xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision c699ce1a) 
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/of_device.h>
26 #include <linux/of_platform.h>
27 #include <linux/of_irq.h>
28 #include <linux/platform_device.h>
29 #include <linux/io.h>
30 #include <linux/serial_core.h>
31 #include <asm/irq.h>
32 
33 #include "apbuart.h"
34 
35 #define SERIAL_APBUART_MAJOR	TTY_MAJOR
36 #define SERIAL_APBUART_MINOR	64
37 #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
38 
39 static void apbuart_tx_chars(struct uart_port *port);
40 
41 static void apbuart_stop_tx(struct uart_port *port)
42 {
43 	unsigned int cr;
44 
45 	cr = UART_GET_CTRL(port);
46 	cr &= ~UART_CTRL_TI;
47 	UART_PUT_CTRL(port, cr);
48 }
49 
50 static void apbuart_start_tx(struct uart_port *port)
51 {
52 	unsigned int cr;
53 
54 	cr = UART_GET_CTRL(port);
55 	cr |= UART_CTRL_TI;
56 	UART_PUT_CTRL(port, cr);
57 
58 	if (UART_GET_STATUS(port) & UART_STATUS_THE)
59 		apbuart_tx_chars(port);
60 }
61 
62 static void apbuart_stop_rx(struct uart_port *port)
63 {
64 	unsigned int cr;
65 
66 	cr = UART_GET_CTRL(port);
67 	cr &= ~(UART_CTRL_RI);
68 	UART_PUT_CTRL(port, cr);
69 }
70 
71 static void apbuart_rx_chars(struct uart_port *port)
72 {
73 	unsigned int status, ch, rsr, flag;
74 	unsigned int max_chars = port->fifosize;
75 
76 	status = UART_GET_STATUS(port);
77 
78 	while (UART_RX_DATA(status) && (max_chars--)) {
79 
80 		ch = UART_GET_CHAR(port);
81 		flag = TTY_NORMAL;
82 
83 		port->icount.rx++;
84 
85 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
86 		UART_PUT_STATUS(port, 0);
87 		if (rsr & UART_STATUS_ERR) {
88 
89 			if (rsr & UART_STATUS_BR) {
90 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
91 				port->icount.brk++;
92 				if (uart_handle_break(port))
93 					goto ignore_char;
94 			} else if (rsr & UART_STATUS_PE) {
95 				port->icount.parity++;
96 			} else if (rsr & UART_STATUS_FE) {
97 				port->icount.frame++;
98 			}
99 			if (rsr & UART_STATUS_OE)
100 				port->icount.overrun++;
101 
102 			rsr &= port->read_status_mask;
103 
104 			if (rsr & UART_STATUS_PE)
105 				flag = TTY_PARITY;
106 			else if (rsr & UART_STATUS_FE)
107 				flag = TTY_FRAME;
108 		}
109 
110 		if (uart_handle_sysrq_char(port, ch))
111 			goto ignore_char;
112 
113 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
114 
115 
116 	      ignore_char:
117 		status = UART_GET_STATUS(port);
118 	}
119 
120 	tty_flip_buffer_push(&port->state->port);
121 }
122 
123 static void apbuart_tx_chars(struct uart_port *port)
124 {
125 	u8 ch;
126 
127 	uart_port_tx_limited(port, ch, port->fifosize >> 1,
128 		true,
129 		UART_PUT_CHAR(port, ch),
130 		({}));
131 }
132 
133 static irqreturn_t apbuart_int(int irq, void *dev_id)
134 {
135 	struct uart_port *port = dev_id;
136 	unsigned int status;
137 
138 	spin_lock(&port->lock);
139 
140 	status = UART_GET_STATUS(port);
141 	if (status & UART_STATUS_DR)
142 		apbuart_rx_chars(port);
143 	if (status & UART_STATUS_THE)
144 		apbuart_tx_chars(port);
145 
146 	spin_unlock(&port->lock);
147 
148 	return IRQ_HANDLED;
149 }
150 
151 static unsigned int apbuart_tx_empty(struct uart_port *port)
152 {
153 	unsigned int status = UART_GET_STATUS(port);
154 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
155 }
156 
157 static unsigned int apbuart_get_mctrl(struct uart_port *port)
158 {
159 	/* The GRLIB APBUART handles flow control in hardware */
160 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
161 }
162 
163 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
164 {
165 	/* The GRLIB APBUART handles flow control in hardware */
166 }
167 
168 static void apbuart_break_ctl(struct uart_port *port, int break_state)
169 {
170 	/* We don't support sending break */
171 }
172 
173 static int apbuart_startup(struct uart_port *port)
174 {
175 	int retval;
176 	unsigned int cr;
177 
178 	/* Allocate the IRQ */
179 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
180 	if (retval)
181 		return retval;
182 
183 	/* Finally, enable interrupts */
184 	cr = UART_GET_CTRL(port);
185 	UART_PUT_CTRL(port,
186 		      cr | UART_CTRL_RE | UART_CTRL_TE |
187 		      UART_CTRL_RI | UART_CTRL_TI);
188 
189 	return 0;
190 }
191 
192 static void apbuart_shutdown(struct uart_port *port)
193 {
194 	unsigned int cr;
195 
196 	/* disable all interrupts, disable the port */
197 	cr = UART_GET_CTRL(port);
198 	UART_PUT_CTRL(port,
199 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
200 			     UART_CTRL_RI | UART_CTRL_TI));
201 
202 	/* Free the interrupt */
203 	free_irq(port->irq, port);
204 }
205 
206 static void apbuart_set_termios(struct uart_port *port,
207 				struct ktermios *termios, const struct ktermios *old)
208 {
209 	unsigned int cr;
210 	unsigned long flags;
211 	unsigned int baud, quot;
212 
213 	/* Ask the core to calculate the divisor for us. */
214 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
215 	if (baud == 0)
216 		panic("invalid baudrate %i\n", port->uartclk / 16);
217 
218 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
219 	quot = (uart_get_divisor(port, baud)) * 2;
220 	cr = UART_GET_CTRL(port);
221 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
222 
223 	if (termios->c_cflag & PARENB) {
224 		cr |= UART_CTRL_PE;
225 		if ((termios->c_cflag & PARODD))
226 			cr |= UART_CTRL_PS;
227 	}
228 
229 	/* Enable flow control. */
230 	if (termios->c_cflag & CRTSCTS)
231 		cr |= UART_CTRL_FL;
232 
233 	spin_lock_irqsave(&port->lock, flags);
234 
235 	/* Update the per-port timeout. */
236 	uart_update_timeout(port, termios->c_cflag, baud);
237 
238 	port->read_status_mask = UART_STATUS_OE;
239 	if (termios->c_iflag & INPCK)
240 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
241 
242 	/* Characters to ignore */
243 	port->ignore_status_mask = 0;
244 	if (termios->c_iflag & IGNPAR)
245 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
246 
247 	/* Ignore all characters if CREAD is not set. */
248 	if ((termios->c_cflag & CREAD) == 0)
249 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
250 
251 	/* Set baud rate */
252 	quot -= 1;
253 	UART_PUT_SCAL(port, quot);
254 	UART_PUT_CTRL(port, cr);
255 
256 	spin_unlock_irqrestore(&port->lock, flags);
257 }
258 
259 static const char *apbuart_type(struct uart_port *port)
260 {
261 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
262 }
263 
264 static void apbuart_release_port(struct uart_port *port)
265 {
266 	release_mem_region(port->mapbase, 0x100);
267 }
268 
269 static int apbuart_request_port(struct uart_port *port)
270 {
271 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
272 	    != NULL ? 0 : -EBUSY;
273 	return 0;
274 }
275 
276 /* Configure/autoconfigure the port */
277 static void apbuart_config_port(struct uart_port *port, int flags)
278 {
279 	if (flags & UART_CONFIG_TYPE) {
280 		port->type = PORT_APBUART;
281 		apbuart_request_port(port);
282 	}
283 }
284 
285 /* Verify the new serial_struct (for TIOCSSERIAL) */
286 static int apbuart_verify_port(struct uart_port *port,
287 			       struct serial_struct *ser)
288 {
289 	int ret = 0;
290 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
291 		ret = -EINVAL;
292 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
293 		ret = -EINVAL;
294 	if (ser->baud_base < 9600)
295 		ret = -EINVAL;
296 	return ret;
297 }
298 
299 static const struct uart_ops grlib_apbuart_ops = {
300 	.tx_empty = apbuart_tx_empty,
301 	.set_mctrl = apbuart_set_mctrl,
302 	.get_mctrl = apbuart_get_mctrl,
303 	.stop_tx = apbuart_stop_tx,
304 	.start_tx = apbuart_start_tx,
305 	.stop_rx = apbuart_stop_rx,
306 	.break_ctl = apbuart_break_ctl,
307 	.startup = apbuart_startup,
308 	.shutdown = apbuart_shutdown,
309 	.set_termios = apbuart_set_termios,
310 	.type = apbuart_type,
311 	.release_port = apbuart_release_port,
312 	.request_port = apbuart_request_port,
313 	.config_port = apbuart_config_port,
314 	.verify_port = apbuart_verify_port,
315 };
316 
317 static struct uart_port grlib_apbuart_ports[UART_NR];
318 static struct device_node *grlib_apbuart_nodes[UART_NR];
319 
320 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
321 {
322 	int ctrl, loop = 0;
323 	int status;
324 	int fifosize;
325 	unsigned long flags;
326 
327 	ctrl = UART_GET_CTRL(port);
328 
329 	/*
330 	 * Enable the transceiver and wait for it to be ready to send data.
331 	 * Clear interrupts so that this process will not be externally
332 	 * interrupted in the middle (which can cause the transceiver to
333 	 * drain prematurely).
334 	 */
335 
336 	local_irq_save(flags);
337 
338 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
339 
340 	while (!UART_TX_READY(UART_GET_STATUS(port)))
341 		loop++;
342 
343 	/*
344 	 * Disable the transceiver so data isn't actually sent during the
345 	 * actual test.
346 	 */
347 
348 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
349 
350 	fifosize = 1;
351 	UART_PUT_CHAR(port, 0);
352 
353 	/*
354 	 * So long as transmitting a character increments the tranceivier FIFO
355 	 * length the FIFO must be at least that big. These bytes will
356 	 * automatically drain off of the FIFO.
357 	 */
358 
359 	status = UART_GET_STATUS(port);
360 	while (((status >> 20) & 0x3F) == fifosize) {
361 		fifosize++;
362 		UART_PUT_CHAR(port, 0);
363 		status = UART_GET_STATUS(port);
364 	}
365 
366 	fifosize--;
367 
368 	UART_PUT_CTRL(port, ctrl);
369 	local_irq_restore(flags);
370 
371 	if (fifosize == 0)
372 		fifosize = 1;
373 
374 	return fifosize;
375 }
376 
377 static void apbuart_flush_fifo(struct uart_port *port)
378 {
379 	int i;
380 
381 	for (i = 0; i < port->fifosize; i++)
382 		UART_GET_CHAR(port);
383 }
384 
385 
386 /* ======================================================================== */
387 /* Console driver, if enabled                                               */
388 /* ======================================================================== */
389 
390 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
391 
392 static void apbuart_console_putchar(struct uart_port *port, unsigned char ch)
393 {
394 	unsigned int status;
395 	do {
396 		status = UART_GET_STATUS(port);
397 	} while (!UART_TX_READY(status));
398 	UART_PUT_CHAR(port, ch);
399 }
400 
401 static void
402 apbuart_console_write(struct console *co, const char *s, unsigned int count)
403 {
404 	struct uart_port *port = &grlib_apbuart_ports[co->index];
405 	unsigned int status, old_cr, new_cr;
406 
407 	/* First save the CR then disable the interrupts */
408 	old_cr = UART_GET_CTRL(port);
409 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
410 	UART_PUT_CTRL(port, new_cr);
411 
412 	uart_console_write(port, s, count, apbuart_console_putchar);
413 
414 	/*
415 	 *      Finally, wait for transmitter to become empty
416 	 *      and restore the TCR
417 	 */
418 	do {
419 		status = UART_GET_STATUS(port);
420 	} while (!UART_TX_READY(status));
421 	UART_PUT_CTRL(port, old_cr);
422 }
423 
424 static void __init
425 apbuart_console_get_options(struct uart_port *port, int *baud,
426 			    int *parity, int *bits)
427 {
428 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
429 
430 		unsigned int quot, status;
431 		status = UART_GET_STATUS(port);
432 
433 		*parity = 'n';
434 		if (status & UART_CTRL_PE) {
435 			if ((status & UART_CTRL_PS) == 0)
436 				*parity = 'e';
437 			else
438 				*parity = 'o';
439 		}
440 
441 		*bits = 8;
442 		quot = UART_GET_SCAL(port) / 8;
443 		*baud = port->uartclk / (16 * (quot + 1));
444 	}
445 }
446 
447 static int __init apbuart_console_setup(struct console *co, char *options)
448 {
449 	struct uart_port *port;
450 	int baud = 38400;
451 	int bits = 8;
452 	int parity = 'n';
453 	int flow = 'n';
454 
455 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
456 		 co, co->index, options);
457 
458 	/*
459 	 * Check whether an invalid uart number has been specified, and
460 	 * if so, search for the first available port that does have
461 	 * console support.
462 	 */
463 	if (co->index >= grlib_apbuart_port_nr)
464 		co->index = 0;
465 
466 	port = &grlib_apbuart_ports[co->index];
467 
468 	spin_lock_init(&port->lock);
469 
470 	if (options)
471 		uart_parse_options(options, &baud, &parity, &bits, &flow);
472 	else
473 		apbuart_console_get_options(port, &baud, &parity, &bits);
474 
475 	return uart_set_options(port, co, baud, parity, bits, flow);
476 }
477 
478 static struct uart_driver grlib_apbuart_driver;
479 
480 static struct console grlib_apbuart_console = {
481 	.name = "ttyS",
482 	.write = apbuart_console_write,
483 	.device = uart_console_device,
484 	.setup = apbuart_console_setup,
485 	.flags = CON_PRINTBUFFER,
486 	.index = -1,
487 	.data = &grlib_apbuart_driver,
488 };
489 
490 
491 static int grlib_apbuart_configure(void);
492 
493 static int __init apbuart_console_init(void)
494 {
495 	if (grlib_apbuart_configure())
496 		return -ENODEV;
497 	register_console(&grlib_apbuart_console);
498 	return 0;
499 }
500 
501 console_initcall(apbuart_console_init);
502 
503 #define APBUART_CONSOLE	(&grlib_apbuart_console)
504 #else
505 #define APBUART_CONSOLE	NULL
506 #endif
507 
508 static struct uart_driver grlib_apbuart_driver = {
509 	.owner = THIS_MODULE,
510 	.driver_name = "serial",
511 	.dev_name = "ttyS",
512 	.major = SERIAL_APBUART_MAJOR,
513 	.minor = SERIAL_APBUART_MINOR,
514 	.nr = UART_NR,
515 	.cons = APBUART_CONSOLE,
516 };
517 
518 
519 /* ======================================================================== */
520 /* OF Platform Driver                                                       */
521 /* ======================================================================== */
522 
523 static int apbuart_probe(struct platform_device *op)
524 {
525 	int i;
526 	struct uart_port *port = NULL;
527 
528 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
529 		if (op->dev.of_node == grlib_apbuart_nodes[i])
530 			break;
531 	}
532 
533 	port = &grlib_apbuart_ports[i];
534 	port->dev = &op->dev;
535 	port->irq = op->archdata.irqs[0];
536 
537 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
538 
539 	apbuart_flush_fifo((struct uart_port *) port);
540 
541 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
542 	       (unsigned long long) port->mapbase, port->irq);
543 	return 0;
544 }
545 
546 static const struct of_device_id apbuart_match[] = {
547 	{
548 	 .name = "GAISLER_APBUART",
549 	 },
550 	{
551 	 .name = "01_00c",
552 	 },
553 	{},
554 };
555 MODULE_DEVICE_TABLE(of, apbuart_match);
556 
557 static struct platform_driver grlib_apbuart_of_driver = {
558 	.probe = apbuart_probe,
559 	.driver = {
560 		.name = "grlib-apbuart",
561 		.of_match_table = apbuart_match,
562 	},
563 };
564 
565 
566 static int __init grlib_apbuart_configure(void)
567 {
568 	struct device_node *np;
569 	int line = 0;
570 
571 	for_each_matching_node(np, apbuart_match) {
572 		const int *ampopts;
573 		const u32 *freq_hz;
574 		const struct amba_prom_registers *regs;
575 		struct uart_port *port;
576 		unsigned long addr;
577 
578 		ampopts = of_get_property(np, "ampopts", NULL);
579 		if (ampopts && (*ampopts == 0))
580 			continue; /* Ignore if used by another OS instance */
581 		regs = of_get_property(np, "reg", NULL);
582 		/* Frequency of APB Bus is frequency of UART */
583 		freq_hz = of_get_property(np, "freq", NULL);
584 
585 		if (!regs || !freq_hz || (*freq_hz == 0))
586 			continue;
587 
588 		grlib_apbuart_nodes[line] = np;
589 
590 		addr = regs->phys_addr;
591 
592 		port = &grlib_apbuart_ports[line];
593 
594 		port->mapbase = addr;
595 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
596 		port->irq = 0;
597 		port->iotype = UPIO_MEM;
598 		port->ops = &grlib_apbuart_ops;
599 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
600 		port->flags = UPF_BOOT_AUTOCONF;
601 		port->line = line;
602 		port->uartclk = *freq_hz;
603 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
604 		line++;
605 
606 		/* We support maximum UART_NR uarts ... */
607 		if (line == UART_NR)
608 			break;
609 	}
610 
611 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
612 	return line ? 0 : -ENODEV;
613 }
614 
615 static int __init grlib_apbuart_init(void)
616 {
617 	int ret;
618 
619 	/* Find all APBUARTS in device the tree and initialize their ports */
620 	ret = grlib_apbuart_configure();
621 	if (ret)
622 		return ret;
623 
624 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
625 
626 	ret = uart_register_driver(&grlib_apbuart_driver);
627 
628 	if (ret) {
629 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
630 		       __FILE__, ret);
631 		return ret;
632 	}
633 
634 	ret = platform_driver_register(&grlib_apbuart_of_driver);
635 	if (ret) {
636 		printk(KERN_ERR
637 		       "%s: platform_driver_register failed (%i)\n",
638 		       __FILE__, ret);
639 		uart_unregister_driver(&grlib_apbuart_driver);
640 		return ret;
641 	}
642 
643 	return ret;
644 }
645 
646 static void __exit grlib_apbuart_exit(void)
647 {
648 	int i;
649 
650 	for (i = 0; i < grlib_apbuart_port_nr; i++)
651 		uart_remove_one_port(&grlib_apbuart_driver,
652 				     &grlib_apbuart_ports[i]);
653 
654 	uart_unregister_driver(&grlib_apbuart_driver);
655 	platform_driver_unregister(&grlib_apbuart_of_driver);
656 }
657 
658 module_init(grlib_apbuart_init);
659 module_exit(grlib_apbuart_exit);
660 
661 MODULE_AUTHOR("Aeroflex Gaisler AB");
662 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
663 MODULE_VERSION("2.1");
664 MODULE_LICENSE("GPL");
665