summaryrefslogtreecommitdiff
path: root/drivers/tty/serial/digicolor-usart.c
blob: 13ac36e2da4f0f2ea36e48c7619f369dde3239bd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
// SPDX-License-Identifier: GPL-2.0+
/*
 *  Driver for Conexant Digicolor serial ports (USART)
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * Copyright (C) 2014 Paradox Innovation Ltd.
 */

#include <linux/module.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/workqueue.h>

#define UA_ENABLE			0x00
#define UA_ENABLE_ENABLE		BIT(0)

#define UA_CONTROL			0x01
#define UA_CONTROL_RX_ENABLE		BIT(0)
#define UA_CONTROL_TX_ENABLE		BIT(1)
#define UA_CONTROL_SOFT_RESET		BIT(2)

#define UA_STATUS			0x02
#define UA_STATUS_PARITY_ERR		BIT(0)
#define UA_STATUS_FRAME_ERR		BIT(1)
#define UA_STATUS_OVERRUN_ERR		BIT(2)
#define UA_STATUS_TX_READY		BIT(6)

#define UA_CONFIG			0x03
#define UA_CONFIG_CHAR_LEN		BIT(0)
#define UA_CONFIG_STOP_BITS		BIT(1)
#define UA_CONFIG_PARITY		BIT(2)
#define UA_CONFIG_ODD_PARITY		BIT(4)

#define UA_EMI_REC			0x04

#define UA_HBAUD_LO			0x08
#define UA_HBAUD_HI			0x09

#define UA_STATUS_FIFO			0x0a
#define UA_STATUS_FIFO_RX_EMPTY		BIT(2)
#define UA_STATUS_FIFO_RX_INT_ALMOST	BIT(3)
#define UA_STATUS_FIFO_TX_FULL		BIT(4)
#define UA_STATUS_FIFO_TX_INT_ALMOST	BIT(7)

#define UA_CONFIG_FIFO			0x0b
#define UA_CONFIG_FIFO_RX_THRESH	7
#define UA_CONFIG_FIFO_RX_FIFO_MODE	BIT(3)
#define UA_CONFIG_FIFO_TX_FIFO_MODE	BIT(7)

#define UA_INTFLAG_CLEAR		0x1c
#define UA_INTFLAG_SET			0x1d
#define UA_INT_ENABLE			0x1e
#define UA_INT_STATUS			0x1f

#define UA_INT_TX			BIT(0)
#define UA_INT_RX			BIT(1)

#define DIGICOLOR_USART_NR		3

/*
 * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
 * only produced when the FIFO is filled more than a certain configurable
 * threshold. Unfortunately, there is no way to set this threshold below half
 * FIFO. This means that we must periodically poll the FIFO status register to
 * see whether there are waiting Rx bytes.
 */

struct digicolor_port {
	struct uart_port port;
	struct delayed_work rx_poll_work;
};

static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];

static bool digicolor_uart_tx_full(struct uart_port *port)
{
	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
		  UA_STATUS_FIFO_TX_FULL);
}

static bool digicolor_uart_rx_empty(struct uart_port *port)
{
	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
		  UA_STATUS_FIFO_RX_EMPTY);
}

static void digicolor_uart_stop_tx(struct uart_port *port)
{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable &= ~UA_INT_TX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
}

static void digicolor_uart_start_tx(struct uart_port *port)
{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable |= UA_INT_TX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
}

static void digicolor_uart_stop_rx(struct uart_port *port)
{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable &= ~UA_INT_RX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
}

static void digicolor_rx_poll(struct work_struct *work)
{
	struct digicolor_port *dp =
		container_of(to_delayed_work(work),
			     struct digicolor_port, rx_poll_work);

	if (!digicolor_uart_rx_empty(&dp->port))
		/* force RX interrupt */
		writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);

	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
}

static void digicolor_uart_rx(struct uart_port *port)
{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	while (1) {
		u8 status, ch;
		unsigned int ch_flag;

		if (digicolor_uart_rx_empty(port))
			break;

		ch = readb_relaxed(port->membase + UA_EMI_REC);
		status = readb_relaxed(port->membase + UA_STATUS);

		port->icount.rx++;
		ch_flag = TTY_NORMAL;

		if (status) {
			if (status & UA_STATUS_PARITY_ERR)
				port->icount.parity++;
			else if (status & UA_STATUS_FRAME_ERR)
				port->icount.frame++;
			else if (status & UA_STATUS_OVERRUN_ERR)
				port->icount.overrun++;

			status &= port->read_status_mask;

			if (status & UA_STATUS_PARITY_ERR)
				ch_flag = TTY_PARITY;
			else if (status & UA_STATUS_FRAME_ERR)
				ch_flag = TTY_FRAME;
			else if (status & UA_STATUS_OVERRUN_ERR)
				ch_flag = TTY_OVERRUN;
		}

		if (status & port->ignore_status_mask)
			continue;

		uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
				 ch_flag);
	}

	spin_unlock_irqrestore(&port->lock, flags);

	tty_flip_buffer_push(&port->state->port);
}

static void digicolor_uart_tx(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;
	unsigned long flags;

	if (digicolor_uart_tx_full(port))
		return;

	spin_lock_irqsave(&port->lock, flags);

	if (port->x_char) {
		writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
		port->icount.tx++;
		port->x_char = 0;
		goto out;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		digicolor_uart_stop_tx(port);
		goto out;
	}

	while (!uart_circ_empty(xmit)) {
		writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;

		if (digicolor_uart_tx_full(port))
			break;
	}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);

out:
	spin_unlock_irqrestore(&port->lock, flags);
}

static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);

	writeb_relaxed(UA_INT_RX | UA_INT_TX,
		       port->membase + UA_INTFLAG_CLEAR);

	if (int_status & UA_INT_RX)
		digicolor_uart_rx(port);
	if (int_status & UA_INT_TX)
		digicolor_uart_tx(port);

	return IRQ_HANDLED;
}

static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
{
	u8 status = readb_relaxed(port->membase + UA_STATUS);

	return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
}

static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
{
	return TIOCM_CTS;
}

static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

static void digicolor_uart_break_ctl(struct uart_port *port, int state)
{
}

static int digicolor_uart_startup(struct uart_port *port)
{
	struct digicolor_port *dp =
		container_of(port, struct digicolor_port, port);

	writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
	writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
	writeb_relaxed(0, port->membase + UA_CONTROL);

	writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
		       | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
		       port->membase + UA_CONFIG_FIFO);
	writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
		       port->membase + UA_STATUS_FIFO);
	writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
		       port->membase + UA_CONTROL);
	writeb_relaxed(UA_INT_TX | UA_INT_RX,
		       port->membase + UA_INT_ENABLE);

	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));

	return 0;
}

static void digicolor_uart_shutdown(struct uart_port *port)
{
	struct digicolor_port *dp =
		container_of(port, struct digicolor_port, port);

	writeb_relaxed(0, port->membase + UA_ENABLE);
	cancel_delayed_work_sync(&dp->rx_poll_work);
}

static void digicolor_uart_set_termios(struct uart_port *port,
				       struct ktermios *termios,
				       struct ktermios *old)
{
	unsigned int baud, divisor;
	u8 config = 0;
	unsigned long flags;

	/* Mask termios capabilities we don't support */
	termios->c_cflag &= ~CMSPAR;
	termios->c_iflag &= ~(BRKINT | IGNBRK);

	/* Limit baud rates so that we don't need the fractional divider */
	baud = uart_get_baud_rate(port, termios, old,
				  port->uartclk / (0x10000*16),
				  port->uartclk / 256);
	divisor = uart_get_divisor(port, baud) - 1;

	switch (termios->c_cflag & CSIZE) {
	case CS7:
		break;
	case CS8:
	default:
		config |= UA_CONFIG_CHAR_LEN;
		break;
	}

	if (termios->c_cflag & CSTOPB)
		config |= UA_CONFIG_STOP_BITS;

	if (termios->c_cflag & PARENB) {
		config |= UA_CONFIG_PARITY;
		if (termios->c_cflag & PARODD)
			config |= UA_CONFIG_ODD_PARITY;
	}

	/* Set read status mask */
	port->read_status_mask = UA_STATUS_OVERRUN_ERR;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= UA_STATUS_PARITY_ERR
			| UA_STATUS_FRAME_ERR;

	/* Set status ignore mask */
	port->ignore_status_mask = 0;
	if (!(termios->c_cflag & CREAD))
		port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
			| UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;

	spin_lock_irqsave(&port->lock, flags);

	uart_update_timeout(port, termios->c_cflag, baud);

	writeb_relaxed(config, port->membase + UA_CONFIG);
	writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
	writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);

	spin_unlock_irqrestore(&port->lock, flags);
}

static const char *digicolor_uart_type(struct uart_port *port)
{
	return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
}

static void digicolor_uart_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE)
		port->type = PORT_DIGICOLOR;
}

static void digicolor_uart_release_port(struct uart_port *port)
{
}

static int digicolor_uart_request_port(struct uart_port *port)
{
	return 0;
}

static const struct uart_ops digicolor_uart_ops = {
	.tx_empty	= digicolor_uart_tx_empty,
	.set_mctrl	= digicolor_uart_set_mctrl,
	.get_mctrl	= digicolor_uart_get_mctrl,
	.stop_tx	= digicolor_uart_stop_tx,
	.start_tx	= digicolor_uart_start_tx,
	.stop_rx	= digicolor_uart_stop_rx,
	.break_ctl	= digicolor_uart_break_ctl,
	.startup	= digicolor_uart_startup,
	.shutdown	= digicolor_uart_shutdown,
	.set_termios	= digicolor_uart_set_termios,
	.type		= digicolor_uart_type,
	.config_port	= digicolor_uart_config_port,
	.release_port	= digicolor_uart_release_port,
	.request_port	= digicolor_uart_request_port,
};

static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
{
	while (digicolor_uart_tx_full(port))
		cpu_relax();

	writeb_relaxed(ch, port->membase + UA_EMI_REC);
}

static void digicolor_uart_console_write(struct console *co, const char *c,
					 unsigned n)
{
	struct uart_port *port = digicolor_ports[co->index];
	u8 status;
	unsigned long flags;
	int locked = 1;

	if (oops_in_progress)
		locked = spin_trylock_irqsave(&port->lock, flags);
	else
		spin_lock_irqsave(&port->lock, flags);

	uart_console_write(port, c, n, digicolor_uart_console_putchar);

	if (locked)
		spin_unlock_irqrestore(&port->lock, flags);

	/* Wait for transmitter to become empty */
	do {
		status = readb_relaxed(port->membase + UA_STATUS);
	} while ((status & UA_STATUS_TX_READY) == 0);
}

static int digicolor_uart_console_setup(struct console *co, char *options)
{
	int baud = 115200, bits = 8, parity = 'n', flow = 'n';
	struct uart_port *port;

	if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
		return -EINVAL;

	port = digicolor_ports[co->index];
	if (!port)
		return -ENODEV;

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct console digicolor_console = {
	.name	= "ttyS",
	.device	= uart_console_device,
	.write	= digicolor_uart_console_write,
	.setup	= digicolor_uart_console_setup,
	.flags	= CON_PRINTBUFFER,
	.index	= -1,
};

static struct uart_driver digicolor_uart = {
	.driver_name	= "digicolor-usart",
	.dev_name	= "ttyS",
	.nr		= DIGICOLOR_USART_NR,
};

static int digicolor_uart_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	int irq, ret, index;
	struct digicolor_port *dp;
	struct resource *res;
	struct clk *uart_clk;

	if (!np) {
		dev_err(&pdev->dev, "Missing device tree node\n");
		return -ENXIO;
	}

	index = of_alias_get_id(np, "serial");
	if (index < 0 || index >= DIGICOLOR_USART_NR)
		return -EINVAL;

	dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
	if (!dp)
		return -ENOMEM;

	uart_clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(uart_clk))
		return PTR_ERR(uart_clk);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	dp->port.mapbase = res->start;
	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(dp->port.membase))
		return PTR_ERR(dp->port.membase);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;
	dp->port.irq = irq;

	dp->port.iotype = UPIO_MEM;
	dp->port.uartclk = clk_get_rate(uart_clk);
	dp->port.fifosize = 16;
	dp->port.dev = &pdev->dev;
	dp->port.ops = &digicolor_uart_ops;
	dp->port.line = index;
	dp->port.type = PORT_DIGICOLOR;
	spin_lock_init(&dp->port.lock);

	digicolor_ports[index] = &dp->port;
	platform_set_drvdata(pdev, &dp->port);

	INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);

	ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
			       dev_name(&pdev->dev), &dp->port);
	if (ret)
		return ret;

	return uart_add_one_port(&digicolor_uart, &dp->port);
}

static int digicolor_uart_remove(struct platform_device *pdev)
{
	struct uart_port *port = platform_get_drvdata(pdev);

	uart_remove_one_port(&digicolor_uart, port);

	return 0;
}

static const struct of_device_id digicolor_uart_dt_ids[] = {
	{ .compatible = "cnxt,cx92755-usart", },
	{ }
};
MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);

static struct platform_driver digicolor_uart_platform = {
	.driver = {
		.name		= "digicolor-usart",
		.of_match_table	= of_match_ptr(digicolor_uart_dt_ids),
	},
	.probe	= digicolor_uart_probe,
	.remove	= digicolor_uart_remove,
};

static int __init digicolor_uart_init(void)
{
	int ret;

	if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
		digicolor_uart.cons = &digicolor_console;
		digicolor_console.data = &digicolor_uart;
	}

	ret = uart_register_driver(&digicolor_uart);
	if (ret)
		return ret;

	ret = platform_driver_register(&digicolor_uart_platform);
	if (ret)
		uart_unregister_driver(&digicolor_uart);

	return ret;
}
module_init(digicolor_uart_init);

static void __exit digicolor_uart_exit(void)
{
	platform_driver_unregister(&digicolor_uart_platform);
	uart_unregister_driver(&digicolor_uart);
}
module_exit(digicolor_uart_exit);

MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
MODULE_LICENSE("GPL");