summaryrefslogtreecommitdiff
path: root/drivers/spi/spi-tegra20-sflash.c
blob: 08794977f21ae38e35186e5347d40d8bb7bdcb7d (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
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
/*
 * SPI driver for Nvidia's Tegra20 Serial Flash Controller.
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/reset.h>
#include <linux/spi/spi.h>

#define SPI_COMMAND				0x000
#define SPI_GO					BIT(30)
#define SPI_M_S					BIT(28)
#define SPI_ACTIVE_SCLK_MASK			(0x3 << 26)
#define SPI_ACTIVE_SCLK_DRIVE_LOW		(0 << 26)
#define SPI_ACTIVE_SCLK_DRIVE_HIGH		(1 << 26)
#define SPI_ACTIVE_SCLK_PULL_LOW		(2 << 26)
#define SPI_ACTIVE_SCLK_PULL_HIGH		(3 << 26)

#define SPI_CK_SDA_FALLING			(1 << 21)
#define SPI_CK_SDA_RISING			(0 << 21)
#define SPI_CK_SDA_MASK				(1 << 21)
#define SPI_ACTIVE_SDA				(0x3 << 18)
#define SPI_ACTIVE_SDA_DRIVE_LOW		(0 << 18)
#define SPI_ACTIVE_SDA_DRIVE_HIGH		(1 << 18)
#define SPI_ACTIVE_SDA_PULL_LOW			(2 << 18)
#define SPI_ACTIVE_SDA_PULL_HIGH		(3 << 18)

#define SPI_CS_POL_INVERT			BIT(16)
#define SPI_TX_EN				BIT(15)
#define SPI_RX_EN				BIT(14)
#define SPI_CS_VAL_HIGH				BIT(13)
#define SPI_CS_VAL_LOW				0x0
#define SPI_CS_SW				BIT(12)
#define SPI_CS_HW				0x0
#define SPI_CS_DELAY_MASK			(7 << 9)
#define SPI_CS3_EN				BIT(8)
#define SPI_CS2_EN				BIT(7)
#define SPI_CS1_EN				BIT(6)
#define SPI_CS0_EN				BIT(5)

#define SPI_CS_MASK			(SPI_CS3_EN | SPI_CS2_EN |	\
					SPI_CS1_EN | SPI_CS0_EN)
#define SPI_BIT_LENGTH(x)		(((x) & 0x1f) << 0)

#define SPI_MODES			(SPI_ACTIVE_SCLK_MASK | SPI_CK_SDA_MASK)

#define SPI_STATUS			0x004
#define SPI_BSY				BIT(31)
#define SPI_RDY				BIT(30)
#define SPI_TXF_FLUSH			BIT(29)
#define SPI_RXF_FLUSH			BIT(28)
#define SPI_RX_UNF			BIT(27)
#define SPI_TX_OVF			BIT(26)
#define SPI_RXF_EMPTY			BIT(25)
#define SPI_RXF_FULL			BIT(24)
#define SPI_TXF_EMPTY			BIT(23)
#define SPI_TXF_FULL			BIT(22)
#define SPI_BLK_CNT(count)		(((count) & 0xffff) + 1)

#define SPI_FIFO_ERROR			(SPI_RX_UNF | SPI_TX_OVF)
#define SPI_FIFO_EMPTY			(SPI_TX_EMPTY | SPI_RX_EMPTY)

#define SPI_RX_CMP			0x8
#define SPI_DMA_CTL			0x0C
#define SPI_DMA_EN			BIT(31)
#define SPI_IE_RXC			BIT(27)
#define SPI_IE_TXC			BIT(26)
#define SPI_PACKED			BIT(20)
#define SPI_RX_TRIG_MASK		(0x3 << 18)
#define SPI_RX_TRIG_1W			(0x0 << 18)
#define SPI_RX_TRIG_4W			(0x1 << 18)
#define SPI_TX_TRIG_MASK		(0x3 << 16)
#define SPI_TX_TRIG_1W			(0x0 << 16)
#define SPI_TX_TRIG_4W			(0x1 << 16)
#define SPI_DMA_BLK_COUNT(count)	(((count) - 1) & 0xFFFF);

#define SPI_TX_FIFO			0x10
#define SPI_RX_FIFO			0x20

#define DATA_DIR_TX			(1 << 0)
#define DATA_DIR_RX			(1 << 1)

#define MAX_CHIP_SELECT			4
#define SPI_FIFO_DEPTH			4
#define SPI_DMA_TIMEOUT               (msecs_to_jiffies(1000))

struct tegra_sflash_data {
	struct device				*dev;
	struct spi_master			*master;
	spinlock_t				lock;

	struct clk				*clk;
	struct reset_control			*rst;
	void __iomem				*base;
	unsigned				irq;
	u32					spi_max_frequency;
	u32					cur_speed;

	struct spi_device			*cur_spi;
	unsigned				cur_pos;
	unsigned				cur_len;
	unsigned				bytes_per_word;
	unsigned				cur_direction;
	unsigned				curr_xfer_words;

	unsigned				cur_rx_pos;
	unsigned				cur_tx_pos;

	u32					tx_status;
	u32					rx_status;
	u32					status_reg;

	u32					def_command_reg;
	u32					command_reg;
	u32					dma_control_reg;

	struct completion			xfer_completion;
	struct spi_transfer			*curr_xfer;
};

static int tegra_sflash_runtime_suspend(struct device *dev);
static int tegra_sflash_runtime_resume(struct device *dev);

static inline u32 tegra_sflash_readl(struct tegra_sflash_data *tsd,
		unsigned long reg)
{
	return readl(tsd->base + reg);
}

static inline void tegra_sflash_writel(struct tegra_sflash_data *tsd,
		u32 val, unsigned long reg)
{
	writel(val, tsd->base + reg);
}

static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
{
	/* Write 1 to clear status register */
	tegra_sflash_writel(tsd, SPI_RDY | SPI_FIFO_ERROR, SPI_STATUS);
}

static unsigned tegra_sflash_calculate_curr_xfer_param(
	struct spi_device *spi, struct tegra_sflash_data *tsd,
	struct spi_transfer *t)
{
	unsigned remain_len = t->len - tsd->cur_pos;
	unsigned max_word;

	tsd->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
	max_word = remain_len / tsd->bytes_per_word;
	if (max_word > SPI_FIFO_DEPTH)
		max_word = SPI_FIFO_DEPTH;
	tsd->curr_xfer_words = max_word;
	return max_word;
}

static unsigned tegra_sflash_fill_tx_fifo_from_client_txbuf(
	struct tegra_sflash_data *tsd, struct spi_transfer *t)
{
	unsigned nbytes;
	u32 status;
	unsigned max_n_32bit = tsd->curr_xfer_words;
	u8 *tx_buf = (u8 *)t->tx_buf + tsd->cur_tx_pos;

	if (max_n_32bit > SPI_FIFO_DEPTH)
		max_n_32bit = SPI_FIFO_DEPTH;
	nbytes = max_n_32bit * tsd->bytes_per_word;

	status = tegra_sflash_readl(tsd, SPI_STATUS);
	while (!(status & SPI_TXF_FULL)) {
		int i;
		u32 x = 0;

		for (i = 0; nbytes && (i < tsd->bytes_per_word);
							i++, nbytes--)
			x |= (u32)(*tx_buf++) << (i * 8);
		tegra_sflash_writel(tsd, x, SPI_TX_FIFO);
		if (!nbytes)
			break;

		status = tegra_sflash_readl(tsd, SPI_STATUS);
	}
	tsd->cur_tx_pos += max_n_32bit * tsd->bytes_per_word;
	return max_n_32bit;
}

static int tegra_sflash_read_rx_fifo_to_client_rxbuf(
		struct tegra_sflash_data *tsd, struct spi_transfer *t)
{
	u32 status;
	unsigned int read_words = 0;
	u8 *rx_buf = (u8 *)t->rx_buf + tsd->cur_rx_pos;

	status = tegra_sflash_readl(tsd, SPI_STATUS);
	while (!(status & SPI_RXF_EMPTY)) {
		int i;
		u32 x = tegra_sflash_readl(tsd, SPI_RX_FIFO);
		for (i = 0; (i < tsd->bytes_per_word); i++)
			*rx_buf++ = (x >> (i*8)) & 0xFF;
		read_words++;
		status = tegra_sflash_readl(tsd, SPI_STATUS);
	}
	tsd->cur_rx_pos += read_words * tsd->bytes_per_word;
	return 0;
}

static int tegra_sflash_start_cpu_based_transfer(
		struct tegra_sflash_data *tsd, struct spi_transfer *t)
{
	u32 val = 0;
	unsigned cur_words;

	if (tsd->cur_direction & DATA_DIR_TX)
		val |= SPI_IE_TXC;

	if (tsd->cur_direction & DATA_DIR_RX)
		val |= SPI_IE_RXC;

	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
	tsd->dma_control_reg = val;

	if (tsd->cur_direction & DATA_DIR_TX)
		cur_words = tegra_sflash_fill_tx_fifo_from_client_txbuf(tsd, t);
	else
		cur_words = tsd->curr_xfer_words;
	val |= SPI_DMA_BLK_COUNT(cur_words);
	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
	tsd->dma_control_reg = val;
	val |= SPI_DMA_EN;
	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
	return 0;
}

static int tegra_sflash_start_transfer_one(struct spi_device *spi,
		struct spi_transfer *t, bool is_first_of_msg,
		bool is_single_xfer)
{
	struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);
	u32 speed;
	u32 command;

	speed = t->speed_hz;
	if (speed != tsd->cur_speed) {
		clk_set_rate(tsd->clk, speed);
		tsd->cur_speed = speed;
	}

	tsd->cur_spi = spi;
	tsd->cur_pos = 0;
	tsd->cur_rx_pos = 0;
	tsd->cur_tx_pos = 0;
	tsd->curr_xfer = t;
	tegra_sflash_calculate_curr_xfer_param(spi, tsd, t);
	if (is_first_of_msg) {
		command = tsd->def_command_reg;
		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
		command |= SPI_CS_VAL_HIGH;

		command &= ~SPI_MODES;
		if (spi->mode & SPI_CPHA)
			command |= SPI_CK_SDA_FALLING;

		if (spi->mode & SPI_CPOL)
			command |= SPI_ACTIVE_SCLK_DRIVE_HIGH;
		else
			command |= SPI_ACTIVE_SCLK_DRIVE_LOW;
		command |= SPI_CS0_EN << spi->chip_select;
	} else {
		command = tsd->command_reg;
		command &= ~SPI_BIT_LENGTH(~0);
		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
		command &= ~(SPI_RX_EN | SPI_TX_EN);
	}

	tsd->cur_direction = 0;
	if (t->rx_buf) {
		command |= SPI_RX_EN;
		tsd->cur_direction |= DATA_DIR_RX;
	}
	if (t->tx_buf) {
		command |= SPI_TX_EN;
		tsd->cur_direction |= DATA_DIR_TX;
	}
	tegra_sflash_writel(tsd, command, SPI_COMMAND);
	tsd->command_reg = command;

	return tegra_sflash_start_cpu_based_transfer(tsd, t);
}

static int tegra_sflash_setup(struct spi_device *spi)
{
	struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);

	/* Set speed to the spi max fequency if spi device has not set */
	spi->max_speed_hz = spi->max_speed_hz ? : tsd->spi_max_frequency;
	return 0;
}

static int tegra_sflash_transfer_one_message(struct spi_master *master,
			struct spi_message *msg)
{
	bool is_first_msg = true;
	int single_xfer;
	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
	struct spi_transfer *xfer;
	struct spi_device *spi = msg->spi;
	int ret;

	msg->status = 0;
	msg->actual_length = 0;
	single_xfer = list_is_singular(&msg->transfers);
	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		reinit_completion(&tsd->xfer_completion);
		ret = tegra_sflash_start_transfer_one(spi, xfer,
					is_first_msg, single_xfer);
		if (ret < 0) {
			dev_err(tsd->dev,
				"spi can not start transfer, err %d\n", ret);
			goto exit;
		}
		is_first_msg = false;
		ret = wait_for_completion_timeout(&tsd->xfer_completion,
						SPI_DMA_TIMEOUT);
		if (WARN_ON(ret == 0)) {
			dev_err(tsd->dev,
				"spi trasfer timeout, err %d\n", ret);
			ret = -EIO;
			goto exit;
		}

		if (tsd->tx_status ||  tsd->rx_status) {
			dev_err(tsd->dev, "Error in Transfer\n");
			ret = -EIO;
			goto exit;
		}
		msg->actual_length += xfer->len;
		if (xfer->cs_change && xfer->delay_usecs) {
			tegra_sflash_writel(tsd, tsd->def_command_reg,
					SPI_COMMAND);
			udelay(xfer->delay_usecs);
		}
	}
	ret = 0;
exit:
	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
	msg->status = ret;
	spi_finalize_current_message(master);
	return ret;
}

static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
{
	struct spi_transfer *t = tsd->curr_xfer;
	unsigned long flags;

	spin_lock_irqsave(&tsd->lock, flags);
	if (tsd->tx_status || tsd->rx_status || (tsd->status_reg & SPI_BSY)) {
		dev_err(tsd->dev,
			"CpuXfer ERROR bit set 0x%x\n", tsd->status_reg);
		dev_err(tsd->dev,
			"CpuXfer 0x%08x:0x%08x\n", tsd->command_reg,
				tsd->dma_control_reg);
		reset_control_assert(tsd->rst);
		udelay(2);
		reset_control_deassert(tsd->rst);
		complete(&tsd->xfer_completion);
		goto exit;
	}

	if (tsd->cur_direction & DATA_DIR_RX)
		tegra_sflash_read_rx_fifo_to_client_rxbuf(tsd, t);

	if (tsd->cur_direction & DATA_DIR_TX)
		tsd->cur_pos = tsd->cur_tx_pos;
	else
		tsd->cur_pos = tsd->cur_rx_pos;

	if (tsd->cur_pos == t->len) {
		complete(&tsd->xfer_completion);
		goto exit;
	}

	tegra_sflash_calculate_curr_xfer_param(tsd->cur_spi, tsd, t);
	tegra_sflash_start_cpu_based_transfer(tsd, t);
exit:
	spin_unlock_irqrestore(&tsd->lock, flags);
	return IRQ_HANDLED;
}

static irqreturn_t tegra_sflash_isr(int irq, void *context_data)
{
	struct tegra_sflash_data *tsd = context_data;

	tsd->status_reg = tegra_sflash_readl(tsd, SPI_STATUS);
	if (tsd->cur_direction & DATA_DIR_TX)
		tsd->tx_status = tsd->status_reg & SPI_TX_OVF;

	if (tsd->cur_direction & DATA_DIR_RX)
		tsd->rx_status = tsd->status_reg & SPI_RX_UNF;
	tegra_sflash_clear_status(tsd);

	return handle_cpu_based_xfer(tsd);
}

static void tegra_sflash_parse_dt(struct tegra_sflash_data *tsd)
{
	struct device_node *np = tsd->dev->of_node;

	if (of_property_read_u32(np, "spi-max-frequency",
					&tsd->spi_max_frequency))
		tsd->spi_max_frequency = 25000000; /* 25MHz */
}

static struct of_device_id tegra_sflash_of_match[] = {
	{ .compatible = "nvidia,tegra20-sflash", },
	{}
};
MODULE_DEVICE_TABLE(of, tegra_sflash_of_match);

static int tegra_sflash_probe(struct platform_device *pdev)
{
	struct spi_master	*master;
	struct tegra_sflash_data	*tsd;
	struct resource		*r;
	int ret;
	const struct of_device_id *match;

	match = of_match_device(tegra_sflash_of_match, &pdev->dev);
	if (!match) {
		dev_err(&pdev->dev, "Error: No device match found\n");
		return -ENODEV;
	}

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

	/* the spi->mode bits understood by this driver: */
	master->mode_bits = SPI_CPOL | SPI_CPHA;
	master->setup = tegra_sflash_setup;
	master->transfer_one_message = tegra_sflash_transfer_one_message;
	master->auto_runtime_pm = true;
	master->num_chipselect = MAX_CHIP_SELECT;
	master->bus_num = -1;

	platform_set_drvdata(pdev, master);
	tsd = spi_master_get_devdata(master);
	tsd->master = master;
	tsd->dev = &pdev->dev;
	spin_lock_init(&tsd->lock);

	tegra_sflash_parse_dt(tsd);

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	tsd->base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(tsd->base)) {
		ret = PTR_ERR(tsd->base);
		goto exit_free_master;
	}

	tsd->irq = platform_get_irq(pdev, 0);
	ret = request_irq(tsd->irq, tegra_sflash_isr, 0,
			dev_name(&pdev->dev), tsd);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
					tsd->irq);
		goto exit_free_master;
	}

	tsd->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(tsd->clk)) {
		dev_err(&pdev->dev, "can not get clock\n");
		ret = PTR_ERR(tsd->clk);
		goto exit_free_irq;
	}

	tsd->rst = devm_reset_control_get(&pdev->dev, "spi");
	if (IS_ERR(tsd->rst)) {
		dev_err(&pdev->dev, "can not get reset\n");
		ret = PTR_ERR(tsd->rst);
		goto exit_free_irq;
	}

	init_completion(&tsd->xfer_completion);
	pm_runtime_enable(&pdev->dev);
	if (!pm_runtime_enabled(&pdev->dev)) {
		ret = tegra_sflash_runtime_resume(&pdev->dev);
		if (ret)
			goto exit_pm_disable;
	}

	ret = pm_runtime_get_sync(&pdev->dev);
	if (ret < 0) {
		dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
		goto exit_pm_disable;
	}

	/* Reset controller */
	reset_control_assert(tsd->rst);
	udelay(2);
	reset_control_deassert(tsd->rst);

	tsd->def_command_reg  = SPI_M_S | SPI_CS_SW;
	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
	pm_runtime_put(&pdev->dev);

	master->dev.of_node = pdev->dev.of_node;
	ret = devm_spi_register_master(&pdev->dev, master);
	if (ret < 0) {
		dev_err(&pdev->dev, "can not register to master err %d\n", ret);
		goto exit_pm_disable;
	}
	return ret;

exit_pm_disable:
	pm_runtime_disable(&pdev->dev);
	if (!pm_runtime_status_suspended(&pdev->dev))
		tegra_sflash_runtime_suspend(&pdev->dev);
exit_free_irq:
	free_irq(tsd->irq, tsd);
exit_free_master:
	spi_master_put(master);
	return ret;
}

static int tegra_sflash_remove(struct platform_device *pdev)
{
	struct spi_master *master = platform_get_drvdata(pdev);
	struct tegra_sflash_data	*tsd = spi_master_get_devdata(master);

	free_irq(tsd->irq, tsd);

	pm_runtime_disable(&pdev->dev);
	if (!pm_runtime_status_suspended(&pdev->dev))
		tegra_sflash_runtime_suspend(&pdev->dev);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tegra_sflash_suspend(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);

	return spi_master_suspend(master);
}

static int tegra_sflash_resume(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
	int ret;

	ret = pm_runtime_get_sync(dev);
	if (ret < 0) {
		dev_err(dev, "pm runtime failed, e = %d\n", ret);
		return ret;
	}
	tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
	pm_runtime_put(dev);

	return spi_master_resume(master);
}
#endif

static int tegra_sflash_runtime_suspend(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);

	/* Flush all write which are in PPSB queue by reading back */
	tegra_sflash_readl(tsd, SPI_COMMAND);

	clk_disable_unprepare(tsd->clk);
	return 0;
}

static int tegra_sflash_runtime_resume(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
	int ret;

	ret = clk_prepare_enable(tsd->clk);
	if (ret < 0) {
		dev_err(tsd->dev, "clk_prepare failed: %d\n", ret);
		return ret;
	}
	return 0;
}

static const struct dev_pm_ops slink_pm_ops = {
	SET_RUNTIME_PM_OPS(tegra_sflash_runtime_suspend,
		tegra_sflash_runtime_resume, NULL)
	SET_SYSTEM_SLEEP_PM_OPS(tegra_sflash_suspend, tegra_sflash_resume)
};
static struct platform_driver tegra_sflash_driver = {
	.driver = {
		.name		= "spi-tegra-sflash",
		.owner		= THIS_MODULE,
		.pm		= &slink_pm_ops,
		.of_match_table	= tegra_sflash_of_match,
	},
	.probe =	tegra_sflash_probe,
	.remove =	tegra_sflash_remove,
};
module_platform_driver(tegra_sflash_driver);

MODULE_ALIAS("platform:spi-tegra-sflash");
MODULE_DESCRIPTION("NVIDIA Tegra20 Serial Flash Controller Driver");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");