xref: /linux/drivers/tty/serial/clps711x.c (revision e0bf6c5ca2d3281f231c5f0c9bf145e9513644de) 
1 /*
2  *  Driver for CLPS711x serial ports
3  *
4  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
5  *
6  *  Copyright 1999 ARM Limited
7  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  */
14 
15 #if defined(CONFIG_SERIAL_CLPS711X_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
16 #define SUPPORT_SYSRQ
17 #endif
18 
19 #include <linux/module.h>
20 #include <linux/device.h>
21 #include <linux/console.h>
22 #include <linux/serial_core.h>
23 #include <linux/serial.h>
24 #include <linux/clk.h>
25 #include <linux/io.h>
26 #include <linux/tty.h>
27 #include <linux/tty_flip.h>
28 #include <linux/ioport.h>
29 #include <linux/of.h>
30 #include <linux/platform_device.h>
31 #include <linux/regmap.h>
32 
33 #include <linux/mfd/syscon.h>
34 #include <linux/mfd/syscon/clps711x.h>
35 
36 #include "serial_mctrl_gpio.h"
37 
38 #define UART_CLPS711X_DEVNAME	"ttyCL"
39 #define UART_CLPS711X_NR	2
40 #define UART_CLPS711X_MAJOR	204
41 #define UART_CLPS711X_MINOR	40
42 
43 #define UARTDR_OFFSET		(0x00)
44 #define UBRLCR_OFFSET		(0x40)
45 
46 #define UARTDR_FRMERR		(1 << 8)
47 #define UARTDR_PARERR		(1 << 9)
48 #define UARTDR_OVERR		(1 << 10)
49 
50 #define UBRLCR_BAUD_MASK	((1 << 12) - 1)
51 #define UBRLCR_BREAK		(1 << 12)
52 #define UBRLCR_PRTEN		(1 << 13)
53 #define UBRLCR_EVENPRT		(1 << 14)
54 #define UBRLCR_XSTOP		(1 << 15)
55 #define UBRLCR_FIFOEN		(1 << 16)
56 #define UBRLCR_WRDLEN5		(0 << 17)
57 #define UBRLCR_WRDLEN6		(1 << 17)
58 #define UBRLCR_WRDLEN7		(2 << 17)
59 #define UBRLCR_WRDLEN8		(3 << 17)
60 #define UBRLCR_WRDLEN_MASK	(3 << 17)
61 
62 struct clps711x_port {
63 	struct uart_port	port;
64 	unsigned int		tx_enabled;
65 	int			rx_irq;
66 	struct regmap		*syscon;
67 	struct mctrl_gpios	*gpios;
68 };
69 
70 static struct uart_driver clps711x_uart = {
71 	.owner		= THIS_MODULE,
72 	.driver_name	= UART_CLPS711X_DEVNAME,
73 	.dev_name	= UART_CLPS711X_DEVNAME,
74 	.major		= UART_CLPS711X_MAJOR,
75 	.minor		= UART_CLPS711X_MINOR,
76 	.nr		= UART_CLPS711X_NR,
77 };
78 
79 static void uart_clps711x_stop_tx(struct uart_port *port)
80 {
81 	struct clps711x_port *s = dev_get_drvdata(port->dev);
82 
83 	if (s->tx_enabled) {
84 		disable_irq(port->irq);
85 		s->tx_enabled = 0;
86 	}
87 }
88 
89 static void uart_clps711x_start_tx(struct uart_port *port)
90 {
91 	struct clps711x_port *s = dev_get_drvdata(port->dev);
92 
93 	if (!s->tx_enabled) {
94 		s->tx_enabled = 1;
95 		enable_irq(port->irq);
96 	}
97 }
98 
99 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
100 {
101 	struct uart_port *port = dev_id;
102 	struct clps711x_port *s = dev_get_drvdata(port->dev);
103 	unsigned int status, flg;
104 	u16 ch;
105 
106 	for (;;) {
107 		u32 sysflg = 0;
108 
109 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
110 		if (sysflg & SYSFLG_URXFE)
111 			break;
112 
113 		ch = readw(port->membase + UARTDR_OFFSET);
114 		status = ch & (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR);
115 		ch &= 0xff;
116 
117 		port->icount.rx++;
118 		flg = TTY_NORMAL;
119 
120 		if (unlikely(status)) {
121 			if (status & UARTDR_PARERR)
122 				port->icount.parity++;
123 			else if (status & UARTDR_FRMERR)
124 				port->icount.frame++;
125 			else if (status & UARTDR_OVERR)
126 				port->icount.overrun++;
127 
128 			status &= port->read_status_mask;
129 
130 			if (status & UARTDR_PARERR)
131 				flg = TTY_PARITY;
132 			else if (status & UARTDR_FRMERR)
133 				flg = TTY_FRAME;
134 			else if (status & UARTDR_OVERR)
135 				flg = TTY_OVERRUN;
136 		}
137 
138 		if (uart_handle_sysrq_char(port, ch))
139 			continue;
140 
141 		if (status & port->ignore_status_mask)
142 			continue;
143 
144 		uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
145 	}
146 
147 	tty_flip_buffer_push(&port->state->port);
148 
149 	return IRQ_HANDLED;
150 }
151 
152 static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
153 {
154 	struct uart_port *port = dev_id;
155 	struct clps711x_port *s = dev_get_drvdata(port->dev);
156 	struct circ_buf *xmit = &port->state->xmit;
157 
158 	if (port->x_char) {
159 		writew(port->x_char, port->membase + UARTDR_OFFSET);
160 		port->icount.tx++;
161 		port->x_char = 0;
162 		return IRQ_HANDLED;
163 	}
164 
165 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
166 		if (s->tx_enabled) {
167 			disable_irq_nosync(port->irq);
168 			s->tx_enabled = 0;
169 		}
170 		return IRQ_HANDLED;
171 	}
172 
173 	while (!uart_circ_empty(xmit)) {
174 		u32 sysflg = 0;
175 
176 		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
177 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
178 		port->icount.tx++;
179 
180 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
181 		if (sysflg & SYSFLG_UTXFF)
182 			break;
183 	}
184 
185 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
186 		uart_write_wakeup(port);
187 
188 	return IRQ_HANDLED;
189 }
190 
191 static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
192 {
193 	struct clps711x_port *s = dev_get_drvdata(port->dev);
194 	u32 sysflg = 0;
195 
196 	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
197 
198 	return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
199 }
200 
201 static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
202 {
203 	unsigned int result = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;
204 	struct clps711x_port *s = dev_get_drvdata(port->dev);
205 
206 	return mctrl_gpio_get(s->gpios, &result);
207 }
208 
209 static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
210 {
211 	struct clps711x_port *s = dev_get_drvdata(port->dev);
212 
213 	mctrl_gpio_set(s->gpios, mctrl);
214 }
215 
216 static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
217 {
218 	unsigned int ubrlcr;
219 
220 	ubrlcr = readl(port->membase + UBRLCR_OFFSET);
221 	if (break_state)
222 		ubrlcr |= UBRLCR_BREAK;
223 	else
224 		ubrlcr &= ~UBRLCR_BREAK;
225 	writel(ubrlcr, port->membase + UBRLCR_OFFSET);
226 }
227 
228 static void uart_clps711x_set_ldisc(struct uart_port *port,
229 				    struct ktermios *termios)
230 {
231 	if (!port->line) {
232 		struct clps711x_port *s = dev_get_drvdata(port->dev);
233 
234 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
235 				   (termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
236 	}
237 }
238 
239 static int uart_clps711x_startup(struct uart_port *port)
240 {
241 	struct clps711x_port *s = dev_get_drvdata(port->dev);
242 
243 	/* Disable break */
244 	writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
245 	       port->membase + UBRLCR_OFFSET);
246 
247 	/* Enable the port */
248 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
249 				  SYSCON_UARTEN, SYSCON_UARTEN);
250 }
251 
252 static void uart_clps711x_shutdown(struct uart_port *port)
253 {
254 	struct clps711x_port *s = dev_get_drvdata(port->dev);
255 
256 	/* Disable the port */
257 	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
258 }
259 
260 static void uart_clps711x_set_termios(struct uart_port *port,
261 				      struct ktermios *termios,
262 				      struct ktermios *old)
263 {
264 	u32 ubrlcr;
265 	unsigned int baud, quot;
266 
267 	/* Mask termios capabilities we don't support */
268 	termios->c_cflag &= ~CMSPAR;
269 	termios->c_iflag &= ~(BRKINT | IGNBRK);
270 
271 	/* Ask the core to calculate the divisor for us */
272 	baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
273 						      port->uartclk / 16);
274 	quot = uart_get_divisor(port, baud);
275 
276 	switch (termios->c_cflag & CSIZE) {
277 	case CS5:
278 		ubrlcr = UBRLCR_WRDLEN5;
279 		break;
280 	case CS6:
281 		ubrlcr = UBRLCR_WRDLEN6;
282 		break;
283 	case CS7:
284 		ubrlcr = UBRLCR_WRDLEN7;
285 		break;
286 	case CS8:
287 	default:
288 		ubrlcr = UBRLCR_WRDLEN8;
289 		break;
290 	}
291 
292 	if (termios->c_cflag & CSTOPB)
293 		ubrlcr |= UBRLCR_XSTOP;
294 
295 	if (termios->c_cflag & PARENB) {
296 		ubrlcr |= UBRLCR_PRTEN;
297 		if (!(termios->c_cflag & PARODD))
298 			ubrlcr |= UBRLCR_EVENPRT;
299 	}
300 
301 	/* Enable FIFO */
302 	ubrlcr |= UBRLCR_FIFOEN;
303 
304 	/* Set read status mask */
305 	port->read_status_mask = UARTDR_OVERR;
306 	if (termios->c_iflag & INPCK)
307 		port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;
308 
309 	/* Set status ignore mask */
310 	port->ignore_status_mask = 0;
311 	if (!(termios->c_cflag & CREAD))
312 		port->ignore_status_mask |= UARTDR_OVERR | UARTDR_PARERR |
313 					    UARTDR_FRMERR;
314 
315 	uart_update_timeout(port, termios->c_cflag, baud);
316 
317 	writel(ubrlcr | (quot - 1), port->membase + UBRLCR_OFFSET);
318 }
319 
320 static const char *uart_clps711x_type(struct uart_port *port)
321 {
322 	return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
323 }
324 
325 static void uart_clps711x_config_port(struct uart_port *port, int flags)
326 {
327 	if (flags & UART_CONFIG_TYPE)
328 		port->type = PORT_CLPS711X;
329 }
330 
331 static void uart_clps711x_nop_void(struct uart_port *port)
332 {
333 }
334 
335 static int uart_clps711x_nop_int(struct uart_port *port)
336 {
337 	return 0;
338 }
339 
340 static const struct uart_ops uart_clps711x_ops = {
341 	.tx_empty	= uart_clps711x_tx_empty,
342 	.set_mctrl	= uart_clps711x_set_mctrl,
343 	.get_mctrl	= uart_clps711x_get_mctrl,
344 	.stop_tx	= uart_clps711x_stop_tx,
345 	.start_tx	= uart_clps711x_start_tx,
346 	.stop_rx	= uart_clps711x_nop_void,
347 	.break_ctl	= uart_clps711x_break_ctl,
348 	.set_ldisc	= uart_clps711x_set_ldisc,
349 	.startup	= uart_clps711x_startup,
350 	.shutdown	= uart_clps711x_shutdown,
351 	.set_termios	= uart_clps711x_set_termios,
352 	.type		= uart_clps711x_type,
353 	.config_port	= uart_clps711x_config_port,
354 	.release_port	= uart_clps711x_nop_void,
355 	.request_port	= uart_clps711x_nop_int,
356 };
357 
358 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
359 static void uart_clps711x_console_putchar(struct uart_port *port, int ch)
360 {
361 	struct clps711x_port *s = dev_get_drvdata(port->dev);
362 	u32 sysflg = 0;
363 
364 	/* Wait for FIFO is not full */
365 	do {
366 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
367 	} while (sysflg & SYSFLG_UTXFF);
368 
369 	writew(ch, port->membase + UARTDR_OFFSET);
370 }
371 
372 static void uart_clps711x_console_write(struct console *co, const char *c,
373 					unsigned n)
374 {
375 	struct uart_port *port = clps711x_uart.state[co->index].uart_port;
376 	struct clps711x_port *s = dev_get_drvdata(port->dev);
377 	u32 sysflg = 0;
378 
379 	uart_console_write(port, c, n, uart_clps711x_console_putchar);
380 
381 	/* Wait for transmitter to become empty */
382 	do {
383 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
384 	} while (sysflg & SYSFLG_UBUSY);
385 }
386 
387 static int uart_clps711x_console_setup(struct console *co, char *options)
388 {
389 	int baud = 38400, bits = 8, parity = 'n', flow = 'n';
390 	int ret, index = co->index;
391 	struct clps711x_port *s;
392 	struct uart_port *port;
393 	unsigned int quot;
394 	u32 ubrlcr;
395 
396 	if (index < 0 || index >= UART_CLPS711X_NR)
397 		return -EINVAL;
398 
399 	port = clps711x_uart.state[index].uart_port;
400 	if (!port)
401 		return -ENODEV;
402 
403 	s = dev_get_drvdata(port->dev);
404 
405 	if (!options) {
406 		u32 syscon = 0;
407 
408 		regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
409 		if (syscon & SYSCON_UARTEN) {
410 			ubrlcr = readl(port->membase + UBRLCR_OFFSET);
411 
412 			if (ubrlcr & UBRLCR_PRTEN) {
413 				if (ubrlcr & UBRLCR_EVENPRT)
414 					parity = 'e';
415 				else
416 					parity = 'o';
417 			}
418 
419 			if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
420 				bits = 7;
421 
422 			quot = ubrlcr & UBRLCR_BAUD_MASK;
423 			baud = port->uartclk / (16 * (quot + 1));
424 		}
425 	} else
426 		uart_parse_options(options, &baud, &parity, &bits, &flow);
427 
428 	ret = uart_set_options(port, co, baud, parity, bits, flow);
429 	if (ret)
430 		return ret;
431 
432 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
433 				  SYSCON_UARTEN, SYSCON_UARTEN);
434 }
435 
436 static struct console clps711x_console = {
437 	.name	= UART_CLPS711X_DEVNAME,
438 	.device	= uart_console_device,
439 	.write	= uart_clps711x_console_write,
440 	.setup	= uart_clps711x_console_setup,
441 	.flags	= CON_PRINTBUFFER,
442 	.index	= -1,
443 };
444 #endif
445 
446 static int uart_clps711x_probe(struct platform_device *pdev)
447 {
448 	struct device_node *np = pdev->dev.of_node;
449 	int ret, index = np ? of_alias_get_id(np, "serial") : pdev->id;
450 	struct clps711x_port *s;
451 	struct resource *res;
452 	struct clk *uart_clk;
453 
454 	if (index < 0 || index >= UART_CLPS711X_NR)
455 		return -EINVAL;
456 
457 	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
458 	if (!s)
459 		return -ENOMEM;
460 
461 	uart_clk = devm_clk_get(&pdev->dev, NULL);
462 	if (IS_ERR(uart_clk))
463 		return PTR_ERR(uart_clk);
464 
465 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
466 	s->port.membase = devm_ioremap_resource(&pdev->dev, res);
467 	if (IS_ERR(s->port.membase))
468 		return PTR_ERR(s->port.membase);
469 
470 	s->port.irq = platform_get_irq(pdev, 0);
471 	if (IS_ERR_VALUE(s->port.irq))
472 		return s->port.irq;
473 
474 	s->rx_irq = platform_get_irq(pdev, 1);
475 	if (IS_ERR_VALUE(s->rx_irq))
476 		return s->rx_irq;
477 
478 	if (!np) {
479 		char syscon_name[9];
480 
481 		sprintf(syscon_name, "syscon.%i", index + 1);
482 		s->syscon = syscon_regmap_lookup_by_pdevname(syscon_name);
483 		if (IS_ERR(s->syscon))
484 			return PTR_ERR(s->syscon);
485 	} else {
486 		s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
487 		if (IS_ERR(s->syscon))
488 			return PTR_ERR(s->syscon);
489 	}
490 
491 	s->port.line		= index;
492 	s->port.dev		= &pdev->dev;
493 	s->port.iotype		= UPIO_MEM32;
494 	s->port.mapbase		= res->start;
495 	s->port.type		= PORT_CLPS711X;
496 	s->port.fifosize	= 16;
497 	s->port.flags		= UPF_SKIP_TEST | UPF_FIXED_TYPE;
498 	s->port.uartclk		= clk_get_rate(uart_clk);
499 	s->port.ops		= &uart_clps711x_ops;
500 
501 	platform_set_drvdata(pdev, s);
502 
503 	s->gpios = mctrl_gpio_init(&pdev->dev, 0);
504 
505 	ret = uart_add_one_port(&clps711x_uart, &s->port);
506 	if (ret)
507 		return ret;
508 
509 	/* Disable port */
510 	if (!uart_console(&s->port))
511 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
512 
513 	s->tx_enabled = 1;
514 
515 	ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
516 			       dev_name(&pdev->dev), &s->port);
517 	if (ret) {
518 		uart_remove_one_port(&clps711x_uart, &s->port);
519 		return ret;
520 	}
521 
522 	ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
523 			       dev_name(&pdev->dev), &s->port);
524 	if (ret)
525 		uart_remove_one_port(&clps711x_uart, &s->port);
526 
527 	return ret;
528 }
529 
530 static int uart_clps711x_remove(struct platform_device *pdev)
531 {
532 	struct clps711x_port *s = platform_get_drvdata(pdev);
533 
534 	return uart_remove_one_port(&clps711x_uart, &s->port);
535 }
536 
537 static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
538 	{ .compatible = "cirrus,clps711x-uart", },
539 	{ }
540 };
541 MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);
542 
543 static struct platform_driver clps711x_uart_platform = {
544 	.driver = {
545 		.name		= "clps711x-uart",
546 		.of_match_table	= of_match_ptr(clps711x_uart_dt_ids),
547 	},
548 	.probe	= uart_clps711x_probe,
549 	.remove	= uart_clps711x_remove,
550 };
551 
552 static int __init uart_clps711x_init(void)
553 {
554 	int ret;
555 
556 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
557 	clps711x_uart.cons = &clps711x_console;
558 	clps711x_console.data = &clps711x_uart;
559 #endif
560 
561 	ret = uart_register_driver(&clps711x_uart);
562 	if (ret)
563 		return ret;
564 
565 	return platform_driver_register(&clps711x_uart_platform);
566 }
567 module_init(uart_clps711x_init);
568 
569 static void __exit uart_clps711x_exit(void)
570 {
571 	platform_driver_unregister(&clps711x_uart_platform);
572 	uart_unregister_driver(&clps711x_uart);
573 }
574 module_exit(uart_clps711x_exit);
575 
576 MODULE_AUTHOR("Deep Blue Solutions Ltd");
577 MODULE_DESCRIPTION("CLPS711X serial driver");
578 MODULE_LICENSE("GPL");
579