xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 01ab991f) 
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 	struct circ_buf *xmit = &port->state->xmit;
126 	int count;
127 
128 	if (port->x_char) {
129 		UART_PUT_CHAR(port, port->x_char);
130 		port->icount.tx++;
131 		port->x_char = 0;
132 		return;
133 	}
134 
135 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
136 		apbuart_stop_tx(port);
137 		return;
138 	}
139 
140 	/* amba: fill FIFO */
141 	count = port->fifosize >> 1;
142 	do {
143 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
144 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
145 		port->icount.tx++;
146 		if (uart_circ_empty(xmit))
147 			break;
148 	} while (--count > 0);
149 
150 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
151 		uart_write_wakeup(port);
152 
153 	if (uart_circ_empty(xmit))
154 		apbuart_stop_tx(port);
155 }
156 
157 static irqreturn_t apbuart_int(int irq, void *dev_id)
158 {
159 	struct uart_port *port = dev_id;
160 	unsigned int status;
161 
162 	spin_lock(&port->lock);
163 
164 	status = UART_GET_STATUS(port);
165 	if (status & UART_STATUS_DR)
166 		apbuart_rx_chars(port);
167 	if (status & UART_STATUS_THE)
168 		apbuart_tx_chars(port);
169 
170 	spin_unlock(&port->lock);
171 
172 	return IRQ_HANDLED;
173 }
174 
175 static unsigned int apbuart_tx_empty(struct uart_port *port)
176 {
177 	unsigned int status = UART_GET_STATUS(port);
178 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
179 }
180 
181 static unsigned int apbuart_get_mctrl(struct uart_port *port)
182 {
183 	/* The GRLIB APBUART handles flow control in hardware */
184 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
185 }
186 
187 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
188 {
189 	/* The GRLIB APBUART handles flow control in hardware */
190 }
191 
192 static void apbuart_break_ctl(struct uart_port *port, int break_state)
193 {
194 	/* We don't support sending break */
195 }
196 
197 static int apbuart_startup(struct uart_port *port)
198 {
199 	int retval;
200 	unsigned int cr;
201 
202 	/* Allocate the IRQ */
203 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
204 	if (retval)
205 		return retval;
206 
207 	/* Finally, enable interrupts */
208 	cr = UART_GET_CTRL(port);
209 	UART_PUT_CTRL(port,
210 		      cr | UART_CTRL_RE | UART_CTRL_TE |
211 		      UART_CTRL_RI | UART_CTRL_TI);
212 
213 	return 0;
214 }
215 
216 static void apbuart_shutdown(struct uart_port *port)
217 {
218 	unsigned int cr;
219 
220 	/* disable all interrupts, disable the port */
221 	cr = UART_GET_CTRL(port);
222 	UART_PUT_CTRL(port,
223 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
224 			     UART_CTRL_RI | UART_CTRL_TI));
225 
226 	/* Free the interrupt */
227 	free_irq(port->irq, port);
228 }
229 
230 static void apbuart_set_termios(struct uart_port *port,
231 				struct ktermios *termios, const struct ktermios *old)
232 {
233 	unsigned int cr;
234 	unsigned long flags;
235 	unsigned int baud, quot;
236 
237 	/* Ask the core to calculate the divisor for us. */
238 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
239 	if (baud == 0)
240 		panic("invalid baudrate %i\n", port->uartclk / 16);
241 
242 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
243 	quot = (uart_get_divisor(port, baud)) * 2;
244 	cr = UART_GET_CTRL(port);
245 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
246 
247 	if (termios->c_cflag & PARENB) {
248 		cr |= UART_CTRL_PE;
249 		if ((termios->c_cflag & PARODD))
250 			cr |= UART_CTRL_PS;
251 	}
252 
253 	/* Enable flow control. */
254 	if (termios->c_cflag & CRTSCTS)
255 		cr |= UART_CTRL_FL;
256 
257 	spin_lock_irqsave(&port->lock, flags);
258 
259 	/* Update the per-port timeout. */
260 	uart_update_timeout(port, termios->c_cflag, baud);
261 
262 	port->read_status_mask = UART_STATUS_OE;
263 	if (termios->c_iflag & INPCK)
264 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
265 
266 	/* Characters to ignore */
267 	port->ignore_status_mask = 0;
268 	if (termios->c_iflag & IGNPAR)
269 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
270 
271 	/* Ignore all characters if CREAD is not set. */
272 	if ((termios->c_cflag & CREAD) == 0)
273 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
274 
275 	/* Set baud rate */
276 	quot -= 1;
277 	UART_PUT_SCAL(port, quot);
278 	UART_PUT_CTRL(port, cr);
279 
280 	spin_unlock_irqrestore(&port->lock, flags);
281 }
282 
283 static const char *apbuart_type(struct uart_port *port)
284 {
285 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
286 }
287 
288 static void apbuart_release_port(struct uart_port *port)
289 {
290 	release_mem_region(port->mapbase, 0x100);
291 }
292 
293 static int apbuart_request_port(struct uart_port *port)
294 {
295 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
296 	    != NULL ? 0 : -EBUSY;
297 	return 0;
298 }
299 
300 /* Configure/autoconfigure the port */
301 static void apbuart_config_port(struct uart_port *port, int flags)
302 {
303 	if (flags & UART_CONFIG_TYPE) {
304 		port->type = PORT_APBUART;
305 		apbuart_request_port(port);
306 	}
307 }
308 
309 /* Verify the new serial_struct (for TIOCSSERIAL) */
310 static int apbuart_verify_port(struct uart_port *port,
311 			       struct serial_struct *ser)
312 {
313 	int ret = 0;
314 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
315 		ret = -EINVAL;
316 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
317 		ret = -EINVAL;
318 	if (ser->baud_base < 9600)
319 		ret = -EINVAL;
320 	return ret;
321 }
322 
323 static const struct uart_ops grlib_apbuart_ops = {
324 	.tx_empty = apbuart_tx_empty,
325 	.set_mctrl = apbuart_set_mctrl,
326 	.get_mctrl = apbuart_get_mctrl,
327 	.stop_tx = apbuart_stop_tx,
328 	.start_tx = apbuart_start_tx,
329 	.stop_rx = apbuart_stop_rx,
330 	.break_ctl = apbuart_break_ctl,
331 	.startup = apbuart_startup,
332 	.shutdown = apbuart_shutdown,
333 	.set_termios = apbuart_set_termios,
334 	.type = apbuart_type,
335 	.release_port = apbuart_release_port,
336 	.request_port = apbuart_request_port,
337 	.config_port = apbuart_config_port,
338 	.verify_port = apbuart_verify_port,
339 };
340 
341 static struct uart_port grlib_apbuart_ports[UART_NR];
342 static struct device_node *grlib_apbuart_nodes[UART_NR];
343 
344 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
345 {
346 	int ctrl, loop = 0;
347 	int status;
348 	int fifosize;
349 	unsigned long flags;
350 
351 	ctrl = UART_GET_CTRL(port);
352 
353 	/*
354 	 * Enable the transceiver and wait for it to be ready to send data.
355 	 * Clear interrupts so that this process will not be externally
356 	 * interrupted in the middle (which can cause the transceiver to
357 	 * drain prematurely).
358 	 */
359 
360 	local_irq_save(flags);
361 
362 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
363 
364 	while (!UART_TX_READY(UART_GET_STATUS(port)))
365 		loop++;
366 
367 	/*
368 	 * Disable the transceiver so data isn't actually sent during the
369 	 * actual test.
370 	 */
371 
372 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
373 
374 	fifosize = 1;
375 	UART_PUT_CHAR(port, 0);
376 
377 	/*
378 	 * So long as transmitting a character increments the tranceivier FIFO
379 	 * length the FIFO must be at least that big. These bytes will
380 	 * automatically drain off of the FIFO.
381 	 */
382 
383 	status = UART_GET_STATUS(port);
384 	while (((status >> 20) & 0x3F) == fifosize) {
385 		fifosize++;
386 		UART_PUT_CHAR(port, 0);
387 		status = UART_GET_STATUS(port);
388 	}
389 
390 	fifosize--;
391 
392 	UART_PUT_CTRL(port, ctrl);
393 	local_irq_restore(flags);
394 
395 	if (fifosize == 0)
396 		fifosize = 1;
397 
398 	return fifosize;
399 }
400 
401 static void apbuart_flush_fifo(struct uart_port *port)
402 {
403 	int i;
404 
405 	for (i = 0; i < port->fifosize; i++)
406 		UART_GET_CHAR(port);
407 }
408 
409 
410 /* ======================================================================== */
411 /* Console driver, if enabled                                               */
412 /* ======================================================================== */
413 
414 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
415 
416 static void apbuart_console_putchar(struct uart_port *port, unsigned char ch)
417 {
418 	unsigned int status;
419 	do {
420 		status = UART_GET_STATUS(port);
421 	} while (!UART_TX_READY(status));
422 	UART_PUT_CHAR(port, ch);
423 }
424 
425 static void
426 apbuart_console_write(struct console *co, const char *s, unsigned int count)
427 {
428 	struct uart_port *port = &grlib_apbuart_ports[co->index];
429 	unsigned int status, old_cr, new_cr;
430 
431 	/* First save the CR then disable the interrupts */
432 	old_cr = UART_GET_CTRL(port);
433 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
434 	UART_PUT_CTRL(port, new_cr);
435 
436 	uart_console_write(port, s, count, apbuart_console_putchar);
437 
438 	/*
439 	 *      Finally, wait for transmitter to become empty
440 	 *      and restore the TCR
441 	 */
442 	do {
443 		status = UART_GET_STATUS(port);
444 	} while (!UART_TX_READY(status));
445 	UART_PUT_CTRL(port, old_cr);
446 }
447 
448 static void __init
449 apbuart_console_get_options(struct uart_port *port, int *baud,
450 			    int *parity, int *bits)
451 {
452 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
453 
454 		unsigned int quot, status;
455 		status = UART_GET_STATUS(port);
456 
457 		*parity = 'n';
458 		if (status & UART_CTRL_PE) {
459 			if ((status & UART_CTRL_PS) == 0)
460 				*parity = 'e';
461 			else
462 				*parity = 'o';
463 		}
464 
465 		*bits = 8;
466 		quot = UART_GET_SCAL(port) / 8;
467 		*baud = port->uartclk / (16 * (quot + 1));
468 	}
469 }
470 
471 static int __init apbuart_console_setup(struct console *co, char *options)
472 {
473 	struct uart_port *port;
474 	int baud = 38400;
475 	int bits = 8;
476 	int parity = 'n';
477 	int flow = 'n';
478 
479 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
480 		 co, co->index, options);
481 
482 	/*
483 	 * Check whether an invalid uart number has been specified, and
484 	 * if so, search for the first available port that does have
485 	 * console support.
486 	 */
487 	if (co->index >= grlib_apbuart_port_nr)
488 		co->index = 0;
489 
490 	port = &grlib_apbuart_ports[co->index];
491 
492 	spin_lock_init(&port->lock);
493 
494 	if (options)
495 		uart_parse_options(options, &baud, &parity, &bits, &flow);
496 	else
497 		apbuart_console_get_options(port, &baud, &parity, &bits);
498 
499 	return uart_set_options(port, co, baud, parity, bits, flow);
500 }
501 
502 static struct uart_driver grlib_apbuart_driver;
503 
504 static struct console grlib_apbuart_console = {
505 	.name = "ttyS",
506 	.write = apbuart_console_write,
507 	.device = uart_console_device,
508 	.setup = apbuart_console_setup,
509 	.flags = CON_PRINTBUFFER,
510 	.index = -1,
511 	.data = &grlib_apbuart_driver,
512 };
513 
514 
515 static int grlib_apbuart_configure(void);
516 
517 static int __init apbuart_console_init(void)
518 {
519 	if (grlib_apbuart_configure())
520 		return -ENODEV;
521 	register_console(&grlib_apbuart_console);
522 	return 0;
523 }
524 
525 console_initcall(apbuart_console_init);
526 
527 #define APBUART_CONSOLE	(&grlib_apbuart_console)
528 #else
529 #define APBUART_CONSOLE	NULL
530 #endif
531 
532 static struct uart_driver grlib_apbuart_driver = {
533 	.owner = THIS_MODULE,
534 	.driver_name = "serial",
535 	.dev_name = "ttyS",
536 	.major = SERIAL_APBUART_MAJOR,
537 	.minor = SERIAL_APBUART_MINOR,
538 	.nr = UART_NR,
539 	.cons = APBUART_CONSOLE,
540 };
541 
542 
543 /* ======================================================================== */
544 /* OF Platform Driver                                                       */
545 /* ======================================================================== */
546 
547 static int apbuart_probe(struct platform_device *op)
548 {
549 	int i;
550 	struct uart_port *port = NULL;
551 
552 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
553 		if (op->dev.of_node == grlib_apbuart_nodes[i])
554 			break;
555 	}
556 
557 	port = &grlib_apbuart_ports[i];
558 	port->dev = &op->dev;
559 	port->irq = op->archdata.irqs[0];
560 
561 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
562 
563 	apbuart_flush_fifo((struct uart_port *) port);
564 
565 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
566 	       (unsigned long long) port->mapbase, port->irq);
567 	return 0;
568 }
569 
570 static const struct of_device_id apbuart_match[] = {
571 	{
572 	 .name = "GAISLER_APBUART",
573 	 },
574 	{
575 	 .name = "01_00c",
576 	 },
577 	{},
578 };
579 MODULE_DEVICE_TABLE(of, apbuart_match);
580 
581 static struct platform_driver grlib_apbuart_of_driver = {
582 	.probe = apbuart_probe,
583 	.driver = {
584 		.name = "grlib-apbuart",
585 		.of_match_table = apbuart_match,
586 	},
587 };
588 
589 
590 static int __init grlib_apbuart_configure(void)
591 {
592 	struct device_node *np;
593 	int line = 0;
594 
595 	for_each_matching_node(np, apbuart_match) {
596 		const int *ampopts;
597 		const u32 *freq_hz;
598 		const struct amba_prom_registers *regs;
599 		struct uart_port *port;
600 		unsigned long addr;
601 
602 		ampopts = of_get_property(np, "ampopts", NULL);
603 		if (ampopts && (*ampopts == 0))
604 			continue; /* Ignore if used by another OS instance */
605 		regs = of_get_property(np, "reg", NULL);
606 		/* Frequency of APB Bus is frequency of UART */
607 		freq_hz = of_get_property(np, "freq", NULL);
608 
609 		if (!regs || !freq_hz || (*freq_hz == 0))
610 			continue;
611 
612 		grlib_apbuart_nodes[line] = np;
613 
614 		addr = regs->phys_addr;
615 
616 		port = &grlib_apbuart_ports[line];
617 
618 		port->mapbase = addr;
619 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
620 		port->irq = 0;
621 		port->iotype = UPIO_MEM;
622 		port->ops = &grlib_apbuart_ops;
623 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
624 		port->flags = UPF_BOOT_AUTOCONF;
625 		port->line = line;
626 		port->uartclk = *freq_hz;
627 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
628 		line++;
629 
630 		/* We support maximum UART_NR uarts ... */
631 		if (line == UART_NR)
632 			break;
633 	}
634 
635 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
636 	return line ? 0 : -ENODEV;
637 }
638 
639 static int __init grlib_apbuart_init(void)
640 {
641 	int ret;
642 
643 	/* Find all APBUARTS in device the tree and initialize their ports */
644 	ret = grlib_apbuart_configure();
645 	if (ret)
646 		return ret;
647 
648 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
649 
650 	ret = uart_register_driver(&grlib_apbuart_driver);
651 
652 	if (ret) {
653 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
654 		       __FILE__, ret);
655 		return ret;
656 	}
657 
658 	ret = platform_driver_register(&grlib_apbuart_of_driver);
659 	if (ret) {
660 		printk(KERN_ERR
661 		       "%s: platform_driver_register failed (%i)\n",
662 		       __FILE__, ret);
663 		uart_unregister_driver(&grlib_apbuart_driver);
664 		return ret;
665 	}
666 
667 	return ret;
668 }
669 
670 static void __exit grlib_apbuart_exit(void)
671 {
672 	int i;
673 
674 	for (i = 0; i < grlib_apbuart_port_nr; i++)
675 		uart_remove_one_port(&grlib_apbuart_driver,
676 				     &grlib_apbuart_ports[i]);
677 
678 	uart_unregister_driver(&grlib_apbuart_driver);
679 	platform_driver_unregister(&grlib_apbuart_of_driver);
680 }
681 
682 module_init(grlib_apbuart_init);
683 module_exit(grlib_apbuart_exit);
684 
685 MODULE_AUTHOR("Aeroflex Gaisler AB");
686 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
687 MODULE_VERSION("2.1");
688 MODULE_LICENSE("GPL");
689