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1/*
2 * Copyright (C) Maxime Coquelin 2015
3 * Authors: Maxime Coquelin <mcoquelin.stm32@gmail.com>
4 * Gerald Baeza <gerald.baeza@st.com>
5 * License terms: GNU General Public License (GPL), version 2
6 *
7 * Inspired by st-asc.c from STMicroelectronics (c)
8 */
9
10#if defined(CONFIG_SERIAL_STM32_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
11#define SUPPORT_SYSRQ
12#endif
13
14#include <linux/clk.h>
15#include <linux/console.h>
16#include <linux/delay.h>
17#include <linux/dma-direction.h>
18#include <linux/dmaengine.h>
19#include <linux/dma-mapping.h>
20#include <linux/io.h>
21#include <linux/iopoll.h>
22#include <linux/irq.h>
23#include <linux/module.h>
24#include <linux/of.h>
25#include <linux/of_platform.h>
26#include <linux/platform_device.h>
27#include <linux/pm_runtime.h>
28#include <linux/serial_core.h>
29#include <linux/serial.h>
30#include <linux/spinlock.h>
31#include <linux/sysrq.h>
32#include <linux/tty_flip.h>
33#include <linux/tty.h>
34
35#include "stm32-usart.h"
36
37static void stm32_stop_tx(struct uart_port *port);
38static void stm32_transmit_chars(struct uart_port *port);
39
40static inline struct stm32_port *to_stm32_port(struct uart_port *port)
41{
42 return container_of(port, struct stm32_port, port);
43}
44
45static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits)
46{
47 u32 val;
48
49 val = readl_relaxed(port->membase + reg);
50 val |= bits;
51 writel_relaxed(val, port->membase + reg);
52}
53
54static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
55{
56 u32 val;
57
58 val = readl_relaxed(port->membase + reg);
59 val &= ~bits;
60 writel_relaxed(val, port->membase + reg);
61}
62
63static int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res,
64 bool threaded)
65{
66 struct stm32_port *stm32_port = to_stm32_port(port);
67 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
68 enum dma_status status;
69 struct dma_tx_state state;
70
71 *sr = readl_relaxed(port->membase + ofs->isr);
72
73 if (threaded && stm32_port->rx_ch) {
74 status = dmaengine_tx_status(stm32_port->rx_ch,
75 stm32_port->rx_ch->cookie,
76 &state);
77 if ((status == DMA_IN_PROGRESS) &&
78 (*last_res != state.residue))
79 return 1;
80 else
81 return 0;
82 } else if (*sr & USART_SR_RXNE) {
83 return 1;
84 }
85 return 0;
86}
87
88static unsigned long
89stm32_get_char(struct uart_port *port, u32 *sr, int *last_res)
90{
91 struct stm32_port *stm32_port = to_stm32_port(port);
92 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
93 unsigned long c;
94
95 if (stm32_port->rx_ch) {
96 c = stm32_port->rx_buf[RX_BUF_L - (*last_res)--];
97 if ((*last_res) == 0)
98 *last_res = RX_BUF_L;
99 return c;
100 } else {
101 return readl_relaxed(port->membase + ofs->rdr);
102 }
103}
104
105static void stm32_receive_chars(struct uart_port *port, bool threaded)
106{
107 struct tty_port *tport = &port->state->port;
108 struct stm32_port *stm32_port = to_stm32_port(port);
109 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
110 unsigned long c;
111 u32 sr;
112 char flag;
113 static int last_res = RX_BUF_L;
114
115 if (port->irq_wake)
116 pm_wakeup_event(tport->tty->dev, 0);
117
118 while (stm32_pending_rx(port, &sr, &last_res, threaded)) {
119 sr |= USART_SR_DUMMY_RX;
120 c = stm32_get_char(port, &sr, &last_res);
121 flag = TTY_NORMAL;
122 port->icount.rx++;
123
124 if (sr & USART_SR_ERR_MASK) {
125 if (sr & USART_SR_LBD) {
126 port->icount.brk++;
127 if (uart_handle_break(port))
128 continue;
129 } else if (sr & USART_SR_ORE) {
130 if (ofs->icr != UNDEF_REG)
131 writel_relaxed(USART_ICR_ORECF,
132 port->membase +
133 ofs->icr);
134 port->icount.overrun++;
135 } else if (sr & USART_SR_PE) {
136 port->icount.parity++;
137 } else if (sr & USART_SR_FE) {
138 port->icount.frame++;
139 }
140
141 sr &= port->read_status_mask;
142
143 if (sr & USART_SR_LBD)
144 flag = TTY_BREAK;
145 else if (sr & USART_SR_PE)
146 flag = TTY_PARITY;
147 else if (sr & USART_SR_FE)
148 flag = TTY_FRAME;
149 }
150
151 if (uart_handle_sysrq_char(port, c))
152 continue;
153 uart_insert_char(port, sr, USART_SR_ORE, c, flag);
154 }
155
156 spin_unlock(&port->lock);
157 tty_flip_buffer_push(tport);
158 spin_lock(&port->lock);
159}
160
161static void stm32_tx_dma_complete(void *arg)
162{
163 struct uart_port *port = arg;
164 struct stm32_port *stm32port = to_stm32_port(port);
165 struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
166 unsigned int isr;
167 int ret;
168
169 ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
170 isr,
171 (isr & USART_SR_TC),
172 10, 100000);
173
174 if (ret)
175 dev_err(port->dev, "terminal count not set\n");
176
177 if (ofs->icr == UNDEF_REG)
178 stm32_clr_bits(port, ofs->isr, USART_SR_TC);
179 else
180 stm32_set_bits(port, ofs->icr, USART_CR_TC);
181
182 stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
183 stm32port->tx_dma_busy = false;
184
185 /* Let's see if we have pending data to send */
186 stm32_transmit_chars(port);
187}
188
189static void stm32_transmit_chars_pio(struct uart_port *port)
190{
191 struct stm32_port *stm32_port = to_stm32_port(port);
192 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
193 struct circ_buf *xmit = &port->state->xmit;
194 unsigned int isr;
195 int ret;
196
197 if (stm32_port->tx_dma_busy) {
198 stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
199 stm32_port->tx_dma_busy = false;
200 }
201
202 ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
203 isr,
204 (isr & USART_SR_TXE),
205 10, 100);
206
207 if (ret)
208 dev_err(port->dev, "tx empty not set\n");
209
210 stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
211
212 writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr);
213 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
214 port->icount.tx++;
215}
216
217static void stm32_transmit_chars_dma(struct uart_port *port)
218{
219 struct stm32_port *stm32port = to_stm32_port(port);
220 struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
221 struct circ_buf *xmit = &port->state->xmit;
222 struct dma_async_tx_descriptor *desc = NULL;
223 dma_cookie_t cookie;
224 unsigned int count, i;
225
226 if (stm32port->tx_dma_busy)
227 return;
228
229 stm32port->tx_dma_busy = true;
230
231 count = uart_circ_chars_pending(xmit);
232
233 if (count > TX_BUF_L)
234 count = TX_BUF_L;
235
236 if (xmit->tail < xmit->head) {
237 memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], count);
238 } else {
239 size_t one = UART_XMIT_SIZE - xmit->tail;
240 size_t two;
241
242 if (one > count)
243 one = count;
244 two = count - one;
245
246 memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], one);
247 if (two)
248 memcpy(&stm32port->tx_buf[one], &xmit->buf[0], two);
249 }
250
251 desc = dmaengine_prep_slave_single(stm32port->tx_ch,
252 stm32port->tx_dma_buf,
253 count,
254 DMA_MEM_TO_DEV,
255 DMA_PREP_INTERRUPT);
256
257 if (!desc) {
258 for (i = count; i > 0; i--)
259 stm32_transmit_chars_pio(port);
260 return;
261 }
262
263 desc->callback = stm32_tx_dma_complete;
264 desc->callback_param = port;
265
266 /* Push current DMA TX transaction in the pending queue */
267 cookie = dmaengine_submit(desc);
268
269 /* Issue pending DMA TX requests */
270 dma_async_issue_pending(stm32port->tx_ch);
271
272 stm32_clr_bits(port, ofs->isr, USART_SR_TC);
273 stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT);
274
275 xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
276 port->icount.tx += count;
277}
278
279static void stm32_transmit_chars(struct uart_port *port)
280{
281 struct stm32_port *stm32_port = to_stm32_port(port);
282 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
283 struct circ_buf *xmit = &port->state->xmit;
284
285 if (port->x_char) {
286 if (stm32_port->tx_dma_busy)
287 stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
288 writel_relaxed(port->x_char, port->membase + ofs->tdr);
289 port->x_char = 0;
290 port->icount.tx++;
291 if (stm32_port->tx_dma_busy)
292 stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT);
293 return;
294 }
295
296 if (uart_tx_stopped(port)) {
297 stm32_stop_tx(port);
298 return;
299 }
300
301 if (uart_circ_empty(xmit)) {
302 stm32_stop_tx(port);
303 return;
304 }
305
306 if (stm32_port->tx_ch)
307 stm32_transmit_chars_dma(port);
308 else
309 stm32_transmit_chars_pio(port);
310
311 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
312 uart_write_wakeup(port);
313
314 if (uart_circ_empty(xmit))
315 stm32_stop_tx(port);
316}
317
318static irqreturn_t stm32_interrupt(int irq, void *ptr)
319{
320 struct uart_port *port = ptr;
321 struct stm32_port *stm32_port = to_stm32_port(port);
322 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
323 u32 sr;
324
325 spin_lock(&port->lock);
326
327 sr = readl_relaxed(port->membase + ofs->isr);
328
329 if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))
330 stm32_receive_chars(port, false);
331
332 if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch))
333 stm32_transmit_chars(port);
334
335 spin_unlock(&port->lock);
336
337 if (stm32_port->rx_ch)
338 return IRQ_WAKE_THREAD;
339 else
340 return IRQ_HANDLED;
341}
342
343static irqreturn_t stm32_threaded_interrupt(int irq, void *ptr)
344{
345 struct uart_port *port = ptr;
346 struct stm32_port *stm32_port = to_stm32_port(port);
347
348 spin_lock(&port->lock);
349
350 if (stm32_port->rx_ch)
351 stm32_receive_chars(port, true);
352
353 spin_unlock(&port->lock);
354
355 return IRQ_HANDLED;
356}
357
358static unsigned int stm32_tx_empty(struct uart_port *port)
359{
360 struct stm32_port *stm32_port = to_stm32_port(port);
361 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
362
363 return readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE;
364}
365
366static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl)
367{
368 struct stm32_port *stm32_port = to_stm32_port(port);
369 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
370
371 if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
372 stm32_set_bits(port, ofs->cr3, USART_CR3_RTSE);
373 else
374 stm32_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
375}
376
377static unsigned int stm32_get_mctrl(struct uart_port *port)
378{
379 /* This routine is used to get signals of: DCD, DSR, RI, and CTS */
380 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
381}
382
383/* Transmit stop */
384static void stm32_stop_tx(struct uart_port *port)
385{
386 struct stm32_port *stm32_port = to_stm32_port(port);
387 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
388
389 stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
390}
391
392/* There are probably characters waiting to be transmitted. */
393static void stm32_start_tx(struct uart_port *port)
394{
395 struct circ_buf *xmit = &port->state->xmit;
396
397 if (uart_circ_empty(xmit))
398 return;
399
400 stm32_transmit_chars(port);
401}
402
403/* Throttle the remote when input buffer is about to overflow. */
404static void stm32_throttle(struct uart_port *port)
405{
406 struct stm32_port *stm32_port = to_stm32_port(port);
407 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
408 unsigned long flags;
409
410 spin_lock_irqsave(&port->lock, flags);
411 stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
412 spin_unlock_irqrestore(&port->lock, flags);
413}
414
415/* Unthrottle the remote, the input buffer can now accept data. */
416static void stm32_unthrottle(struct uart_port *port)
417{
418 struct stm32_port *stm32_port = to_stm32_port(port);
419 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
420 unsigned long flags;
421
422 spin_lock_irqsave(&port->lock, flags);
423 stm32_set_bits(port, ofs->cr1, USART_CR1_RXNEIE);
424 spin_unlock_irqrestore(&port->lock, flags);
425}
426
427/* Receive stop */
428static void stm32_stop_rx(struct uart_port *port)
429{
430 struct stm32_port *stm32_port = to_stm32_port(port);
431 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
432
433 stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
434}
435
436/* Handle breaks - ignored by us */
437static void stm32_break_ctl(struct uart_port *port, int break_state)
438{
439}
440
441static int stm32_startup(struct uart_port *port)
442{
443 struct stm32_port *stm32_port = to_stm32_port(port);
444 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
445 const char *name = to_platform_device(port->dev)->name;
446 u32 val;
447 int ret;
448
449 ret = request_threaded_irq(port->irq, stm32_interrupt,
450 stm32_threaded_interrupt,
451 IRQF_NO_SUSPEND, name, port);
452 if (ret)
453 return ret;
454
455 val = USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
456 stm32_set_bits(port, ofs->cr1, val);
457
458 return 0;
459}
460
461static void stm32_shutdown(struct uart_port *port)
462{
463 struct stm32_port *stm32_port = to_stm32_port(port);
464 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
465 struct stm32_usart_config *cfg = &stm32_port->info->cfg;
466 u32 val;
467
468 val = USART_CR1_TXEIE | USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
469 val |= BIT(cfg->uart_enable_bit);
470 stm32_clr_bits(port, ofs->cr1, val);
471
472 free_irq(port->irq, port);
473}
474
475static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
476 struct ktermios *old)
477{
478 struct stm32_port *stm32_port = to_stm32_port(port);
479 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
480 struct stm32_usart_config *cfg = &stm32_port->info->cfg;
481 unsigned int baud;
482 u32 usartdiv, mantissa, fraction, oversampling;
483 tcflag_t cflag = termios->c_cflag;
484 u32 cr1, cr2, cr3;
485 unsigned long flags;
486
487 if (!stm32_port->hw_flow_control)
488 cflag &= ~CRTSCTS;
489
490 baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 8);
491
492 spin_lock_irqsave(&port->lock, flags);
493
494 /* Stop serial port and reset value */
495 writel_relaxed(0, port->membase + ofs->cr1);
496
497 cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE;
498 cr1 |= BIT(cfg->uart_enable_bit);
499 cr2 = 0;
500 cr3 = 0;
501
502 if (cflag & CSTOPB)
503 cr2 |= USART_CR2_STOP_2B;
504
505 if (cflag & PARENB) {
506 cr1 |= USART_CR1_PCE;
507 if ((cflag & CSIZE) == CS8) {
508 if (cfg->has_7bits_data)
509 cr1 |= USART_CR1_M0;
510 else
511 cr1 |= USART_CR1_M;
512 }
513 }
514
515 if (cflag & PARODD)
516 cr1 |= USART_CR1_PS;
517
518 port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS);
519 if (cflag & CRTSCTS) {
520 port->status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
521 cr3 |= USART_CR3_CTSE;
522 }
523
524 usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
525
526 /*
527 * The USART supports 16 or 8 times oversampling.
528 * By default we prefer 16 times oversampling, so that the receiver
529 * has a better tolerance to clock deviations.
530 * 8 times oversampling is only used to achieve higher speeds.
531 */
532 if (usartdiv < 16) {
533 oversampling = 8;
534 stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
535 } else {
536 oversampling = 16;
537 stm32_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
538 }
539
540 mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT;
541 fraction = usartdiv % oversampling;
542 writel_relaxed(mantissa | fraction, port->membase + ofs->brr);
543
544 uart_update_timeout(port, cflag, baud);
545
546 port->read_status_mask = USART_SR_ORE;
547 if (termios->c_iflag & INPCK)
548 port->read_status_mask |= USART_SR_PE | USART_SR_FE;
549 if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
550 port->read_status_mask |= USART_SR_LBD;
551
552 /* Characters to ignore */
553 port->ignore_status_mask = 0;
554 if (termios->c_iflag & IGNPAR)
555 port->ignore_status_mask = USART_SR_PE | USART_SR_FE;
556 if (termios->c_iflag & IGNBRK) {
557 port->ignore_status_mask |= USART_SR_LBD;
558 /*
559 * If we're ignoring parity and break indicators,
560 * ignore overruns too (for real raw support).
561 */
562 if (termios->c_iflag & IGNPAR)
563 port->ignore_status_mask |= USART_SR_ORE;
564 }
565
566 /* Ignore all characters if CREAD is not set */
567 if ((termios->c_cflag & CREAD) == 0)
568 port->ignore_status_mask |= USART_SR_DUMMY_RX;
569
570 if (stm32_port->rx_ch)
571 cr3 |= USART_CR3_DMAR;
572
573 writel_relaxed(cr3, port->membase + ofs->cr3);
574 writel_relaxed(cr2, port->membase + ofs->cr2);
575 writel_relaxed(cr1, port->membase + ofs->cr1);
576
577 spin_unlock_irqrestore(&port->lock, flags);
578}
579
580static const char *stm32_type(struct uart_port *port)
581{
582 return (port->type == PORT_STM32) ? DRIVER_NAME : NULL;
583}
584
585static void stm32_release_port(struct uart_port *port)
586{
587}
588
589static int stm32_request_port(struct uart_port *port)
590{
591 return 0;
592}
593
594static void stm32_config_port(struct uart_port *port, int flags)
595{
596 if (flags & UART_CONFIG_TYPE)
597 port->type = PORT_STM32;
598}
599
600static int
601stm32_verify_port(struct uart_port *port, struct serial_struct *ser)
602{
603 /* No user changeable parameters */
604 return -EINVAL;
605}
606
607static void stm32_pm(struct uart_port *port, unsigned int state,
608 unsigned int oldstate)
609{
610 struct stm32_port *stm32port = container_of(port,
611 struct stm32_port, port);
612 struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
613 struct stm32_usart_config *cfg = &stm32port->info->cfg;
614 unsigned long flags = 0;
615
616 switch (state) {
617 case UART_PM_STATE_ON:
618 clk_prepare_enable(stm32port->clk);
619 break;
620 case UART_PM_STATE_OFF:
621 spin_lock_irqsave(&port->lock, flags);
622 stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
623 spin_unlock_irqrestore(&port->lock, flags);
624 clk_disable_unprepare(stm32port->clk);
625 break;
626 }
627}
628
629static const struct uart_ops stm32_uart_ops = {
630 .tx_empty = stm32_tx_empty,
631 .set_mctrl = stm32_set_mctrl,
632 .get_mctrl = stm32_get_mctrl,
633 .stop_tx = stm32_stop_tx,
634 .start_tx = stm32_start_tx,
635 .throttle = stm32_throttle,
636 .unthrottle = stm32_unthrottle,
637 .stop_rx = stm32_stop_rx,
638 .break_ctl = stm32_break_ctl,
639 .startup = stm32_startup,
640 .shutdown = stm32_shutdown,
641 .set_termios = stm32_set_termios,
642 .pm = stm32_pm,
643 .type = stm32_type,
644 .release_port = stm32_release_port,
645 .request_port = stm32_request_port,
646 .config_port = stm32_config_port,
647 .verify_port = stm32_verify_port,
648};
649
650static int stm32_init_port(struct stm32_port *stm32port,
651 struct platform_device *pdev)
652{
653 struct uart_port *port = &stm32port->port;
654 struct resource *res;
655 int ret;
656
657 port->iotype = UPIO_MEM;
658 port->flags = UPF_BOOT_AUTOCONF;
659 port->ops = &stm32_uart_ops;
660 port->dev = &pdev->dev;
661 port->irq = platform_get_irq(pdev, 0);
662
663 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
664 port->membase = devm_ioremap_resource(&pdev->dev, res);
665 if (IS_ERR(port->membase))
666 return PTR_ERR(port->membase);
667 port->mapbase = res->start;
668
669 spin_lock_init(&port->lock);
670
671 stm32port->clk = devm_clk_get(&pdev->dev, NULL);
672 if (IS_ERR(stm32port->clk))
673 return PTR_ERR(stm32port->clk);
674
675 /* Ensure that clk rate is correct by enabling the clk */
676 ret = clk_prepare_enable(stm32port->clk);
677 if (ret)
678 return ret;
679
680 stm32port->port.uartclk = clk_get_rate(stm32port->clk);
681 if (!stm32port->port.uartclk)
682 ret = -EINVAL;
683
684 return ret;
685}
686
687static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
688{
689 struct device_node *np = pdev->dev.of_node;
690 int id;
691
692 if (!np)
693 return NULL;
694
695 id = of_alias_get_id(np, "serial");
696 if (id < 0)
697 id = 0;
698
699 if (WARN_ON(id >= STM32_MAX_PORTS))
700 return NULL;
701
702 stm32_ports[id].hw_flow_control = of_property_read_bool(np,
703 "st,hw-flow-ctrl");
704 stm32_ports[id].port.line = id;
705 return &stm32_ports[id];
706}
707
708#ifdef CONFIG_OF
709static const struct of_device_id stm32_match[] = {
710 { .compatible = "st,stm32-usart", .data = &stm32f4_info},
711 { .compatible = "st,stm32-uart", .data = &stm32f4_info},
712 { .compatible = "st,stm32f7-usart", .data = &stm32f7_info},
713 { .compatible = "st,stm32f7-uart", .data = &stm32f7_info},
714 {},
715};
716
717MODULE_DEVICE_TABLE(of, stm32_match);
718#endif
719
720static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
721 struct platform_device *pdev)
722{
723 struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
724 struct uart_port *port = &stm32port->port;
725 struct device *dev = &pdev->dev;
726 struct dma_slave_config config;
727 struct dma_async_tx_descriptor *desc = NULL;
728 dma_cookie_t cookie;
729 int ret;
730
731 /* Request DMA RX channel */
732 stm32port->rx_ch = dma_request_slave_channel(dev, "rx");
733 if (!stm32port->rx_ch) {
734 dev_info(dev, "rx dma alloc failed\n");
735 return -ENODEV;
736 }
737 stm32port->rx_buf = dma_alloc_coherent(&pdev->dev, RX_BUF_L,
738 &stm32port->rx_dma_buf,
739 GFP_KERNEL);
740 if (!stm32port->rx_buf) {
741 ret = -ENOMEM;
742 goto alloc_err;
743 }
744
745 /* Configure DMA channel */
746 memset(&config, 0, sizeof(config));
747 config.src_addr = port->mapbase + ofs->rdr;
748 config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
749
750 ret = dmaengine_slave_config(stm32port->rx_ch, &config);
751 if (ret < 0) {
752 dev_err(dev, "rx dma channel config failed\n");
753 ret = -ENODEV;
754 goto config_err;
755 }
756
757 /* Prepare a DMA cyclic transaction */
758 desc = dmaengine_prep_dma_cyclic(stm32port->rx_ch,
759 stm32port->rx_dma_buf,
760 RX_BUF_L, RX_BUF_P, DMA_DEV_TO_MEM,
761 DMA_PREP_INTERRUPT);
762 if (!desc) {
763 dev_err(dev, "rx dma prep cyclic failed\n");
764 ret = -ENODEV;
765 goto config_err;
766 }
767
768 /* No callback as dma buffer is drained on usart interrupt */
769 desc->callback = NULL;
770 desc->callback_param = NULL;
771
772 /* Push current DMA transaction in the pending queue */
773 cookie = dmaengine_submit(desc);
774
775 /* Issue pending DMA requests */
776 dma_async_issue_pending(stm32port->rx_ch);
777
778 return 0;
779
780config_err:
781 dma_free_coherent(&pdev->dev,
782 RX_BUF_L, stm32port->rx_buf,
783 stm32port->rx_dma_buf);
784
785alloc_err:
786 dma_release_channel(stm32port->rx_ch);
787 stm32port->rx_ch = NULL;
788
789 return ret;
790}
791
792static int stm32_of_dma_tx_probe(struct stm32_port *stm32port,
793 struct platform_device *pdev)
794{
795 struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
796 struct uart_port *port = &stm32port->port;
797 struct device *dev = &pdev->dev;
798 struct dma_slave_config config;
799 int ret;
800
801 stm32port->tx_dma_busy = false;
802
803 /* Request DMA TX channel */
804 stm32port->tx_ch = dma_request_slave_channel(dev, "tx");
805 if (!stm32port->tx_ch) {
806 dev_info(dev, "tx dma alloc failed\n");
807 return -ENODEV;
808 }
809 stm32port->tx_buf = dma_alloc_coherent(&pdev->dev, TX_BUF_L,
810 &stm32port->tx_dma_buf,
811 GFP_KERNEL);
812 if (!stm32port->tx_buf) {
813 ret = -ENOMEM;
814 goto alloc_err;
815 }
816
817 /* Configure DMA channel */
818 memset(&config, 0, sizeof(config));
819 config.dst_addr = port->mapbase + ofs->tdr;
820 config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
821
822 ret = dmaengine_slave_config(stm32port->tx_ch, &config);
823 if (ret < 0) {
824 dev_err(dev, "tx dma channel config failed\n");
825 ret = -ENODEV;
826 goto config_err;
827 }
828
829 return 0;
830
831config_err:
832 dma_free_coherent(&pdev->dev,
833 TX_BUF_L, stm32port->tx_buf,
834 stm32port->tx_dma_buf);
835
836alloc_err:
837 dma_release_channel(stm32port->tx_ch);
838 stm32port->tx_ch = NULL;
839
840 return ret;
841}
842
843static int stm32_serial_probe(struct platform_device *pdev)
844{
845 const struct of_device_id *match;
846 struct stm32_port *stm32port;
847 int ret;
848
849 stm32port = stm32_of_get_stm32_port(pdev);
850 if (!stm32port)
851 return -ENODEV;
852
853 match = of_match_device(stm32_match, &pdev->dev);
854 if (match && match->data)
855 stm32port->info = (struct stm32_usart_info *)match->data;
856 else
857 return -EINVAL;
858
859 ret = stm32_init_port(stm32port, pdev);
860 if (ret)
861 return ret;
862
863 ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
864 if (ret)
865 return ret;
866
867 ret = stm32_of_dma_rx_probe(stm32port, pdev);
868 if (ret)
869 dev_info(&pdev->dev, "interrupt mode used for rx (no dma)\n");
870
871 ret = stm32_of_dma_tx_probe(stm32port, pdev);
872 if (ret)
873 dev_info(&pdev->dev, "interrupt mode used for tx (no dma)\n");
874
875 platform_set_drvdata(pdev, &stm32port->port);
876
877 return 0;
878}
879
880static int stm32_serial_remove(struct platform_device *pdev)
881{
882 struct uart_port *port = platform_get_drvdata(pdev);
883 struct stm32_port *stm32_port = to_stm32_port(port);
884 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
885
886 stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
887
888 if (stm32_port->rx_ch)
889 dma_release_channel(stm32_port->rx_ch);
890
891 if (stm32_port->rx_dma_buf)
892 dma_free_coherent(&pdev->dev,
893 RX_BUF_L, stm32_port->rx_buf,
894 stm32_port->rx_dma_buf);
895
896 stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
897
898 if (stm32_port->tx_ch)
899 dma_release_channel(stm32_port->tx_ch);
900
901 if (stm32_port->tx_dma_buf)
902 dma_free_coherent(&pdev->dev,
903 TX_BUF_L, stm32_port->tx_buf,
904 stm32_port->tx_dma_buf);
905
906 clk_disable_unprepare(stm32_port->clk);
907
908 return uart_remove_one_port(&stm32_usart_driver, port);
909}
910
911
912#ifdef CONFIG_SERIAL_STM32_CONSOLE
913static void stm32_console_putchar(struct uart_port *port, int ch)
914{
915 struct stm32_port *stm32_port = to_stm32_port(port);
916 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
917
918 while (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE))
919 cpu_relax();
920
921 writel_relaxed(ch, port->membase + ofs->tdr);
922}
923
924static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
925{
926 struct uart_port *port = &stm32_ports[co->index].port;
927 struct stm32_port *stm32_port = to_stm32_port(port);
928 struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
929 struct stm32_usart_config *cfg = &stm32_port->info->cfg;
930 unsigned long flags;
931 u32 old_cr1, new_cr1;
932 int locked = 1;
933
934 local_irq_save(flags);
935 if (port->sysrq)
936 locked = 0;
937 else if (oops_in_progress)
938 locked = spin_trylock(&port->lock);
939 else
940 spin_lock(&port->lock);
941
942 /* Save and disable interrupts, enable the transmitter */
943 old_cr1 = readl_relaxed(port->membase + ofs->cr1);
944 new_cr1 = old_cr1 & ~USART_CR1_IE_MASK;
945 new_cr1 |= USART_CR1_TE | BIT(cfg->uart_enable_bit);
946 writel_relaxed(new_cr1, port->membase + ofs->cr1);
947
948 uart_console_write(port, s, cnt, stm32_console_putchar);
949
950 /* Restore interrupt state */
951 writel_relaxed(old_cr1, port->membase + ofs->cr1);
952
953 if (locked)
954 spin_unlock(&port->lock);
955 local_irq_restore(flags);
956}
957
958static int stm32_console_setup(struct console *co, char *options)
959{
960 struct stm32_port *stm32port;
961 int baud = 9600;
962 int bits = 8;
963 int parity = 'n';
964 int flow = 'n';
965
966 if (co->index >= STM32_MAX_PORTS)
967 return -ENODEV;
968
969 stm32port = &stm32_ports[co->index];
970
971 /*
972 * This driver does not support early console initialization
973 * (use ARM early printk support instead), so we only expect
974 * this to be called during the uart port registration when the
975 * driver gets probed and the port should be mapped at that point.
976 */
977 if (stm32port->port.mapbase == 0 || stm32port->port.membase == NULL)
978 return -ENXIO;
979
980 if (options)
981 uart_parse_options(options, &baud, &parity, &bits, &flow);
982
983 return uart_set_options(&stm32port->port, co, baud, parity, bits, flow);
984}
985
986static struct console stm32_console = {
987 .name = STM32_SERIAL_NAME,
988 .device = uart_console_device,
989 .write = stm32_console_write,
990 .setup = stm32_console_setup,
991 .flags = CON_PRINTBUFFER,
992 .index = -1,
993 .data = &stm32_usart_driver,
994};
995
996#define STM32_SERIAL_CONSOLE (&stm32_console)
997
998#else
999#define STM32_SERIAL_CONSOLE NULL
1000#endif /* CONFIG_SERIAL_STM32_CONSOLE */
1001
1002static struct uart_driver stm32_usart_driver = {
1003 .driver_name = DRIVER_NAME,
1004 .dev_name = STM32_SERIAL_NAME,
1005 .major = 0,
1006 .minor = 0,
1007 .nr = STM32_MAX_PORTS,
1008 .cons = STM32_SERIAL_CONSOLE,
1009};
1010
1011static struct platform_driver stm32_serial_driver = {
1012 .probe = stm32_serial_probe,
1013 .remove = stm32_serial_remove,
1014 .driver = {
1015 .name = DRIVER_NAME,
1016 .of_match_table = of_match_ptr(stm32_match),
1017 },
1018};
1019
1020static int __init usart_init(void)
1021{
1022 static char banner[] __initdata = "STM32 USART driver initialized";
1023 int ret;
1024
1025 pr_info("%s\n", banner);
1026
1027 ret = uart_register_driver(&stm32_usart_driver);
1028 if (ret)
1029 return ret;
1030
1031 ret = platform_driver_register(&stm32_serial_driver);
1032 if (ret)
1033 uart_unregister_driver(&stm32_usart_driver);
1034
1035 return ret;
1036}
1037
1038static void __exit usart_exit(void)
1039{
1040 platform_driver_unregister(&stm32_serial_driver);
1041 uart_unregister_driver(&stm32_usart_driver);
1042}
1043
1044module_init(usart_init);
1045module_exit(usart_exit);
1046
1047MODULE_ALIAS("platform:" DRIVER_NAME);
1048MODULE_DESCRIPTION("STMicroelectronics STM32 serial port driver");
1049MODULE_LICENSE("GPL v2");