1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Driver for Conexant Digicolor serial ports (USART)
4 *
5 * Author: Baruch Siach <baruch@tkos.co.il>
6 *
7 * Copyright (C) 2014 Paradox Innovation Ltd.
8 */
9
10 #include <linux/module.h>
11 #include <linux/console.h>
12 #include <linux/serial_core.h>
13 #include <linux/serial.h>
14 #include <linux/clk.h>
15 #include <linux/io.h>
16 #include <linux/tty.h>
17 #include <linux/tty_flip.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/workqueue.h>
21
22 #define UA_ENABLE 0x00
23 #define UA_ENABLE_ENABLE BIT(0)
24
25 #define UA_CONTROL 0x01
26 #define UA_CONTROL_RX_ENABLE BIT(0)
27 #define UA_CONTROL_TX_ENABLE BIT(1)
28 #define UA_CONTROL_SOFT_RESET BIT(2)
29
30 #define UA_STATUS 0x02
31 #define UA_STATUS_PARITY_ERR BIT(0)
32 #define UA_STATUS_FRAME_ERR BIT(1)
33 #define UA_STATUS_OVERRUN_ERR BIT(2)
34 #define UA_STATUS_TX_READY BIT(6)
35
36 #define UA_CONFIG 0x03
37 #define UA_CONFIG_CHAR_LEN BIT(0)
38 #define UA_CONFIG_STOP_BITS BIT(1)
39 #define UA_CONFIG_PARITY BIT(2)
40 #define UA_CONFIG_ODD_PARITY BIT(4)
41
42 #define UA_EMI_REC 0x04
43
44 #define UA_HBAUD_LO 0x08
45 #define UA_HBAUD_HI 0x09
46
47 #define UA_STATUS_FIFO 0x0a
48 #define UA_STATUS_FIFO_RX_EMPTY BIT(2)
49 #define UA_STATUS_FIFO_RX_INT_ALMOST BIT(3)
50 #define UA_STATUS_FIFO_TX_FULL BIT(4)
51 #define UA_STATUS_FIFO_TX_INT_ALMOST BIT(7)
52
53 #define UA_CONFIG_FIFO 0x0b
54 #define UA_CONFIG_FIFO_RX_THRESH 7
55 #define UA_CONFIG_FIFO_RX_FIFO_MODE BIT(3)
56 #define UA_CONFIG_FIFO_TX_FIFO_MODE BIT(7)
57
58 #define UA_INTFLAG_CLEAR 0x1c
59 #define UA_INTFLAG_SET 0x1d
60 #define UA_INT_ENABLE 0x1e
61 #define UA_INT_STATUS 0x1f
62
63 #define UA_INT_TX BIT(0)
64 #define UA_INT_RX BIT(1)
65
66 #define DIGICOLOR_USART_NR 3
67
68 /*
69 * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
70 * only produced when the FIFO is filled more than a certain configurable
71 * threshold. Unfortunately, there is no way to set this threshold below half
72 * FIFO. This means that we must periodically poll the FIFO status register to
73 * see whether there are waiting Rx bytes.
74 */
75
76 struct digicolor_port {
77 struct uart_port port;
78 struct delayed_work rx_poll_work;
79 };
80
81 static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
82
digicolor_uart_tx_full(struct uart_port * port)83 static bool digicolor_uart_tx_full(struct uart_port *port)
84 {
85 return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
86 UA_STATUS_FIFO_TX_FULL);
87 }
88
digicolor_uart_rx_empty(struct uart_port * port)89 static bool digicolor_uart_rx_empty(struct uart_port *port)
90 {
91 return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
92 UA_STATUS_FIFO_RX_EMPTY);
93 }
94
digicolor_uart_stop_tx(struct uart_port * port)95 static void digicolor_uart_stop_tx(struct uart_port *port)
96 {
97 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
98
99 int_enable &= ~UA_INT_TX;
100 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
101 }
102
digicolor_uart_start_tx(struct uart_port * port)103 static void digicolor_uart_start_tx(struct uart_port *port)
104 {
105 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
106
107 int_enable |= UA_INT_TX;
108 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
109 }
110
digicolor_uart_stop_rx(struct uart_port * port)111 static void digicolor_uart_stop_rx(struct uart_port *port)
112 {
113 u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
114
115 int_enable &= ~UA_INT_RX;
116 writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
117 }
118
digicolor_rx_poll(struct work_struct * work)119 static void digicolor_rx_poll(struct work_struct *work)
120 {
121 struct digicolor_port *dp =
122 container_of(to_delayed_work(work),
123 struct digicolor_port, rx_poll_work);
124
125 if (!digicolor_uart_rx_empty(&dp->port))
126 /* force RX interrupt */
127 writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
128
129 schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
130 }
131
digicolor_uart_rx(struct uart_port * port)132 static void digicolor_uart_rx(struct uart_port *port)
133 {
134 unsigned long flags;
135
136 spin_lock_irqsave(&port->lock, flags);
137
138 while (1) {
139 u8 status, ch, ch_flag;
140
141 if (digicolor_uart_rx_empty(port))
142 break;
143
144 ch = readb_relaxed(port->membase + UA_EMI_REC);
145 status = readb_relaxed(port->membase + UA_STATUS);
146
147 port->icount.rx++;
148 ch_flag = TTY_NORMAL;
149
150 if (status) {
151 if (status & UA_STATUS_PARITY_ERR)
152 port->icount.parity++;
153 else if (status & UA_STATUS_FRAME_ERR)
154 port->icount.frame++;
155 else if (status & UA_STATUS_OVERRUN_ERR)
156 port->icount.overrun++;
157
158 status &= port->read_status_mask;
159
160 if (status & UA_STATUS_PARITY_ERR)
161 ch_flag = TTY_PARITY;
162 else if (status & UA_STATUS_FRAME_ERR)
163 ch_flag = TTY_FRAME;
164 else if (status & UA_STATUS_OVERRUN_ERR)
165 ch_flag = TTY_OVERRUN;
166 }
167
168 if (status & port->ignore_status_mask)
169 continue;
170
171 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
172 ch_flag);
173 }
174
175 spin_unlock_irqrestore(&port->lock, flags);
176
177 tty_flip_buffer_push(&port->state->port);
178 }
179
digicolor_uart_tx(struct uart_port * port)180 static void digicolor_uart_tx(struct uart_port *port)
181 {
182 struct circ_buf *xmit = &port->state->xmit;
183 unsigned long flags;
184
185 if (digicolor_uart_tx_full(port))
186 return;
187
188 spin_lock_irqsave(&port->lock, flags);
189
190 if (port->x_char) {
191 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
192 port->icount.tx++;
193 port->x_char = 0;
194 goto out;
195 }
196
197 if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
198 digicolor_uart_stop_tx(port);
199 goto out;
200 }
201
202 while (!uart_circ_empty(xmit)) {
203 writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
204 uart_xmit_advance(port, 1);
205
206 if (digicolor_uart_tx_full(port))
207 break;
208 }
209
210 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
211 uart_write_wakeup(port);
212
213 out:
214 spin_unlock_irqrestore(&port->lock, flags);
215 }
216
digicolor_uart_int(int irq,void * dev_id)217 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
218 {
219 struct uart_port *port = dev_id;
220 u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
221
222 writeb_relaxed(UA_INT_RX | UA_INT_TX,
223 port->membase + UA_INTFLAG_CLEAR);
224
225 if (int_status & UA_INT_RX)
226 digicolor_uart_rx(port);
227 if (int_status & UA_INT_TX)
228 digicolor_uart_tx(port);
229
230 return IRQ_HANDLED;
231 }
232
digicolor_uart_tx_empty(struct uart_port * port)233 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
234 {
235 u8 status = readb_relaxed(port->membase + UA_STATUS);
236
237 return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
238 }
239
digicolor_uart_get_mctrl(struct uart_port * port)240 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
241 {
242 return TIOCM_CTS;
243 }
244
digicolor_uart_set_mctrl(struct uart_port * port,unsigned int mctrl)245 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
246 {
247 }
248
digicolor_uart_break_ctl(struct uart_port * port,int state)249 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
250 {
251 }
252
digicolor_uart_startup(struct uart_port * port)253 static int digicolor_uart_startup(struct uart_port *port)
254 {
255 struct digicolor_port *dp =
256 container_of(port, struct digicolor_port, port);
257
258 writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
259 writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
260 writeb_relaxed(0, port->membase + UA_CONTROL);
261
262 writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
263 | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
264 port->membase + UA_CONFIG_FIFO);
265 writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
266 port->membase + UA_STATUS_FIFO);
267 writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
268 port->membase + UA_CONTROL);
269 writeb_relaxed(UA_INT_TX | UA_INT_RX,
270 port->membase + UA_INT_ENABLE);
271
272 schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
273
274 return 0;
275 }
276
digicolor_uart_shutdown(struct uart_port * port)277 static void digicolor_uart_shutdown(struct uart_port *port)
278 {
279 struct digicolor_port *dp =
280 container_of(port, struct digicolor_port, port);
281
282 writeb_relaxed(0, port->membase + UA_ENABLE);
283 cancel_delayed_work_sync(&dp->rx_poll_work);
284 }
285
digicolor_uart_set_termios(struct uart_port * port,struct ktermios * termios,const struct ktermios * old)286 static void digicolor_uart_set_termios(struct uart_port *port,
287 struct ktermios *termios,
288 const struct ktermios *old)
289 {
290 unsigned int baud, divisor;
291 u8 config = 0;
292 unsigned long flags;
293
294 /* Mask termios capabilities we don't support */
295 termios->c_cflag &= ~CMSPAR;
296 termios->c_iflag &= ~(BRKINT | IGNBRK);
297
298 /* Limit baud rates so that we don't need the fractional divider */
299 baud = uart_get_baud_rate(port, termios, old,
300 port->uartclk / (0x10000*16),
301 port->uartclk / 256);
302 divisor = uart_get_divisor(port, baud) - 1;
303
304 switch (termios->c_cflag & CSIZE) {
305 case CS7:
306 break;
307 case CS8:
308 default:
309 config |= UA_CONFIG_CHAR_LEN;
310 termios->c_cflag &= ~CSIZE;
311 termios->c_cflag |= CS8;
312 break;
313 }
314
315 if (termios->c_cflag & CSTOPB)
316 config |= UA_CONFIG_STOP_BITS;
317
318 if (termios->c_cflag & PARENB) {
319 config |= UA_CONFIG_PARITY;
320 if (termios->c_cflag & PARODD)
321 config |= UA_CONFIG_ODD_PARITY;
322 }
323
324 /* Set read status mask */
325 port->read_status_mask = UA_STATUS_OVERRUN_ERR;
326 if (termios->c_iflag & INPCK)
327 port->read_status_mask |= UA_STATUS_PARITY_ERR
328 | UA_STATUS_FRAME_ERR;
329
330 /* Set status ignore mask */
331 port->ignore_status_mask = 0;
332 if (!(termios->c_cflag & CREAD))
333 port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
334 | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
335
336 spin_lock_irqsave(&port->lock, flags);
337
338 uart_update_timeout(port, termios->c_cflag, baud);
339
340 writeb_relaxed(config, port->membase + UA_CONFIG);
341 writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
342 writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
343
344 spin_unlock_irqrestore(&port->lock, flags);
345 }
346
digicolor_uart_type(struct uart_port * port)347 static const char *digicolor_uart_type(struct uart_port *port)
348 {
349 return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
350 }
351
digicolor_uart_config_port(struct uart_port * port,int flags)352 static void digicolor_uart_config_port(struct uart_port *port, int flags)
353 {
354 if (flags & UART_CONFIG_TYPE)
355 port->type = PORT_DIGICOLOR;
356 }
357
digicolor_uart_release_port(struct uart_port * port)358 static void digicolor_uart_release_port(struct uart_port *port)
359 {
360 }
361
digicolor_uart_request_port(struct uart_port * port)362 static int digicolor_uart_request_port(struct uart_port *port)
363 {
364 return 0;
365 }
366
367 static const struct uart_ops digicolor_uart_ops = {
368 .tx_empty = digicolor_uart_tx_empty,
369 .set_mctrl = digicolor_uart_set_mctrl,
370 .get_mctrl = digicolor_uart_get_mctrl,
371 .stop_tx = digicolor_uart_stop_tx,
372 .start_tx = digicolor_uart_start_tx,
373 .stop_rx = digicolor_uart_stop_rx,
374 .break_ctl = digicolor_uart_break_ctl,
375 .startup = digicolor_uart_startup,
376 .shutdown = digicolor_uart_shutdown,
377 .set_termios = digicolor_uart_set_termios,
378 .type = digicolor_uart_type,
379 .config_port = digicolor_uart_config_port,
380 .release_port = digicolor_uart_release_port,
381 .request_port = digicolor_uart_request_port,
382 };
383
digicolor_uart_console_putchar(struct uart_port * port,unsigned char ch)384 static void digicolor_uart_console_putchar(struct uart_port *port, unsigned char ch)
385 {
386 while (digicolor_uart_tx_full(port))
387 cpu_relax();
388
389 writeb_relaxed(ch, port->membase + UA_EMI_REC);
390 }
391
digicolor_uart_console_write(struct console * co,const char * c,unsigned n)392 static void digicolor_uart_console_write(struct console *co, const char *c,
393 unsigned n)
394 {
395 struct uart_port *port = digicolor_ports[co->index];
396 u8 status;
397 unsigned long flags;
398 int locked = 1;
399
400 if (oops_in_progress)
401 locked = spin_trylock_irqsave(&port->lock, flags);
402 else
403 spin_lock_irqsave(&port->lock, flags);
404
405 uart_console_write(port, c, n, digicolor_uart_console_putchar);
406
407 if (locked)
408 spin_unlock_irqrestore(&port->lock, flags);
409
410 /* Wait for transmitter to become empty */
411 do {
412 status = readb_relaxed(port->membase + UA_STATUS);
413 } while ((status & UA_STATUS_TX_READY) == 0);
414 }
415
digicolor_uart_console_setup(struct console * co,char * options)416 static int digicolor_uart_console_setup(struct console *co, char *options)
417 {
418 int baud = 115200, bits = 8, parity = 'n', flow = 'n';
419 struct uart_port *port;
420
421 if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
422 return -EINVAL;
423
424 port = digicolor_ports[co->index];
425 if (!port)
426 return -ENODEV;
427
428 if (options)
429 uart_parse_options(options, &baud, &parity, &bits, &flow);
430
431 return uart_set_options(port, co, baud, parity, bits, flow);
432 }
433
434 static struct console digicolor_console = {
435 .name = "ttyS",
436 .device = uart_console_device,
437 .write = digicolor_uart_console_write,
438 .setup = digicolor_uart_console_setup,
439 .flags = CON_PRINTBUFFER,
440 .index = -1,
441 };
442
443 static struct uart_driver digicolor_uart = {
444 .driver_name = "digicolor-usart",
445 .dev_name = "ttyS",
446 .nr = DIGICOLOR_USART_NR,
447 };
448
digicolor_uart_probe(struct platform_device * pdev)449 static int digicolor_uart_probe(struct platform_device *pdev)
450 {
451 struct device_node *np = pdev->dev.of_node;
452 int irq, ret, index;
453 struct digicolor_port *dp;
454 struct resource *res;
455 struct clk *uart_clk;
456
457 if (!np) {
458 dev_err(&pdev->dev, "Missing device tree node\n");
459 return -ENXIO;
460 }
461
462 index = of_alias_get_id(np, "serial");
463 if (index < 0 || index >= DIGICOLOR_USART_NR)
464 return -EINVAL;
465
466 dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
467 if (!dp)
468 return -ENOMEM;
469
470 uart_clk = devm_clk_get(&pdev->dev, NULL);
471 if (IS_ERR(uart_clk))
472 return PTR_ERR(uart_clk);
473
474 dp->port.membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
475 if (IS_ERR(dp->port.membase))
476 return PTR_ERR(dp->port.membase);
477 dp->port.mapbase = res->start;
478
479 irq = platform_get_irq(pdev, 0);
480 if (irq < 0)
481 return irq;
482 dp->port.irq = irq;
483
484 dp->port.iotype = UPIO_MEM;
485 dp->port.uartclk = clk_get_rate(uart_clk);
486 dp->port.fifosize = 16;
487 dp->port.dev = &pdev->dev;
488 dp->port.ops = &digicolor_uart_ops;
489 dp->port.line = index;
490 dp->port.type = PORT_DIGICOLOR;
491 spin_lock_init(&dp->port.lock);
492
493 digicolor_ports[index] = &dp->port;
494 platform_set_drvdata(pdev, &dp->port);
495
496 INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
497
498 ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
499 dev_name(&pdev->dev), &dp->port);
500 if (ret)
501 return ret;
502
503 return uart_add_one_port(&digicolor_uart, &dp->port);
504 }
505
digicolor_uart_remove(struct platform_device * pdev)506 static int digicolor_uart_remove(struct platform_device *pdev)
507 {
508 struct uart_port *port = platform_get_drvdata(pdev);
509
510 uart_remove_one_port(&digicolor_uart, port);
511
512 return 0;
513 }
514
515 static const struct of_device_id digicolor_uart_dt_ids[] = {
516 { .compatible = "cnxt,cx92755-usart", },
517 { }
518 };
519 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
520
521 static struct platform_driver digicolor_uart_platform = {
522 .driver = {
523 .name = "digicolor-usart",
524 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
525 },
526 .probe = digicolor_uart_probe,
527 .remove = digicolor_uart_remove,
528 };
529
digicolor_uart_init(void)530 static int __init digicolor_uart_init(void)
531 {
532 int ret;
533
534 if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
535 digicolor_uart.cons = &digicolor_console;
536 digicolor_console.data = &digicolor_uart;
537 }
538
539 ret = uart_register_driver(&digicolor_uart);
540 if (ret)
541 return ret;
542
543 ret = platform_driver_register(&digicolor_uart_platform);
544 if (ret)
545 uart_unregister_driver(&digicolor_uart);
546
547 return ret;
548 }
549 module_init(digicolor_uart_init);
550
digicolor_uart_exit(void)551 static void __exit digicolor_uart_exit(void)
552 {
553 platform_driver_unregister(&digicolor_uart_platform);
554 uart_unregister_driver(&digicolor_uart);
555 }
556 module_exit(digicolor_uart_exit);
557
558 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
559 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
560 MODULE_LICENSE("GPL");
561