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 
35 struct 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 
45 static struct asc_port asc_ports[ASC_MAX_PORTS];
46 static 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 
to_asc_port(struct uart_port * port)146 static inline struct asc_port *to_asc_port(struct uart_port *port)
147 {
148 	return container_of(port, struct asc_port, port);
149 }
150 
asc_in(struct uart_port * port,u32 offset)151 static 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 
asc_out(struct uart_port * port,u32 offset,u32 value)160 static 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  */
asc_disable_tx_interrupts(struct uart_port * port)173 static 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 
asc_enable_tx_interrupts(struct uart_port * port)180 static 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 
asc_disable_rx_interrupts(struct uart_port * port)186 static 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 
asc_enable_rx_interrupts(struct uart_port * port)193 static 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 
asc_txfifo_is_empty(struct uart_port * port)199 static inline u32 asc_txfifo_is_empty(struct uart_port *port)
200 {
201 	return asc_in(port, ASC_STA) & ASC_STA_TE;
202 }
203 
asc_txfifo_is_half_empty(struct uart_port * port)204 static inline u32 asc_txfifo_is_half_empty(struct uart_port *port)
205 {
206 	return asc_in(port, ASC_STA) & ASC_STA_THE;
207 }
208 
asc_port_name(struct uart_port * port)209 static 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 
asc_hw_txroom(struct uart_port * port)221 static 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  */
asc_transmit_chars(struct uart_port * port)238 static 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 
asc_receive_chars(struct uart_port * port)248 static 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 
asc_interrupt(int irq,void * ptr)317 static irqreturn_t asc_interrupt(int irq, void *ptr)
318 {
319 	struct uart_port *port = ptr;
320 	u32 status;
321 
322 	spin_lock(&port->lock);
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 	spin_unlock(&port->lock);
338 
339 	return IRQ_HANDLED;
340 }
341 
342 /*----------------------------------------------------------------------*/
343 
344 /*
345  * UART Functions
346  */
347 
asc_tx_empty(struct uart_port * port)348 static unsigned int asc_tx_empty(struct uart_port *port)
349 {
350 	return asc_txfifo_is_empty(port) ? TIOCSER_TEMT : 0;
351 }
352 
asc_set_mctrl(struct uart_port * port,unsigned int mctrl)353 static 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 
asc_get_mctrl(struct uart_port * port)378 static 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. */
asc_start_tx(struct uart_port * port)388 static 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 */
asc_stop_tx(struct uart_port * port)397 static void asc_stop_tx(struct uart_port *port)
398 {
399 	asc_disable_tx_interrupts(port);
400 }
401 
402 /* Receive stop */
asc_stop_rx(struct uart_port * port)403 static void asc_stop_rx(struct uart_port *port)
404 {
405 	asc_disable_rx_interrupts(port);
406 }
407 
408 /* Handle breaks - ignored by us */
asc_break_ctl(struct uart_port * port,int break_state)409 static 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  */
asc_startup(struct uart_port * port)417 static 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 
asc_shutdown(struct uart_port * port)431 static 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 
asc_pm(struct uart_port * port,unsigned int state,unsigned int oldstate)438 static 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 		spin_lock_irqsave(&port->lock, flags);
456 		ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
457 		asc_out(port, ASC_CTL, ctl);
458 		spin_unlock_irqrestore(&port->lock, flags);
459 		clk_disable_unprepare(ascport->clk);
460 		break;
461 	}
462 }
463 
asc_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old)464 static 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 	spin_lock_irqsave(&port->lock, 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 	spin_unlock_irqrestore(&port->lock, flags);
598 }
599 
asc_type(struct uart_port * port)600 static const char *asc_type(struct uart_port *port)
601 {
602 	return (port->type == PORT_ASC) ? DRIVER_NAME : NULL;
603 }
604 
asc_release_port(struct uart_port * port)605 static void asc_release_port(struct uart_port *port)
606 {
607 }
608 
asc_request_port(struct uart_port * port)609 static 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  */
asc_config_port(struct uart_port * port,int flags)618 static void asc_config_port(struct uart_port *port, int flags)
619 {
620 	if ((flags & UART_CONFIG_TYPE))
621 		port->type = PORT_ASC;
622 }
623 
624 static int
asc_verify_port(struct uart_port * port,struct serial_struct * ser)625 asc_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 
asc_get_poll_char(struct uart_port * port)637 static 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 
asc_put_poll_char(struct uart_port * port,unsigned char c)645 static 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 
656 static 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 
asc_init_port(struct asc_port * ascport,struct platform_device * pdev)679 static 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 
asc_of_get_asc_port(struct platform_device * pdev)738 static 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
766 static const struct of_device_id asc_match[] = {
767 	{ .compatible = "st,asc", },
768 	{},
769 };
770 
771 MODULE_DEVICE_TABLE(of, asc_match);
772 #endif
773 
asc_serial_probe(struct platform_device * pdev)774 static 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 
asc_serial_remove(struct platform_device * pdev)796 static int 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 	return 0;
803 }
804 
805 #ifdef CONFIG_PM_SLEEP
asc_serial_suspend(struct device * dev)806 static int asc_serial_suspend(struct device *dev)
807 {
808 	struct uart_port *port = dev_get_drvdata(dev);
809 
810 	return uart_suspend_port(&asc_uart_driver, port);
811 }
812 
asc_serial_resume(struct device * dev)813 static int asc_serial_resume(struct device *dev)
814 {
815 	struct uart_port *port = dev_get_drvdata(dev);
816 
817 	return uart_resume_port(&asc_uart_driver, port);
818 }
819 
820 #endif /* CONFIG_PM_SLEEP */
821 
822 /*----------------------------------------------------------------------*/
823 
824 #ifdef CONFIG_SERIAL_ST_ASC_CONSOLE
asc_console_putchar(struct uart_port * port,unsigned char ch)825 static void asc_console_putchar(struct uart_port *port, unsigned char ch)
826 {
827 	unsigned int timeout = 1000000;
828 
829 	/* Wait for upto 1 second in case flow control is stopping us. */
830 	while (--timeout && !asc_txfifo_is_half_empty(port))
831 		udelay(1);
832 
833 	asc_out(port, ASC_TXBUF, ch);
834 }
835 
836 /*
837  *  Print a string to the serial port trying not to disturb
838  *  any possible real use of the port...
839  */
840 
asc_console_write(struct console * co,const char * s,unsigned count)841 static void asc_console_write(struct console *co, const char *s, unsigned count)
842 {
843 	struct uart_port *port = &asc_ports[co->index].port;
844 	unsigned long flags;
845 	unsigned long timeout = 1000000;
846 	int locked = 1;
847 	u32 intenable;
848 
849 	if (port->sysrq)
850 		locked = 0; /* asc_interrupt has already claimed the lock */
851 	else if (oops_in_progress)
852 		locked = spin_trylock_irqsave(&port->lock, flags);
853 	else
854 		spin_lock_irqsave(&port->lock, flags);
855 
856 	/*
857 	 * Disable interrupts so we don't get the IRQ line bouncing
858 	 * up and down while interrupts are disabled.
859 	 */
860 	intenable = asc_in(port, ASC_INTEN);
861 	asc_out(port, ASC_INTEN, 0);
862 	(void)asc_in(port, ASC_INTEN);	/* Defeat bus write posting */
863 
864 	uart_console_write(port, s, count, asc_console_putchar);
865 
866 	while (--timeout && !asc_txfifo_is_empty(port))
867 		udelay(1);
868 
869 	asc_out(port, ASC_INTEN, intenable);
870 
871 	if (locked)
872 		spin_unlock_irqrestore(&port->lock, flags);
873 }
874 
asc_console_setup(struct console * co,char * options)875 static int asc_console_setup(struct console *co, char *options)
876 {
877 	struct asc_port *ascport;
878 	int baud = 115200;
879 	int bits = 8;
880 	int parity = 'n';
881 	int flow = 'n';
882 
883 	if (co->index >= ASC_MAX_PORTS)
884 		return -ENODEV;
885 
886 	ascport = &asc_ports[co->index];
887 
888 	/*
889 	 * This driver does not support early console initialization
890 	 * (use ARM early printk support instead), so we only expect
891 	 * this to be called during the uart port registration when the
892 	 * driver gets probed and the port should be mapped at that point.
893 	 */
894 	if (ascport->port.mapbase == 0 || ascport->port.membase == NULL)
895 		return -ENXIO;
896 
897 	if (options)
898 		uart_parse_options(options, &baud, &parity, &bits, &flow);
899 
900 	return uart_set_options(&ascport->port, co, baud, parity, bits, flow);
901 }
902 
903 static struct console asc_console = {
904 	.name		= ASC_SERIAL_NAME,
905 	.device		= uart_console_device,
906 	.write		= asc_console_write,
907 	.setup		= asc_console_setup,
908 	.flags		= CON_PRINTBUFFER,
909 	.index		= -1,
910 	.data		= &asc_uart_driver,
911 };
912 
913 #define ASC_SERIAL_CONSOLE (&asc_console)
914 
915 #else
916 #define ASC_SERIAL_CONSOLE NULL
917 #endif /* CONFIG_SERIAL_ST_ASC_CONSOLE */
918 
919 static struct uart_driver asc_uart_driver = {
920 	.owner		= THIS_MODULE,
921 	.driver_name	= DRIVER_NAME,
922 	.dev_name	= ASC_SERIAL_NAME,
923 	.major		= 0,
924 	.minor		= 0,
925 	.nr		= ASC_MAX_PORTS,
926 	.cons		= ASC_SERIAL_CONSOLE,
927 };
928 
929 static const struct dev_pm_ops asc_serial_pm_ops = {
930 	SET_SYSTEM_SLEEP_PM_OPS(asc_serial_suspend, asc_serial_resume)
931 };
932 
933 static struct platform_driver asc_serial_driver = {
934 	.probe		= asc_serial_probe,
935 	.remove		= asc_serial_remove,
936 	.driver	= {
937 		.name	= DRIVER_NAME,
938 		.pm	= &asc_serial_pm_ops,
939 		.of_match_table = of_match_ptr(asc_match),
940 	},
941 };
942 
asc_init(void)943 static int __init asc_init(void)
944 {
945 	int ret;
946 	static const char banner[] __initconst =
947 		KERN_INFO "STMicroelectronics ASC driver initialized\n";
948 
949 	printk(banner);
950 
951 	ret = uart_register_driver(&asc_uart_driver);
952 	if (ret)
953 		return ret;
954 
955 	ret = platform_driver_register(&asc_serial_driver);
956 	if (ret)
957 		uart_unregister_driver(&asc_uart_driver);
958 
959 	return ret;
960 }
961 
asc_exit(void)962 static void __exit asc_exit(void)
963 {
964 	platform_driver_unregister(&asc_serial_driver);
965 	uart_unregister_driver(&asc_uart_driver);
966 }
967 
968 module_init(asc_init);
969 module_exit(asc_exit);
970 
971 MODULE_ALIAS("platform:" DRIVER_NAME);
972 MODULE_AUTHOR("STMicroelectronics (R&D) Limited");
973 MODULE_DESCRIPTION("STMicroelectronics ASC serial port driver");
974 MODULE_LICENSE("GPL");
975