;
464 }
465 
466 /*
467  * Set state of the modem control output lines
468  */
469 static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
470 {
471 	unsigned int control = 0;
472 	unsigned int mode = atmel_uart_readl(port, ATMEL_US_MR);
473 	unsigned int rts_paused, rts_ready;
474 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
475 
476 	/* override mode to RS485 if needed, otherwise keep the current mode */
477 	if (port->rs485.flags & SER_RS485_ENABLED) {
478 		atmel_uart_writel(port, ATMEL_US_TTGR,
479 				  port->rs485.delay_rts_after_send);
480 		mode &= ~ATMEL_US_USMODE;
481 		mode |= ATMEL_US_USMODE_RS485;
482 	}
483 
484 	/* set the RTS line state according to the mode */
485 	if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
486 		/* force RTS line to high level */
487 		rts_paused = ATMEL_US_RTSEN;
488 
489 		/* give the control of the RTS line back to the hardware */
490 		rts_ready = ATMEL_US_RTSDIS;
491 	} else {
492 		/* force RTS line to high level */
493 		rts_paused = ATMEL_US_RTSDIS;
494 
495 		/* force RTS line to low level */
496 		rts_ready = ATMEL_US_RTSEN;
497 	}
498 
499 	if (mctrl & TIOCM_RTS)
500 		control |= rts_ready;
501 	else
502 		control |= rts_paused;
503 
504 	if (mctrl & TIOCM_DTR)
505 		control |= ATMEL_US_DTREN;
506 	else
507 		control |= ATMEL_US_DTRDIS;
508 
509 	atmel_uart_writel(port, ATMEL_US_CR, control);
510 
511 	mctrl_gpio_set(atmel_port->gpios, mctrl);
512 
513 	/* Local loopback mode? */
514 	mode &= ~ATMEL_US_CHMODE;
515 	if (mctrl & TIOCM_LOOP)
516 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
517 	else
518 		mode |= ATMEL_US_CHMODE_NORMAL;
519 
520 	atmel_uart_writel(port, ATMEL_US_MR, mode);
521 }
522 
523 /*
524  * Get state of the modem control input lines
525  */
526 static u_int atmel_get_mctrl(struct uart_port *port)
527 {
528 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
529 	unsigned int ret = 0, status;
530 
531 	status = atmel_uart_readl(port, ATMEL_US_CSR);
532 
533 	/*
534 	 * The control signals are active low.
535 	 */
536 	if (!(status & ATMEL_US_DCD))
537 		ret |= TIOCM_CD;
538 	if (!(status & ATMEL_US_CTS))
539 		ret |= TIOCM_CTS;
540 	if (!(status & ATMEL_US_DSR))
541 		ret |= TIOCM_DSR;
542 	if (!(status & ATMEL_US_RI))
543 		ret |= TIOCM_RI;
544 
545 	return mctrl_gpio_get(atmel_port->gpios, &ret);
546 }
547 
548 /*
549  * Stop transmitting.
550  */
551 static void atmel_stop_tx(struct uart_port *port)
552 {
553 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
554 	bool is_pdc = atmel_use_pdc_tx(port);
555 	bool is_dma = is_pdc || atmel_use_dma_tx(port);
556 
557 	if (is_pdc) {
558 		/* disable PDC transmit */
559 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
560 	}
561 
562 	if (is_dma) {
563 		/*
564 		 * Disable the transmitter.
565 		 * This is mandatory when DMA is used, otherwise the DMA buffer
566 		 * is fully transmitted.
567 		 */
568 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS);
569 		atmel_port->tx_stopped = true;
570 	}
571 
572 	/* Disable interrupts */
573 	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
574 
575 	if (atmel_uart_is_half_duplex(port))
576 		if (!atomic_read(&atmel_port->tasklet_shutdown))
577 			atmel_start_rx(port);
578 }
579 
580 /*
581  * Start transmitting.
582  */
583 static void atmel_start_tx(struct uart_port *port)
584 {
585 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
586 	bool is_pdc = atmel_use_pdc_tx(port);
587 	bool is_dma = is_pdc || atmel_use_dma_tx(port);
588 
589 	if (is_pdc && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
590 				       & ATMEL_PDC_TXTEN))
591 		/* The transmitter is already running.  Yes, we
592 		   really need this.*/
593 		return;
594 
595 	if (is_dma && atmel_uart_is_half_duplex(port))
596 		atmel_stop_rx(port);
597 
598 	if (is_pdc) {
599 		/* re-enable PDC transmit */
600 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
601 	}
602 
603 	/* Enable interrupts */
604 	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
605 
606 	if (is_dma) {
607 		/* re-enable the transmitter */
608 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);
609 		atmel_port->tx_stopped = false;
610 	}
611 }
612 
613 /*
614  * start receiving - port is in process of being opened.
615  */
616 static void atmel_start_rx(struct uart_port *port)
617 {
618 	/* reset status and receiver */
619 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA);
620 
621 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RXEN);
622 
623 	if (atmel_use_pdc_rx(port)) {
624 		/* enable PDC controller */
625 		atmel_uart_writel(port, ATMEL_US_IER,
626 				  ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
627 				  port->read_status_mask);
628 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_RXTEN);
629 	} else {
630 		atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_RXRDY);
631 	}
632 }
633 
634 /*
635  * Stop receiving - port is in process of being closed.
636  */
637 static void atmel_stop_rx(struct uart_port *port)
638 {
639 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RXDIS);
640 
641 	if (atmel_use_pdc_rx(port)) {
642 		/* disable PDC receive */
643 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_RXTDIS);
644 		atmel_uart_writel(port, ATMEL_US_IDR,
645 				  ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
646 				  port->read_status_mask);
647 	} else {
648 		atmel_uart_writel(port, ATMEL_US_IDR, ATMEL_US_RXRDY);
649 	}
650 }
651 
652 /*
653  * Enable modem status interrupts
654  */
655 static void atmel_enable_ms(struct uart_port *port)
656 {
657 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
658 	uint32_t ier = 0;
659 
660 	/*
661 	 * Interrupt should not be enabled twice
662 	 */
663 	if (atmel_port->ms_irq_enabled)
664 		return;
665 
666 	atmel_port->ms_irq_enabled = true;
667 
668 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS))
669 		ier |= ATMEL_US_CTSIC;
670 
671 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_DSR))
672 		ier |= ATMEL_US_DSRIC;
673 
674 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_RI))
675 		ier |= ATMEL_US_RIIC;
676 
677 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_DCD))
678 		ier |= ATMEL_US_DCDIC;
679 
680 	atmel_uart_writel(port, ATMEL_US_IER, ier);
681 
682 	mctrl_gpio_enable_ms(atmel_port->gpios);
683 }
684 
685 /*
686  * Disable modem status interrupts
687  */
688 static void atmel_disable_ms(struct uart_port *port)
689 {
690 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
691 	uint32_t idr = 0;
692 
693 	/*
694 	 * Interrupt should not be disabled twice
695 	 */
696 	if (!atmel_port->ms_irq_enabled)
697 		return;
698 
699 	atmel_port->ms_irq_enabled = false;
700 
701 	mctrl_gpio_disable_ms(atmel_port->gpios);
702 
703 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS))
704 		idr |= ATMEL_US_CTSIC;
705 
706 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_DSR))
707 		idr |= ATMEL_US_DSRIC;
708 
709 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_RI))
710 		idr |= ATMEL_US_RIIC;
711 
712 	if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_DCD))
713 		idr |= ATMEL_US_DCDIC;
714 
715 	atmel_uart_writel(port, ATMEL_US_IDR, idr);
716 }
717 
718 /*
719  * Control the transmission of a break signal
720  */
721 static void atmel_break_ctl(struct uart_port *port, int break_state)
722 {
723 	if (break_state != 0)
724 		/* start break */
725 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTBRK);
726 	else
727 		/* stop break */
728 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STPBRK);
729 }
730 
731 /*
732  * Stores the incoming character in the ring buffer
733  */
734 static void
735 atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
736 		     unsigned int ch)
737 {
738 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
739 	struct circ_buf *ring = &atmel_port->rx_ring;
740 	struct atmel_uart_char *c;
741 
742 	if (!CIRC_SPACE(ring->head, ring->tail, ATMEL_SERIAL_RINGSIZE))
743 		/* Buffer overflow, ignore char */
744 		return;
745 
746 	c = &((struct atmel_uart_char *)ring->buf)[ring->head];
747 	c->status	= status;
748 	c->ch		= ch;
749 
750 	/* Make sure the character is stored before we update head. */
751 	smp_wmb();
752 
753 	ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
754 }
755 
756 /*
757  * Deal with parity, framing and overrun errors.
758  */
759 static void atmel_pdc_rxerr(struct uart_port *port, unsigned int status)
760 {
761 	/* clear error */
762 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA);
763 
764 	if (status & ATMEL_US_RXBRK) {
765 		/* ignore side-effect */
766 		status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
767 		port->icount.brk++;
768 	}
769 	if (status & ATMEL_US_PARE)
770 		port->icount.parity++;
771 	if (status & ATMEL_US_FRAME)
772 		port->icount.frame++;
773 	if (status & ATMEL_US_OVRE)
774 		port->icount.overrun++;
775 }
776 
777 /*
778  * Characters received (called from interrupt handler)
779  */
780 static void atmel_rx_chars(struct uart_port *port)
781 {
782 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
783 	unsigned int status, ch;
784 
785 	status = atmel_uart_readl(port, ATMEL_US_CSR);
786 	while (status & ATMEL_US_RXRDY) {
787 		ch = atmel_uart_read_char(port);
788 
789 		/*
790 		 * note that the error handling code is
791 		 * out of the main execution path
792 		 */
793 		if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
794 				       | ATMEL_US_OVRE | ATMEL_US_RXBRK)
795 			     || atmel_port->break_active)) {
796 
797 			/* clear error */
798 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA);
799 
800 			if (status & ATMEL_US_RXBRK
801 			    && !atmel_port->break_active) {
802 				atmel_port->break_active = 1;
803 				atmel_uart_writel(port, ATMEL_US_IER,
804 						  ATMEL_US_RXBRK);
805 			} else {
806 				/*
807 				 * This is either the end-of-break
808 				 * condition or we've received at
809 				 * least one character without RXBRK
810 				 * being set. In both cases, the next
811 				 * RXBRK will indicate start-of-break.
812 				 */
813 				atmel_uart_writel(port, ATMEL_US_IDR,
814 						  ATMEL_US_RXBRK);
815 				status &= ~ATMEL_US_RXBRK;
816 				atmel_port->break_active = 0;
817 			}
818 		}
819 
820 		atmel_buffer_rx_char(port, status, ch);
821 		status = atmel_uart_readl(port, ATMEL_US_CSR);
822 	}
823 
824 	atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_rx);
825 }
826 
827 /*
828  * Transmit characters (called from tasklet with TXRDY interrupt
829  * disabled)
830  */
831 static void atmel_tx_chars(struct uart_port *port)
832 {
833 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
834 	bool pending;
835 	u8 ch;
836 
837 	pending = uart_port_tx(port, ch,
838 		atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY,
839 		atmel_uart_write_char(port, ch));
840 	if (pending) {
841 		/* we still have characters to transmit, so we should continue
842 		 * transmitting them when TX is ready, regardless of
843 		 * mode or duplexity
844 		 */
845 		atmel_port->tx_done_mask |= ATMEL_US_TXRDY;
846 
847 		/* Enable interrupts */
848 		atmel_uart_writel(port, ATMEL_US_IER,
849 				  atmel_port->tx_done_mask);
850 	} else {
851 		if (atmel_uart_is_half_duplex(port))
852 			atmel_port->tx_done_mask &= ~ATMEL_US_TXRDY;
853 	}
854 }
855 
856 static void atmel_complete_tx_dma(void *arg)
857 {
858 	struct atmel_uart_port *atmel_port = arg;
859 	struct uart_port *port = &atmel_port->uart;
860 	struct circ_buf *xmit = &port->state->xmit;
861 	struct dma_chan *chan = atmel_port->chan_tx;
862 	unsigned long flags;
863 
864 	uart_port_lock_irqsave(port, &flags);
865 
866 	if (chan)
867 		dmaengine_terminate_all(chan);
868 	uart_xmit_advance(port, atmel_port->tx_len);
869 
870 	spin_lock(&atmel_port->lock_tx);
871 	async_tx_ack(atmel_port->desc_tx);
872 	atmel_port->cookie_tx = -EINVAL;
873 	atmel_port->desc_tx = NULL;
874 	spin_unlock(&atmel_port->lock_tx);
875 
876 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
877 		uart_write_wakeup(port);
878 
879 	/*
880 	 * xmit is a circular buffer so, if we have just send data from
881 	 * xmit->tail to the end of xmit->buf, now we have to transmit the
882 	 * remaining data from the beginning of xmit->buf to xmit->head.
883 	 */
884 	if (!uart_circ_empty(xmit))
885 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
886 	else if (atmel_uart_is_half_duplex(port)) {
887 		/*
888 		 * DMA done, re-enable TXEMPTY and signal that we can stop
889 		 * TX and start RX for RS485
890 		 */
891 		atmel_port->hd_start_rx = true;
892 		atmel_uart_writel(port, ATMEL_US_IER,
893 				  atmel_port->tx_done_mask);
894 	}
895 
896 	uart_port_unlock_irqrestore(port, flags);
897 }
898 
899 static void atmel_release_tx_dma(struct uart_port *port)
900 {
901 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
902 	struct dma_chan *chan = atmel_port->chan_tx;
903 
904 	if (chan) {
905 		dmaengine_terminate_all(chan);
906 		dma_release_channel(chan);
907 		dma_unmap_sg(port->dev, &atmel_port->sg_tx, 1,
908 				DMA_TO_DEVICE);
909 	}
910 
911 	atmel_port->desc_tx = NULL;
912 	atmel_port->chan_tx = NULL;
913 	atmel_port->cookie_tx = -EINVAL;
914 }
915 
916 /*
917  * Called from tasklet with TXRDY interrupt is disabled.
918  */
919 static void atmel_tx_dma(struct uart_port *port)
920 {
921 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
922 	struct circ_buf *xmit = &port->state->xmit;
923 	struct dma_chan *chan = atmel_port->chan_tx;
924 	struct dma_async_tx_descriptor *desc;
925 	struct scatterlist sgl[2], *sg, *sg_tx = &atmel_port->sg_tx;
926 	unsigned int tx_len, part1_len, part2_len, sg_len;
927 	dma_addr_t phys_addr;
928 
929 	/* Make sure we have an idle channel */
930 	if (atmel_port->desc_tx != NULL)
931 		return;
932 
933 	if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
934 		/*
935 		 * DMA is idle now.
936 		 * Port xmit buffer is already mapped,
937 		 * and it is one page... Just adjust
938 		 * offsets and lengths. Since it is a circular buffer,
939 		 * we have to transmit till the end, and then the rest.
940 		 * Take the port lock to get a
941 		 * consistent xmit buffer state.
942 		 */
943 		tx_len = CIRC_CNT_TO_END(xmit->head,
944 					 xmit->tail,
945 					 UART_XMIT_SIZE);
946 
947 		if (atmel_port->fifo_size) {
948 			/* multi data mode */
949 			part1_len = (tx_len & ~0x3); /* DWORD access */
950 			part2_len = (tx_len & 0x3); /* BYTE access */
951 		} else {
952 			/* single data (legacy) mode */
953 			part1_len = 0;
954 			part2_len = tx_len; /* BYTE access only */
955 		}
956 
957 		sg_init_table(sgl, 2);
958 		sg_len = 0;
959 		phys_addr = sg_dma_address(sg_tx) + xmit->tail;
960 		if (part1_len) {
961 			sg = &sgl[sg_len++];
962 			sg_dma_address(sg) = phys_addr;
963 			sg_dma_len(sg) = part1_len;
964 
965 			phys_addr += part1_len;
966 		}
967 
968 		if (part2_len) {
969 			sg = &sgl[sg_len++];
970 			sg_dma_address(sg) = phys_addr;
971 			sg_dma_len(sg) = part2_len;
972 		}
973 
974 		/*
975 		 * save tx_len so atmel_complete_tx_dma() will increase
976 		 * xmit->tail correctly
977 		 */
978 		atmel_port->tx_len = tx_len;
979 
980 		desc = dmaengine_prep_slave_sg(chan,
981 					       sgl,
982 					       sg_len,
983 					       DMA_MEM_TO_DEV,
984 					       DMA_PREP_INTERRUPT |
985 					       DMA_CTRL_ACK);
986 		if (!desc) {
987 			dev_err(port->dev, "Failed to send via dma!\n");
988 			return;
989 		}
990 
991 		dma_sync_sg_for_device(port->dev, sg_tx, 1, DMA_TO_DEVICE);
992 
993 		atmel_port->desc_tx = desc;
994 		desc->callback = atmel_complete_tx_dma;
995 		desc->callback_param = atmel_port;
996 		atmel_port->cookie_tx = dmaengine_submit(desc);
997 		if (dma_submit_error(atmel_port->cookie_tx)) {
998 			dev_err(port->dev, "dma_submit_error %d\n",
999 				atmel_port->cookie_tx);
1000 			return;
1001 		}
1002 
1003 		dma_async_issue_pending(chan);
1004 	}
1005 
1006 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
1007 		uart_write_wakeup(port);
1008 }
1009 
1010 static int atmel_prepare_tx_dma(struct uart_port *port)
1011 {
1012 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1013 	struct device *mfd_dev = port->dev->parent;
1014 	dma_cap_mask_t		mask;
1015 	struct dma_slave_config config;
1016 	int ret, nent;
1017 
1018 	dma_cap_zero(mask);
1019 	dma_cap_set(DMA_SLAVE, mask);
1020 
1021 	atmel_port->chan_tx = dma_request_slave_channel(mfd_dev, "tx");
1022 	if (atmel_port->chan_tx == NULL)
1023 		goto chan_err;
1024 	dev_info(port->dev, "using %s for tx DMA transfers\n",
1025 		dma_chan_name(atmel_port->chan_tx));
1026 
1027 	spin_lock_init(&atmel_port->lock_tx);
1028 	sg_init_table(&atmel_port->sg_tx, 1);
1029 	/* UART circular tx buffer is an aligned page. */
1030 	BUG_ON(!PAGE_ALIGNED(port->state->xmit.buf));
1031 	sg_set_page(&atmel_port->sg_tx,
1032 			virt_to_page(port->state->xmit.buf),
1033 			UART_XMIT_SIZE,
1034 			offset_in_page(port->state->xmit.buf));
1035 	nent = dma_map_sg(port->dev,
1036 				&atmel_port->sg_tx,
1037 				1,
1038 				DMA_TO_DEVICE);
1039 
1040 	if (!nent) {
1041 		dev_dbg(port->dev, "need to release resource of dma\n");
1042 		goto chan_err;
1043 	} else {
1044 		dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
1045 			sg_dma_len(&atmel_port->sg_tx),
1046 			port->state->xmit.buf,
1047 			&sg_dma_address(&atmel_port->sg_tx));
1048 	}
1049 
1050 	/* Configure the slave DMA */
1051 	memset(&config, 0, sizeof(config));
1052 	config.direction = DMA_MEM_TO_DEV;
1053 	config.dst_addr_width = (atmel_port->fifo_size) ?
1054 				DMA_SLAVE_BUSWIDTH_4_BYTES :
1055 				DMA_SLAVE_BUSWIDTH_1_BYTE;
1056 	config.dst_addr = port->mapbase + ATMEL_US_THR;
1057 	config.dst_maxburst = 1;
1058 
1059 	ret = dmaengine_slave_config(atmel_port->chan_tx,
1060 				     &config);
1061 	if (ret) {
1062 		dev_err(port->dev, "DMA tx slave configuration failed\n");
1063 		goto chan_err;
1064 	}
1065 
1066 	return 0;
1067 
1068 chan_err:
1069 	dev_err(port->dev, "TX channel not available, switch to pio\n");
1070 	atmel_port->use_dma_tx = false;
1071 	if (atmel_port->chan_tx)
1072 		atmel_release_tx_dma(port);
1073 	return -EINVAL;
1074 }
1075 
1076 static void atmel_complete_rx_dma(void *arg)
1077 {
1078 	struct uart_port *port = arg;
1079 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1080 
1081 	atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_rx);
1082 }
1083 
1084 static void atmel_release_rx_dma(struct uart_port *port)
1085 {
1086 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1087 	struct dma_chan *chan = atmel_port->chan_rx;
1088 
1089 	if (chan) {
1090 		dmaengine_terminate_all(chan);
1091 		dma_release_channel(chan);
1092 		dma_unmap_sg(port->dev, &atmel_port->sg_rx, 1,
1093 				DMA_FROM_DEVICE);
1094 	}
1095 
1096 	atmel_port->desc_rx = NULL;
1097 	atmel_port->chan_rx = NULL;
1098 	atmel_port->cookie_rx = -EINVAL;
1099 }
1100 
1101 static void atmel_rx_from_dma(struct uart_port *port)
1102 {
1103 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1104 	struct tty_port *tport = &port->state->port;
1105 	struct circ_buf *ring = &atmel_port->rx_ring;
1106 	struct dma_chan *chan = atmel_port->chan_rx;
1107 	struct dma_tx_state state;
1108 	enum dma_status dmastat;
1109 	size_t count;
1110 
1111 
1112 	/* Reset the UART timeout early so that we don't miss one */
1113 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
1114 	dmastat = dmaengine_tx_status(chan,
1115 				atmel_port->cookie_rx,
1116 				&state);
1117 	/* Restart a new tasklet if DMA status is error */
1118 	if (dmastat == DMA_ERROR) {
1119 		dev_dbg(port->dev, "Get residue error, restart tasklet\n");
1120 		atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_TIMEOUT);
1121 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_rx);
1122 		return;
1123 	}
1124 
1125 	/* CPU claims ownership of RX DMA buffer */
1126 	dma_sync_sg_for_cpu(port->dev,
1127 			    &atmel_port->sg_rx,
1128 			    1,
1129 			    DMA_FROM_DEVICE);
1130 
1131 	/*
1132 	 * ring->head points to the end of data already written by the DMA.
1133 	 * ring->tail points to the beginning of data to be read by the
1134 	 * framework.
1135 	 * The current transfer size should not be larger than the dma buffer
1136 	 * length.
1137 	 */
1138 	ring->head = sg_dma_len(&atmel_port->sg_rx) - state.residue;
1139 	BUG_ON(ring->head > sg_dma_len(&atmel_port->sg_rx));
1140 	/*
1141 	 * At this point ring->head may point to the first byte right after the
1142 	 * last byte of the dma buffer:
1143 	 * 0 <= ring->head <= sg_dma_len(&atmel_port->sg_rx)
1144 	 *
1145 	 * However ring->tail must always points inside the dma buffer:
1146 	 * 0 <= ring->tail <= sg_dma_len(&atmel_port->sg_rx) - 1
1147 	 *
1148 	 * Since we use a ring buffer, we have to handle the case
1149 	 * where head is lower than tail. In such a case, we first read from
1150 	 * tail to the end of the buffer then reset tail.
1151 	 */
1152 	if (ring->head < ring->tail) {
1153 		count = sg_dma_len(&atmel_port->sg_rx) - ring->tail;
1154 
1155 		tty_insert_flip_string(tport, ring->buf + ring->tail, count);
1156 		ring->tail = 0;
1157 		port->icount.rx += count;
1158 	}
1159 
1160 	/* Finally we read data from tail to head */
1161 	if (ring->tail < ring->head) {
1162 		count = ring->head - ring->tail;
1163 
1164 		tty_insert_flip_string(tport, ring->buf + ring->tail, count);
1165 		/* Wrap ring->head if needed */
1166 		if (ring->head >= sg_dma_len(&atmel_port->sg_rx))
1167 			ring->head = 0;
1168 		ring->tail = ring->head;
1169 		port->icount.rx += count;
1170 	}
1171 
1172 	/* USART retreives ownership of RX DMA buffer */
1173 	dma_sync_sg_for_device(port->dev,
1174 			       &atmel_port->sg_rx,
1175 			       1,
1176 			       DMA_FROM_DEVICE);
1177 
1178 	tty_flip_buffer_push(tport);
1179 
1180 	atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_TIMEOUT);
1181 }
1182 
1183 static int atmel_prepare_rx_dma(struct uart_port *port)
1184 {
1185 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1186 	struct device *mfd_dev = port->dev->parent;
1187 	struct dma_async_tx_descriptor *desc;
1188 	dma_cap_mask_t		mask;
1189 	struct dma_slave_config config;
1190 	struct circ_buf		*ring;
1191 	int ret, nent;
1192 
1193 	ring = &atmel_port->rx_ring;
1194 
1195 	dma_cap_zero(mask);
1196 	dma_cap_set(DMA_CYCLIC, mask);
1197 
1198 	atmel_port->chan_rx = dma_request_slave_channel(mfd_dev, "rx");
1199 	if (atmel_port->chan_rx == NULL)
1200 		goto chan_err;
1201 	dev_info(port->dev, "using %s for rx DMA transfers\n",
1202 		dma_chan_name(atmel_port->chan_rx));
1203 
1204 	spin_lock_init(&atmel_port->lock_rx);
1205 	sg_init_table(&atmel_port->sg_rx, 1);
1206 	/* UART circular rx buffer is an aligned page. */
1207 	BUG_ON(!PAGE_ALIGNED(ring->buf));
1208 	sg_set_page(&atmel_port->sg_rx,
1209 		    virt_to_page(ring->buf),
1210 		    sizeof(struct atmel_uart_char) * ATMEL_SERIAL_RINGSIZE,
1211 		    offset_in_page(ring->buf));
1212 	nent = dma_map_sg(port->dev,
1213 			  &atmel_port->sg_rx,
1214 			  1,
1215 			  DMA_FROM_DEVICE);
1216 
1217 	if (!nent) {
1218 		dev_dbg(port->dev, "need to release resource of dma\n");
1219 		goto chan_err;
1220 	} else {
1221 		dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
1222 			sg_dma_len(&atmel_port->sg_rx),
1223 			ring->buf,
1224 			&sg_dma_address(&atmel_port->sg_rx));
1225 	}
1226 
1227 	/* Configure the slave DMA */
1228 	memset(&config, 0, sizeof(config));
1229 	config.direction = DMA_DEV_TO_MEM;
1230 	config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
1231 	config.src_addr = port->mapbase + ATMEL_US_RHR;
1232 	config.src_maxburst = 1;
1233 
1234 	ret = dmaengine_slave_config(atmel_port->chan_rx,
1235 				     &config);
1236 	if (ret) {
1237 		dev_err(port->dev, "DMA rx slave configuration failed\n");
1238 		goto chan_err;
1239 	}
1240 	/*
1241 	 * Prepare a cyclic dma transfer, assign 2 descriptors,
1242 	 * each one is half ring buffer size
1243 	 */
1244 	desc = dmaengine_prep_dma_cyclic(atmel_port->chan_rx,
1245 					 sg_dma_address(&atmel_port->sg_rx),
1246 					 sg_dma_len(&atmel_port->sg_rx),
1247 					 sg_dma_len(&atmel_port->sg_rx)/2,
1248 					 DMA_DEV_TO_MEM,
1249 					 DMA_PREP_INTERRUPT);
1250 	if (!desc) {
1251 		dev_err(port->dev, "Preparing DMA cyclic failed\n");
1252 		goto chan_err;
1253 	}
1254 	desc->callback = atmel_complete_rx_dma;
1255 	desc->callback_param = port;
1256 	atmel_port->desc_rx = desc;
1257 	atmel_port->cookie_rx = dmaengine_submit(desc);
1258 	if (dma_submit_error(atmel_port->cookie_rx)) {
1259 		dev_err(port->dev, "dma_submit_error %d\n",
1260 			atmel_port->cookie_rx);
1261 		goto chan_err;
1262 	}
1263 
1264 	dma_async_issue_pending(atmel_port->chan_rx);
1265 
1266 	return 0;
1267 
1268 chan_err:
1269 	dev_err(port->dev, "RX channel not available, switch to pio\n");
1270 	atmel_port->use_dma_rx = false;
1271 	if (atmel_port->chan_rx)
1272 		atmel_release_rx_dma(port);
1273 	return -EINVAL;
1274 }
1275 
1276 static void atmel_uart_timer_callback(struct timer_list *t)
1277 {
1278 	struct atmel_uart_port *atmel_port = from_timer(atmel_port, t,
1279 							uart_timer);
1280 	struct uart_port *port = &atmel_port->uart;
1281 
1282 	if (!atomic_read(&atmel_port->tasklet_shutdown)) {
1283 		tasklet_schedule(&atmel_port->tasklet_rx);
1284 		mod_timer(&atmel_port->uart_timer,
1285 			  jiffies + uart_poll_timeout(port));
1286 	}
1287 }
1288 
1289 /*
1290  * receive interrupt handler.
1291  */
1292 static void
1293 atmel_handle_receive(struct uart_port *port, unsigned int pending)
1294 {
1295 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1296 
1297 	if (atmel_use_pdc_rx(port)) {
1298 		/*
1299 		 * PDC receive. Just schedule the tasklet and let it
1300 		 * figure out the details.
1301 		 *
1302 		 * TODO: We're not handling error flags correctly at
1303 		 * the moment.
1304 		 */
1305 		if (pending & (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT)) {
1306 			atmel_uart_writel(port, ATMEL_US_IDR,
1307 					  (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT));
1308 			atmel_tasklet_schedule(atmel_port,
1309 					       &atmel_port->tasklet_rx);
1310 		}
1311 
1312 		if (pending & (ATMEL_US_RXBRK | ATMEL_US_OVRE |
1313 				ATMEL_US_FRAME | ATMEL_US_PARE))
1314 			atmel_pdc_rxerr(port, pending);
1315 	}
1316 
1317 	if (atmel_use_dma_rx(port)) {
1318 		if (pending & ATMEL_US_TIMEOUT) {
1319 			atmel_uart_writel(port, ATMEL_US_IDR,
1320 					  ATMEL_US_TIMEOUT);
1321 			atmel_tasklet_schedule(atmel_port,
1322 					       &atmel_port->tasklet_rx);
1323 		}
1324 	}
1325 
1326 	/* Interrupt receive */
1327 	if (pending & ATMEL_US_RXRDY)
1328 		atmel_rx_chars(port);
1329 	else if (pending & ATMEL_US_RXBRK) {
1330 		/*
1331 		 * End of break detected. If it came along with a
1332 		 * character, atmel_rx_chars will handle it.
1333 		 */
1334 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA);
1335 		atmel_uart_writel(port, ATMEL_US_IDR, ATMEL_US_RXBRK);
1336 		atmel_port->break_active = 0;
1337 	}
1338 }
1339 
1340 /*
1341  * transmit interrupt handler. (Transmit is IRQF_NODELAY safe)
1342  */
1343 static void
1344 atmel_handle_transmit(struct uart_port *port, unsigned int pending)
1345 {
1346 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1347 
1348 	if (pending & atmel_port->tx_done_mask) {
1349 		atmel_uart_writel(port, ATMEL_US_IDR,
1350 				  atmel_port->tx_done_mask);
1351 
1352 		/* Start RX if flag was set and FIFO is empty */
1353 		if (atmel_port->hd_start_rx) {
1354 			if (!(atmel_uart_readl(port, ATMEL_US_CSR)
1355 					& ATMEL_US_TXEMPTY))
1356 				dev_warn(port->dev, "Should start RX, but TX fifo is not empty\n");
1357 
1358 			atmel_port->hd_start_rx = false;
1359 			atmel_start_rx(port);
1360 		}
1361 
1362 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
1363 	}
1364 }
1365 
1366 /*
1367  * status flags interrupt handler.
1368  */
1369 static void
1370 atmel_handle_status(struct uart_port *port, unsigned int pending,
1371 		    unsigned int status)
1372 {
1373 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1374 	unsigned int status_change;
1375 
1376 	if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC
1377 				| ATMEL_US_CTSIC)) {
1378 		status_change = status ^ atmel_port->irq_status_prev;
1379 		atmel_port->irq_status_prev = status;
1380 
1381 		if (status_change & (ATMEL_US_RI | ATMEL_US_DSR
1382 					| ATMEL_US_DCD | ATMEL_US_CTS)) {
1383 			/* TODO: All reads to CSR will clear these interrupts! */
1384 			if (status_change & ATMEL_US_RI)
1385 				port->icount.rng++;
1386 			if (status_change & ATMEL_US_DSR)
1387 				port->icount.dsr++;
1388 			if (status_change & ATMEL_US_DCD)
1389 				uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
1390 			if (status_change & ATMEL_US_CTS)
1391 				uart_handle_cts_change(port, !(status & ATMEL_US_CTS));
1392 
1393 			wake_up_interruptible(&port->state->port.delta_msr_wait);
1394 		}
1395 	}
1396 
1397 	if (pending & (ATMEL_US_NACK | ATMEL_US_ITERATION))
1398 		dev_dbg(port->dev, "ISO7816 ERROR (0x%08x)\n", pending);
1399 }
1400 
1401 /*
1402  * Interrupt handler
1403  */
1404 static irqreturn_t atmel_interrupt(int irq, void *dev_id)
1405 {
1406 	struct uart_port *port = dev_id;
1407 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1408 	unsigned int status, pending, mask, pass_counter = 0;
1409 
1410 	spin_lock(&atmel_port->lock_suspended);
1411 
1412 	do {
1413 		status = atmel_uart_readl(port, ATMEL_US_CSR);
1414 		mask = atmel_uart_readl(port, ATMEL_US_IMR);
1415 		pending = status & mask;
1416 		if (!pending)
1417 			break;
1418 
1419 		if (atmel_port->suspended) {
1420 			atmel_port->pending |= pending;
1421 			atmel_port->pending_status = status;
1422 			atmel_uart_writel(port, ATMEL_US_IDR, mask);
1423 			pm_system_wakeup();
1424 			break;
1425 		}
1426 
1427 		atmel_handle_receive(port, pending);
1428 		atmel_handle_status(port, pending, status);
1429 		atmel_handle_transmit(port, pending);
1430 	} while (pass_counter++ < ATMEL_ISR_PASS_LIMIT);
1431 
1432 	spin_unlock(&atmel_port->lock_suspended);
1433 
1434 	return pass_counter ? IRQ_HANDLED : IRQ_NONE;
1435 }
1436 
1437 static void atmel_release_tx_pdc(struct uart_port *port)
1438 {
1439 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1440 	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
1441 
1442 	dma_unmap_single(port->dev,
1443 			 pdc->dma_addr,
1444 			 pdc->dma_size,
1445 			 DMA_TO_DEVICE);
1446 }
1447 
1448 /*
1449  * Called from tasklet with ENDTX and TXBUFE interrupts disabled.
1450  */
1451 static void atmel_tx_pdc(struct uart_port *port)
1452 {
1453 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1454 	struct circ_buf *xmit = &port->state->xmit;
1455 	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
1456 	int count;
1457 
1458 	/* nothing left to transmit? */
1459 	if (atmel_uart_readl(port, ATMEL_PDC_TCR))
1460 		return;
1461 	uart_xmit_advance(port, pdc->ofs);
1462 	pdc->ofs = 0;
1463 
1464 	/* more to transmit - setup next transfer */
1465 
1466 	/* disable PDC transmit */
1467 	atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
1468 
1469 	if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
1470 		dma_sync_single_for_device(port->dev,
1471 					   pdc->dma_addr,
1472 					   pdc->dma_size,
1473 					   DMA_TO_DEVICE);
1474 
1475 		count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
1476 		pdc->ofs = count;
1477 
1478 		atmel_uart_writel(port, ATMEL_PDC_TPR,
1479 				  pdc->dma_addr + xmit->tail);
1480 		atmel_uart_writel(port, ATMEL_PDC_TCR, count);
1481 		/* re-enable PDC transmit */
1482 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
1483 		/* Enable interrupts */
1484 		atmel_uart_writel(port, ATMEL_US_IER,
1485 				  atmel_port->tx_done_mask);
1486 	} else {
1487 		if (atmel_uart_is_half_duplex(port)) {
1488 			/* DMA done, stop TX, start RX for RS485 */
1489 			atmel_start_rx(port);
1490 		}
1491 	}
1492 
1493 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
1494 		uart_write_wakeup(port);
1495 }
1496 
1497 static int atmel_prepare_tx_pdc(struct uart_port *port)
1498 {
1499 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1500 	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
1501 	struct circ_buf *xmit = &port->state->xmit;
1502 
1503 	pdc->buf = xmit->buf;
1504 	pdc->dma_addr = dma_map_single(port->dev,
1505 					pdc->buf,
1506 					UART_XMIT_SIZE,
1507 					DMA_TO_DEVICE);
1508 	pdc->dma_size = UART_XMIT_SIZE;
1509 	pdc->ofs = 0;
1510 
1511 	return 0;
1512 }
1513 
1514 static void atmel_rx_from_ring(struct uart_port *port)
1515 {
1516 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1517 	struct circ_buf *ring = &atmel_port->rx_ring;
1518 	unsigned int status;
1519 	u8 flg;
1520 
1521 	while (ring->head != ring->tail) {
1522 		struct atmel_uart_char c;
1523 
1524 		/* Make sure c is loaded after head. */
1525 		smp_rmb();
1526 
1527 		c = ((struct atmel_uart_char *)ring->buf)[ring->tail];
1528 
1529 		ring->tail = (ring->tail + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
1530 
1531 		port->icount.rx++;
1532 		status = c.status;
1533 		flg = TTY_NORMAL;
1534 
1535 		/*
1536 		 * note that the error handling code is
1537 		 * out of the main execution path
1538 		 */
1539 		if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
1540 				       | ATMEL_US_OVRE | ATMEL_US_RXBRK))) {
1541 			if (status & ATMEL_US_RXBRK) {
1542 				/* ignore side-effect */
1543 				status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
1544 
1545 				port->icount.brk++;
1546 				if (uart_handle_break(port))
1547 					continue;
1548 			}
1549 			if (status & ATMEL_US_PARE)
1550 				port->icount.parity++;
1551 			if (status & ATMEL_US_FRAME)
1552 				port->icount.frame++;
1553 			if (status & ATMEL_US_OVRE)
1554 				port->icount.overrun++;
1555 
1556 			status &= port->read_status_mask;
1557 
1558 			if (status & ATMEL_US_RXBRK)
1559 				flg = TTY_BREAK;
1560 			else if (status & ATMEL_US_PARE)
1561 				flg = TTY_PARITY;
1562 			else if (status & ATMEL_US_FRAME)
1563 				flg = TTY_FRAME;
1564 		}
1565 
1566 
1567 		if (uart_handle_sysrq_char(port, c.ch))
1568 			continue;
1569 
1570 		uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg);
1571 	}
1572 
1573 	tty_flip_buffer_push(&port->state->port);
1574 }
1575 
1576 static void atmel_release_rx_pdc(struct uart_port *port)
1577 {
1578 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1579 	int i;
1580 
1581 	for (i = 0; i < 2; i++) {
1582 		struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];
1583 
1584 		dma_unmap_single(port->dev,
1585 				 pdc->dma_addr,
1586 				 pdc->dma_size,
1587 				 DMA_FROM_DEVICE);
1588 		kfree(pdc->buf);
1589 	}
1590 }
1591 
1592 static void atmel_rx_from_pdc(struct uart_port *port)
1593 {
1594 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1595 	struct tty_port *tport = &port->state->port;
1596 	struct atmel_dma_buffer *pdc;
1597 	int rx_idx = atmel_port->pdc_rx_idx;
1598 	unsigned int head;
1599 	unsigned int tail;
1600 	unsigned int count;
1601 
1602 	do {
1603 		/* Reset the UART timeout early so that we don't miss one */
1604 		atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
1605 
1606 		pdc = &atmel_port->pdc_rx[rx_idx];
1607 		head = atmel_uart_readl(port, ATMEL_PDC_RPR) - pdc->dma_addr;
1608 		tail = pdc->ofs;
1609 
1610 		/* If the PDC has switched buffers, RPR won't contain
1611 		 * any address within the current buffer. Since head
1612 		 * is unsigned, we just need a one-way comparison to
1613 		 * find out.
1614 		 *
1615 		 * In this case, we just need to consume the entire
1616 		 * buffer and resubmit it for DMA. This will clear the
1617 		 * ENDRX bit as well, so that we can safely re-enable
1618 		 * all interrupts below.
1619 		 */
1620 		head = min(head, pdc->dma_size);
1621 
1622 		if (likely(head != tail)) {
1623 			dma_sync_single_for_cpu(port->dev, pdc->dma_addr,
1624 					pdc->dma_size, DMA_FROM_DEVICE);
1625 
1626 			/*
1627 			 * head will only wrap around when we recycle
1628 			 * the DMA buffer, and when that happens, we
1629 			 * explicitly set tail to 0. So head will
1630 			 * always be greater than tail.
1631 			 */
1632 			count = head - tail;
1633 
1634 			tty_insert_flip_string(tport, pdc->buf + pdc->ofs,
1635 						count);
1636 
1637 			dma_sync_single_for_device(port->dev, pdc->dma_addr,
1638 					pdc->dma_size, DMA_FROM_DEVICE);
1639 
1640 			port->icount.rx += count;
1641 			pdc->ofs = head;
1642 		}
1643 
1644 		/*
1645 		 * If the current buffer is full, we need to check if
1646 		 * the next one contains any additional data.
1647 		 */
1648 		if (head >= pdc->dma_size) {
1649 			pdc->ofs = 0;
1650 			atmel_uart_writel(port, ATMEL_PDC_RNPR, pdc->dma_addr);
1651 			atmel_uart_writel(port, ATMEL_PDC_RNCR, pdc->dma_size);
1652 
1653 			rx_idx = !rx_idx;
1654 			atmel_port->pdc_rx_idx = rx_idx;
1655 		}
1656 	} while (head >= pdc->dma_size);
1657 
1658 	tty_flip_buffer_push(tport);
1659 
1660 	atmel_uart_writel(port, ATMEL_US_IER,
1661 			  ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
1662 }
1663 
1664 static int atmel_prepare_rx_pdc(struct uart_port *port)
1665 {
1666 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1667 	int i;
1668 
1669 	for (i = 0; i < 2; i++) {
1670 		struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];
1671 
1672 		pdc->buf = kmalloc(PDC_BUFFER_SIZE, GFP_KERNEL);
1673 		if (pdc->buf == NULL) {
1674 			if (i != 0) {
1675 				dma_unmap_single(port->dev,
1676 					atmel_port->pdc_rx[0].dma_addr,
1677 					PDC_BUFFER_SIZE,
1678 					DMA_FROM_DEVICE);
1679 				kfree(atmel_port->pdc_rx[0].buf);
1680 			}
1681 			atmel_port->use_pdc_rx = false;
1682 			return -ENOMEM;
1683 		}
1684 		pdc->dma_addr = dma_map_single(port->dev,
1685 						pdc->buf,
1686 						PDC_BUFFER_SIZE,
1687 						DMA_FROM_DEVICE);
1688 		pdc->dma_size = PDC_BUFFER_SIZE;
1689 		pdc->ofs = 0;
1690 	}
1691 
1692 	atmel_port->pdc_rx_idx = 0;
1693 
1694 	atmel_uart_writel(port, ATMEL_PDC_RPR, atmel_port->pdc_rx[0].dma_addr);
1695 	atmel_uart_writel(port, ATMEL_PDC_RCR, PDC_BUFFER_SIZE);
1696 
1697 	atmel_uart_writel(port, ATMEL_PDC_RNPR,
1698 			  atmel_port->pdc_rx[1].dma_addr);
1699 	atmel_uart_writel(port, ATMEL_PDC_RNCR, PDC_BUFFER_SIZE);
1700 
1701 	return 0;
1702 }
1703 
1704 /*
1705  * tasklet handling tty stuff outside the interrupt handler.
1706  */
1707 static void atmel_tasklet_rx_func(struct tasklet_struct *t)
1708 {
1709 	struct atmel_uart_port *atmel_port = from_tasklet(atmel_port, t,
1710 							  tasklet_rx);
1711 	struct uart_port *port = &atmel_port->uart;
1712 
1713 	/* The interrupt handler does not take the lock */
1714 	uart_port_lock(port);
1715 	atmel_port->schedule_rx(port);
1716 	uart_port_unlock(port);
1717 }
1718 
1719 static void atmel_tasklet_tx_func(struct tasklet_struct *t)
1720 {
1721 	struct atmel_uart_port *atmel_port = from_tasklet(atmel_port, t,
1722 							  tasklet_tx);
1723 	struct uart_port *port = &atmel_port->uart;
1724 
1725 	/* The interrupt handler does not take the lock */
1726 	uart_port_lock(port);
1727 	atmel_port->schedule_tx(port);
1728 	uart_port_unlock(port);
1729 }
1730 
1731 static void atmel_init_property(struct atmel_uart_port *atmel_port,
1732 				struct platform_device *pdev)
1733 {
1734 	struct device_node *np = pdev->dev.of_node;
1735 
1736 	/* DMA/PDC usage specification */
1737 	if (of_property_read_bool(np, "atmel,use-dma-rx")) {
1738 		if (of_property_read_bool(np, "dmas")) {
1739 			atmel_port->use_dma_rx  = true;
1740 			atmel_port->use_pdc_rx  = false;
1741 		} else {
1742 			atmel_port->use_dma_rx  = false;
1743 			atmel_port->use_pdc_rx  = true;
1744 		}
1745 	} else {
1746 		atmel_port->use_dma_rx  = false;
1747 		atmel_port->use_pdc_rx  = false;
1748 	}
1749 
1750 	if (of_property_read_bool(np, "atmel,use-dma-tx")) {
1751 		if (of_property_read_bool(np, "dmas")) {
1752 			atmel_port->use_dma_tx  = true;
1753 			atmel_port->use_pdc_tx  = false;
1754 		} else {
1755 			atmel_port->use_dma_tx  = false;
1756 			atmel_port->use_pdc_tx  = true;
1757 		}
1758 	} else {
1759 		atmel_port->use_dma_tx  = false;
1760 		atmel_port->use_pdc_tx  = false;
1761 	}
1762 }
1763 
1764 static void atmel_set_ops(struct uart_port *port)
1765 {
1766 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1767 
1768 	if (atmel_use_dma_rx(port)) {
1769 		atmel_port->prepare_rx = &atmel_prepare_rx_dma;
1770 		atmel_port->schedule_rx = &atmel_rx_from_dma;
1771 		atmel_port->release_rx = &atmel_release_rx_dma;
1772 	} else if (atmel_use_pdc_rx(port)) {
1773 		atmel_port->prepare_rx = &atmel_prepare_rx_pdc;
1774 		atmel_port->schedule_rx = &atmel_rx_from_pdc;
1775 		atmel_port->release_rx = &atmel_release_rx_pdc;
1776 	} else {
1777 		atmel_port->prepare_rx = NULL;
1778 		atmel_port->schedule_rx = &atmel_rx_from_ring;
1779 		atmel_port->release_rx = NULL;
1780 	}
1781 
1782 	if (atmel_use_dma_tx(port)) {
1783 		atmel_port->prepare_tx = &atmel_prepare_tx_dma;
1784 		atmel_port->schedule_tx = &atmel_tx_dma;
1785 		atmel_port->release_tx = &atmel_release_tx_dma;
1786 	} else if (atmel_use_pdc_tx(port)) {
1787 		atmel_port->prepare_tx = &atmel_prepare_tx_pdc;
1788 		atmel_port->schedule_tx = &atmel_tx_pdc;
1789 		atmel_port->release_tx = &atmel_release_tx_pdc;
1790 	} else {
1791 		atmel_port->prepare_tx = NULL;
1792 		atmel_port->schedule_tx = &atmel_tx_chars;
1793 		atmel_port->release_tx = NULL;
1794 	}
1795 }
1796 
1797 /*
1798  * Get ip name usart or uart
1799  */
1800 static void atmel_get_ip_name(struct uart_port *port)
1801 {
1802 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1803 	int name = atmel_uart_readl(port, ATMEL_US_NAME);
1804 	u32 version;
1805 	u32 usart, dbgu_uart, new_uart;
1806 	/* ASCII decoding for IP version */
1807 	usart = 0x55534152;	/* USAR(T) */
1808 	dbgu_uart = 0x44424755;	/* DBGU */
1809 	new_uart = 0x55415254;	/* UART */
1810 
1811 	/*
1812 	 * Only USART devices from at91sam9260 SOC implement fractional
1813 	 * baudrate. It is available for all asynchronous modes, with the
1814 	 * following restriction: the sampling clock's duty cycle is not
1815 	 * constant.
1816 	 */
1817 	atmel_port->has_frac_baudrate = false;
1818 	atmel_port->has_hw_timer = false;
1819 	atmel_port->is_usart = false;
1820 
1821 	if (name == new_uart) {
1822 		dev_dbg(port->dev, "Uart with hw timer");
1823 		atmel_port->has_hw_timer = true;
1824 		atmel_port->rtor = ATMEL_UA_RTOR;
1825 	} else if (name == usart) {
1826 		dev_dbg(port->dev, "Usart\n");
1827 		atmel_port->has_frac_baudrate = true;
1828 		atmel_port->has_hw_timer = true;
1829 		atmel_port->is_usart = true;
1830 		atmel_port->rtor = ATMEL_US_RTOR;
1831 		version = atmel_uart_readl(port, ATMEL_US_VERSION);
1832 		switch (version) {
1833 		case 0x814:	/* sama5d2 */
1834 			fallthrough;
1835 		case 0x701:	/* sama5d4 */
1836 			atmel_port->fidi_min = 3;
1837 			atmel_port->fidi_max = 65535;
1838 			break;
1839 		case 0x502:	/* sam9x5, sama5d3 */
1840 			atmel_port->fidi_min = 3;
1841 			atmel_port->fidi_max = 2047;
1842 			break;
1843 		default:
1844 			atmel_port->fidi_min = 1;
1845 			atmel_port->fidi_max = 2047;
1846 		}
1847 	} else if (name == dbgu_uart) {
1848 		dev_dbg(port->dev, "Dbgu or uart without hw timer\n");
1849 	} else {
1850 		/* fallback for older SoCs: use version field */
1851 		version = atmel_uart_readl(port, ATMEL_US_VERSION);
1852 		switch (version) {
1853 		case 0x302:
1854 		case 0x10213:
1855 		case 0x10302:
1856 			dev_dbg(port->dev, "This version is usart\n");
1857 			atmel_port->has_frac_baudrate = true;
1858 			atmel_port->has_hw_timer = true;
1859 			atmel_port->is_usart = true;
1860 			atmel_port->rtor = ATMEL_US_RTOR;
1861 			break;
1862 		case 0x203:
1863 		case 0x10202:
1864 			dev_dbg(port->dev, "This version is uart\n");
1865 			break;
1866 		default:
1867 			dev_err(port->dev, "Not supported ip name nor version, set to uart\n");
1868 		}
1869 	}
1870 }
1871 
1872 /*
1873  * Perform initialization and enable port for reception
1874  */
1875 static int atmel_startup(struct uart_port *port)
1876 {
1877 	struct platform_device *pdev = to_platform_device(port->dev);
1878 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
1879 	int retval;
1880 
1881 	/*
1882 	 * Ensure that no interrupts are enabled otherwise when
1883 	 * request_irq() is called we could get stuck trying to
1884 	 * handle an unexpected interrupt
1885 	 */
1886 	atmel_uart_writel(port, ATMEL_US_IDR, -1);
1887 	atmel_port->ms_irq_enabled = false;
1888 
1889 	/*
1890 	 * Allocate the IRQ
1891 	 */
1892 	retval = request_irq(port->irq, atmel_interrupt,
1893 			     IRQF_SHARED | IRQF_COND_SUSPEND,
1894 			     dev_name(&pdev->dev), port);
1895 	if (retval) {
1896 		dev_err(port->dev, "atmel_startup - Can't get irq\n");
1897 		return retval;
1898 	}
1899 
1900 	atomic_set(&atmel_port->tasklet_shutdown, 0);
1901 	tasklet_setup(&atmel_port->tasklet_rx, atmel_tasklet_rx_func);
1902 	tasklet_setup(&atmel_port->tasklet_tx, atmel_tasklet_tx_func);
1903 
1904 	/*
1905 	 * Initialize DMA (if necessary)
1906 	 */
1907 	atmel_init_property(atmel_port, pdev);
1908 	atmel_set_ops(port);
1909 
1910 	if (atmel_port->prepare_rx) {
1911 		retval = atmel_port->prepare_rx(port);
1912 		if (retval < 0)
1913 			atmel_set_ops(port);
1914 	}
1915 
1916 	if (atmel_port->prepare_tx) {
1917 		retval = atmel_port->prepare_tx(port);
1918 		if (retval < 0)
1919 			atmel_set_ops(port);
1920 	}
1921 
1922 	/*
1923 	 * Enable FIFO when available
1924 	 */
1925 	if (atmel_port->fifo_size) {
1926 		unsigned int txrdym = ATMEL_US_ONE_DATA;
1927 		unsigned int rxrdym = ATMEL_US_ONE_DATA;
1928 		unsigned int fmr;
1929 
1930 		atmel_uart_writel(port, ATMEL_US_CR,
1931 				  ATMEL_US_FIFOEN |
1932 				  ATMEL_US_RXFCLR |
1933 				  ATMEL_US_TXFLCLR);
1934 
1935 		if (atmel_use_dma_tx(port))
1936 			txrdym = ATMEL_US_FOUR_DATA;
1937 
1938 		fmr = ATMEL_US_TXRDYM(txrdym) | ATMEL_US_RXRDYM(rxrdym);
1939 		if (atmel_port->rts_high &&
1940 		    atmel_port->rts_low)
1941 			fmr |=	ATMEL_US_FRTSC |
1942 				ATMEL_US_RXFTHRES(atmel_port->rts_high) |
1943 				ATMEL_US_RXFTHRES2(atmel_port->rts_low);
1944 
1945 		atmel_uart_writel(port, ATMEL_US_FMR, fmr);
1946 	}
1947 
1948 	/* Save current CSR for comparison in atmel_tasklet_func() */
1949 	atmel_port->irq_status_prev = atmel_uart_readl(port, ATMEL_US_CSR);
1950 
1951 	/*
1952 	 * Finally, enable the serial port
1953 	 */
1954 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
1955 	/* enable xmit & rcvr */
1956 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
1957 	atmel_port->tx_stopped = false;
1958 
1959 	timer_setup(&atmel_port->uart_timer, atmel_uart_timer_callback, 0);
1960 
1961 	if (atmel_use_pdc_rx(port)) {
1962 		/* set UART timeout */
1963 		if (!atmel_port->has_hw_timer) {
1964 			mod_timer(&atmel_port->uart_timer,
1965 					jiffies + uart_poll_timeout(port));
1966 		/* set USART timeout */
1967 		} else {
1968 			atmel_uart_writel(port, atmel_port->rtor,
1969 					  PDC_RX_TIMEOUT);
1970 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
1971 
1972 			atmel_uart_writel(port, ATMEL_US_IER,
1973 					  ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
1974 		}
1975 		/* enable PDC controller */
1976 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_RXTEN);
1977 	} else if (atmel_use_dma_rx(port)) {
1978 		/* set UART timeout */
1979 		if (!atmel_port->has_hw_timer) {
1980 			mod_timer(&atmel_port->uart_timer,
1981 					jiffies + uart_poll_timeout(port));
1982 		/* set USART timeout */
1983 		} else {
1984 			atmel_uart_writel(port, atmel_port->rtor,
1985 					  PDC_RX_TIMEOUT);
1986 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_STTTO);
1987 
1988 			atmel_uart_writel(port, ATMEL_US_IER,
1989 					  ATMEL_US_TIMEOUT);
1990 		}
1991 	} else {
1992 		/* enable receive only */
1993 		atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_RXRDY);
1994 	}
1995 
1996 	return 0;
1997 }
1998 
1999 /*
2000  * Flush any TX data submitted for DMA. Called when the TX circular
2001  * buffer is reset.
2002  */
2003 static void atmel_flush_buffer(struct uart_port *port)
2004 {
2005 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2006 
2007 	if (atmel_use_pdc_tx(port)) {
2008 		atmel_uart_writel(port, ATMEL_PDC_TCR, 0);
2009 		atmel_port->pdc_tx.ofs = 0;
2010 	}
2011 	/*
2012 	 * in uart_flush_buffer(), the xmit circular buffer has just
2013 	 * been cleared, so we have to reset tx_len accordingly.
2014 	 */
2015 	atmel_port->tx_len = 0;
2016 }
2017 
2018 /*
2019  * Disable the port
2020  */
2021 static void atmel_shutdown(struct uart_port *port)
2022 {
2023 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2024 
2025 	/* Disable modem control lines interrupts */
2026 	atmel_disable_ms(port);
2027 
2028 	/* Disable interrupts at device level */
2029 	atmel_uart_writel(port, ATMEL_US_IDR, -1);
2030 
2031 	/* Prevent spurious interrupts from scheduling the tasklet */
2032 	atomic_inc(&atmel_port->tasklet_shutdown);
2033 
2034 	/*
2035 	 * Prevent any tasklets being scheduled during
2036 	 * cleanup
2037 	 */
2038 	del_timer_sync(&atmel_port->uart_timer);
2039 
2040 	/* Make sure that no interrupt is on the fly */
2041 	synchronize_irq(port->irq);
2042 
2043 	/*
2044 	 * Clear out any scheduled tasklets before
2045 	 * we destroy the buffers
2046 	 */
2047 	tasklet_kill(&atmel_port->tasklet_rx);
2048 	tasklet_kill(&atmel_port->tasklet_tx);
2049 
2050 	/*
2051 	 * Ensure everything is stopped and
2052 	 * disable port and break condition.
2053 	 */
2054 	atmel_stop_rx(port);
2055 	atmel_stop_tx(port);
2056 
2057 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA);
2058 
2059 	/*
2060 	 * Shut-down the DMA.
2061 	 */
2062 	if (atmel_port->release_rx)
2063 		atmel_port->release_rx(port);
2064 	if (atmel_port->release_tx)
2065 		atmel_port->release_tx(port);
2066 
2067 	/*
2068 	 * Reset ring buffer pointers
2069 	 */
2070 	atmel_port->rx_ring.head = 0;
2071 	atmel_port->rx_ring.tail = 0;
2072 
2073 	/*
2074 	 * Free the interrupts
2075 	 */
2076 	free_irq(port->irq, port);
2077 
2078 	atmel_flush_buffer(port);
2079 }
2080 
2081 /*
2082  * Power / Clock management.
2083  */
2084 static void atmel_serial_pm(struct uart_port *port, unsigned int state,
2085 			    unsigned int oldstate)
2086 {
2087 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2088 
2089 	switch (state) {
2090 	case UART_PM_STATE_ON:
2091 		/*
2092 		 * Enable the peripheral clock for this serial port.
2093 		 * This is called on uart_open() or a resume event.
2094 		 */
2095 		clk_prepare_enable(atmel_port->clk);
2096 
2097 		/* re-enable interrupts if we disabled some on suspend */
2098 		atmel_uart_writel(port, ATMEL_US_IER, atmel_port->backup_imr);
2099 		break;
2100 	case UART_PM_STATE_OFF:
2101 		/* Back up the interrupt mask and disable all interrupts */
2102 		atmel_port->backup_imr = atmel_uart_readl(port, ATMEL_US_IMR);
2103 		atmel_uart_writel(port, ATMEL_US_IDR, -1);
2104 
2105 		/*
2106 		 * Disable the peripheral clock for this serial port.
2107 		 * This is called on uart_close() or a suspend event.
2108 		 */
2109 		clk_disable_unprepare(atmel_port->clk);
2110 		if (__clk_is_enabled(atmel_port->gclk))
2111 			clk_disable_unprepare(atmel_port->gclk);
2112 		break;
2113 	default:
2114 		dev_err(port->dev, "atmel_serial: unknown pm %d\n", state);
2115 	}
2116 }
2117 
2118 /*
2119  * Change the port parameters
2120  */
2121 static void atmel_set_termios(struct uart_port *port,
2122 			      struct ktermios *termios,
2123 			      const struct ktermios *old)
2124 {
2125 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2126 	unsigned long flags;
2127 	unsigned int old_mode, mode, imr, quot, div, cd, fp = 0;
2128 	unsigned int baud, actual_baud, gclk_rate;
2129 	int ret;
2130 
2131 	/* save the current mode register */
2132 	mode = old_mode = atmel_uart_readl(port, ATMEL_US_MR);
2133 
2134 	/* reset the mode, clock divisor, parity, stop bits and data size */
2135 	if (atmel_port->is_usart)
2136 		mode &= ~(ATMEL_US_NBSTOP | ATMEL_US_PAR | ATMEL_US_CHRL |
2137 			  ATMEL_US_USCLKS | ATMEL_US_USMODE);
2138 	else
2139 		mode &= ~(ATMEL_UA_BRSRCCK | ATMEL_US_PAR | ATMEL_UA_FILTER);
2140 
2141 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
2142 
2143 	/* byte size */
2144 	switch (termios->c_cflag & CSIZE) {
2145 	case CS5:
2146 		mode |= ATMEL_US_CHRL_5;
2147 		break;
2148 	case CS6:
2149 		mode |= ATMEL_US_CHRL_6;
2150 		break;
2151 	case CS7:
2152 		mode |= ATMEL_US_CHRL_7;
2153 		break;
2154 	default:
2155 		mode |= ATMEL_US_CHRL_8;
2156 		break;
2157 	}
2158 
2159 	/* stop bits */
2160 	if (termios->c_cflag & CSTOPB)
2161 		mode |= ATMEL_US_NBSTOP_2;
2162 
2163 	/* parity */
2164 	if (termios->c_cflag & PARENB) {
2165 		/* Mark or Space parity */
2166 		if (termios->c_cflag & CMSPAR) {
2167 			if (termios->c_cflag & PARODD)
2168 				mode |= ATMEL_US_PAR_MARK;
2169 			else
2170 				mode |= ATMEL_US_PAR_SPACE;
2171 		} else if (termios->c_cflag & PARODD)
2172 			mode |= ATMEL_US_PAR_ODD;
2173 		else
2174 			mode |= ATMEL_US_PAR_EVEN;
2175 	} else
2176 		mode |= ATMEL_US_PAR_NONE;
2177 
2178 	uart_port_lock_irqsave(port, &flags);
2179 
2180 	port->read_status_mask = ATMEL_US_OVRE;
2181 	if (termios->c_iflag & INPCK)
2182 		port->read_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
2183 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
2184 		port->read_status_mask |= ATMEL_US_RXBRK;
2185 
2186 	if (atmel_use_pdc_rx(port))
2187 		/* need to enable error interrupts */
2188 		atmel_uart_writel(port, ATMEL_US_IER, port->read_status_mask);
2189 
2190 	/*
2191 	 * Characters to ignore
2192 	 */
2193 	port->ignore_status_mask = 0;
2194 	if (termios->c_iflag & IGNPAR)
2195 		port->ignore_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
2196 	if (termios->c_iflag & IGNBRK) {
2197 		port->ignore_status_mask |= ATMEL_US_RXBRK;
2198 		/*
2199 		 * If we're ignoring parity and break indicators,
2200 		 * ignore overruns too (for real raw support).
2201 		 */
2202 		if (termios->c_iflag & IGNPAR)
2203 			port->ignore_status_mask |= ATMEL_US_OVRE;
2204 	}
2205 	/* TODO: Ignore all characters if CREAD is set.*/
2206 
2207 	/* update the per-port timeout */
2208 	uart_update_timeout(port, termios->c_cflag, baud);
2209 
2210 	/*
2211 	 * save/disable interrupts. The tty layer will ensure that the
2212 	 * transmitter is empty if requested by the caller, so there's
2213 	 * no need to wait for it here.
2214 	 */
2215 	imr = atmel_uart_readl(port, ATMEL_US_IMR);
2216 	atmel_uart_writel(port, ATMEL_US_IDR, -1);
2217 
2218 	/* disable receiver and transmitter */
2219 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
2220 	atmel_port->tx_stopped = true;
2221 
2222 	/* mode */
2223 	if (port->rs485.flags & SER_RS485_ENABLED) {
2224 		atmel_uart_writel(port, ATMEL_US_TTGR,
2225 				  port->rs485.delay_rts_after_send);
2226 		mode |= ATMEL_US_USMODE_RS485;
2227 	} else if (port->iso7816.flags & SER_ISO7816_ENABLED) {
2228 		atmel_uart_writel(port, ATMEL_US_TTGR, port->iso7816.tg);
2229 		/* select mck clock, and output  */
2230 		mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
2231 		/* set max iterations */
2232 		mode |= ATMEL_US_MAX_ITER(3);
2233 		if ((port->iso7816.flags & SER_ISO7816_T_PARAM)
2234 				== SER_ISO7816_T(0))
2235 			mode |= ATMEL_US_USMODE_ISO7816_T0;
2236 		else
2237 			mode |= ATMEL_US_USMODE_ISO7816_T1;
2238 	} else if (termios->c_cflag & CRTSCTS) {
2239 		/* RS232 with hardware handshake (RTS/CTS) */
2240 		if (atmel_use_fifo(port) &&
2241 		    !mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS)) {
2242 			/*
2243 			 * with ATMEL_US_USMODE_HWHS set, the controller will
2244 			 * be able to drive the RTS pin high/low when the RX
2245 			 * FIFO is above RXFTHRES/below RXFTHRES2.
2246 			 * It will also disable the transmitter when the CTS
2247 			 * pin is high.
2248 			 * This mode is not activated if CTS pin is a GPIO
2249 			 * because in this case, the transmitter is always
2250 			 * disabled (there must be an internal pull-up
2251 			 * responsible for this behaviour).
2252 			 * If the RTS pin is a GPIO, the controller won't be
2253 			 * able to drive it according to the FIFO thresholds,
2254 			 * but it will be handled by the driver.
2255 			 */
2256 			mode |= ATMEL_US_USMODE_HWHS;
2257 		} else {
2258 			/*
2259 			 * For platforms without FIFO, the flow control is
2260 			 * handled by the driver.
2261 			 */
2262 			mode |= ATMEL_US_USMODE_NORMAL;
2263 		}
2264 	} else {
2265 		/* RS232 without hadware handshake */
2266 		mode |= ATMEL_US_USMODE_NORMAL;
2267 	}
2268 
2269 	/*
2270 	 * Set the baud rate:
2271 	 * Fractional baudrate allows to setup output frequency more
2272 	 * accurately. This feature is enabled only when using normal mode.
2273 	 * baudrate = selected clock / (8 * (2 - OVER) * (CD + FP / 8))
2274 	 * Currently, OVER is always set to 0 so we get
2275 	 * baudrate = selected clock / (16 * (CD + FP / 8))
2276 	 * then
2277 	 * 8 CD + FP = selected clock / (2 * baudrate)
2278 	 */
2279 	if (atmel_port->has_frac_baudrate) {
2280 		div = DIV_ROUND_CLOSEST(port->uartclk, baud * 2);
2281 		cd = div >> 3;
2282 		fp = div & ATMEL_US_FP_MASK;
2283 	} else {
2284 		cd = uart_get_divisor(port, baud);
2285 	}
2286 
2287 	/*
2288 	 * If the current value of the Clock Divisor surpasses the 16 bit
2289 	 * ATMEL_US_CD mask and the IP is USART, switch to the Peripheral
2290 	 * Clock implicitly divided by 8.
2291 	 * If the IP is UART however, keep the highest possible value for
2292 	 * the CD and avoid needless division of CD, since UART IP's do not
2293 	 * support implicit division of the Peripheral Clock.
2294 	 */
2295 	if (atmel_port->is_usart && cd > ATMEL_US_CD) {
2296 		cd /= 8;
2297 		mode |= ATMEL_US_USCLKS_MCK_DIV8;
2298 	} else {
2299 		cd = min_t(unsigned int, cd, ATMEL_US_CD);
2300 	}
2301 
2302 	/*
2303 	 * If there is no Fractional Part, there is a high chance that
2304 	 * we may be able to generate a baudrate closer to the desired one
2305 	 * if we use the GCLK as the clock source driving the baudrate
2306 	 * generator.
2307 	 */
2308 	if (!atmel_port->has_frac_baudrate) {
2309 		if (__clk_is_enabled(atmel_port->gclk))
2310 			clk_disable_unprepare(atmel_port->gclk);
2311 		gclk_rate = clk_round_rate(atmel_port->gclk, 16 * baud);
2312 		actual_baud = clk_get_rate(atmel_port->clk) / (16 * cd);
2313 		if (gclk_rate && abs(atmel_error_rate(baud, actual_baud)) >
2314 		    abs(atmel_error_rate(baud, gclk_rate / 16))) {
2315 			clk_set_rate(atmel_port->gclk, 16 * baud);
2316 			ret = clk_prepare_enable(atmel_port->gclk);
2317 			if (ret)
2318 				goto gclk_fail;
2319 
2320 			if (atmel_port->is_usart) {
2321 				mode &= ~ATMEL_US_USCLKS;
2322 				mode |= ATMEL_US_USCLKS_GCLK;
2323 			} else {
2324 				mode |= ATMEL_UA_BRSRCCK;
2325 			}
2326 
2327 			/*
2328 			 * Set the Clock Divisor for GCLK to 1.
2329 			 * Since we were able to generate the smallest
2330 			 * multiple of the desired baudrate times 16,
2331 			 * then we surely can generate a bigger multiple
2332 			 * with the exact error rate for an equally increased
2333 			 * CD. Thus no need to take into account
2334 			 * a higher value for CD.
2335 			 */
2336 			cd = 1;
2337 		}
2338 	}
2339 
2340 gclk_fail:
2341 	quot = cd | fp << ATMEL_US_FP_OFFSET;
2342 
2343 	if (!(port->iso7816.flags & SER_ISO7816_ENABLED))
2344 		atmel_uart_writel(port, ATMEL_US_BRGR, quot);
2345 
2346 	/* set the mode, clock divisor, parity, stop bits and data size */
2347 	atmel_uart_writel(port, ATMEL_US_MR, mode);
2348 
2349 	/*
2350 	 * when switching the mode, set the RTS line state according to the
2351 	 * new mode, otherwise keep the former state
2352 	 */
2353 	if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) {
2354 		unsigned int rts_state;
2355 
2356 		if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
2357 			/* let the hardware control the RTS line */
2358 			rts_state = ATMEL_US_RTSDIS;
2359 		} else {
2360 			/* force RTS line to low level */
2361 			rts_state = ATMEL_US_RTSEN;
2362 		}
2363 
2364 		atmel_uart_writel(port, ATMEL_US_CR, rts_state);
2365 	}
2366 
2367 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
2368 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
2369 	atmel_port->tx_stopped = false;
2370 
2371 	/* restore interrupts */
2372 	atmel_uart_writel(port, ATMEL_US_IER, imr);
2373 
2374 	/* CTS flow-control and modem-status interrupts */
2375 	if (UART_ENABLE_MS(port, termios->c_cflag))
2376 		atmel_enable_ms(port);
2377 	else
2378 		atmel_disable_ms(port);
2379 
2380 	uart_port_unlock_irqrestore(port, flags);
2381 }
2382 
2383 static void atmel_set_ldisc(struct uart_port *port, struct ktermios *termios)
2384 {
2385 	if (termios->c_line == N_PPS) {
2386 		port->flags |= UPF_HARDPPS_CD;
2387 		uart_port_lock_irq(port);
2388 		atmel_enable_ms(port);
2389 		uart_port_unlock_irq(port);
2390 	} else {
2391 		port->flags &= ~UPF_HARDPPS_CD;
2392 		if (!UART_ENABLE_MS(port, termios->c_cflag)) {
2393 			uart_port_lock_irq(port);
2394 			atmel_disable_ms(port);
2395 			uart_port_unlock_irq(port);
2396 		}
2397 	}
2398 }
2399 
2400 /*
2401  * Return string describing the specified port
2402  */
2403 static const char *atmel_type(struct uart_port *port)
2404 {
2405 	return (port->type == PORT_ATMEL) ? "ATMEL_SERIAL" : NULL;
2406 }
2407 
2408 /*
2409  * Release the memory region(s) being used by 'port'.
2410  */
2411 static void atmel_release_port(struct uart_port *port)
2412 {
2413 	struct platform_device *mpdev = to_platform_device(port->dev->parent);
2414 	int size = resource_size(mpdev->resource);
2415 
2416 	release_mem_region(port->mapbase, size);
2417 
2418 	if (port->flags & UPF_IOREMAP) {
2419 		iounmap(port->membase);
2420 		port->membase = NULL;
2421 	}
2422 }
2423 
2424 /*
2425  * Request the memory region(s) being used by 'port'.
2426  */
2427 static int atmel_request_port(struct uart_port *port)
2428 {
2429 	struct platform_device *mpdev = to_platform_device(port->dev->parent);
2430 	int size = resource_size(mpdev->resource);
2431 
2432 	if (!request_mem_region(port->mapbase, size, "atmel_serial"))
2433 		return -EBUSY;
2434 
2435 	if (port->flags & UPF_IOREMAP) {
2436 		port->membase = ioremap(port->mapbase, size);
2437 		if (port->membase == NULL) {
2438 			release_mem_region(port->mapbase, size);
2439 			return -ENOMEM;
2440 		}
2441 	}
2442 
2443 	return 0;
2444 }
2445 
2446 /*
2447  * Configure/autoconfigure the port.
2448  */
2449 static void atmel_config_port(struct uart_port *port, int flags)
2450 {
2451 	if (flags & UART_CONFIG_TYPE) {
2452 		port->type = PORT_ATMEL;
2453 		atmel_request_port(port);
2454 	}
2455 }
2456 
2457 /*
2458  * Verify the new serial_struct (for TIOCSSERIAL).
2459  */
2460 static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
2461 {
2462 	int ret = 0;
2463 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ATMEL)
2464 		ret = -EINVAL;
2465 	if (port->irq != ser->irq)
2466 		ret = -EINVAL;
2467 	if (ser->io_type != SERIAL_IO_MEM)
2468 		ret = -EINVAL;
2469 	if (port->uartclk / 16 != ser->baud_base)
2470 		ret = -EINVAL;
2471 	if (port->mapbase != (unsigned long)ser->iomem_base)
2472 		ret = -EINVAL;
2473 	if (port->iobase != ser->port)
2474 		ret = -EINVAL;
2475 	if (ser->hub6 != 0)
2476 		ret = -EINVAL;
2477 	return ret;
2478 }
2479 
2480 #ifdef CONFIG_CONSOLE_POLL
2481 static int atmel_poll_get_char(struct uart_port *port)
2482 {
2483 	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_RXRDY))
2484 		cpu_relax();
2485 
2486 	return atmel_uart_read_char(port);
2487 }
2488 
2489 static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
2490 {
2491 	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY))
2492 		cpu_relax();
2493 
2494 	atmel_uart_write_char(port, ch);
2495 }
2496 #endif
2497 
2498 static const struct uart_ops atmel_pops = {
2499 	.tx_empty	= atmel_tx_empty,
2500 	.set_mctrl	= atmel_set_mctrl,
2501 	.get_mctrl	= atmel_get_mctrl,
2502 	.stop_tx	= atmel_stop_tx,
2503 	.start_tx	= atmel_start_tx,
2504 	.stop_rx	= atmel_stop_rx,
2505 	.enable_ms	= atmel_enable_ms,
2506 	.break_ctl	= atmel_break_ctl,
2507 	.startup	= atmel_startup,
2508 	.shutdown	= atmel_shutdown,
2509 	.flush_buffer	= atmel_flush_buffer,
2510 	.set_termios	= atmel_set_termios,
2511 	.set_ldisc	= atmel_set_ldisc,
2512 	.type		= atmel_type,
2513 	.release_port	= atmel_release_port,
2514 	.request_port	= atmel_request_port,
2515 	.config_port	= atmel_config_port,
2516 	.verify_port	= atmel_verify_port,
2517 	.pm		= atmel_serial_pm,
2518 #ifdef CONFIG_CONSOLE_POLL
2519 	.poll_get_char	= atmel_poll_get_char,
2520 	.poll_put_char	= atmel_poll_put_char,
2521 #endif
2522 };
2523 
2524 static const struct serial_rs485 atmel_rs485_supported = {
2525 	.flags = SER_RS485_ENABLED | SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX,
2526 	.delay_rts_before_send = 1,
2527 	.delay_rts_after_send = 1,
2528 };
2529 
2530 /*
2531  * Configure the port from the platform device resource info.
2532  */
2533 static int atmel_init_port(struct atmel_uart_port *atmel_port,
2534 				      struct platform_device *pdev)
2535 {
2536 	int ret;
2537 	struct uart_port *port = &atmel_port->uart;
2538 	struct platform_device *mpdev = to_platform_device(pdev->dev.parent);
2539 
2540 	atmel_init_property(atmel_port, pdev);
2541 	atmel_set_ops(port);
2542 
2543 	port->iotype		= UPIO_MEM;
2544 	port->flags		= UPF_BOOT_AUTOCONF | UPF_IOREMAP;
2545 	port->ops		= &atmel_pops;
2546 	port->fifosize		= 1;
2547 	port->dev		= &pdev->dev;
2548 	port->mapbase		= mpdev->resource[0].start;
2549 	port->irq		= platform_get_irq(mpdev, 0);
2550 	port->rs485_config	= atmel_config_rs485;
2551 	port->rs485_supported	= atmel_rs485_supported;
2552 	port->iso7816_config	= atmel_config_iso7816;
2553 	port->membase		= NULL;
2554 
2555 	memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));
2556 
2557 	ret = uart_get_rs485_mode(port);
2558 	if (ret)
2559 		return ret;
2560 
2561 	port->uartclk = clk_get_rate(atmel_port->clk);
2562 
2563 	/*
2564 	 * Use TXEMPTY for interrupt when rs485 or ISO7816 else TXRDY or
2565 	 * ENDTX|TXBUFE
2566 	 */
2567 	if (atmel_uart_is_half_duplex(port))
2568 		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
2569 	else if (atmel_use_pdc_tx(port)) {
2570 		port->fifosize = PDC_BUFFER_SIZE;
2571 		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
2572 	} else {
2573 		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
2574 	}
2575 
2576 	return 0;
2577 }
2578 
2579 #ifdef CONFIG_SERIAL_ATMEL_CONSOLE
2580 static void atmel_console_putchar(struct uart_port *port, unsigned char ch)
2581 {
2582 	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY))
2583 		cpu_relax();
2584 	atmel_uart_write_char(port, ch);
2585 }
2586 
2587 /*
2588  * Interrupts are disabled on entering
2589  */
2590 static void atmel_console_write(struct console *co, const char *s, u_int count)
2591 {
2592 	struct uart_port *port = &atmel_ports[co->index].uart;
2593 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2594 	unsigned int status, imr;
2595 	unsigned int pdc_tx;
2596 
2597 	/*
2598 	 * First, save IMR and then disable interrupts
2599 	 */
2600 	imr = atmel_uart_readl(port, ATMEL_US_IMR);
2601 	atmel_uart_writel(port, ATMEL_US_IDR,
2602 			  ATMEL_US_RXRDY | atmel_port->tx_done_mask);
2603 
2604 	/* Store PDC transmit status and disable it */
2605 	pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN;
2606 	atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
2607 
2608 	/* Make sure that tx path is actually able to send characters */
2609 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);
2610 	atmel_port->tx_stopped = false;
2611 
2612 	uart_console_write(port, s, count, atmel_console_putchar);
2613 
2614 	/*
2615 	 * Finally, wait for transmitter to become empty
2616 	 * and restore IMR
2617 	 */
2618 	do {
2619 		status = atmel_uart_readl(port, ATMEL_US_CSR);
2620 	} while (!(status & ATMEL_US_TXRDY));
2621 
2622 	/* Restore PDC transmit status */
2623 	if (pdc_tx)
2624 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
2625 
2626 	/* set interrupts back the way they were */
2627 	atmel_uart_writel(port, ATMEL_US_IER, imr);
2628 }
2629 
2630 /*
2631  * If the port was already initialised (eg, by a boot loader),
2632  * try to determine the current setup.
2633  */
2634 static void __init atmel_console_get_options(struct uart_port *port, int *baud,
2635 					     int *parity, int *bits)
2636 {
2637 	unsigned int mr, quot;
2638 
2639 	/*
2640 	 * If the baud rate generator isn't running, the port wasn't
2641 	 * initialized by the boot loader.
2642 	 */
2643 	quot = atmel_uart_readl(port, ATMEL_US_BRGR) & ATMEL_US_CD;
2644 	if (!quot)
2645 		return;
2646 
2647 	mr = atmel_uart_readl(port, ATMEL_US_MR) & ATMEL_US_CHRL;
2648 	if (mr == ATMEL_US_CHRL_8)
2649 		*bits = 8;
2650 	else
2651 		*bits = 7;
2652 
2653 	mr = atmel_uart_readl(port, ATMEL_US_MR) & ATMEL_US_PAR;
2654 	if (mr == ATMEL_US_PAR_EVEN)
2655 		*parity = 'e';
2656 	else if (mr == ATMEL_US_PAR_ODD)
2657 		*parity = 'o';
2658 
2659 	*baud = port->uartclk / (16 * quot);
2660 }
2661 
2662 static int __init atmel_console_setup(struct console *co, char *options)
2663 {
2664 	struct uart_port *port = &atmel_ports[co->index].uart;
2665 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2666 	int baud = 115200;
2667 	int bits = 8;
2668 	int parity = 'n';
2669 	int flow = 'n';
2670 
2671 	if (port->membase == NULL) {
2672 		/* Port not initialized yet - delay setup */
2673 		return -ENODEV;
2674 	}
2675 
2676 	atmel_uart_writel(port, ATMEL_US_IDR, -1);
2677 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
2678 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
2679 	atmel_port->tx_stopped = false;
2680 
2681 	if (options)
2682 		uart_parse_options(options, &baud, &parity, &bits, &flow);
2683 	else
2684 		atmel_console_get_options(port, &baud, &parity, &bits);
2685 
2686 	return uart_set_options(port, co, baud, parity, bits, flow);
2687 }
2688 
2689 static struct uart_driver atmel_uart;
2690 
2691 static struct console atmel_console = {
2692 	.name		= ATMEL_DEVICENAME,
2693 	.write		= atmel_console_write,
2694 	.device		= uart_console_device,
2695 	.setup		= atmel_console_setup,
2696 	.flags		= CON_PRINTBUFFER,
2697 	.index		= -1,
2698 	.data		= &atmel_uart,
2699 };
2700 
2701 static void atmel_serial_early_write(struct console *con, const char *s,
2702 				     unsigned int n)
2703 {
2704 	struct earlycon_device *dev = con->data;
2705 
2706 	uart_console_write(&dev->port, s, n, atmel_console_putchar);
2707 }
2708 
2709 static int __init atmel_early_console_setup(struct earlycon_device *device,
2710 					    const char *options)
2711 {
2712 	if (!device->port.membase)
2713 		return -ENODEV;
2714 
2715 	device->con->write = atmel_serial_early_write;
2716 
2717 	return 0;
2718 }
2719 
2720 OF_EARLYCON_DECLARE(atmel_serial, "atmel,at91rm9200-usart",
2721 		    atmel_early_console_setup);
2722 OF_EARLYCON_DECLARE(atmel_serial, "atmel,at91sam9260-usart",
2723 		    atmel_early_console_setup);
2724 
2725 #define ATMEL_CONSOLE_DEVICE	(&atmel_console)
2726 
2727 #else
2728 #define ATMEL_CONSOLE_DEVICE	NULL
2729 #endif
2730 
2731 static struct uart_driver atmel_uart = {
2732 	.owner		= THIS_MODULE,
2733 	.driver_name	= "atmel_serial",
2734 	.dev_name	= ATMEL_DEVICENAME,
2735 	.major		= SERIAL_ATMEL_MAJOR,
2736 	.minor		= MINOR_START,
2737 	.nr		= ATMEL_MAX_UART,
2738 	.cons		= ATMEL_CONSOLE_DEVICE,
2739 };
2740 
2741 static bool atmel_serial_clk_will_stop(void)
2742 {
2743 #ifdef CONFIG_ARCH_AT91
2744 	return at91_suspend_entering_slow_clock();
2745 #else
2746 	return false;
2747 #endif
2748 }
2749 
2750 static int __maybe_unused atmel_serial_suspend(struct device *dev)
2751 {
2752 	struct uart_port *port = dev_get_drvdata(dev);
2753 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2754 
2755 	if (uart_console(port) && console_suspend_enabled) {
2756 		/* Drain the TX shifter */
2757 		while (!(atmel_uart_readl(port, ATMEL_US_CSR) &
2758 			 ATMEL_US_TXEMPTY))
2759 			cpu_relax();
2760 	}
2761 
2762 	if (uart_console(port) && !console_suspend_enabled) {
2763 		/* Cache register values as we won't get a full shutdown/startup
2764 		 * cycle
2765 		 */
2766 		atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR);
2767 		atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR);
2768 		atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
2769 		atmel_port->cache.rtor = atmel_uart_readl(port,
2770 							  atmel_port->rtor);
2771 		atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR);
2772 		atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR);
2773 		atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR);
2774 	}
2775 
2776 	/* we can not wake up if we're running on slow clock */
2777 	atmel_port->may_wakeup = device_may_wakeup(dev);
2778 	if (atmel_serial_clk_will_stop()) {
2779 		unsigned long flags;
2780 
2781 		spin_lock_irqsave(&atmel_port->lock_suspended, flags);
2782 		atmel_port->suspended = true;
2783 		spin_unlock_irqrestore(&atmel_port->lock_suspended, flags);
2784 		device_set_wakeup_enable(dev, 0);
2785 	}
2786 
2787 	uart_suspend_port(&atmel_uart, port);
2788 
2789 	return 0;
2790 }
2791 
2792 static int __maybe_unused atmel_serial_resume(struct device *dev)
2793 {
2794 	struct uart_port *port = dev_get_drvdata(dev);
2795 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
2796 	unsigned long flags;
2797 
2798 	if (uart_console(port) && !console_suspend_enabled) {
2799 		atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr);
2800 		atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr);
2801 		atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr);
2802 		atmel_uart_writel(port, atmel_port->rtor,
2803 				  atmel_port->cache.rtor);
2804 		atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr);
2805 
2806 		if (atmel_port->fifo_size) {
2807 			atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN |
2808 					  ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR);
2809 			atmel_uart_writel(port, ATMEL_US_FMR,
2810 					  atmel_port->cache.fmr);
2811 			atmel_uart_writel(port, ATMEL_US_FIER,
2812 					  atmel_port->cache.fimr);
2813 		}
2814 		atmel_start_rx(port);
2815 	}
2816 
2817 	spin_lock_irqsave(&atmel_port->lock_suspended, flags);
2818 	if (atmel_port->pending) {
2819 		atmel_handle_receive(port, atmel_port->pending);
2820 		atmel_handle_status(port, atmel_port->pending,
2821 				    atmel_port->pending_status);
2822 		atmel_handle_transmit(port, atmel_port->pending);
2823 		atmel_port->pending = 0;
2824 	}
2825 	atmel_port->suspended = false;
2826 	spin_unlock_irqrestore(&atmel_port->lock_suspended, flags);
2827 
2828 	uart_resume_port(&atmel_uart, port);
2829 	device_set_wakeup_enable(dev, atmel_port->may_wakeup);
2830 
2831 	return 0;
2832 }
2833 
2834 static void atmel_serial_probe_fifos(struct atmel_uart_port *atmel_port,
2835 				     struct platform_device *pdev)
2836 {
2837 	atmel_port->fifo_size = 0;
2838 	atmel_port->rts_low = 0;
2839 	atmel_port->rts_high = 0;
2840 
2841 	if (of_property_read_u32(pdev->dev.of_node,
2842 				 "atmel,fifo-size",
2843 				 &atmel_port->fifo_size))
2844 		return;
2845 
2846 	if (!atmel_port->fifo_size)
2847 		return;
2848 
2849 	if (atmel_port->fifo_size < ATMEL_MIN_FIFO_SIZE) {
2850 		atmel_port->fifo_size = 0;
2851 		dev_err(&pdev->dev, "Invalid FIFO size\n");
2852 		return;
2853 	}
2854 
2855 	/*
2856 	 * 0 <= rts_low <= rts_high <= fifo_size
2857 	 * Once their CTS line asserted by the remote peer, some x86 UARTs tend
2858 	 * to flush their internal TX FIFO, commonly up to 16 data, before
2859 	 * actually stopping to send new data. So we try to set the RTS High
2860 	 * Threshold to a reasonably high value respecting this 16 data
2861 	 * empirical rule when possible.
2862 	 */
2863 	atmel_port->rts_high = max_t(int, atmel_port->fifo_size >> 1,
2864 			       atmel_port->fifo_size - ATMEL_RTS_HIGH_OFFSET);
2865 	atmel_port->rts_low  = max_t(int, atmel_port->fifo_size >> 2,
2866 			       atmel_port->fifo_size - ATMEL_RTS_LOW_OFFSET);
2867 
2868 	dev_info(&pdev->dev, "Using FIFO (%u data)\n",
2869 		 atmel_port->fifo_size);
2870 	dev_dbg(&pdev->dev, "RTS High Threshold : %2u data\n",
2871 		atmel_port->rts_high);
2872 	dev_dbg(&pdev->dev, "RTS Low Threshold  : %2u data\n",
2873 		atmel_port->rts_low);
2874 }
2875 
2876 static int atmel_serial_probe(struct platform_device *pdev)
2877 {
2878 	struct atmel_uart_port *atmel_port;
2879 	struct device_node *np = pdev->dev.parent->of_node;
2880 	void *data;
2881 	int ret;
2882 	bool rs485_enabled;
2883 
2884 	BUILD_BUG_ON(ATMEL_SERIAL_RINGSIZE & (ATMEL_SERIAL_RINGSIZE - 1));
2885 
2886 	/*
2887 	 * In device tree there is no node with "atmel,at91rm9200-usart-serial"
2888 	 * as compatible string. This driver is probed by at91-usart mfd driver
2889 	 * which is just a wrapper over the atmel_serial driver and
2890 	 * spi-at91-usart driver. All attributes needed by this driver are
2891 	 * found in of_node of parent.
2892 	 */
2893 	pdev->dev.of_node = np;
2894 
2895 	ret = of_alias_get_id(np, "serial");
2896 	if (ret < 0)
2897 		/* port id not found in platform data nor device-tree aliases:
2898 		 * auto-enumerate it */
2899 		ret = find_first_zero_bit(atmel_ports_in_use, ATMEL_MAX_UART);
2900 
2901 	if (ret >= ATMEL_MAX_UART) {
2902 		ret = -ENODEV;
2903 		goto err;
2904 	}
2905 
2906 	if (test_and_set_bit(ret, atmel_ports_in_use)) {
2907 		/* port already in use */
2908 		ret = -EBUSY;
2909 		goto err;
2910 	}
2911 
2912 	atmel_port = &atmel_ports[ret];
2913 	atmel_port->backup_imr = 0;
2914 	atmel_port->uart.line = ret;
2915 	atmel_port->uart.has_sysrq = IS_ENABLED(CONFIG_SERIAL_ATMEL_CONSOLE);
2916 	atmel_serial_probe_fifos(atmel_port, pdev);
2917 
2918 	atomic_set(&atmel_port->tasklet_shutdown, 0);
2919 	spin_lock_init(&atmel_port->lock_suspended);
2920 
2921 	atmel_port->clk = devm_clk_get(&pdev->dev, "usart");
2922 	if (IS_ERR(atmel_port->clk)) {
2923 		ret = PTR_ERR(atmel_port->clk);
2924 		goto err;
2925 	}
2926 	ret = clk_prepare_enable(atmel_port->clk);
2927 	if (ret)
2928 		goto err;
2929 
2930 	atmel_port->gclk = devm_clk_get_optional(&pdev->dev, "gclk");
2931 	if (IS_ERR(atmel_port->gclk)) {
2932 		ret = PTR_ERR(atmel_port->gclk);
2933 		goto err_clk_disable_unprepare;
2934 	}
2935 
2936 	ret = atmel_init_port(atmel_port, pdev);
2937 	if (ret)
2938 		goto err_clk_disable_unprepare;
2939 
2940 	atmel_port->gpios = mctrl_gpio_init(&atmel_port->uart, 0);
2941 	if (IS_ERR(atmel_port->gpios)) {
2942 		ret = PTR_ERR(atmel_port->gpios);
2943 		goto err_clk_disable_unprepare;
2944 	}
2945 
2946 	if (!atmel_use_pdc_rx(&atmel_port->uart)) {
2947 		ret = -ENOMEM;
2948 		data = kmalloc_array(ATMEL_SERIAL_RINGSIZE,
2949 				     sizeof(struct atmel_uart_char),
2950 				     GFP_KERNEL);
2951 		if (!data)
2952 			goto err_clk_disable_unprepare;
2953 		atmel_port->rx_ring.buf = data;
2954 	}
2955 
2956 	rs485_enabled = atmel_port->uart.rs485.flags & SER_RS485_ENABLED;
2957 
2958 	ret = uart_add_one_port(&atmel_uart, &atmel_port->uart);
2959 	if (ret)
2960 		goto err_add_port;
2961 
2962 	device_init_wakeup(&pdev->dev, 1);
2963 	platform_set_drvdata(pdev, atmel_port);
2964 
2965 	if (rs485_enabled) {
2966 		atmel_uart_writel(&atmel_port->uart, ATMEL_US_MR,
2967 				  ATMEL_US_USMODE_NORMAL);
2968 		atmel_uart_writel(&atmel_port->uart, ATMEL_US_CR,
2969 				  ATMEL_US_RTSEN);
2970 	}
2971 
2972 	/*
2973 	 * Get port name of usart or uart
2974 	 */
2975 	atmel_get_ip_name(&atmel_port->uart);
2976 
2977 	/*
2978 	 * The peripheral clock can now safely be disabled till the port
2979 	 * is used
2980 	 */
2981 	clk_disable_unprepare(atmel_port->clk);
2982 
2983 	return 0;
2984 
2985 err_add_port:
2986 	kfree(atmel_port->rx_ring.buf);
2987 	atmel_port->rx_ring.buf = NULL;
2988 err_clk_disable_unprepare:
2989 	clk_disable_unprepare(atmel_port->clk);
2990 	clear_bit(atmel_port->uart.line, atmel_ports_in_use);
2991 err:
2992 	return ret;
2993 }
2994 
2995 /*
2996  * Even if the driver is not modular, it makes sense to be able to
2997  * unbind a device: there can be many bound devices, and there are
2998  * situations where dynamic binding and unbinding can be useful.
2999  *
3000  * For example, a connected device can require a specific firmware update
3001  * protocol that needs bitbanging on IO lines, but use the regular serial
3002  * port in the normal case.
3003  */
3004 static int atmel_serial_remove(struct platform_device *pdev)
3005 {
3006 	struct uart_port *port = platform_get_drvdata(pdev);
3007 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
3008 
3009 	tasklet_kill(&atmel_port->tasklet_rx);
3010 	tasklet_kill(&atmel_port->tasklet_tx);
3011 
3012 	device_init_wakeup(&pdev->dev, 0);
3013 
3014 	uart_remove_one_port(&atmel_uart, port);
3015 
3016 	kfree(atmel_port->rx_ring.buf);
3017 
3018 	/* "port" is allocated statically, so we shouldn't free it */
3019 
3020 	clear_bit(port->line, atmel_ports_in_use);
3021 
3022 	pdev->dev.of_node = NULL;
3023 
3024 	return 0;
3025 }
3026 
3027 static SIMPLE_DEV_PM_OPS(atmel_serial_pm_ops, atmel_serial_suspend,
3028 			 atmel_serial_resume);
3029 
3030 static struct platform_driver atmel_serial_driver = {
3031 	.probe		= atmel_serial_probe,
3032 	.remove		= atmel_serial_remove,
3033 	.driver		= {
3034 		.name			= "atmel_usart_serial",
3035 		.of_match_table		= of_match_ptr(atmel_serial_dt_ids),
3036 		.pm			= pm_ptr(&atmel_serial_pm_ops),
3037 	},
3038 };
3039 
3040 static int __init atmel_serial_init(void)
3041 {
3042 	int ret;
3043 
3044 	ret = uart_register_driver(&atmel_uart);
3045 	if (ret)
3046 		return ret;
3047 
3048 	ret = platform_driver_register(&atmel_serial_driver);
3049 	if (ret)
3050 		uart_unregister_driver(&atmel_uart);
3051 
3052 	return ret;
3053 }
3054 device_initcall(atmel_serial_init);
3055