summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/timbuart.c
blob: e76c8b747fb83876dbf3c685c41fdb4dcedd4415 (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
/*
 * timbuart.c timberdale FPGA UART driver
 * Copyright (c) 2009 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* Supports:
 * Timberdale FPGA UART
 */

#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/serial_core.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/module.h>

#include "timbuart.h"

struct timbuart_port {
	struct uart_port	port;
	struct tasklet_struct	tasklet;
	int			usedma;
	u32			last_ier;
	struct platform_device  *dev;
};

static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
	921600, 1843200, 3250000};

static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);

static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);

static void timbuart_stop_rx(struct uart_port *port)
{
	/* spin lock held by upper layer, disable all RX interrupts */
	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
	iowrite32(ier, port->membase + TIMBUART_IER);
}

static void timbuart_stop_tx(struct uart_port *port)
{
	/* spinlock held by upper layer, disable TX interrupt */
	u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
	iowrite32(ier, port->membase + TIMBUART_IER);
}

static void timbuart_start_tx(struct uart_port *port)
{
	struct timbuart_port *uart =
		container_of(port, struct timbuart_port, port);

	/* do not transfer anything here -> fire off the tasklet */
	tasklet_schedule(&uart->tasklet);
}

static unsigned int timbuart_tx_empty(struct uart_port *port)
{
	u32 isr = ioread32(port->membase + TIMBUART_ISR);

	return (isr & TXBE) ? TIOCSER_TEMT : 0;
}

static void timbuart_flush_buffer(struct uart_port *port)
{
	if (!timbuart_tx_empty(port)) {
		u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
			TIMBUART_CTRL_FLSHTX;

		iowrite8(ctl, port->membase + TIMBUART_CTRL);
		iowrite32(TXBF, port->membase + TIMBUART_ISR);
	}
}

static void timbuart_rx_chars(struct uart_port *port)
{
	struct tty_struct *tty = port->state->port.tty;

	while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
		u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
		port->icount.rx++;
		tty_insert_flip_char(tty, ch, TTY_NORMAL);
	}

	spin_unlock(&port->lock);
	tty_flip_buffer_push(port->state->port.tty);
	spin_lock(&port->lock);

	dev_dbg(port->dev, "%s - total read %d bytes\n",
		__func__, port->icount.rx);
}

static void timbuart_tx_chars(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;

	while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
		!uart_circ_empty(xmit)) {
		iowrite8(xmit->buf[xmit->tail],
			port->membase + TIMBUART_TXFIFO);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
	}

	dev_dbg(port->dev,
		"%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
		 __func__,
		port->icount.tx,
		ioread8(port->membase + TIMBUART_CTRL),
		port->mctrl & TIOCM_RTS,
		ioread8(port->membase + TIMBUART_BAUDRATE));
}

static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
{
	struct timbuart_port *uart =
		container_of(port, struct timbuart_port, port);
	struct circ_buf *xmit = &port->state->xmit;

	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
		return;

	if (port->x_char)
		return;

	if (isr & TXFLAGS) {
		timbuart_tx_chars(port);
		/* clear all TX interrupts */
		iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);

		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
			uart_write_wakeup(port);
	} else
		/* Re-enable any tx interrupt */
		*ier |= uart->last_ier & TXFLAGS;

	/* enable interrupts if there are chars in the transmit buffer,
	 * Or if we delivered some bytes and want the almost empty interrupt
	 * we wake up the upper layer later when we got the interrupt
	 * to give it some time to go out...
	 */
	if (!uart_circ_empty(xmit))
		*ier |= TXBAE;

	dev_dbg(port->dev, "%s - leaving\n", __func__);
}

void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
{
	if (isr & RXFLAGS) {
		/* Some RX status is set */
		if (isr & RXBF) {
			u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
				TIMBUART_CTRL_FLSHRX;
			iowrite8(ctl, port->membase + TIMBUART_CTRL);
			port->icount.overrun++;
		} else if (isr & (RXDP))
			timbuart_rx_chars(port);

		/* ack all RX interrupts */
		iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
	}

	/* always have the RX interrupts enabled */
	*ier |= RXBAF | RXBF | RXTT;

	dev_dbg(port->dev, "%s - leaving\n", __func__);
}

void timbuart_tasklet(unsigned long arg)
{
	struct timbuart_port *uart = (struct timbuart_port *)arg;
	u32 isr, ier = 0;

	spin_lock(&uart->port.lock);

	isr = ioread32(uart->port.membase + TIMBUART_ISR);
	dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);

	if (!uart->usedma)
		timbuart_handle_tx_port(&uart->port, isr, &ier);

	timbuart_mctrl_check(&uart->port, isr, &ier);

	if (!uart->usedma)
		timbuart_handle_rx_port(&uart->port, isr, &ier);

	iowrite32(ier, uart->port.membase + TIMBUART_IER);

	spin_unlock(&uart->port.lock);
	dev_dbg(uart->port.dev, "%s leaving\n", __func__);
}

static unsigned int timbuart_get_mctrl(struct uart_port *port)
{
	u8 cts = ioread8(port->membase + TIMBUART_CTRL);
	dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);

	if (cts & TIMBUART_CTRL_CTS)
		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
	else
		return TIOCM_DSR | TIOCM_CAR;
}

static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);

	if (mctrl & TIOCM_RTS)
		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
	else
		iowrite8(0, port->membase + TIMBUART_CTRL);
}

static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
{
	unsigned int cts;

	if (isr & CTS_DELTA) {
		/* ack */
		iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
		cts = timbuart_get_mctrl(port);
		uart_handle_cts_change(port, cts & TIOCM_CTS);
		wake_up_interruptible(&port->state->port.delta_msr_wait);
	}

	*ier |= CTS_DELTA;
}

static void timbuart_enable_ms(struct uart_port *port)
{
	/* N/A */
}

static void timbuart_break_ctl(struct uart_port *port, int ctl)
{
	/* N/A */
}

static int timbuart_startup(struct uart_port *port)
{
	struct timbuart_port *uart =
		container_of(port, struct timbuart_port, port);

	dev_dbg(port->dev, "%s\n", __func__);

	iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
	iowrite32(0x1ff, port->membase + TIMBUART_ISR);
	/* Enable all but TX interrupts */
	iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
		port->membase + TIMBUART_IER);

	return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
		"timb-uart", uart);
}

static void timbuart_shutdown(struct uart_port *port)
{
	struct timbuart_port *uart =
		container_of(port, struct timbuart_port, port);
	dev_dbg(port->dev, "%s\n", __func__);
	free_irq(port->irq, uart);
	iowrite32(0, port->membase + TIMBUART_IER);
}

static int get_bindex(int baud)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(baudrates); i++)
		if (baud <= baudrates[i])
			return i;

	return -1;
}

static void timbuart_set_termios(struct uart_port *port,
	struct ktermios *termios,
	struct ktermios *old)
{
	unsigned int baud;
	short bindex;
	unsigned long flags;

	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
	bindex = get_bindex(baud);
	dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);

	if (bindex < 0)
		bindex = 0;
	baud = baudrates[bindex];

	/* The serial layer calls into this once with old = NULL when setting
	   up initially */
	if (old)
		tty_termios_copy_hw(termios, old);
	tty_termios_encode_baud_rate(termios, baud, baud);

	spin_lock_irqsave(&port->lock, flags);
	iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
	uart_update_timeout(port, termios->c_cflag, baud);
	spin_unlock_irqrestore(&port->lock, flags);
}

static const char *timbuart_type(struct uart_port *port)
{
	return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
}

/* We do not request/release mappings of the registers here,
 * currently it's done in the proble function.
 */
static void timbuart_release_port(struct uart_port *port)
{
	struct platform_device *pdev = to_platform_device(port->dev);
	int size =
		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));

	if (port->flags & UPF_IOREMAP) {
		iounmap(port->membase);
		port->membase = NULL;
	}

	release_mem_region(port->mapbase, size);
}

static int timbuart_request_port(struct uart_port *port)
{
	struct platform_device *pdev = to_platform_device(port->dev);
	int size =
		resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));

	if (!request_mem_region(port->mapbase, size, "timb-uart"))
		return -EBUSY;

	if (port->flags & UPF_IOREMAP) {
		port->membase = ioremap(port->mapbase, size);
		if (port->membase == NULL) {
			release_mem_region(port->mapbase, size);
			return -ENOMEM;
		}
	}

	return 0;
}

static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
{
	struct timbuart_port *uart = (struct timbuart_port *)devid;

	if (ioread8(uart->port.membase + TIMBUART_IPR)) {
		uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);

		/* disable interrupts, the tasklet enables them again */
		iowrite32(0, uart->port.membase + TIMBUART_IER);

		/* fire off bottom half */
		tasklet_schedule(&uart->tasklet);

		return IRQ_HANDLED;
	} else
		return IRQ_NONE;
}

/*
 * Configure/autoconfigure the port.
 */
static void timbuart_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE) {
		port->type = PORT_TIMBUART;
		timbuart_request_port(port);
	}
}

static int timbuart_verify_port(struct uart_port *port,
	struct serial_struct *ser)
{
	/* we don't want the core code to modify any port params */
	return -EINVAL;
}

static struct uart_ops timbuart_ops = {
	.tx_empty = timbuart_tx_empty,
	.set_mctrl = timbuart_set_mctrl,
	.get_mctrl = timbuart_get_mctrl,
	.stop_tx = timbuart_stop_tx,
	.start_tx = timbuart_start_tx,
	.flush_buffer = timbuart_flush_buffer,
	.stop_rx = timbuart_stop_rx,
	.enable_ms = timbuart_enable_ms,
	.break_ctl = timbuart_break_ctl,
	.startup = timbuart_startup,
	.shutdown = timbuart_shutdown,
	.set_termios = timbuart_set_termios,
	.type = timbuart_type,
	.release_port = timbuart_release_port,
	.request_port = timbuart_request_port,
	.config_port = timbuart_config_port,
	.verify_port = timbuart_verify_port
};

static struct uart_driver timbuart_driver = {
	.owner = THIS_MODULE,
	.driver_name = "timberdale_uart",
	.dev_name = "ttyTU",
	.major = TIMBUART_MAJOR,
	.minor = TIMBUART_MINOR,
	.nr = 1
};

static int __devinit timbuart_probe(struct platform_device *dev)
{
	int err, irq;
	struct timbuart_port *uart;
	struct resource *iomem;

	dev_dbg(&dev->dev, "%s\n", __func__);

	uart = kzalloc(sizeof(*uart), GFP_KERNEL);
	if (!uart) {
		err = -EINVAL;
		goto err_mem;
	}

	uart->usedma = 0;

	uart->port.uartclk = 3250000 * 16;
	uart->port.fifosize  = TIMBUART_FIFO_SIZE;
	uart->port.regshift  = 2;
	uart->port.iotype  = UPIO_MEM;
	uart->port.ops = &timbuart_ops;
	uart->port.irq = 0;
	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
	uart->port.line  = 0;
	uart->port.dev	= &dev->dev;

	iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
	if (!iomem) {
		err = -ENOMEM;
		goto err_register;
	}
	uart->port.mapbase = iomem->start;
	uart->port.membase = NULL;

	irq = platform_get_irq(dev, 0);
	if (irq < 0) {
		err = -EINVAL;
		goto err_register;
	}
	uart->port.irq = irq;

	tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);

	err = uart_register_driver(&timbuart_driver);
	if (err)
		goto err_register;

	err = uart_add_one_port(&timbuart_driver, &uart->port);
	if (err)
		goto err_add_port;

	platform_set_drvdata(dev, uart);

	return 0;

err_add_port:
	uart_unregister_driver(&timbuart_driver);
err_register:
	kfree(uart);
err_mem:
	printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
		err);

	return err;
}

static int __devexit timbuart_remove(struct platform_device *dev)
{
	struct timbuart_port *uart = platform_get_drvdata(dev);

	tasklet_kill(&uart->tasklet);
	uart_remove_one_port(&timbuart_driver, &uart->port);
	uart_unregister_driver(&timbuart_driver);
	kfree(uart);

	return 0;
}

static struct platform_driver timbuart_platform_driver = {
	.driver = {
		.name	= "timb-uart",
		.owner	= THIS_MODULE,
	},
	.probe		= timbuart_probe,
	.remove		= __devexit_p(timbuart_remove),
};

/*--------------------------------------------------------------------------*/

static int __init timbuart_init(void)
{
	return platform_driver_register(&timbuart_platform_driver);
}

static void __exit timbuart_exit(void)
{
	platform_driver_unregister(&timbuart_platform_driver);
}

module_init(timbuart_init);
module_exit(timbuart_exit);

MODULE_DESCRIPTION("Timberdale UART driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:timb-uart");

OpenPOWER on IntegriCloud