xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 31a254f6) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Driver for GRLIB serial ports (APBUART)
4  *
5  *  Based on linux/drivers/serial/amba.c
6  *
7  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
8  *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
9  *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
10  *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
11  *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
12  */
13 
14 #include <linux/module.h>
15 #include <linux/tty.h>
16 #include <linux/tty_flip.h>
17 #include <linux/ioport.h>
18 #include <linux/init.h>
19 #include <linux/serial.h>
20 #include <linux/console.h>
21 #include <linux/sysrq.h>
22 #include <linux/kthread.h>
23 #include <linux/device.h>
24 #include <linux/of.h>
25 #include <linux/platform_device.h>
26 #include <linux/io.h>
27 #include <linux/serial_core.h>
28 #include <asm/irq.h>
29 
30 #include "apbuart.h"
31 
32 #define SERIAL_APBUART_MAJOR	TTY_MAJOR
33 #define SERIAL_APBUART_MINOR	64
34 #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
35 
36 static void apbuart_tx_chars(struct uart_port *port);
37 
38 static void apbuart_stop_tx(struct uart_port *port)
39 {
40 	unsigned int cr;
41 
42 	cr = UART_GET_CTRL(port);
43 	cr &= ~UART_CTRL_TI;
44 	UART_PUT_CTRL(port, cr);
45 }
46 
47 static void apbuart_start_tx(struct uart_port *port)
48 {
49 	unsigned int cr;
50 
51 	cr = UART_GET_CTRL(port);
52 	cr |= UART_CTRL_TI;
53 	UART_PUT_CTRL(port, cr);
54 
55 	if (UART_GET_STATUS(port) & UART_STATUS_THE)
56 		apbuart_tx_chars(port);
57 }
58 
59 static void apbuart_stop_rx(struct uart_port *port)
60 {
61 	unsigned int cr;
62 
63 	cr = UART_GET_CTRL(port);
64 	cr &= ~(UART_CTRL_RI);
65 	UART_PUT_CTRL(port, cr);
66 }
67 
68 static void apbuart_rx_chars(struct uart_port *port)
69 {
70 	unsigned int status, rsr;
71 	unsigned int max_chars = port->fifosize;
72 	u8 ch, flag;
73 
74 	status = UART_GET_STATUS(port);
75 
76 	while (UART_RX_DATA(status) && (max_chars--)) {
77 
78 		ch = UART_GET_CHAR(port);
79 		flag = TTY_NORMAL;
80 
81 		port->icount.rx++;
82 
83 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
84 		UART_PUT_STATUS(port, 0);
85 		if (rsr & UART_STATUS_ERR) {
86 
87 			if (rsr & UART_STATUS_BR) {
88 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
89 				port->icount.brk++;
90 				if (uart_handle_break(port))
91 					goto ignore_char;
92 			} else if (rsr & UART_STATUS_PE) {
93 				port->icount.parity++;
94 			} else if (rsr & UART_STATUS_FE) {
95 				port->icount.frame++;
96 			}
97 			if (rsr & UART_STATUS_OE)
98 				port->icount.overrun++;
99 
100 			rsr &= port->read_status_mask;
101 
102 			if (rsr & UART_STATUS_PE)
103 				flag = TTY_PARITY;
104 			else if (rsr & UART_STATUS_FE)
105 				flag = TTY_FRAME;
106 		}
107 
108 		if (uart_handle_sysrq_char(port, ch))
109 			goto ignore_char;
110 
111 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
112 
113 
114 	      ignore_char:
115 		status = UART_GET_STATUS(port);
116 	}
117 
118 	tty_flip_buffer_push(&port->state->port);
119 }
120 
121 static void apbuart_tx_chars(struct uart_port *port)
122 {
123 	u8 ch;
124 
125 	uart_port_tx_limited(port, ch, port->fifosize,
126 		true,
127 		UART_PUT_CHAR(port, ch),
128 		({}));
129 }
130 
131 static irqreturn_t apbuart_int(int irq, void *dev_id)
132 {
133 	struct uart_port *port = dev_id;
134 	unsigned int status;
135 
136 	spin_lock(&port->lock);
137 
138 	status = UART_GET_STATUS(port);
139 	if (status & UART_STATUS_DR)
140 		apbuart_rx_chars(port);
141 	if (status & UART_STATUS_THE)
142 		apbuart_tx_chars(port);
143 
144 	spin_unlock(&port->lock);
145 
146 	return IRQ_HANDLED;
147 }
148 
149 static unsigned int apbuart_tx_empty(struct uart_port *port)
150 {
151 	unsigned int status = UART_GET_STATUS(port);
152 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
153 }
154 
155 static unsigned int apbuart_get_mctrl(struct uart_port *port)
156 {
157 	/* The GRLIB APBUART handles flow control in hardware */
158 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
159 }
160 
161 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
162 {
163 	/* The GRLIB APBUART handles flow control in hardware */
164 }
165 
166 static void apbuart_break_ctl(struct uart_port *port, int break_state)
167 {
168 	/* We don't support sending break */
169 }
170 
171 static int apbuart_startup(struct uart_port *port)
172 {
173 	int retval;
174 	unsigned int cr;
175 
176 	/* Allocate the IRQ */
177 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
178 	if (retval)
179 		return retval;
180 
181 	/* Finally, enable interrupts */
182 	cr = UART_GET_CTRL(port);
183 	UART_PUT_CTRL(port,
184 		      cr | UART_CTRL_RE | UART_CTRL_TE |
185 		      UART_CTRL_RI | UART_CTRL_TI);
186 
187 	return 0;
188 }
189 
190 static void apbuart_shutdown(struct uart_port *port)
191 {
192 	unsigned int cr;
193 
194 	/* disable all interrupts, disable the port */
195 	cr = UART_GET_CTRL(port);
196 	UART_PUT_CTRL(port,
197 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
198 			     UART_CTRL_RI | UART_CTRL_TI));
199 
200 	/* Free the interrupt */
201 	free_irq(port->irq, port);
202 }
203 
204 static void apbuart_set_termios(struct uart_port *port,
205 				struct ktermios *termios, const struct ktermios *old)
206 {
207 	unsigned int cr;
208 	unsigned long flags;
209 	unsigned int baud, quot;
210 
211 	/* Ask the core to calculate the divisor for us. */
212 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
213 	if (baud == 0)
214 		panic("invalid baudrate %i\n", port->uartclk / 16);
215 
216 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
217 	quot = (uart_get_divisor(port, baud)) * 2;
218 	cr = UART_GET_CTRL(port);
219 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
220 
221 	if (termios->c_cflag & PARENB) {
222 		cr |= UART_CTRL_PE;
223 		if ((termios->c_cflag & PARODD))
224 			cr |= UART_CTRL_PS;
225 	}
226 
227 	/* Enable flow control. */
228 	if (termios->c_cflag & CRTSCTS)
229 		cr |= UART_CTRL_FL;
230 
231 	spin_lock_irqsave(&port->lock, flags);
232 
233 	/* Update the per-port timeout. */
234 	uart_update_timeout(port, termios->c_cflag, baud);
235 
236 	port->read_status_mask = UART_STATUS_OE;
237 	if (termios->c_iflag & INPCK)
238 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
239 
240 	/* Characters to ignore */
241 	port->ignore_status_mask = 0;
242 	if (termios->c_iflag & IGNPAR)
243 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
244 
245 	/* Ignore all characters if CREAD is not set. */
246 	if ((termios->c_cflag & CREAD) == 0)
247 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
248 
249 	/* Set baud rate */
250 	quot -= 1;
251 	UART_PUT_SCAL(port, quot);
252 	UART_PUT_CTRL(port, cr);
253 
254 	spin_unlock_irqrestore(&port->lock, flags);
255 }
256 
257 static const char *apbuart_type(struct uart_port *port)
258 {
259 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
260 }
261 
262 static void apbuart_release_port(struct uart_port *port)
263 {
264 	release_mem_region(port->mapbase, 0x100);
265 }
266 
267 static int apbuart_request_port(struct uart_port *port)
268 {
269 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
270 	    != NULL ? 0 : -EBUSY;
271 	return 0;
272 }
273 
274 /* Configure/autoconfigure the port */
275 static void apbuart_config_port(struct uart_port *port, int flags)
276 {
277 	if (flags & UART_CONFIG_TYPE) {
278 		port->type = PORT_APBUART;
279 		apbuart_request_port(port);
280 	}
281 }
282 
283 /* Verify the new serial_struct (for TIOCSSERIAL) */
284 static int apbuart_verify_port(struct uart_port *port,
285 			       struct serial_struct *ser)
286 {
287 	int ret = 0;
288 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
289 		ret = -EINVAL;
290 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
291 		ret = -EINVAL;
292 	if (ser->baud_base < 9600)
293 		ret = -EINVAL;
294 	return ret;
295 }
296 
297 static const struct uart_ops grlib_apbuart_ops = {
298 	.tx_empty = apbuart_tx_empty,
299 	.set_mctrl = apbuart_set_mctrl,
300 	.get_mctrl = apbuart_get_mctrl,
301 	.stop_tx = apbuart_stop_tx,
302 	.start_tx = apbuart_start_tx,
303 	.stop_rx = apbuart_stop_rx,
304 	.break_ctl = apbuart_break_ctl,
305 	.startup = apbuart_startup,
306 	.shutdown = apbuart_shutdown,
307 	.set_termios = apbuart_set_termios,
308 	.type = apbuart_type,
309 	.release_port = apbuart_release_port,
310 	.request_port = apbuart_request_port,
311 	.config_port = apbuart_config_port,
312 	.verify_port = apbuart_verify_port,
313 };
314 
315 static struct uart_port grlib_apbuart_ports[UART_NR];
316 static struct device_node *grlib_apbuart_nodes[UART_NR];
317 
318 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
319 {
320 	int ctrl, loop = 0;
321 	int status;
322 	int fifosize;
323 	unsigned long flags;
324 
325 	ctrl = UART_GET_CTRL(port);
326 
327 	/*
328 	 * Enable the transceiver and wait for it to be ready to send data.
329 	 * Clear interrupts so that this process will not be externally
330 	 * interrupted in the middle (which can cause the transceiver to
331 	 * drain prematurely).
332 	 */
333 
334 	local_irq_save(flags);
335 
336 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
337 
338 	while (!UART_TX_READY(UART_GET_STATUS(port)))
339 		loop++;
340 
341 	/*
342 	 * Disable the transceiver so data isn't actually sent during the
343 	 * actual test.
344 	 */
345 
346 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
347 
348 	fifosize = 1;
349 	UART_PUT_CHAR(port, 0);
350 
351 	/*
352 	 * So long as transmitting a character increments the tranceivier FIFO
353 	 * length the FIFO must be at least that big. These bytes will
354 	 * automatically drain off of the FIFO.
355 	 */
356 
357 	status = UART_GET_STATUS(port);
358 	while (((status >> 20) & 0x3F) == fifosize) {
359 		fifosize++;
360 		UART_PUT_CHAR(port, 0);
361 		status = UART_GET_STATUS(port);
362 	}
363 
364 	fifosize--;
365 
366 	UART_PUT_CTRL(port, ctrl);
367 	local_irq_restore(flags);
368 
369 	if (fifosize == 0)
370 		fifosize = 1;
371 
372 	return fifosize;
373 }
374 
375 static void apbuart_flush_fifo(struct uart_port *port)
376 {
377 	int i;
378 
379 	for (i = 0; i < port->fifosize; i++)
380 		UART_GET_CHAR(port);
381 }
382 
383 
384 /* ======================================================================== */
385 /* Console driver, if enabled                                               */
386 /* ======================================================================== */
387 
388 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
389 
390 static void apbuart_console_putchar(struct uart_port *port, unsigned char ch)
391 {
392 	unsigned int status;
393 	do {
394 		status = UART_GET_STATUS(port);
395 	} while (!UART_TX_READY(status));
396 	UART_PUT_CHAR(port, ch);
397 }
398 
399 static void
400 apbuart_console_write(struct console *co, const char *s, unsigned int count)
401 {
402 	struct uart_port *port = &grlib_apbuart_ports[co->index];
403 	unsigned int status, old_cr, new_cr;
404 
405 	/* First save the CR then disable the interrupts */
406 	old_cr = UART_GET_CTRL(port);
407 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
408 	UART_PUT_CTRL(port, new_cr);
409 
410 	uart_console_write(port, s, count, apbuart_console_putchar);
411 
412 	/*
413 	 *      Finally, wait for transmitter to become empty
414 	 *      and restore the TCR
415 	 */
416 	do {
417 		status = UART_GET_STATUS(port);
418 	} while (!UART_TX_READY(status));
419 	UART_PUT_CTRL(port, old_cr);
420 }
421 
422 static void __init
423 apbuart_console_get_options(struct uart_port *port, int *baud,
424 			    int *parity, int *bits)
425 {
426 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
427 
428 		unsigned int quot, status;
429 		status = UART_GET_STATUS(port);
430 
431 		*parity = 'n';
432 		if (status & UART_CTRL_PE) {
433 			if ((status & UART_CTRL_PS) == 0)
434 				*parity = 'e';
435 			else
436 				*parity = 'o';
437 		}
438 
439 		*bits = 8;
440 		quot = UART_GET_SCAL(port) / 8;
441 		*baud = port->uartclk / (16 * (quot + 1));
442 	}
443 }
444 
445 static int __init apbuart_console_setup(struct console *co, char *options)
446 {
447 	struct uart_port *port;
448 	int baud = 38400;
449 	int bits = 8;
450 	int parity = 'n';
451 	int flow = 'n';
452 
453 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
454 		 co, co->index, options);
455 
456 	/*
457 	 * Check whether an invalid uart number has been specified, and
458 	 * if so, search for the first available port that does have
459 	 * console support.
460 	 */
461 	if (co->index >= grlib_apbuart_port_nr)
462 		co->index = 0;
463 
464 	port = &grlib_apbuart_ports[co->index];
465 
466 	spin_lock_init(&port->lock);
467 
468 	if (options)
469 		uart_parse_options(options, &baud, &parity, &bits, &flow);
470 	else
471 		apbuart_console_get_options(port, &baud, &parity, &bits);
472 
473 	return uart_set_options(port, co, baud, parity, bits, flow);
474 }
475 
476 static struct uart_driver grlib_apbuart_driver;
477 
478 static struct console grlib_apbuart_console = {
479 	.name = "ttyS",
480 	.write = apbuart_console_write,
481 	.device = uart_console_device,
482 	.setup = apbuart_console_setup,
483 	.flags = CON_PRINTBUFFER,
484 	.index = -1,
485 	.data = &grlib_apbuart_driver,
486 };
487 
488 
489 static int grlib_apbuart_configure(void);
490 
491 static int __init apbuart_console_init(void)
492 {
493 	if (grlib_apbuart_configure())
494 		return -ENODEV;
495 	register_console(&grlib_apbuart_console);
496 	return 0;
497 }
498 
499 console_initcall(apbuart_console_init);
500 
501 #define APBUART_CONSOLE	(&grlib_apbuart_console)
502 #else
503 #define APBUART_CONSOLE	NULL
504 #endif
505 
506 static struct uart_driver grlib_apbuart_driver = {
507 	.owner = THIS_MODULE,
508 	.driver_name = "serial",
509 	.dev_name = "ttyS",
510 	.major = SERIAL_APBUART_MAJOR,
511 	.minor = SERIAL_APBUART_MINOR,
512 	.nr = UART_NR,
513 	.cons = APBUART_CONSOLE,
514 };
515 
516 
517 /* ======================================================================== */
518 /* OF Platform Driver                                                       */
519 /* ======================================================================== */
520 
521 static int apbuart_probe(struct platform_device *op)
522 {
523 	int i;
524 	struct uart_port *port = NULL;
525 
526 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
527 		if (op->dev.of_node == grlib_apbuart_nodes[i])
528 			break;
529 	}
530 
531 	port = &grlib_apbuart_ports[i];
532 	port->dev = &op->dev;
533 	port->irq = op->archdata.irqs[0];
534 
535 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
536 
537 	apbuart_flush_fifo((struct uart_port *) port);
538 
539 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
540 	       (unsigned long long) port->mapbase, port->irq);
541 	return 0;
542 }
543 
544 static const struct of_device_id apbuart_match[] = {
545 	{
546 	 .name = "GAISLER_APBUART",
547 	 },
548 	{
549 	 .name = "01_00c",
550 	 },
551 	{},
552 };
553 MODULE_DEVICE_TABLE(of, apbuart_match);
554 
555 static struct platform_driver grlib_apbuart_of_driver = {
556 	.probe = apbuart_probe,
557 	.driver = {
558 		.name = "grlib-apbuart",
559 		.of_match_table = apbuart_match,
560 	},
561 };
562 
563 
564 static int __init grlib_apbuart_configure(void)
565 {
566 	struct device_node *np;
567 	int line = 0;
568 
569 	for_each_matching_node(np, apbuart_match) {
570 		const int *ampopts;
571 		const u32 *freq_hz;
572 		const struct amba_prom_registers *regs;
573 		struct uart_port *port;
574 		unsigned long addr;
575 
576 		ampopts = of_get_property(np, "ampopts", NULL);
577 		if (ampopts && (*ampopts == 0))
578 			continue; /* Ignore if used by another OS instance */
579 		regs = of_get_property(np, "reg", NULL);
580 		/* Frequency of APB Bus is frequency of UART */
581 		freq_hz = of_get_property(np, "freq", NULL);
582 
583 		if (!regs || !freq_hz || (*freq_hz == 0))
584 			continue;
585 
586 		grlib_apbuart_nodes[line] = np;
587 
588 		addr = regs->phys_addr;
589 
590 		port = &grlib_apbuart_ports[line];
591 
592 		port->mapbase = addr;
593 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
594 		port->irq = 0;
595 		port->iotype = UPIO_MEM;
596 		port->ops = &grlib_apbuart_ops;
597 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
598 		port->flags = UPF_BOOT_AUTOCONF;
599 		port->line = line;
600 		port->uartclk = *freq_hz;
601 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
602 		line++;
603 
604 		/* We support maximum UART_NR uarts ... */
605 		if (line == UART_NR)
606 			break;
607 	}
608 
609 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
610 	return line ? 0 : -ENODEV;
611 }
612 
613 static int __init grlib_apbuart_init(void)
614 {
615 	int ret;
616 
617 	/* Find all APBUARTS in device the tree and initialize their ports */
618 	ret = grlib_apbuart_configure();
619 	if (ret)
620 		return ret;
621 
622 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
623 
624 	ret = uart_register_driver(&grlib_apbuart_driver);
625 
626 	if (ret) {
627 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
628 		       __FILE__, ret);
629 		return ret;
630 	}
631 
632 	ret = platform_driver_register(&grlib_apbuart_of_driver);
633 	if (ret) {
634 		printk(KERN_ERR
635 		       "%s: platform_driver_register failed (%i)\n",
636 		       __FILE__, ret);
637 		uart_unregister_driver(&grlib_apbuart_driver);
638 		return ret;
639 	}
640 
641 	return ret;
642 }
643 
644 static void __exit grlib_apbuart_exit(void)
645 {
646 	int i;
647 
648 	for (i = 0; i < grlib_apbuart_port_nr; i++)
649 		uart_remove_one_port(&grlib_apbuart_driver,
650 				     &grlib_apbuart_ports[i]);
651 
652 	uart_unregister_driver(&grlib_apbuart_driver);
653 	platform_driver_unregister(&grlib_apbuart_of_driver);
654 }
655 
656 module_init(grlib_apbuart_init);
657 module_exit(grlib_apbuart_exit);
658 
659 MODULE_AUTHOR("Aeroflex Gaisler AB");
660 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
661 MODULE_VERSION("2.1");
662 MODULE_LICENSE("GPL");
663