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[mirror_ubuntu-hirsute-kernel.git] / drivers / tty / serial / digicolor-usart.c
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
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
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
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
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
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
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
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;
140 unsigned int ch_flag;
141
142 if (digicolor_uart_rx_empty(port))
143 break;
144
145 ch = readb_relaxed(port->membase + UA_EMI_REC);
146 status = readb_relaxed(port->membase + UA_STATUS);
147
148 port->icount.rx++;
149 ch_flag = TTY_NORMAL;
150
151 if (status) {
152 if (status & UA_STATUS_PARITY_ERR)
153 port->icount.parity++;
154 else if (status & UA_STATUS_FRAME_ERR)
155 port->icount.frame++;
156 else if (status & UA_STATUS_OVERRUN_ERR)
157 port->icount.overrun++;
158
159 status &= port->read_status_mask;
160
161 if (status & UA_STATUS_PARITY_ERR)
162 ch_flag = TTY_PARITY;
163 else if (status & UA_STATUS_FRAME_ERR)
164 ch_flag = TTY_FRAME;
165 else if (status & UA_STATUS_OVERRUN_ERR)
166 ch_flag = TTY_OVERRUN;
167 }
168
169 if (status & port->ignore_status_mask)
170 continue;
171
172 uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
173 ch_flag);
174 }
175
176 spin_unlock_irqrestore(&port->lock, flags);
177
178 tty_flip_buffer_push(&port->state->port);
179 }
180
181 static void digicolor_uart_tx(struct uart_port *port)
182 {
183 struct circ_buf *xmit = &port->state->xmit;
184 unsigned long flags;
185
186 if (digicolor_uart_tx_full(port))
187 return;
188
189 spin_lock_irqsave(&port->lock, flags);
190
191 if (port->x_char) {
192 writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
193 port->icount.tx++;
194 port->x_char = 0;
195 goto out;
196 }
197
198 if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
199 digicolor_uart_stop_tx(port);
200 goto out;
201 }
202
203 while (!uart_circ_empty(xmit)) {
204 writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
205 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
206 port->icount.tx++;
207
208 if (digicolor_uart_tx_full(port))
209 break;
210 }
211
212 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
213 uart_write_wakeup(port);
214
215 out:
216 spin_unlock_irqrestore(&port->lock, flags);
217 }
218
219 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
220 {
221 struct uart_port *port = dev_id;
222 u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
223
224 writeb_relaxed(UA_INT_RX | UA_INT_TX,
225 port->membase + UA_INTFLAG_CLEAR);
226
227 if (int_status & UA_INT_RX)
228 digicolor_uart_rx(port);
229 if (int_status & UA_INT_TX)
230 digicolor_uart_tx(port);
231
232 return IRQ_HANDLED;
233 }
234
235 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
236 {
237 u8 status = readb_relaxed(port->membase + UA_STATUS);
238
239 return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
240 }
241
242 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
243 {
244 return TIOCM_CTS;
245 }
246
247 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
248 {
249 }
250
251 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
252 {
253 }
254
255 static int digicolor_uart_startup(struct uart_port *port)
256 {
257 struct digicolor_port *dp =
258 container_of(port, struct digicolor_port, port);
259
260 writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
261 writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
262 writeb_relaxed(0, port->membase + UA_CONTROL);
263
264 writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
265 | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
266 port->membase + UA_CONFIG_FIFO);
267 writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
268 port->membase + UA_STATUS_FIFO);
269 writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
270 port->membase + UA_CONTROL);
271 writeb_relaxed(UA_INT_TX | UA_INT_RX,
272 port->membase + UA_INT_ENABLE);
273
274 schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
275
276 return 0;
277 }
278
279 static void digicolor_uart_shutdown(struct uart_port *port)
280 {
281 struct digicolor_port *dp =
282 container_of(port, struct digicolor_port, port);
283
284 writeb_relaxed(0, port->membase + UA_ENABLE);
285 cancel_delayed_work_sync(&dp->rx_poll_work);
286 }
287
288 static void digicolor_uart_set_termios(struct uart_port *port,
289 struct ktermios *termios,
290 struct ktermios *old)
291 {
292 unsigned int baud, divisor;
293 u8 config = 0;
294 unsigned long flags;
295
296 /* Mask termios capabilities we don't support */
297 termios->c_cflag &= ~CMSPAR;
298 termios->c_iflag &= ~(BRKINT | IGNBRK);
299
300 /* Limit baud rates so that we don't need the fractional divider */
301 baud = uart_get_baud_rate(port, termios, old,
302 port->uartclk / (0x10000*16),
303 port->uartclk / 256);
304 divisor = uart_get_divisor(port, baud) - 1;
305
306 switch (termios->c_cflag & CSIZE) {
307 case CS7:
308 break;
309 case CS8:
310 default:
311 config |= UA_CONFIG_CHAR_LEN;
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
347 static const char *digicolor_uart_type(struct uart_port *port)
348 {
349 return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
350 }
351
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
358 static void digicolor_uart_release_port(struct uart_port *port)
359 {
360 }
361
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
384 static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
385 {
386 while (digicolor_uart_tx_full(port))
387 cpu_relax();
388
389 writeb_relaxed(ch, port->membase + UA_EMI_REC);
390 }
391
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
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
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 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
475 dp->port.mapbase = res->start;
476 dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
477 if (IS_ERR(dp->port.membase))
478 return PTR_ERR(dp->port.membase);
479
480 irq = platform_get_irq(pdev, 0);
481 if (irq < 0)
482 return irq;
483 dp->port.irq = irq;
484
485 dp->port.iotype = UPIO_MEM;
486 dp->port.uartclk = clk_get_rate(uart_clk);
487 dp->port.fifosize = 16;
488 dp->port.dev = &pdev->dev;
489 dp->port.ops = &digicolor_uart_ops;
490 dp->port.line = index;
491 dp->port.type = PORT_DIGICOLOR;
492 spin_lock_init(&dp->port.lock);
493
494 digicolor_ports[index] = &dp->port;
495 platform_set_drvdata(pdev, &dp->port);
496
497 INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
498
499 ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
500 dev_name(&pdev->dev), &dp->port);
501 if (ret)
502 return ret;
503
504 return uart_add_one_port(&digicolor_uart, &dp->port);
505 }
506
507 static int digicolor_uart_remove(struct platform_device *pdev)
508 {
509 struct uart_port *port = platform_get_drvdata(pdev);
510
511 uart_remove_one_port(&digicolor_uart, port);
512
513 return 0;
514 }
515
516 static const struct of_device_id digicolor_uart_dt_ids[] = {
517 { .compatible = "cnxt,cx92755-usart", },
518 { }
519 };
520 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
521
522 static struct platform_driver digicolor_uart_platform = {
523 .driver = {
524 .name = "digicolor-usart",
525 .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
526 },
527 .probe = digicolor_uart_probe,
528 .remove = digicolor_uart_remove,
529 };
530
531 static int __init digicolor_uart_init(void)
532 {
533 int ret;
534
535 if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
536 digicolor_uart.cons = &digicolor_console;
537 digicolor_console.data = &digicolor_uart;
538 }
539
540 ret = uart_register_driver(&digicolor_uart);
541 if (ret)
542 return ret;
543
544 return platform_driver_register(&digicolor_uart_platform);
545 }
546 module_init(digicolor_uart_init);
547
548 static void __exit digicolor_uart_exit(void)
549 {
550 platform_driver_unregister(&digicolor_uart_platform);
551 uart_unregister_driver(&digicolor_uart);
552 }
553 module_exit(digicolor_uart_exit);
554
555 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
556 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
557 MODULE_LICENSE("GPL");
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