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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * st-asc.c: ST Asynchronous serial controller (ASC) driver
4 *
5 * Copyright (C) 2003-2013 STMicroelectronics (R&D) Limited
6 */
7
8#include <linux/module.h>
9#include <linux/serial.h>
10#include <linux/console.h>
11#include <linux/sysrq.h>
12#include <linux/pinctrl/consumer.h>
13#include <linux/platform_device.h>
14#include <linux/io.h>
15#include <linux/irq.h>
16#include <linux/tty.h>
17#include <linux/tty_flip.h>
18#include <linux/delay.h>
19#include <linux/spinlock.h>
20#include <linux/of.h>
21#include <linux/of_platform.h>
22#include <linux/serial_core.h>
23#include <linux/clk.h>
24#include <linux/gpio/consumer.h>
25
26#define DRIVER_NAME "st-asc"
27#define ASC_SERIAL_NAME "ttyAS"
28#define ASC_FIFO_SIZE 16
29#define ASC_MAX_PORTS 8
30
31/* Pinctrl states */
32#define DEFAULT 0
33#define NO_HW_FLOWCTRL 1
34
35struct asc_port {
36 struct uart_port port;
37 struct gpio_desc *rts;
38 struct clk *clk;
39 struct pinctrl *pinctrl;
40 struct pinctrl_state *states[2];
41 unsigned int hw_flow_control:1;
42 unsigned int force_m1:1;
43};
44
45static struct asc_port asc_ports[ASC_MAX_PORTS];
46static struct uart_driver asc_uart_driver;
47
48/*---- UART Register definitions ------------------------------*/
49
50/* Register offsets */
51
52#define ASC_BAUDRATE 0x00
53#define ASC_TXBUF 0x04
54#define ASC_RXBUF 0x08
55#define ASC_CTL 0x0C
56#define ASC_INTEN 0x10
57#define ASC_STA 0x14
58#define ASC_GUARDTIME 0x18
59#define ASC_TIMEOUT 0x1C
60#define ASC_TXRESET 0x20
61#define ASC_RXRESET 0x24
62#define ASC_RETRIES 0x28
63
64/* ASC_RXBUF */
65#define ASC_RXBUF_PE 0x100
66#define ASC_RXBUF_FE 0x200
67/*
68 * Some of status comes from higher bits of the character and some come from
69 * the status register. Combining both of them in to single status using dummy
70 * bits.
71 */
72#define ASC_RXBUF_DUMMY_RX 0x10000
73#define ASC_RXBUF_DUMMY_BE 0x20000
74#define ASC_RXBUF_DUMMY_OE 0x40000
75
76/* ASC_CTL */
77
78#define ASC_CTL_MODE_MSK 0x0007
79#define ASC_CTL_MODE_8BIT 0x0001
80#define ASC_CTL_MODE_7BIT_PAR 0x0003
81#define ASC_CTL_MODE_9BIT 0x0004
82#define ASC_CTL_MODE_8BIT_WKUP 0x0005
83#define ASC_CTL_MODE_8BIT_PAR 0x0007
84#define ASC_CTL_STOP_MSK 0x0018
85#define ASC_CTL_STOP_HALFBIT 0x0000
86#define ASC_CTL_STOP_1BIT 0x0008
87#define ASC_CTL_STOP_1_HALFBIT 0x0010
88#define ASC_CTL_STOP_2BIT 0x0018
89#define ASC_CTL_PARITYODD 0x0020
90#define ASC_CTL_LOOPBACK 0x0040
91#define ASC_CTL_RUN 0x0080
92#define ASC_CTL_RXENABLE 0x0100
93#define ASC_CTL_SCENABLE 0x0200
94#define ASC_CTL_FIFOENABLE 0x0400
95#define ASC_CTL_CTSENABLE 0x0800
96#define ASC_CTL_BAUDMODE 0x1000
97
98/* ASC_GUARDTIME */
99
100#define ASC_GUARDTIME_MSK 0x00FF
101
102/* ASC_INTEN */
103
104#define ASC_INTEN_RBE 0x0001
105#define ASC_INTEN_TE 0x0002
106#define ASC_INTEN_THE 0x0004
107#define ASC_INTEN_PE 0x0008
108#define ASC_INTEN_FE 0x0010
109#define ASC_INTEN_OE 0x0020
110#define ASC_INTEN_TNE 0x0040
111#define ASC_INTEN_TOI 0x0080
112#define ASC_INTEN_RHF 0x0100
113
114/* ASC_RETRIES */
115
116#define ASC_RETRIES_MSK 0x00FF
117
118/* ASC_RXBUF */
119
120#define ASC_RXBUF_MSK 0x03FF
121
122/* ASC_STA */
123
124#define ASC_STA_RBF 0x0001
125#define ASC_STA_TE 0x0002
126#define ASC_STA_THE 0x0004
127#define ASC_STA_PE 0x0008
128#define ASC_STA_FE 0x0010
129#define ASC_STA_OE 0x0020
130#define ASC_STA_TNE 0x0040
131#define ASC_STA_TOI 0x0080
132#define ASC_STA_RHF 0x0100
133#define ASC_STA_TF 0x0200
134#define ASC_STA_NKD 0x0400
135
136/* ASC_TIMEOUT */
137
138#define ASC_TIMEOUT_MSK 0x00FF
139
140/* ASC_TXBUF */
141
142#define ASC_TXBUF_MSK 0x01FF
143
144/*---- Inline function definitions ---------------------------*/
145
146static inline struct asc_port *to_asc_port(struct uart_port *port)
147{
148 return container_of(port, struct asc_port, port);
149}
150
151static inline u32 asc_in(struct uart_port *port, u32 offset)
152{
153#ifdef readl_relaxed
154 return readl_relaxed(port->membase + offset);
155#else
156 return readl(port->membase + offset);
157#endif
158}
159
160static inline void asc_out(struct uart_port *port, u32 offset, u32 value)
161{
162#ifdef writel_relaxed
163 writel_relaxed(value, port->membase + offset);
164#else
165 writel(value, port->membase + offset);
166#endif
167}
168
169/*
170 * Some simple utility functions to enable and disable interrupts.
171 * Note that these need to be called with interrupts disabled.
172 */
173static inline void asc_disable_tx_interrupts(struct uart_port *port)
174{
175 u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_THE;
176 asc_out(port, ASC_INTEN, intenable);
177 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
178}
179
180static inline void asc_enable_tx_interrupts(struct uart_port *port)
181{
182 u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_THE;
183 asc_out(port, ASC_INTEN, intenable);
184}
185
186static inline void asc_disable_rx_interrupts(struct uart_port *port)
187{
188 u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_RBE;
189 asc_out(port, ASC_INTEN, intenable);
190 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
191}
192
193static inline void asc_enable_rx_interrupts(struct uart_port *port)
194{
195 u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_RBE;
196 asc_out(port, ASC_INTEN, intenable);
197}
198
199static inline u32 asc_txfifo_is_empty(struct uart_port *port)
200{
201 return asc_in(port, ASC_STA) & ASC_STA_TE;
202}
203
204static inline u32 asc_txfifo_is_half_empty(struct uart_port *port)
205{
206 return asc_in(port, ASC_STA) & ASC_STA_THE;
207}
208
209static inline const char *asc_port_name(struct uart_port *port)
210{
211 return to_platform_device(port->dev)->name;
212}
213
214/*----------------------------------------------------------------------*/
215
216/*
217 * This section contains code to support the use of the ASC as a
218 * generic serial port.
219 */
220
221static inline unsigned asc_hw_txroom(struct uart_port *port)
222{
223 u32 status = asc_in(port, ASC_STA);
224
225 if (status & ASC_STA_THE)
226 return port->fifosize / 2;
227 else if (!(status & ASC_STA_TF))
228 return 1;
229
230 return 0;
231}
232
233/*
234 * Start transmitting chars.
235 * This is called from both interrupt and task level.
236 * Either way interrupts are disabled.
237 */
238static void asc_transmit_chars(struct uart_port *port)
239{
240 u8 ch;
241
242 uart_port_tx_limited(port, ch, asc_hw_txroom(port),
243 true,
244 asc_out(port, ASC_TXBUF, ch),
245 ({}));
246}
247
248static void asc_receive_chars(struct uart_port *port)
249{
250 struct tty_port *tport = &port->state->port;
251 unsigned long status, mode;
252 unsigned long c = 0;
253 u8 flag;
254 bool ignore_pe = false;
255
256 /*
257 * Datasheet states: If the MODE field selects an 8-bit frame then
258 * this [parity error] bit is undefined. Software should ignore this
259 * bit when reading 8-bit frames.
260 */
261 mode = asc_in(port, ASC_CTL) & ASC_CTL_MODE_MSK;
262 if (mode == ASC_CTL_MODE_8BIT || mode == ASC_CTL_MODE_8BIT_PAR)
263 ignore_pe = true;
264
265 if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
266 pm_wakeup_event(tport->tty->dev, 0);
267
268 while ((status = asc_in(port, ASC_STA)) & ASC_STA_RBF) {
269 c = asc_in(port, ASC_RXBUF) | ASC_RXBUF_DUMMY_RX;
270 flag = TTY_NORMAL;
271 port->icount.rx++;
272
273 if (status & ASC_STA_OE || c & ASC_RXBUF_FE ||
274 (c & ASC_RXBUF_PE && !ignore_pe)) {
275
276 if (c & ASC_RXBUF_FE) {
277 if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {
278 port->icount.brk++;
279 if (uart_handle_break(port))
280 continue;
281 c |= ASC_RXBUF_DUMMY_BE;
282 } else {
283 port->icount.frame++;
284 }
285 } else if (c & ASC_RXBUF_PE) {
286 port->icount.parity++;
287 }
288 /*
289 * Reading any data from the RX FIFO clears the
290 * overflow error condition.
291 */
292 if (status & ASC_STA_OE) {
293 port->icount.overrun++;
294 c |= ASC_RXBUF_DUMMY_OE;
295 }
296
297 c &= port->read_status_mask;
298
299 if (c & ASC_RXBUF_DUMMY_BE)
300 flag = TTY_BREAK;
301 else if (c & ASC_RXBUF_PE)
302 flag = TTY_PARITY;
303 else if (c & ASC_RXBUF_FE)
304 flag = TTY_FRAME;
305 }
306
307 if (uart_handle_sysrq_char(port, c & 0xff))
308 continue;
309
310 uart_insert_char(port, c, ASC_RXBUF_DUMMY_OE, c & 0xff, flag);
311 }
312
313 /* Tell the rest of the system the news. New characters! */
314 tty_flip_buffer_push(tport);
315}
316
317static irqreturn_t asc_interrupt(int irq, void *ptr)
318{
319 struct uart_port *port = ptr;
320 u32 status;
321
322 uart_port_lock(port);
323
324 status = asc_in(port, ASC_STA);
325
326 if (status & ASC_STA_RBF) {
327 /* Receive FIFO not empty */
328 asc_receive_chars(port);
329 }
330
331 if ((status & ASC_STA_THE) &&
332 (asc_in(port, ASC_INTEN) & ASC_INTEN_THE)) {
333 /* Transmitter FIFO at least half empty */
334 asc_transmit_chars(port);
335 }
336
337 uart_port_unlock(port);
338
339 return IRQ_HANDLED;
340}
341
342/*----------------------------------------------------------------------*/
343
344/*
345 * UART Functions
346 */
347
348static unsigned int asc_tx_empty(struct uart_port *port)
349{
350 return asc_txfifo_is_empty(port) ? TIOCSER_TEMT : 0;
351}
352
353static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl)
354{
355 struct asc_port *ascport = to_asc_port(port);
356
357 /*
358 * This routine is used for seting signals of: DTR, DCD, CTS and RTS.
359 * We use ASC's hardware for CTS/RTS when hardware flow-control is
360 * enabled, however if the RTS line is required for another purpose,
361 * commonly controlled using HUP from userspace, then we need to toggle
362 * it manually, using GPIO.
363 *
364 * Some boards also have DTR and DCD implemented using PIO pins, code to
365 * do this should be hooked in here.
366 */
367
368 if (!ascport->rts)
369 return;
370
371 /* If HW flow-control is enabled, we can't fiddle with the RTS line */
372 if (asc_in(port, ASC_CTL) & ASC_CTL_CTSENABLE)
373 return;
374
375 gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);
376}
377
378static unsigned int asc_get_mctrl(struct uart_port *port)
379{
380 /*
381 * This routine is used for geting signals of: DTR, DCD, DSR, RI,
382 * and CTS/RTS
383 */
384 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
385}
386
387/* There are probably characters waiting to be transmitted. */
388static void asc_start_tx(struct uart_port *port)
389{
390 struct circ_buf *xmit = &port->state->xmit;
391
392 if (!uart_circ_empty(xmit))
393 asc_enable_tx_interrupts(port);
394}
395
396/* Transmit stop */
397static void asc_stop_tx(struct uart_port *port)
398{
399 asc_disable_tx_interrupts(port);
400}
401
402/* Receive stop */
403static void asc_stop_rx(struct uart_port *port)
404{
405 asc_disable_rx_interrupts(port);
406}
407
408/* Handle breaks - ignored by us */
409static void asc_break_ctl(struct uart_port *port, int break_state)
410{
411 /* Nothing here yet .. */
412}
413
414/*
415 * Enable port for reception.
416 */
417static int asc_startup(struct uart_port *port)
418{
419 if (request_irq(port->irq, asc_interrupt, 0,
420 asc_port_name(port), port)) {
421 dev_err(port->dev, "cannot allocate irq.\n");
422 return -ENODEV;
423 }
424
425 asc_transmit_chars(port);
426 asc_enable_rx_interrupts(port);
427
428 return 0;
429}
430
431static void asc_shutdown(struct uart_port *port)
432{
433 asc_disable_tx_interrupts(port);
434 asc_disable_rx_interrupts(port);
435 free_irq(port->irq, port);
436}
437
438static void asc_pm(struct uart_port *port, unsigned int state,
439 unsigned int oldstate)
440{
441 struct asc_port *ascport = to_asc_port(port);
442 unsigned long flags;
443 u32 ctl;
444
445 switch (state) {
446 case UART_PM_STATE_ON:
447 clk_prepare_enable(ascport->clk);
448 break;
449 case UART_PM_STATE_OFF:
450 /*
451 * Disable the ASC baud rate generator, which is as close as
452 * we can come to turning it off. Note this is not called with
453 * the port spinlock held.
454 */
455 uart_port_lock_irqsave(port, &flags);
456 ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
457 asc_out(port, ASC_CTL, ctl);
458 uart_port_unlock_irqrestore(port, flags);
459 clk_disable_unprepare(ascport->clk);
460 break;
461 }
462}
463
464static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
465 const struct ktermios *old)
466{
467 struct asc_port *ascport = to_asc_port(port);
468 struct gpio_desc *gpiod;
469 unsigned int baud;
470 u32 ctrl_val;
471 tcflag_t cflag;
472 unsigned long flags;
473
474 /* Update termios to reflect hardware capabilities */
475 termios->c_cflag &= ~(CMSPAR |
476 (ascport->hw_flow_control ? 0 : CRTSCTS));
477
478 port->uartclk = clk_get_rate(ascport->clk);
479
480 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
481 cflag = termios->c_cflag;
482
483 uart_port_lock_irqsave(port, &flags);
484
485 /* read control register */
486 ctrl_val = asc_in(port, ASC_CTL);
487
488 /* stop serial port and reset value */
489 asc_out(port, ASC_CTL, (ctrl_val & ~ASC_CTL_RUN));
490 ctrl_val = ASC_CTL_RXENABLE | ASC_CTL_FIFOENABLE;
491
492 /* reset fifo rx & tx */
493 asc_out(port, ASC_TXRESET, 1);
494 asc_out(port, ASC_RXRESET, 1);
495
496 /* set character length */
497 if ((cflag & CSIZE) == CS7) {
498 ctrl_val |= ASC_CTL_MODE_7BIT_PAR;
499 cflag |= PARENB;
500 } else {
501 ctrl_val |= (cflag & PARENB) ? ASC_CTL_MODE_8BIT_PAR :
502 ASC_CTL_MODE_8BIT;
503 cflag &= ~CSIZE;
504 cflag |= CS8;
505 }
506 termios->c_cflag = cflag;
507
508 /* set stop bit */
509 ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT;
510
511 /* odd parity */
512 if (cflag & PARODD)
513 ctrl_val |= ASC_CTL_PARITYODD;
514
515 /* hardware flow control */
516 if ((cflag & CRTSCTS)) {
517 ctrl_val |= ASC_CTL_CTSENABLE;
518
519 /* If flow-control selected, stop handling RTS manually */
520 if (ascport->rts) {
521 devm_gpiod_put(port->dev, ascport->rts);
522 ascport->rts = NULL;
523
524 pinctrl_select_state(ascport->pinctrl,
525 ascport->states[DEFAULT]);
526 }
527 } else {
528 /* If flow-control disabled, it's safe to handle RTS manually */
529 if (!ascport->rts && ascport->states[NO_HW_FLOWCTRL]) {
530 pinctrl_select_state(ascport->pinctrl,
531 ascport->states[NO_HW_FLOWCTRL]);
532
533 gpiod = devm_gpiod_get(port->dev, "rts", GPIOD_OUT_LOW);
534 if (!IS_ERR(gpiod)) {
535 gpiod_set_consumer_name(gpiod,
536 port->dev->of_node->name);
537 ascport->rts = gpiod;
538 }
539 }
540 }
541
542 if ((baud < 19200) && !ascport->force_m1) {
543 asc_out(port, ASC_BAUDRATE, (port->uartclk / (16 * baud)));
544 } else {
545 /*
546 * MODE 1: recommended for high bit rates (above 19.2K)
547 *
548 * baudrate * 16 * 2^16
549 * ASCBaudRate = ------------------------
550 * inputclock
551 *
552 * To keep maths inside 64bits, we divide inputclock by 16.
553 */
554 u64 dividend = (u64)baud * (1 << 16);
555
556 do_div(dividend, port->uartclk / 16);
557 asc_out(port, ASC_BAUDRATE, dividend);
558 ctrl_val |= ASC_CTL_BAUDMODE;
559 }
560
561 uart_update_timeout(port, cflag, baud);
562
563 ascport->port.read_status_mask = ASC_RXBUF_DUMMY_OE;
564 if (termios->c_iflag & INPCK)
565 ascport->port.read_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
566 if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
567 ascport->port.read_status_mask |= ASC_RXBUF_DUMMY_BE;
568
569 /*
570 * Characters to ignore
571 */
572 ascport->port.ignore_status_mask = 0;
573 if (termios->c_iflag & IGNPAR)
574 ascport->port.ignore_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
575 if (termios->c_iflag & IGNBRK) {
576 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_BE;
577 /*
578 * If we're ignoring parity and break indicators,
579 * ignore overruns too (for real raw support).
580 */
581 if (termios->c_iflag & IGNPAR)
582 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_OE;
583 }
584
585 /*
586 * Ignore all characters if CREAD is not set.
587 */
588 if (!(termios->c_cflag & CREAD))
589 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_RX;
590
591 /* Set the timeout */
592 asc_out(port, ASC_TIMEOUT, 20);
593
594 /* write final value and enable port */
595 asc_out(port, ASC_CTL, (ctrl_val | ASC_CTL_RUN));
596
597 uart_port_unlock_irqrestore(port, flags);
598}
599
600static const char *asc_type(struct uart_port *port)
601{
602 return (port->type == PORT_ASC) ? DRIVER_NAME : NULL;
603}
604
605static void asc_release_port(struct uart_port *port)
606{
607}
608
609static int asc_request_port(struct uart_port *port)
610{
611 return 0;
612}
613
614/*
615 * Called when the port is opened, and UPF_BOOT_AUTOCONF flag is set
616 * Set type field if successful
617 */
618static void asc_config_port(struct uart_port *port, int flags)
619{
620 if ((flags & UART_CONFIG_TYPE))
621 port->type = PORT_ASC;
622}
623
624static int
625asc_verify_port(struct uart_port *port, struct serial_struct *ser)
626{
627 /* No user changeable parameters */
628 return -EINVAL;
629}
630
631#ifdef CONFIG_CONSOLE_POLL
632/*
633 * Console polling routines for writing and reading from the uart while
634 * in an interrupt or debug context (i.e. kgdb).
635 */
636
637static int asc_get_poll_char(struct uart_port *port)
638{
639 if (!(asc_in(port, ASC_STA) & ASC_STA_RBF))
640 return NO_POLL_CHAR;
641
642 return asc_in(port, ASC_RXBUF);
643}
644
645static void asc_put_poll_char(struct uart_port *port, unsigned char c)
646{
647 while (!asc_txfifo_is_half_empty(port))
648 cpu_relax();
649 asc_out(port, ASC_TXBUF, c);
650}
651
652#endif /* CONFIG_CONSOLE_POLL */
653
654/*---------------------------------------------------------------------*/
655
656static const struct uart_ops asc_uart_ops = {
657 .tx_empty = asc_tx_empty,
658 .set_mctrl = asc_set_mctrl,
659 .get_mctrl = asc_get_mctrl,
660 .start_tx = asc_start_tx,
661 .stop_tx = asc_stop_tx,
662 .stop_rx = asc_stop_rx,
663 .break_ctl = asc_break_ctl,
664 .startup = asc_startup,
665 .shutdown = asc_shutdown,
666 .set_termios = asc_set_termios,
667 .type = asc_type,
668 .release_port = asc_release_port,
669 .request_port = asc_request_port,
670 .config_port = asc_config_port,
671 .verify_port = asc_verify_port,
672 .pm = asc_pm,
673#ifdef CONFIG_CONSOLE_POLL
674 .poll_get_char = asc_get_poll_char,
675 .poll_put_char = asc_put_poll_char,
676#endif /* CONFIG_CONSOLE_POLL */
677};
678
679static int asc_init_port(struct asc_port *ascport,
680 struct platform_device *pdev)
681{
682 struct uart_port *port = &ascport->port;
683 struct resource *res;
684 int ret;
685
686 port->iotype = UPIO_MEM;
687 port->flags = UPF_BOOT_AUTOCONF;
688 port->ops = &asc_uart_ops;
689 port->fifosize = ASC_FIFO_SIZE;
690 port->dev = &pdev->dev;
691 port->irq = platform_get_irq(pdev, 0);
692 port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ST_ASC_CONSOLE);
693
694 port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
695 if (IS_ERR(port->membase))
696 return PTR_ERR(port->membase);
697 port->mapbase = res->start;
698
699 spin_lock_init(&port->lock);
700
701 ascport->clk = devm_clk_get(&pdev->dev, NULL);
702
703 if (WARN_ON(IS_ERR(ascport->clk)))
704 return -EINVAL;
705 /* ensure that clk rate is correct by enabling the clk */
706 ret = clk_prepare_enable(ascport->clk);
707 if (ret)
708 return ret;
709 ascport->port.uartclk = clk_get_rate(ascport->clk);
710 WARN_ON(ascport->port.uartclk == 0);
711 clk_disable_unprepare(ascport->clk);
712
713 ascport->pinctrl = devm_pinctrl_get(&pdev->dev);
714 if (IS_ERR(ascport->pinctrl)) {
715 ret = PTR_ERR(ascport->pinctrl);
716 dev_err(&pdev->dev, "Failed to get Pinctrl: %d\n", ret);
717 return ret;
718 }
719
720 ascport->states[DEFAULT] =
721 pinctrl_lookup_state(ascport->pinctrl, "default");
722 if (IS_ERR(ascport->states[DEFAULT])) {
723 ret = PTR_ERR(ascport->states[DEFAULT]);
724 dev_err(&pdev->dev,
725 "Failed to look up Pinctrl state 'default': %d\n", ret);
726 return ret;
727 }
728
729 /* "no-hw-flowctrl" state is optional */
730 ascport->states[NO_HW_FLOWCTRL] =
731 pinctrl_lookup_state(ascport->pinctrl, "no-hw-flowctrl");
732 if (IS_ERR(ascport->states[NO_HW_FLOWCTRL]))
733 ascport->states[NO_HW_FLOWCTRL] = NULL;
734
735 return 0;
736}
737
738static struct asc_port *asc_of_get_asc_port(struct platform_device *pdev)
739{
740 struct device_node *np = pdev->dev.of_node;
741 int id;
742
743 if (!np)
744 return NULL;
745
746 id = of_alias_get_id(np, "serial");
747 if (id < 0)
748 id = of_alias_get_id(np, ASC_SERIAL_NAME);
749
750 if (id < 0)
751 id = 0;
752
753 if (WARN_ON(id >= ASC_MAX_PORTS))
754 return NULL;
755
756 asc_ports[id].hw_flow_control = of_property_read_bool(np,
757 "uart-has-rtscts");
758 asc_ports[id].force_m1 = of_property_read_bool(np, "st,force-m1");
759 asc_ports[id].port.line = id;
760 asc_ports[id].rts = NULL;
761
762 return &asc_ports[id];
763}
764
765#ifdef CONFIG_OF
766static const struct of_device_id asc_match[] = {
767 { .compatible = "st,asc", },
768 {},
769};
770
771MODULE_DEVICE_TABLE(of, asc_match);
772#endif
773
774static int asc_serial_probe(struct platform_device *pdev)
775{
776 int ret;
777 struct asc_port *ascport;
778
779 ascport = asc_of_get_asc_port(pdev);
780 if (!ascport)
781 return -ENODEV;
782
783 ret = asc_init_port(ascport, pdev);
784 if (ret)
785 return ret;
786
787 ret = uart_add_one_port(&asc_uart_driver, &ascport->port);
788 if (ret)
789 return ret;
790
791 platform_set_drvdata(pdev, &ascport->port);
792
793 return 0;
794}
795
796static void asc_serial_remove(struct platform_device *pdev)
797{
798 struct uart_port *port = platform_get_drvdata(pdev);
799
800 uart_remove_one_port(&asc_uart_driver, port);
801}
802
803#ifdef CONFIG_PM_SLEEP
804static int asc_serial_suspend(struct device *dev)
805{
806 struct uart_port *port = dev_get_drvdata(dev);
807
808 return uart_suspend_port(&asc_uart_driver, port);
809}
810
811static int asc_serial_resume(struct device *dev)
812{
813 struct uart_port *port = dev_get_drvdata(dev);
814
815 return uart_resume_port(&asc_uart_driver, port);
816}
817
818#endif /* CONFIG_PM_SLEEP */
819
820/*----------------------------------------------------------------------*/
821
822#ifdef CONFIG_SERIAL_ST_ASC_CONSOLE
823static void asc_console_putchar(struct uart_port *port, unsigned char ch)
824{
825 unsigned int timeout = 1000000;
826
827 /* Wait for upto 1 second in case flow control is stopping us. */
828 while (--timeout && !asc_txfifo_is_half_empty(port))
829 udelay(1);
830
831 asc_out(port, ASC_TXBUF, ch);
832}
833
834/*
835 * Print a string to the serial port trying not to disturb
836 * any possible real use of the port...
837 */
838
839static void asc_console_write(struct console *co, const char *s, unsigned count)
840{
841 struct uart_port *port = &asc_ports[co->index].port;
842 unsigned long flags;
843 unsigned long timeout = 1000000;
844 int locked = 1;
845 u32 intenable;
846
847 if (port->sysrq)
848 locked = 0; /* asc_interrupt has already claimed the lock */
849 else if (oops_in_progress)
850 locked = uart_port_trylock_irqsave(port, &flags);
851 else
852 uart_port_lock_irqsave(port, &flags);
853
854 /*
855 * Disable interrupts so we don't get the IRQ line bouncing
856 * up and down while interrupts are disabled.
857 */
858 intenable = asc_in(port, ASC_INTEN);
859 asc_out(port, ASC_INTEN, 0);
860 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
861
862 uart_console_write(port, s, count, asc_console_putchar);
863
864 while (--timeout && !asc_txfifo_is_empty(port))
865 udelay(1);
866
867 asc_out(port, ASC_INTEN, intenable);
868
869 if (locked)
870 uart_port_unlock_irqrestore(port, flags);
871}
872
873static int asc_console_setup(struct console *co, char *options)
874{
875 struct asc_port *ascport;
876 int baud = 115200;
877 int bits = 8;
878 int parity = 'n';
879 int flow = 'n';
880
881 if (co->index >= ASC_MAX_PORTS)
882 return -ENODEV;
883
884 ascport = &asc_ports[co->index];
885
886 /*
887 * This driver does not support early console initialization
888 * (use ARM early printk support instead), so we only expect
889 * this to be called during the uart port registration when the
890 * driver gets probed and the port should be mapped at that point.
891 */
892 if (ascport->port.mapbase == 0 || ascport->port.membase == NULL)
893 return -ENXIO;
894
895 if (options)
896 uart_parse_options(options, &baud, &parity, &bits, &flow);
897
898 return uart_set_options(&ascport->port, co, baud, parity, bits, flow);
899}
900
901static struct console asc_console = {
902 .name = ASC_SERIAL_NAME,
903 .device = uart_console_device,
904 .write = asc_console_write,
905 .setup = asc_console_setup,
906 .flags = CON_PRINTBUFFER,
907 .index = -1,
908 .data = &asc_uart_driver,
909};
910
911#define ASC_SERIAL_CONSOLE (&asc_console)
912
913#else
914#define ASC_SERIAL_CONSOLE NULL
915#endif /* CONFIG_SERIAL_ST_ASC_CONSOLE */
916
917static struct uart_driver asc_uart_driver = {
918 .owner = THIS_MODULE,
919 .driver_name = DRIVER_NAME,
920 .dev_name = ASC_SERIAL_NAME,
921 .major = 0,
922 .minor = 0,
923 .nr = ASC_MAX_PORTS,
924 .cons = ASC_SERIAL_CONSOLE,
925};
926
927static const struct dev_pm_ops asc_serial_pm_ops = {
928 SET_SYSTEM_SLEEP_PM_OPS(asc_serial_suspend, asc_serial_resume)
929};
930
931static struct platform_driver asc_serial_driver = {
932 .probe = asc_serial_probe,
933 .remove_new = asc_serial_remove,
934 .driver = {
935 .name = DRIVER_NAME,
936 .pm = &asc_serial_pm_ops,
937 .of_match_table = of_match_ptr(asc_match),
938 },
939};
940
941static int __init asc_init(void)
942{
943 int ret;
944 static const char banner[] __initconst =
945 KERN_INFO "STMicroelectronics ASC driver initialized\n";
946
947 printk(banner);
948
949 ret = uart_register_driver(&asc_uart_driver);
950 if (ret)
951 return ret;
952
953 ret = platform_driver_register(&asc_serial_driver);
954 if (ret)
955 uart_unregister_driver(&asc_uart_driver);
956
957 return ret;
958}
959
960static void __exit asc_exit(void)
961{
962 platform_driver_unregister(&asc_serial_driver);
963 uart_unregister_driver(&asc_uart_driver);
964}
965
966module_init(asc_init);
967module_exit(asc_exit);
968
969MODULE_ALIAS("platform:" DRIVER_NAME);
970MODULE_AUTHOR("STMicroelectronics (R&D) Limited");
971MODULE_DESCRIPTION("STMicroelectronics ASC serial port driver");
972MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * st-asc.c: ST Asynchronous serial controller (ASC) driver
4 *
5 * Copyright (C) 2003-2013 STMicroelectronics (R&D) Limited
6 */
7
8#include <linux/module.h>
9#include <linux/serial.h>
10#include <linux/console.h>
11#include <linux/sysrq.h>
12#include <linux/pinctrl/consumer.h>
13#include <linux/platform_device.h>
14#include <linux/io.h>
15#include <linux/irq.h>
16#include <linux/tty.h>
17#include <linux/tty_flip.h>
18#include <linux/delay.h>
19#include <linux/spinlock.h>
20#include <linux/pm_runtime.h>
21#include <linux/of.h>
22#include <linux/of_platform.h>
23#include <linux/serial_core.h>
24#include <linux/clk.h>
25#include <linux/gpio/consumer.h>
26
27#define DRIVER_NAME "st-asc"
28#define ASC_SERIAL_NAME "ttyAS"
29#define ASC_FIFO_SIZE 16
30#define ASC_MAX_PORTS 8
31
32/* Pinctrl states */
33#define DEFAULT 0
34#define NO_HW_FLOWCTRL 1
35
36struct asc_port {
37 struct uart_port port;
38 struct gpio_desc *rts;
39 struct clk *clk;
40 struct pinctrl *pinctrl;
41 struct pinctrl_state *states[2];
42 unsigned int hw_flow_control:1;
43 unsigned int force_m1:1;
44};
45
46static struct asc_port asc_ports[ASC_MAX_PORTS];
47static struct uart_driver asc_uart_driver;
48
49/*---- UART Register definitions ------------------------------*/
50
51/* Register offsets */
52
53#define ASC_BAUDRATE 0x00
54#define ASC_TXBUF 0x04
55#define ASC_RXBUF 0x08
56#define ASC_CTL 0x0C
57#define ASC_INTEN 0x10
58#define ASC_STA 0x14
59#define ASC_GUARDTIME 0x18
60#define ASC_TIMEOUT 0x1C
61#define ASC_TXRESET 0x20
62#define ASC_RXRESET 0x24
63#define ASC_RETRIES 0x28
64
65/* ASC_RXBUF */
66#define ASC_RXBUF_PE 0x100
67#define ASC_RXBUF_FE 0x200
68/*
69 * Some of status comes from higher bits of the character and some come from
70 * the status register. Combining both of them in to single status using dummy
71 * bits.
72 */
73#define ASC_RXBUF_DUMMY_RX 0x10000
74#define ASC_RXBUF_DUMMY_BE 0x20000
75#define ASC_RXBUF_DUMMY_OE 0x40000
76
77/* ASC_CTL */
78
79#define ASC_CTL_MODE_MSK 0x0007
80#define ASC_CTL_MODE_8BIT 0x0001
81#define ASC_CTL_MODE_7BIT_PAR 0x0003
82#define ASC_CTL_MODE_9BIT 0x0004
83#define ASC_CTL_MODE_8BIT_WKUP 0x0005
84#define ASC_CTL_MODE_8BIT_PAR 0x0007
85#define ASC_CTL_STOP_MSK 0x0018
86#define ASC_CTL_STOP_HALFBIT 0x0000
87#define ASC_CTL_STOP_1BIT 0x0008
88#define ASC_CTL_STOP_1_HALFBIT 0x0010
89#define ASC_CTL_STOP_2BIT 0x0018
90#define ASC_CTL_PARITYODD 0x0020
91#define ASC_CTL_LOOPBACK 0x0040
92#define ASC_CTL_RUN 0x0080
93#define ASC_CTL_RXENABLE 0x0100
94#define ASC_CTL_SCENABLE 0x0200
95#define ASC_CTL_FIFOENABLE 0x0400
96#define ASC_CTL_CTSENABLE 0x0800
97#define ASC_CTL_BAUDMODE 0x1000
98
99/* ASC_GUARDTIME */
100
101#define ASC_GUARDTIME_MSK 0x00FF
102
103/* ASC_INTEN */
104
105#define ASC_INTEN_RBE 0x0001
106#define ASC_INTEN_TE 0x0002
107#define ASC_INTEN_THE 0x0004
108#define ASC_INTEN_PE 0x0008
109#define ASC_INTEN_FE 0x0010
110#define ASC_INTEN_OE 0x0020
111#define ASC_INTEN_TNE 0x0040
112#define ASC_INTEN_TOI 0x0080
113#define ASC_INTEN_RHF 0x0100
114
115/* ASC_RETRIES */
116
117#define ASC_RETRIES_MSK 0x00FF
118
119/* ASC_RXBUF */
120
121#define ASC_RXBUF_MSK 0x03FF
122
123/* ASC_STA */
124
125#define ASC_STA_RBF 0x0001
126#define ASC_STA_TE 0x0002
127#define ASC_STA_THE 0x0004
128#define ASC_STA_PE 0x0008
129#define ASC_STA_FE 0x0010
130#define ASC_STA_OE 0x0020
131#define ASC_STA_TNE 0x0040
132#define ASC_STA_TOI 0x0080
133#define ASC_STA_RHF 0x0100
134#define ASC_STA_TF 0x0200
135#define ASC_STA_NKD 0x0400
136
137/* ASC_TIMEOUT */
138
139#define ASC_TIMEOUT_MSK 0x00FF
140
141/* ASC_TXBUF */
142
143#define ASC_TXBUF_MSK 0x01FF
144
145/*---- Inline function definitions ---------------------------*/
146
147static inline struct asc_port *to_asc_port(struct uart_port *port)
148{
149 return container_of(port, struct asc_port, port);
150}
151
152static inline u32 asc_in(struct uart_port *port, u32 offset)
153{
154#ifdef readl_relaxed
155 return readl_relaxed(port->membase + offset);
156#else
157 return readl(port->membase + offset);
158#endif
159}
160
161static inline void asc_out(struct uart_port *port, u32 offset, u32 value)
162{
163#ifdef writel_relaxed
164 writel_relaxed(value, port->membase + offset);
165#else
166 writel(value, port->membase + offset);
167#endif
168}
169
170/*
171 * Some simple utility functions to enable and disable interrupts.
172 * Note that these need to be called with interrupts disabled.
173 */
174static inline void asc_disable_tx_interrupts(struct uart_port *port)
175{
176 u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_THE;
177 asc_out(port, ASC_INTEN, intenable);
178 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
179}
180
181static inline void asc_enable_tx_interrupts(struct uart_port *port)
182{
183 u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_THE;
184 asc_out(port, ASC_INTEN, intenable);
185}
186
187static inline void asc_disable_rx_interrupts(struct uart_port *port)
188{
189 u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_RBE;
190 asc_out(port, ASC_INTEN, intenable);
191 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
192}
193
194static inline void asc_enable_rx_interrupts(struct uart_port *port)
195{
196 u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_RBE;
197 asc_out(port, ASC_INTEN, intenable);
198}
199
200static inline u32 asc_txfifo_is_empty(struct uart_port *port)
201{
202 return asc_in(port, ASC_STA) & ASC_STA_TE;
203}
204
205static inline u32 asc_txfifo_is_half_empty(struct uart_port *port)
206{
207 return asc_in(port, ASC_STA) & ASC_STA_THE;
208}
209
210static inline const char *asc_port_name(struct uart_port *port)
211{
212 return to_platform_device(port->dev)->name;
213}
214
215/*----------------------------------------------------------------------*/
216
217/*
218 * This section contains code to support the use of the ASC as a
219 * generic serial port.
220 */
221
222static inline unsigned asc_hw_txroom(struct uart_port *port)
223{
224 u32 status = asc_in(port, ASC_STA);
225
226 if (status & ASC_STA_THE)
227 return port->fifosize / 2;
228 else if (!(status & ASC_STA_TF))
229 return 1;
230
231 return 0;
232}
233
234/*
235 * Start transmitting chars.
236 * This is called from both interrupt and task level.
237 * Either way interrupts are disabled.
238 */
239static void asc_transmit_chars(struct uart_port *port)
240{
241 struct circ_buf *xmit = &port->state->xmit;
242 int txroom;
243 unsigned char c;
244
245 txroom = asc_hw_txroom(port);
246
247 if ((txroom != 0) && port->x_char) {
248 c = port->x_char;
249 port->x_char = 0;
250 asc_out(port, ASC_TXBUF, c);
251 port->icount.tx++;
252 txroom = asc_hw_txroom(port);
253 }
254
255 if (uart_tx_stopped(port)) {
256 /*
257 * We should try and stop the hardware here, but I
258 * don't think the ASC has any way to do that.
259 */
260 asc_disable_tx_interrupts(port);
261 return;
262 }
263
264 if (uart_circ_empty(xmit)) {
265 asc_disable_tx_interrupts(port);
266 return;
267 }
268
269 if (txroom == 0)
270 return;
271
272 do {
273 c = xmit->buf[xmit->tail];
274 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
275 asc_out(port, ASC_TXBUF, c);
276 port->icount.tx++;
277 txroom--;
278 } while ((txroom > 0) && (!uart_circ_empty(xmit)));
279
280 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
281 uart_write_wakeup(port);
282
283 if (uart_circ_empty(xmit))
284 asc_disable_tx_interrupts(port);
285}
286
287static void asc_receive_chars(struct uart_port *port)
288{
289 struct tty_port *tport = &port->state->port;
290 unsigned long status, mode;
291 unsigned long c = 0;
292 char flag;
293 bool ignore_pe = false;
294
295 /*
296 * Datasheet states: If the MODE field selects an 8-bit frame then
297 * this [parity error] bit is undefined. Software should ignore this
298 * bit when reading 8-bit frames.
299 */
300 mode = asc_in(port, ASC_CTL) & ASC_CTL_MODE_MSK;
301 if (mode == ASC_CTL_MODE_8BIT || mode == ASC_CTL_MODE_8BIT_PAR)
302 ignore_pe = true;
303
304 if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
305 pm_wakeup_event(tport->tty->dev, 0);
306
307 while ((status = asc_in(port, ASC_STA)) & ASC_STA_RBF) {
308 c = asc_in(port, ASC_RXBUF) | ASC_RXBUF_DUMMY_RX;
309 flag = TTY_NORMAL;
310 port->icount.rx++;
311
312 if (status & ASC_STA_OE || c & ASC_RXBUF_FE ||
313 (c & ASC_RXBUF_PE && !ignore_pe)) {
314
315 if (c & ASC_RXBUF_FE) {
316 if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {
317 port->icount.brk++;
318 if (uart_handle_break(port))
319 continue;
320 c |= ASC_RXBUF_DUMMY_BE;
321 } else {
322 port->icount.frame++;
323 }
324 } else if (c & ASC_RXBUF_PE) {
325 port->icount.parity++;
326 }
327 /*
328 * Reading any data from the RX FIFO clears the
329 * overflow error condition.
330 */
331 if (status & ASC_STA_OE) {
332 port->icount.overrun++;
333 c |= ASC_RXBUF_DUMMY_OE;
334 }
335
336 c &= port->read_status_mask;
337
338 if (c & ASC_RXBUF_DUMMY_BE)
339 flag = TTY_BREAK;
340 else if (c & ASC_RXBUF_PE)
341 flag = TTY_PARITY;
342 else if (c & ASC_RXBUF_FE)
343 flag = TTY_FRAME;
344 }
345
346 if (uart_handle_sysrq_char(port, c & 0xff))
347 continue;
348
349 uart_insert_char(port, c, ASC_RXBUF_DUMMY_OE, c & 0xff, flag);
350 }
351
352 /* Tell the rest of the system the news. New characters! */
353 tty_flip_buffer_push(tport);
354}
355
356static irqreturn_t asc_interrupt(int irq, void *ptr)
357{
358 struct uart_port *port = ptr;
359 u32 status;
360
361 spin_lock(&port->lock);
362
363 status = asc_in(port, ASC_STA);
364
365 if (status & ASC_STA_RBF) {
366 /* Receive FIFO not empty */
367 asc_receive_chars(port);
368 }
369
370 if ((status & ASC_STA_THE) &&
371 (asc_in(port, ASC_INTEN) & ASC_INTEN_THE)) {
372 /* Transmitter FIFO at least half empty */
373 asc_transmit_chars(port);
374 }
375
376 spin_unlock(&port->lock);
377
378 return IRQ_HANDLED;
379}
380
381/*----------------------------------------------------------------------*/
382
383/*
384 * UART Functions
385 */
386
387static unsigned int asc_tx_empty(struct uart_port *port)
388{
389 return asc_txfifo_is_empty(port) ? TIOCSER_TEMT : 0;
390}
391
392static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl)
393{
394 struct asc_port *ascport = to_asc_port(port);
395
396 /*
397 * This routine is used for seting signals of: DTR, DCD, CTS and RTS.
398 * We use ASC's hardware for CTS/RTS when hardware flow-control is
399 * enabled, however if the RTS line is required for another purpose,
400 * commonly controlled using HUP from userspace, then we need to toggle
401 * it manually, using GPIO.
402 *
403 * Some boards also have DTR and DCD implemented using PIO pins, code to
404 * do this should be hooked in here.
405 */
406
407 if (!ascport->rts)
408 return;
409
410 /* If HW flow-control is enabled, we can't fiddle with the RTS line */
411 if (asc_in(port, ASC_CTL) & ASC_CTL_CTSENABLE)
412 return;
413
414 gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);
415}
416
417static unsigned int asc_get_mctrl(struct uart_port *port)
418{
419 /*
420 * This routine is used for geting signals of: DTR, DCD, DSR, RI,
421 * and CTS/RTS
422 */
423 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
424}
425
426/* There are probably characters waiting to be transmitted. */
427static void asc_start_tx(struct uart_port *port)
428{
429 struct circ_buf *xmit = &port->state->xmit;
430
431 if (!uart_circ_empty(xmit))
432 asc_enable_tx_interrupts(port);
433}
434
435/* Transmit stop */
436static void asc_stop_tx(struct uart_port *port)
437{
438 asc_disable_tx_interrupts(port);
439}
440
441/* Receive stop */
442static void asc_stop_rx(struct uart_port *port)
443{
444 asc_disable_rx_interrupts(port);
445}
446
447/* Handle breaks - ignored by us */
448static void asc_break_ctl(struct uart_port *port, int break_state)
449{
450 /* Nothing here yet .. */
451}
452
453/*
454 * Enable port for reception.
455 */
456static int asc_startup(struct uart_port *port)
457{
458 if (request_irq(port->irq, asc_interrupt, 0,
459 asc_port_name(port), port)) {
460 dev_err(port->dev, "cannot allocate irq.\n");
461 return -ENODEV;
462 }
463
464 asc_transmit_chars(port);
465 asc_enable_rx_interrupts(port);
466
467 return 0;
468}
469
470static void asc_shutdown(struct uart_port *port)
471{
472 asc_disable_tx_interrupts(port);
473 asc_disable_rx_interrupts(port);
474 free_irq(port->irq, port);
475}
476
477static void asc_pm(struct uart_port *port, unsigned int state,
478 unsigned int oldstate)
479{
480 struct asc_port *ascport = to_asc_port(port);
481 unsigned long flags;
482 u32 ctl;
483
484 switch (state) {
485 case UART_PM_STATE_ON:
486 clk_prepare_enable(ascport->clk);
487 break;
488 case UART_PM_STATE_OFF:
489 /*
490 * Disable the ASC baud rate generator, which is as close as
491 * we can come to turning it off. Note this is not called with
492 * the port spinlock held.
493 */
494 spin_lock_irqsave(&port->lock, flags);
495 ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
496 asc_out(port, ASC_CTL, ctl);
497 spin_unlock_irqrestore(&port->lock, flags);
498 clk_disable_unprepare(ascport->clk);
499 break;
500 }
501}
502
503static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
504 struct ktermios *old)
505{
506 struct asc_port *ascport = to_asc_port(port);
507 struct gpio_desc *gpiod;
508 unsigned int baud;
509 u32 ctrl_val;
510 tcflag_t cflag;
511 unsigned long flags;
512
513 /* Update termios to reflect hardware capabilities */
514 termios->c_cflag &= ~(CMSPAR |
515 (ascport->hw_flow_control ? 0 : CRTSCTS));
516
517 port->uartclk = clk_get_rate(ascport->clk);
518
519 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
520 cflag = termios->c_cflag;
521
522 spin_lock_irqsave(&port->lock, flags);
523
524 /* read control register */
525 ctrl_val = asc_in(port, ASC_CTL);
526
527 /* stop serial port and reset value */
528 asc_out(port, ASC_CTL, (ctrl_val & ~ASC_CTL_RUN));
529 ctrl_val = ASC_CTL_RXENABLE | ASC_CTL_FIFOENABLE;
530
531 /* reset fifo rx & tx */
532 asc_out(port, ASC_TXRESET, 1);
533 asc_out(port, ASC_RXRESET, 1);
534
535 /* set character length */
536 if ((cflag & CSIZE) == CS7) {
537 ctrl_val |= ASC_CTL_MODE_7BIT_PAR;
538 } else {
539 ctrl_val |= (cflag & PARENB) ? ASC_CTL_MODE_8BIT_PAR :
540 ASC_CTL_MODE_8BIT;
541 }
542
543 /* set stop bit */
544 ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT;
545
546 /* odd parity */
547 if (cflag & PARODD)
548 ctrl_val |= ASC_CTL_PARITYODD;
549
550 /* hardware flow control */
551 if ((cflag & CRTSCTS)) {
552 ctrl_val |= ASC_CTL_CTSENABLE;
553
554 /* If flow-control selected, stop handling RTS manually */
555 if (ascport->rts) {
556 devm_gpiod_put(port->dev, ascport->rts);
557 ascport->rts = NULL;
558
559 pinctrl_select_state(ascport->pinctrl,
560 ascport->states[DEFAULT]);
561 }
562 } else {
563 /* If flow-control disabled, it's safe to handle RTS manually */
564 if (!ascport->rts && ascport->states[NO_HW_FLOWCTRL]) {
565 pinctrl_select_state(ascport->pinctrl,
566 ascport->states[NO_HW_FLOWCTRL]);
567
568 gpiod = devm_gpiod_get(port->dev, "rts", GPIOD_OUT_LOW);
569 if (!IS_ERR(gpiod)) {
570 gpiod_set_consumer_name(gpiod,
571 port->dev->of_node->name);
572 ascport->rts = gpiod;
573 }
574 }
575 }
576
577 if ((baud < 19200) && !ascport->force_m1) {
578 asc_out(port, ASC_BAUDRATE, (port->uartclk / (16 * baud)));
579 } else {
580 /*
581 * MODE 1: recommended for high bit rates (above 19.2K)
582 *
583 * baudrate * 16 * 2^16
584 * ASCBaudRate = ------------------------
585 * inputclock
586 *
587 * To keep maths inside 64bits, we divide inputclock by 16.
588 */
589 u64 dividend = (u64)baud * (1 << 16);
590
591 do_div(dividend, port->uartclk / 16);
592 asc_out(port, ASC_BAUDRATE, dividend);
593 ctrl_val |= ASC_CTL_BAUDMODE;
594 }
595
596 uart_update_timeout(port, cflag, baud);
597
598 ascport->port.read_status_mask = ASC_RXBUF_DUMMY_OE;
599 if (termios->c_iflag & INPCK)
600 ascport->port.read_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
601 if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
602 ascport->port.read_status_mask |= ASC_RXBUF_DUMMY_BE;
603
604 /*
605 * Characters to ignore
606 */
607 ascport->port.ignore_status_mask = 0;
608 if (termios->c_iflag & IGNPAR)
609 ascport->port.ignore_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
610 if (termios->c_iflag & IGNBRK) {
611 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_BE;
612 /*
613 * If we're ignoring parity and break indicators,
614 * ignore overruns too (for real raw support).
615 */
616 if (termios->c_iflag & IGNPAR)
617 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_OE;
618 }
619
620 /*
621 * Ignore all characters if CREAD is not set.
622 */
623 if (!(termios->c_cflag & CREAD))
624 ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_RX;
625
626 /* Set the timeout */
627 asc_out(port, ASC_TIMEOUT, 20);
628
629 /* write final value and enable port */
630 asc_out(port, ASC_CTL, (ctrl_val | ASC_CTL_RUN));
631
632 spin_unlock_irqrestore(&port->lock, flags);
633}
634
635static const char *asc_type(struct uart_port *port)
636{
637 return (port->type == PORT_ASC) ? DRIVER_NAME : NULL;
638}
639
640static void asc_release_port(struct uart_port *port)
641{
642}
643
644static int asc_request_port(struct uart_port *port)
645{
646 return 0;
647}
648
649/*
650 * Called when the port is opened, and UPF_BOOT_AUTOCONF flag is set
651 * Set type field if successful
652 */
653static void asc_config_port(struct uart_port *port, int flags)
654{
655 if ((flags & UART_CONFIG_TYPE))
656 port->type = PORT_ASC;
657}
658
659static int
660asc_verify_port(struct uart_port *port, struct serial_struct *ser)
661{
662 /* No user changeable parameters */
663 return -EINVAL;
664}
665
666#ifdef CONFIG_CONSOLE_POLL
667/*
668 * Console polling routines for writing and reading from the uart while
669 * in an interrupt or debug context (i.e. kgdb).
670 */
671
672static int asc_get_poll_char(struct uart_port *port)
673{
674 if (!(asc_in(port, ASC_STA) & ASC_STA_RBF))
675 return NO_POLL_CHAR;
676
677 return asc_in(port, ASC_RXBUF);
678}
679
680static void asc_put_poll_char(struct uart_port *port, unsigned char c)
681{
682 while (!asc_txfifo_is_half_empty(port))
683 cpu_relax();
684 asc_out(port, ASC_TXBUF, c);
685}
686
687#endif /* CONFIG_CONSOLE_POLL */
688
689/*---------------------------------------------------------------------*/
690
691static const struct uart_ops asc_uart_ops = {
692 .tx_empty = asc_tx_empty,
693 .set_mctrl = asc_set_mctrl,
694 .get_mctrl = asc_get_mctrl,
695 .start_tx = asc_start_tx,
696 .stop_tx = asc_stop_tx,
697 .stop_rx = asc_stop_rx,
698 .break_ctl = asc_break_ctl,
699 .startup = asc_startup,
700 .shutdown = asc_shutdown,
701 .set_termios = asc_set_termios,
702 .type = asc_type,
703 .release_port = asc_release_port,
704 .request_port = asc_request_port,
705 .config_port = asc_config_port,
706 .verify_port = asc_verify_port,
707 .pm = asc_pm,
708#ifdef CONFIG_CONSOLE_POLL
709 .poll_get_char = asc_get_poll_char,
710 .poll_put_char = asc_put_poll_char,
711#endif /* CONFIG_CONSOLE_POLL */
712};
713
714static int asc_init_port(struct asc_port *ascport,
715 struct platform_device *pdev)
716{
717 struct uart_port *port = &ascport->port;
718 struct resource *res;
719 int ret;
720
721 port->iotype = UPIO_MEM;
722 port->flags = UPF_BOOT_AUTOCONF;
723 port->ops = &asc_uart_ops;
724 port->fifosize = ASC_FIFO_SIZE;
725 port->dev = &pdev->dev;
726 port->irq = platform_get_irq(pdev, 0);
727 port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ST_ASC_CONSOLE);
728
729 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
730 port->membase = devm_ioremap_resource(&pdev->dev, res);
731 if (IS_ERR(port->membase))
732 return PTR_ERR(port->membase);
733 port->mapbase = res->start;
734
735 spin_lock_init(&port->lock);
736
737 ascport->clk = devm_clk_get(&pdev->dev, NULL);
738
739 if (WARN_ON(IS_ERR(ascport->clk)))
740 return -EINVAL;
741 /* ensure that clk rate is correct by enabling the clk */
742 clk_prepare_enable(ascport->clk);
743 ascport->port.uartclk = clk_get_rate(ascport->clk);
744 WARN_ON(ascport->port.uartclk == 0);
745 clk_disable_unprepare(ascport->clk);
746
747 ascport->pinctrl = devm_pinctrl_get(&pdev->dev);
748 if (IS_ERR(ascport->pinctrl)) {
749 ret = PTR_ERR(ascport->pinctrl);
750 dev_err(&pdev->dev, "Failed to get Pinctrl: %d\n", ret);
751 return ret;
752 }
753
754 ascport->states[DEFAULT] =
755 pinctrl_lookup_state(ascport->pinctrl, "default");
756 if (IS_ERR(ascport->states[DEFAULT])) {
757 ret = PTR_ERR(ascport->states[DEFAULT]);
758 dev_err(&pdev->dev,
759 "Failed to look up Pinctrl state 'default': %d\n", ret);
760 return ret;
761 }
762
763 /* "no-hw-flowctrl" state is optional */
764 ascport->states[NO_HW_FLOWCTRL] =
765 pinctrl_lookup_state(ascport->pinctrl, "no-hw-flowctrl");
766 if (IS_ERR(ascport->states[NO_HW_FLOWCTRL]))
767 ascport->states[NO_HW_FLOWCTRL] = NULL;
768
769 return 0;
770}
771
772static struct asc_port *asc_of_get_asc_port(struct platform_device *pdev)
773{
774 struct device_node *np = pdev->dev.of_node;
775 int id;
776
777 if (!np)
778 return NULL;
779
780 id = of_alias_get_id(np, "serial");
781 if (id < 0)
782 id = of_alias_get_id(np, ASC_SERIAL_NAME);
783
784 if (id < 0)
785 id = 0;
786
787 if (WARN_ON(id >= ASC_MAX_PORTS))
788 return NULL;
789
790 asc_ports[id].hw_flow_control = of_property_read_bool(np,
791 "uart-has-rtscts");
792 asc_ports[id].force_m1 = of_property_read_bool(np, "st,force_m1");
793 asc_ports[id].port.line = id;
794 asc_ports[id].rts = NULL;
795
796 return &asc_ports[id];
797}
798
799#ifdef CONFIG_OF
800static const struct of_device_id asc_match[] = {
801 { .compatible = "st,asc", },
802 {},
803};
804
805MODULE_DEVICE_TABLE(of, asc_match);
806#endif
807
808static int asc_serial_probe(struct platform_device *pdev)
809{
810 int ret;
811 struct asc_port *ascport;
812
813 ascport = asc_of_get_asc_port(pdev);
814 if (!ascport)
815 return -ENODEV;
816
817 ret = asc_init_port(ascport, pdev);
818 if (ret)
819 return ret;
820
821 ret = uart_add_one_port(&asc_uart_driver, &ascport->port);
822 if (ret)
823 return ret;
824
825 platform_set_drvdata(pdev, &ascport->port);
826
827 return 0;
828}
829
830static int asc_serial_remove(struct platform_device *pdev)
831{
832 struct uart_port *port = platform_get_drvdata(pdev);
833
834 return uart_remove_one_port(&asc_uart_driver, port);
835}
836
837#ifdef CONFIG_PM_SLEEP
838static int asc_serial_suspend(struct device *dev)
839{
840 struct uart_port *port = dev_get_drvdata(dev);
841
842 return uart_suspend_port(&asc_uart_driver, port);
843}
844
845static int asc_serial_resume(struct device *dev)
846{
847 struct uart_port *port = dev_get_drvdata(dev);
848
849 return uart_resume_port(&asc_uart_driver, port);
850}
851
852#endif /* CONFIG_PM_SLEEP */
853
854/*----------------------------------------------------------------------*/
855
856#ifdef CONFIG_SERIAL_ST_ASC_CONSOLE
857static void asc_console_putchar(struct uart_port *port, int ch)
858{
859 unsigned int timeout = 1000000;
860
861 /* Wait for upto 1 second in case flow control is stopping us. */
862 while (--timeout && !asc_txfifo_is_half_empty(port))
863 udelay(1);
864
865 asc_out(port, ASC_TXBUF, ch);
866}
867
868/*
869 * Print a string to the serial port trying not to disturb
870 * any possible real use of the port...
871 */
872
873static void asc_console_write(struct console *co, const char *s, unsigned count)
874{
875 struct uart_port *port = &asc_ports[co->index].port;
876 unsigned long flags;
877 unsigned long timeout = 1000000;
878 int locked = 1;
879 u32 intenable;
880
881 if (port->sysrq)
882 locked = 0; /* asc_interrupt has already claimed the lock */
883 else if (oops_in_progress)
884 locked = spin_trylock_irqsave(&port->lock, flags);
885 else
886 spin_lock_irqsave(&port->lock, flags);
887
888 /*
889 * Disable interrupts so we don't get the IRQ line bouncing
890 * up and down while interrupts are disabled.
891 */
892 intenable = asc_in(port, ASC_INTEN);
893 asc_out(port, ASC_INTEN, 0);
894 (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */
895
896 uart_console_write(port, s, count, asc_console_putchar);
897
898 while (--timeout && !asc_txfifo_is_empty(port))
899 udelay(1);
900
901 asc_out(port, ASC_INTEN, intenable);
902
903 if (locked)
904 spin_unlock_irqrestore(&port->lock, flags);
905}
906
907static int asc_console_setup(struct console *co, char *options)
908{
909 struct asc_port *ascport;
910 int baud = 115200;
911 int bits = 8;
912 int parity = 'n';
913 int flow = 'n';
914
915 if (co->index >= ASC_MAX_PORTS)
916 return -ENODEV;
917
918 ascport = &asc_ports[co->index];
919
920 /*
921 * This driver does not support early console initialization
922 * (use ARM early printk support instead), so we only expect
923 * this to be called during the uart port registration when the
924 * driver gets probed and the port should be mapped at that point.
925 */
926 if (ascport->port.mapbase == 0 || ascport->port.membase == NULL)
927 return -ENXIO;
928
929 if (options)
930 uart_parse_options(options, &baud, &parity, &bits, &flow);
931
932 return uart_set_options(&ascport->port, co, baud, parity, bits, flow);
933}
934
935static struct console asc_console = {
936 .name = ASC_SERIAL_NAME,
937 .device = uart_console_device,
938 .write = asc_console_write,
939 .setup = asc_console_setup,
940 .flags = CON_PRINTBUFFER,
941 .index = -1,
942 .data = &asc_uart_driver,
943};
944
945#define ASC_SERIAL_CONSOLE (&asc_console)
946
947#else
948#define ASC_SERIAL_CONSOLE NULL
949#endif /* CONFIG_SERIAL_ST_ASC_CONSOLE */
950
951static struct uart_driver asc_uart_driver = {
952 .owner = THIS_MODULE,
953 .driver_name = DRIVER_NAME,
954 .dev_name = ASC_SERIAL_NAME,
955 .major = 0,
956 .minor = 0,
957 .nr = ASC_MAX_PORTS,
958 .cons = ASC_SERIAL_CONSOLE,
959};
960
961static const struct dev_pm_ops asc_serial_pm_ops = {
962 SET_SYSTEM_SLEEP_PM_OPS(asc_serial_suspend, asc_serial_resume)
963};
964
965static struct platform_driver asc_serial_driver = {
966 .probe = asc_serial_probe,
967 .remove = asc_serial_remove,
968 .driver = {
969 .name = DRIVER_NAME,
970 .pm = &asc_serial_pm_ops,
971 .of_match_table = of_match_ptr(asc_match),
972 },
973};
974
975static int __init asc_init(void)
976{
977 int ret;
978 static const char banner[] __initconst =
979 KERN_INFO "STMicroelectronics ASC driver initialized\n";
980
981 printk(banner);
982
983 ret = uart_register_driver(&asc_uart_driver);
984 if (ret)
985 return ret;
986
987 ret = platform_driver_register(&asc_serial_driver);
988 if (ret)
989 uart_unregister_driver(&asc_uart_driver);
990
991 return ret;
992}
993
994static void __exit asc_exit(void)
995{
996 platform_driver_unregister(&asc_serial_driver);
997 uart_unregister_driver(&asc_uart_driver);
998}
999
1000module_init(asc_init);
1001module_exit(asc_exit);
1002
1003MODULE_ALIAS("platform:" DRIVER_NAME);
1004MODULE_AUTHOR("STMicroelectronics (R&D) Limited");
1005MODULE_DESCRIPTION("STMicroelectronics ASC serial port driver");
1006MODULE_LICENSE("GPL");