summaryrefslogtreecommitdiff
path: root/target/linux/ramips/files/drivers/spi/spi-ramips.c
blob: e6a2d8e56180c65efb2e64d408c78e722d46458a (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
/*
 * ramips_spi.c -- Ralink RT288x/RT305x SPI controller driver
 *
 * Copyright (C) 2011 Sergiy <piratfm@gmail.com>
 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
 *
 * 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.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/spi/spi.h>

#define DRIVER_NAME			"ramips-spi"
#define RALINK_NUM_CHIPSELECTS		1 /* only one slave is supported*/
#define RALINK_SPI_WAIT_RDY_MAX_LOOP	2000 /* in usec */

#define RAMIPS_SPI_STAT			0x00
#define RAMIPS_SPI_CFG			0x10
#define RAMIPS_SPI_CTL			0x14
#define RAMIPS_SPI_DATA			0x20

/* SPISTAT register bit field */
#define SPISTAT_BUSY			BIT(0)

/* SPICFG register bit field */
#define SPICFG_LSBFIRST			0
#define SPICFG_MSBFIRST			BIT(8)
#define SPICFG_SPICLKPOL		BIT(6)
#define SPICFG_RXCLKEDGE_FALLING	BIT(5)
#define SPICFG_TXCLKEDGE_FALLING	BIT(4)
#define SPICFG_SPICLK_PRESCALE_MASK	0x7
#define SPICFG_SPICLK_DIV2		0
#define SPICFG_SPICLK_DIV4		1
#define SPICFG_SPICLK_DIV8		2
#define SPICFG_SPICLK_DIV16		3
#define SPICFG_SPICLK_DIV32		4
#define SPICFG_SPICLK_DIV64		5
#define SPICFG_SPICLK_DIV128		6
#define SPICFG_SPICLK_DISABLE		7

/* SPICTL register bit field */
#define SPICTL_HIZSDO			BIT(3)
#define SPICTL_STARTWR			BIT(2)
#define SPICTL_STARTRD			BIT(1)
#define SPICTL_SPIENA			BIT(0)

#ifdef DEBUG
#define spi_debug(args...) printk(args)
#else
#define spi_debug(args...)
#endif

struct ramips_spi {
	struct work_struct	work;

	/* Lock access to transfer list.*/
	spinlock_t		lock;

	struct list_head	msg_queue;
	struct spi_master	*master;
	void __iomem		*base;
	unsigned int		sys_freq;
	unsigned int		speed;

	struct clk		*clk;
};

static struct workqueue_struct *ramips_spi_wq;

static inline struct ramips_spi *ramips_spidev_to_rs(struct spi_device *spi)
{
	return spi_master_get_devdata(spi->master);
}

static inline u32 ramips_spi_read(struct ramips_spi *rs, u32 reg)
{
	return ioread32(rs->base + reg);
}

static inline void ramips_spi_write(struct ramips_spi *rs, u32 reg, u32 val)
{
	iowrite32(val, rs->base + reg);
}

static inline void ramips_spi_setbits(struct ramips_spi *rs, u32 reg, u32 mask)
{
	void __iomem *addr = rs->base + reg;
	u32 val;

	val = ioread32(addr);
	val |= mask;
	iowrite32(val, addr);
}

static inline void ramips_spi_clrbits(struct ramips_spi *rs, u32 reg, u32 mask)
{
	void __iomem *addr = rs->base + reg;
	u32 val;

	val = ioread32(addr);
	val &= ~mask;
	iowrite32(val, addr);
}

static int ramips_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
{
	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
	u32 rate;
	u32 prescale;
	u32 reg;

	spi_debug("%s: speed:%u\n", __func__, speed);

	/*
	 * the supported rates are: 2,4,8...128
	 * round up as we look for equal or less speed
	 */
	rate = DIV_ROUND_UP(rs->sys_freq, speed);
	spi_debug("%s: rate-1:%u\n", __func__, rate);
	rate = roundup_pow_of_two(rate);
	spi_debug("%s: rate-2:%u\n", __func__, rate);

	/* check if requested speed is too small */
	if (rate > 128)
		return -EINVAL;

	if (rate < 2)
		rate = 2;

	/* Convert the rate to SPI clock divisor value.	*/
	prescale = ilog2(rate/2);
	spi_debug("%s: prescale:%u\n", __func__, prescale);

	reg = ramips_spi_read(rs, RAMIPS_SPI_CFG);
	reg = ((reg & ~SPICFG_SPICLK_PRESCALE_MASK) | prescale);
	ramips_spi_write(rs, RAMIPS_SPI_CFG, reg);
	rs->speed = speed;
	return 0;
}

/*
 * called only when no transfer is active on the bus
 */
static int
ramips_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
{
	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
	unsigned int speed = spi->max_speed_hz;
	int	rc;
	unsigned int bits_per_word = 8;

	if ((t != NULL) && t->speed_hz)
		speed = t->speed_hz;

	if ((t != NULL) && t->bits_per_word)
		bits_per_word = t->bits_per_word;

	if (rs->speed != speed) {
		spi_debug("%s: speed_hz:%u\n", __func__, speed);
		rc = ramips_spi_baudrate_set(spi, speed);
		if (rc)
			return rc;
	}

	if (bits_per_word != 8) {
		spi_debug("%s: bad bits_per_word: %u\n", __func__,
			  bits_per_word);
		return -EINVAL;
	}

	return 0;
}

static void ramips_spi_set_cs(struct ramips_spi *rs, int enable)
{
	if (enable)
		ramips_spi_clrbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
	else
		ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
}

static inline int ramips_spi_wait_till_ready(struct ramips_spi *rs)
{
	int i;

	for (i = 0; i < RALINK_SPI_WAIT_RDY_MAX_LOOP; i++) {
		u32 status;

		status = ramips_spi_read(rs, RAMIPS_SPI_STAT);
		if ((status & SPISTAT_BUSY) == 0)
			return 0;

		udelay(1);
	}

	return -ETIMEDOUT;
}

static unsigned int
ramips_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
{
	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
	unsigned count = 0;
	u8 *rx = xfer->rx_buf;
	const u8 *tx = xfer->tx_buf;
	int err;

	spi_debug("%s(%d): %s %s\n", __func__, xfer->len,
		  (tx != NULL) ? "tx" : "  ",
		  (rx != NULL) ? "rx" : "  ");

	if (tx) {
		for (count = 0; count < xfer->len; count++) {
			ramips_spi_write(rs, RAMIPS_SPI_DATA, tx[count]);
			ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTWR);
			err = ramips_spi_wait_till_ready(rs);
			if (err) {
				dev_err(&spi->dev, "TX failed, err=%d\n", err);
				goto out;
			}
		}
	}

	if (rx) {
		for (count = 0; count < xfer->len; count++) {
			ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTRD);
			err = ramips_spi_wait_till_ready(rs);
			if (err) {
				dev_err(&spi->dev, "RX failed, err=%d\n", err);
				goto out;
			}
			rx[count] = (u8) ramips_spi_read(rs, RAMIPS_SPI_DATA);
		}
	}

out:
	return count;
}

static void ramips_spi_work(struct work_struct *work)
{
	struct ramips_spi *rs =
		container_of(work, struct ramips_spi, work);

	spin_lock_irq(&rs->lock);
	while (!list_empty(&rs->msg_queue)) {
		struct spi_message *m;
		struct spi_device *spi;
		struct spi_transfer *t = NULL;
		int par_override = 0;
		int status = 0;
		int cs_active = 0;

		m = container_of(rs->msg_queue.next, struct spi_message,
				 queue);

		list_del_init(&m->queue);
		spin_unlock_irq(&rs->lock);

		spi = m->spi;

		/* Load defaults */
		status = ramips_spi_setup_transfer(spi, NULL);

		if (status < 0)
			goto msg_done;

		list_for_each_entry(t, &m->transfers, transfer_list) {
			if (par_override || t->speed_hz || t->bits_per_word) {
				par_override = 1;
				status = ramips_spi_setup_transfer(spi, t);
				if (status < 0)
					break;
				if (!t->speed_hz && !t->bits_per_word)
					par_override = 0;
			}

			if (!cs_active) {
				ramips_spi_set_cs(rs, 1);
				cs_active = 1;
			}

			if (t->len)
				m->actual_length +=
					ramips_spi_write_read(spi, t);

			if (t->delay_usecs)
				udelay(t->delay_usecs);

			if (t->cs_change) {
				ramips_spi_set_cs(rs, 0);
				cs_active = 0;
			}
		}

msg_done:
		if (cs_active)
			ramips_spi_set_cs(rs, 0);

		m->status = status;
		m->complete(m->context);

		spin_lock_irq(&rs->lock);
	}

	spin_unlock_irq(&rs->lock);
}

static int ramips_spi_setup(struct spi_device *spi)
{
	struct ramips_spi *rs = ramips_spidev_to_rs(spi);

	if ((spi->max_speed_hz == 0) ||
	    (spi->max_speed_hz > (rs->sys_freq / 2)))
		spi->max_speed_hz = (rs->sys_freq / 2);

	if (spi->max_speed_hz < (rs->sys_freq/128)) {
		dev_err(&spi->dev, "setup: requested speed too low %d Hz\n",
			spi->max_speed_hz);
		return -EINVAL;
	}

	if (spi->bits_per_word != 0 && spi->bits_per_word != 8) {
		dev_err(&spi->dev,
			"setup: requested bits per words - os wrong %d bpw\n",
			spi->bits_per_word);
		return -EINVAL;
	}

	if (spi->bits_per_word == 0)
		spi->bits_per_word = 8;

	/*
	 * baudrate & width will be set ramips_spi_setup_transfer
	 */
	return 0;
}

static int ramips_spi_transfer(struct spi_device *spi, struct spi_message *m)
{
	struct ramips_spi *rs;
	struct spi_transfer *t = NULL;
	unsigned long flags;

	m->actual_length = 0;
	m->status = 0;

	/* reject invalid messages and transfers */
	if (list_empty(&m->transfers) || !m->complete)
		return -EINVAL;

	rs = ramips_spidev_to_rs(spi);

	list_for_each_entry(t, &m->transfers, transfer_list) {
		unsigned int bits_per_word = spi->bits_per_word;

		if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
			dev_err(&spi->dev,
				"message rejected : "
				"invalid transfer data buffers\n");
			goto msg_rejected;
		}

		if (t->bits_per_word)
			bits_per_word = t->bits_per_word;

		if (bits_per_word != 8) {
			dev_err(&spi->dev,
				"message rejected : "
				"invalid transfer bits_per_word (%d bits)\n",
				bits_per_word);
			goto msg_rejected;
		}

		if (t->speed_hz && t->speed_hz < (rs->sys_freq/128)) {
			dev_err(&spi->dev,
				"message rejected : "
				"device min speed (%d Hz) exceeds "
				"required transfer speed (%d Hz)\n",
				(rs->sys_freq/128), t->speed_hz);
			goto msg_rejected;
		}
	}


	spin_lock_irqsave(&rs->lock, flags);
	list_add_tail(&m->queue, &rs->msg_queue);
	queue_work(ramips_spi_wq, &rs->work);
	spin_unlock_irqrestore(&rs->lock, flags);

	return 0;
msg_rejected:
	/* Message rejected and not queued */
	m->status = -EINVAL;
	if (m->complete)
		m->complete(m->context);
	return -EINVAL;
}

static void __init ramips_spi_reset(struct ramips_spi *rs)
{
	ramips_spi_write(rs, RAMIPS_SPI_CFG,
			 SPICFG_MSBFIRST | SPICFG_TXCLKEDGE_FALLING |
			 SPICFG_SPICLK_DIV16 | SPICFG_SPICLKPOL);
	ramips_spi_write(rs, RAMIPS_SPI_CTL, SPICTL_HIZSDO | SPICTL_SPIENA);
}

static int __init ramips_spi_probe(struct platform_device *pdev)
{
	struct spi_master *master;
	struct ramips_spi *rs;
	struct resource *r;
	int status = 0;

	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
	if (master == NULL) {
		dev_dbg(&pdev->dev, "master allocation failed\n");
		return -ENOMEM;
	}

	if (pdev->id != -1)
		master->bus_num = pdev->id;

	/* we support only mode 0, and no options */
	master->mode_bits = 0;

	master->setup = ramips_spi_setup;
	master->transfer = ramips_spi_transfer;
	master->num_chipselect = RALINK_NUM_CHIPSELECTS;

	dev_set_drvdata(&pdev->dev, master);

	rs = spi_master_get_devdata(master);
	rs->master = master;

	rs->clk = clk_get(NULL, "sys");
	if (IS_ERR(rs->clk)) {
		status = PTR_ERR(rs->clk);
		dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
			status);
		goto out_put_master;
	}

	status = clk_enable(rs->clk);
	if (status)
		goto out_put_clk;

	rs->sys_freq = clk_get_rate(rs->clk);
	spi_debug("%s: sys_freq: %ld\n", __func__, rs->sys_freq);

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (r == NULL) {
		status = -ENODEV;
		goto out_disable_clk;
	}

	if (!request_mem_region(r->start, (r->end - r->start) + 1,
				dev_name(&pdev->dev))) {
		status = -EBUSY;
		goto out_disable_clk;
	}

	rs->base = ioremap(r->start, resource_size(r));
	if (rs->base == NULL) {
		dev_err(&pdev->dev, "ioremap failed\n");
		status = -ENOMEM;
		goto out_rel_mem;
	}

	INIT_WORK(&rs->work, ramips_spi_work);

	spin_lock_init(&rs->lock);
	INIT_LIST_HEAD(&rs->msg_queue);

	ramips_spi_reset(rs);

	status = spi_register_master(master);
	if (status)
		goto out_unmap_base;

	return 0;

out_unmap_base:
	iounmap(rs->base);
out_rel_mem:
	release_mem_region(r->start, (r->end - r->start) + 1);
out_disable_clk:
	clk_disable(rs->clk);
out_put_clk:
	clk_put(rs->clk);
out_put_master:
	spi_master_put(master);
	return status;
}

static int __devexit ramips_spi_remove(struct platform_device *pdev)
{
	struct spi_master *master;
	struct ramips_spi *rs;
	struct resource *r;

	master = dev_get_drvdata(&pdev->dev);
	rs = spi_master_get_devdata(master);

	cancel_work_sync(&rs->work);

	iounmap(rs->base);
	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	release_mem_region(r->start, (r->end - r->start) + 1);

	clk_disable(rs->clk);
	clk_put(rs->clk);
	spi_unregister_master(master);

	return 0;
}

MODULE_ALIAS("platform:" DRIVER_NAME);

static struct platform_driver ramips_spi_driver = {
	.driver = {
		.name	= DRIVER_NAME,
		.owner	= THIS_MODULE,
	},
	.remove		= __devexit_p(ramips_spi_remove),
};

static int __init ramips_spi_init(void)
{
	ramips_spi_wq = create_singlethread_workqueue(
				ramips_spi_driver.driver.name);
	if (ramips_spi_wq == NULL)
		return -ENOMEM;

	return platform_driver_probe(&ramips_spi_driver, ramips_spi_probe);
}
module_init(ramips_spi_init);

static void __exit ramips_spi_exit(void)
{
	flush_workqueue(ramips_spi_wq);
	platform_driver_unregister(&ramips_spi_driver);

	destroy_workqueue(ramips_spi_wq);
}
module_exit(ramips_spi_exit);

MODULE_DESCRIPTION("Ralink SPI driver");
MODULE_AUTHOR("Sergiy <piratfm@gmail.com>");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL");