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
apbuart_stop_tx(struct uart_port * port)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
apbuart_start_tx(struct uart_port * port)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
apbuart_stop_rx(struct uart_port * port)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
apbuart_rx_chars(struct uart_port * port)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
apbuart_tx_chars(struct uart_port * port)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
apbuart_int(int irq,void * dev_id)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
apbuart_tx_empty(struct uart_port * port)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
apbuart_get_mctrl(struct uart_port * port)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
apbuart_set_mctrl(struct uart_port * port,unsigned int mctrl)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
apbuart_break_ctl(struct uart_port * port,int break_state)192 static void apbuart_break_ctl(struct uart_port *port, int break_state)
193 {
194 /* We don't support sending break */
195 }
196
apbuart_startup(struct uart_port * port)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
apbuart_shutdown(struct uart_port * port)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
apbuart_set_termios(struct uart_port * port,struct ktermios * termios,struct ktermios * old)230 static void apbuart_set_termios(struct uart_port *port,
231 struct ktermios *termios, 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
apbuart_type(struct uart_port * port)283 static const char *apbuart_type(struct uart_port *port)
284 {
285 return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
286 }
287
apbuart_release_port(struct uart_port * port)288 static void apbuart_release_port(struct uart_port *port)
289 {
290 release_mem_region(port->mapbase, 0x100);
291 }
292
apbuart_request_port(struct uart_port * port)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 */
apbuart_config_port(struct uart_port * port,int flags)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) */
apbuart_verify_port(struct uart_port * port,struct serial_struct * ser)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
apbuart_scan_fifo_size(struct uart_port * port,int portnumber)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
apbuart_flush_fifo(struct uart_port * port)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
apbuart_console_putchar(struct uart_port * port,int ch)416 static void apbuart_console_putchar(struct uart_port *port, int 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
apbuart_console_write(struct console * co,const char * s,unsigned int count)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
apbuart_console_get_options(struct uart_port * port,int * baud,int * parity,int * bits)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
apbuart_console_setup(struct console * co,char * options)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
apbuart_console_init(void)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
apbuart_probe(struct platform_device * op)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
grlib_apbuart_configure(void)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
grlib_apbuart_init(void)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
grlib_apbuart_exit(void)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