1 /*
2  * SPI driver for Nvidia's Tegra20 Serial Flash Controller.
3  *
4  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
5  *
6  * Author: Laxman Dewangan <ldewangan@nvidia.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms and conditions of the GNU General Public License,
10  * version 2, as published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15  * more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include <linux/clk.h>
22 #include <linux/completion.h>
23 #include <linux/delay.h>
24 #include <linux/err.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/io.h>
28 #include <linux/kernel.h>
29 #include <linux/kthread.h>
30 #include <linux/module.h>
31 #include <linux/platform_device.h>
32 #include <linux/pm_runtime.h>
33 #include <linux/of.h>
34 #include <linux/of_device.h>
35 #include <linux/reset.h>
36 #include <linux/spi/spi.h>
37 
38 #define SPI_COMMAND				0x000
39 #define SPI_GO					BIT(30)
40 #define SPI_M_S					BIT(28)
41 #define SPI_ACTIVE_SCLK_MASK			(0x3 << 26)
42 #define SPI_ACTIVE_SCLK_DRIVE_LOW		(0 << 26)
43 #define SPI_ACTIVE_SCLK_DRIVE_HIGH		(1 << 26)
44 #define SPI_ACTIVE_SCLK_PULL_LOW		(2 << 26)
45 #define SPI_ACTIVE_SCLK_PULL_HIGH		(3 << 26)
46 
47 #define SPI_CK_SDA_FALLING			(1 << 21)
48 #define SPI_CK_SDA_RISING			(0 << 21)
49 #define SPI_CK_SDA_MASK				(1 << 21)
50 #define SPI_ACTIVE_SDA				(0x3 << 18)
51 #define SPI_ACTIVE_SDA_DRIVE_LOW		(0 << 18)
52 #define SPI_ACTIVE_SDA_DRIVE_HIGH		(1 << 18)
53 #define SPI_ACTIVE_SDA_PULL_LOW			(2 << 18)
54 #define SPI_ACTIVE_SDA_PULL_HIGH		(3 << 18)
55 
56 #define SPI_CS_POL_INVERT			BIT(16)
57 #define SPI_TX_EN				BIT(15)
58 #define SPI_RX_EN				BIT(14)
59 #define SPI_CS_VAL_HIGH				BIT(13)
60 #define SPI_CS_VAL_LOW				0x0
61 #define SPI_CS_SW				BIT(12)
62 #define SPI_CS_HW				0x0
63 #define SPI_CS_DELAY_MASK			(7 << 9)
64 #define SPI_CS3_EN				BIT(8)
65 #define SPI_CS2_EN				BIT(7)
66 #define SPI_CS1_EN				BIT(6)
67 #define SPI_CS0_EN				BIT(5)
68 
69 #define SPI_CS_MASK			(SPI_CS3_EN | SPI_CS2_EN |	\
70 					SPI_CS1_EN | SPI_CS0_EN)
71 #define SPI_BIT_LENGTH(x)		(((x) & 0x1f) << 0)
72 
73 #define SPI_MODES			(SPI_ACTIVE_SCLK_MASK | SPI_CK_SDA_MASK)
74 
75 #define SPI_STATUS			0x004
76 #define SPI_BSY				BIT(31)
77 #define SPI_RDY				BIT(30)
78 #define SPI_TXF_FLUSH			BIT(29)
79 #define SPI_RXF_FLUSH			BIT(28)
80 #define SPI_RX_UNF			BIT(27)
81 #define SPI_TX_OVF			BIT(26)
82 #define SPI_RXF_EMPTY			BIT(25)
83 #define SPI_RXF_FULL			BIT(24)
84 #define SPI_TXF_EMPTY			BIT(23)
85 #define SPI_TXF_FULL			BIT(22)
86 #define SPI_BLK_CNT(count)		(((count) & 0xffff) + 1)
87 
88 #define SPI_FIFO_ERROR			(SPI_RX_UNF | SPI_TX_OVF)
89 #define SPI_FIFO_EMPTY			(SPI_TX_EMPTY | SPI_RX_EMPTY)
90 
91 #define SPI_RX_CMP			0x8
92 #define SPI_DMA_CTL			0x0C
93 #define SPI_DMA_EN			BIT(31)
94 #define SPI_IE_RXC			BIT(27)
95 #define SPI_IE_TXC			BIT(26)
96 #define SPI_PACKED			BIT(20)
97 #define SPI_RX_TRIG_MASK		(0x3 << 18)
98 #define SPI_RX_TRIG_1W			(0x0 << 18)
99 #define SPI_RX_TRIG_4W			(0x1 << 18)
100 #define SPI_TX_TRIG_MASK		(0x3 << 16)
101 #define SPI_TX_TRIG_1W			(0x0 << 16)
102 #define SPI_TX_TRIG_4W			(0x1 << 16)
103 #define SPI_DMA_BLK_COUNT(count)	(((count) - 1) & 0xFFFF);
104 
105 #define SPI_TX_FIFO			0x10
106 #define SPI_RX_FIFO			0x20
107 
108 #define DATA_DIR_TX			(1 << 0)
109 #define DATA_DIR_RX			(1 << 1)
110 
111 #define MAX_CHIP_SELECT			4
112 #define SPI_FIFO_DEPTH			4
113 #define SPI_DMA_TIMEOUT               (msecs_to_jiffies(1000))
114 
115 struct tegra_sflash_data {
116 	struct device				*dev;
117 	struct spi_master			*master;
118 	spinlock_t				lock;
119 
120 	struct clk				*clk;
121 	struct reset_control			*rst;
122 	void __iomem				*base;
123 	unsigned				irq;
124 	u32					spi_max_frequency;
125 	u32					cur_speed;
126 
127 	struct spi_device			*cur_spi;
128 	unsigned				cur_pos;
129 	unsigned				cur_len;
130 	unsigned				bytes_per_word;
131 	unsigned				cur_direction;
132 	unsigned				curr_xfer_words;
133 
134 	unsigned				cur_rx_pos;
135 	unsigned				cur_tx_pos;
136 
137 	u32					tx_status;
138 	u32					rx_status;
139 	u32					status_reg;
140 
141 	u32					def_command_reg;
142 	u32					command_reg;
143 	u32					dma_control_reg;
144 
145 	struct completion			xfer_completion;
146 	struct spi_transfer			*curr_xfer;
147 };
148 
149 static int tegra_sflash_runtime_suspend(struct device *dev);
150 static int tegra_sflash_runtime_resume(struct device *dev);
151 
152 static inline u32 tegra_sflash_readl(struct tegra_sflash_data *tsd,
153 		unsigned long reg)
154 {
155 	return readl(tsd->base + reg);
156 }
157 
158 static inline void tegra_sflash_writel(struct tegra_sflash_data *tsd,
159 		u32 val, unsigned long reg)
160 {
161 	writel(val, tsd->base + reg);
162 }
163 
164 static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
165 {
166 	/* Write 1 to clear status register */
167 	tegra_sflash_writel(tsd, SPI_RDY | SPI_FIFO_ERROR, SPI_STATUS);
168 }
169 
170 static unsigned tegra_sflash_calculate_curr_xfer_param(
171 	struct spi_device *spi, struct tegra_sflash_data *tsd,
172 	struct spi_transfer *t)
173 {
174 	unsigned remain_len = t->len - tsd->cur_pos;
175 	unsigned max_word;
176 
177 	tsd->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
178 	max_word = remain_len / tsd->bytes_per_word;
179 	if (max_word > SPI_FIFO_DEPTH)
180 		max_word = SPI_FIFO_DEPTH;
181 	tsd->curr_xfer_words = max_word;
182 	return max_word;
183 }
184 
185 static unsigned tegra_sflash_fill_tx_fifo_from_client_txbuf(
186 	struct tegra_sflash_data *tsd, struct spi_transfer *t)
187 {
188 	unsigned nbytes;
189 	u32 status;
190 	unsigned max_n_32bit = tsd->curr_xfer_words;
191 	u8 *tx_buf = (u8 *)t->tx_buf + tsd->cur_tx_pos;
192 
193 	if (max_n_32bit > SPI_FIFO_DEPTH)
194 		max_n_32bit = SPI_FIFO_DEPTH;
195 	nbytes = max_n_32bit * tsd->bytes_per_word;
196 
197 	status = tegra_sflash_readl(tsd, SPI_STATUS);
198 	while (!(status & SPI_TXF_FULL)) {
199 		int i;
200 		u32 x = 0;
201 
202 		for (i = 0; nbytes && (i < tsd->bytes_per_word);
203 							i++, nbytes--)
204 			x |= (u32)(*tx_buf++) << (i * 8);
205 		tegra_sflash_writel(tsd, x, SPI_TX_FIFO);
206 		if (!nbytes)
207 			break;
208 
209 		status = tegra_sflash_readl(tsd, SPI_STATUS);
210 	}
211 	tsd->cur_tx_pos += max_n_32bit * tsd->bytes_per_word;
212 	return max_n_32bit;
213 }
214 
215 static int tegra_sflash_read_rx_fifo_to_client_rxbuf(
216 		struct tegra_sflash_data *tsd, struct spi_transfer *t)
217 {
218 	u32 status;
219 	unsigned int read_words = 0;
220 	u8 *rx_buf = (u8 *)t->rx_buf + tsd->cur_rx_pos;
221 
222 	status = tegra_sflash_readl(tsd, SPI_STATUS);
223 	while (!(status & SPI_RXF_EMPTY)) {
224 		int i;
225 		u32 x = tegra_sflash_readl(tsd, SPI_RX_FIFO);
226 		for (i = 0; (i < tsd->bytes_per_word); i++)
227 			*rx_buf++ = (x >> (i*8)) & 0xFF;
228 		read_words++;
229 		status = tegra_sflash_readl(tsd, SPI_STATUS);
230 	}
231 	tsd->cur_rx_pos += read_words * tsd->bytes_per_word;
232 	return 0;
233 }
234 
235 static int tegra_sflash_start_cpu_based_transfer(
236 		struct tegra_sflash_data *tsd, struct spi_transfer *t)
237 {
238 	u32 val = 0;
239 	unsigned cur_words;
240 
241 	if (tsd->cur_direction & DATA_DIR_TX)
242 		val |= SPI_IE_TXC;
243 
244 	if (tsd->cur_direction & DATA_DIR_RX)
245 		val |= SPI_IE_RXC;
246 
247 	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
248 	tsd->dma_control_reg = val;
249 
250 	if (tsd->cur_direction & DATA_DIR_TX)
251 		cur_words = tegra_sflash_fill_tx_fifo_from_client_txbuf(tsd, t);
252 	else
253 		cur_words = tsd->curr_xfer_words;
254 	val |= SPI_DMA_BLK_COUNT(cur_words);
255 	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
256 	tsd->dma_control_reg = val;
257 	val |= SPI_DMA_EN;
258 	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
259 	return 0;
260 }
261 
262 static int tegra_sflash_start_transfer_one(struct spi_device *spi,
263 		struct spi_transfer *t, bool is_first_of_msg,
264 		bool is_single_xfer)
265 {
266 	struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);
267 	u32 speed;
268 	u32 command;
269 
270 	speed = t->speed_hz;
271 	if (speed != tsd->cur_speed) {
272 		clk_set_rate(tsd->clk, speed);
273 		tsd->cur_speed = speed;
274 	}
275 
276 	tsd->cur_spi = spi;
277 	tsd->cur_pos = 0;
278 	tsd->cur_rx_pos = 0;
279 	tsd->cur_tx_pos = 0;
280 	tsd->curr_xfer = t;
281 	tegra_sflash_calculate_curr_xfer_param(spi, tsd, t);
282 	if (is_first_of_msg) {
283 		command = tsd->def_command_reg;
284 		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
285 		command |= SPI_CS_VAL_HIGH;
286 
287 		command &= ~SPI_MODES;
288 		if (spi->mode & SPI_CPHA)
289 			command |= SPI_CK_SDA_FALLING;
290 
291 		if (spi->mode & SPI_CPOL)
292 			command |= SPI_ACTIVE_SCLK_DRIVE_HIGH;
293 		else
294 			command |= SPI_ACTIVE_SCLK_DRIVE_LOW;
295 		command |= SPI_CS0_EN << spi->chip_select;
296 	} else {
297 		command = tsd->command_reg;
298 		command &= ~SPI_BIT_LENGTH(~0);
299 		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
300 		command &= ~(SPI_RX_EN | SPI_TX_EN);
301 	}
302 
303 	tsd->cur_direction = 0;
304 	if (t->rx_buf) {
305 		command |= SPI_RX_EN;
306 		tsd->cur_direction |= DATA_DIR_RX;
307 	}
308 	if (t->tx_buf) {
309 		command |= SPI_TX_EN;
310 		tsd->cur_direction |= DATA_DIR_TX;
311 	}
312 	tegra_sflash_writel(tsd, command, SPI_COMMAND);
313 	tsd->command_reg = command;
314 
315 	return tegra_sflash_start_cpu_based_transfer(tsd, t);
316 }
317 
318 static int tegra_sflash_setup(struct spi_device *spi)
319 {
320 	struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);
321 
322 	/* Set speed to the spi max fequency if spi device has not set */
323 	spi->max_speed_hz = spi->max_speed_hz ? : tsd->spi_max_frequency;
324 	return 0;
325 }
326 
327 static int tegra_sflash_transfer_one_message(struct spi_master *master,
328 			struct spi_message *msg)
329 {
330 	bool is_first_msg = true;
331 	int single_xfer;
332 	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
333 	struct spi_transfer *xfer;
334 	struct spi_device *spi = msg->spi;
335 	int ret;
336 
337 	msg->status = 0;
338 	msg->actual_length = 0;
339 	single_xfer = list_is_singular(&msg->transfers);
340 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
341 		reinit_completion(&tsd->xfer_completion);
342 		ret = tegra_sflash_start_transfer_one(spi, xfer,
343 					is_first_msg, single_xfer);
344 		if (ret < 0) {
345 			dev_err(tsd->dev,
346 				"spi can not start transfer, err %d\n", ret);
347 			goto exit;
348 		}
349 		is_first_msg = false;
350 		ret = wait_for_completion_timeout(&tsd->xfer_completion,
351 						SPI_DMA_TIMEOUT);
352 		if (WARN_ON(ret == 0)) {
353 			dev_err(tsd->dev,
354 				"spi trasfer timeout, err %d\n", ret);
355 			ret = -EIO;
356 			goto exit;
357 		}
358 
359 		if (tsd->tx_status ||  tsd->rx_status) {
360 			dev_err(tsd->dev, "Error in Transfer\n");
361 			ret = -EIO;
362 			goto exit;
363 		}
364 		msg->actual_length += xfer->len;
365 		if (xfer->cs_change && xfer->delay_usecs) {
366 			tegra_sflash_writel(tsd, tsd->def_command_reg,
367 					SPI_COMMAND);
368 			udelay(xfer->delay_usecs);
369 		}
370 	}
371 	ret = 0;
372 exit:
373 	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
374 	msg->status = ret;
375 	spi_finalize_current_message(master);
376 	return ret;
377 }
378 
379 static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
380 {
381 	struct spi_transfer *t = tsd->curr_xfer;
382 	unsigned long flags;
383 
384 	spin_lock_irqsave(&tsd->lock, flags);
385 	if (tsd->tx_status || tsd->rx_status || (tsd->status_reg & SPI_BSY)) {
386 		dev_err(tsd->dev,
387 			"CpuXfer ERROR bit set 0x%x\n", tsd->status_reg);
388 		dev_err(tsd->dev,
389 			"CpuXfer 0x%08x:0x%08x\n", tsd->command_reg,
390 				tsd->dma_control_reg);
391 		reset_control_assert(tsd->rst);
392 		udelay(2);
393 		reset_control_deassert(tsd->rst);
394 		complete(&tsd->xfer_completion);
395 		goto exit;
396 	}
397 
398 	if (tsd->cur_direction & DATA_DIR_RX)
399 		tegra_sflash_read_rx_fifo_to_client_rxbuf(tsd, t);
400 
401 	if (tsd->cur_direction & DATA_DIR_TX)
402 		tsd->cur_pos = tsd->cur_tx_pos;
403 	else
404 		tsd->cur_pos = tsd->cur_rx_pos;
405 
406 	if (tsd->cur_pos == t->len) {
407 		complete(&tsd->xfer_completion);
408 		goto exit;
409 	}
410 
411 	tegra_sflash_calculate_curr_xfer_param(tsd->cur_spi, tsd, t);
412 	tegra_sflash_start_cpu_based_transfer(tsd, t);
413 exit:
414 	spin_unlock_irqrestore(&tsd->lock, flags);
415 	return IRQ_HANDLED;
416 }
417 
418 static irqreturn_t tegra_sflash_isr(int irq, void *context_data)
419 {
420 	struct tegra_sflash_data *tsd = context_data;
421 
422 	tsd->status_reg = tegra_sflash_readl(tsd, SPI_STATUS);
423 	if (tsd->cur_direction & DATA_DIR_TX)
424 		tsd->tx_status = tsd->status_reg & SPI_TX_OVF;
425 
426 	if (tsd->cur_direction & DATA_DIR_RX)
427 		tsd->rx_status = tsd->status_reg & SPI_RX_UNF;
428 	tegra_sflash_clear_status(tsd);
429 
430 	return handle_cpu_based_xfer(tsd);
431 }
432 
433 static void tegra_sflash_parse_dt(struct tegra_sflash_data *tsd)
434 {
435 	struct device_node *np = tsd->dev->of_node;
436 
437 	if (of_property_read_u32(np, "spi-max-frequency",
438 					&tsd->spi_max_frequency))
439 		tsd->spi_max_frequency = 25000000; /* 25MHz */
440 }
441 
442 static struct of_device_id tegra_sflash_of_match[] = {
443 	{ .compatible = "nvidia,tegra20-sflash", },
444 	{}
445 };
446 MODULE_DEVICE_TABLE(of, tegra_sflash_of_match);
447 
448 static int tegra_sflash_probe(struct platform_device *pdev)
449 {
450 	struct spi_master	*master;
451 	struct tegra_sflash_data	*tsd;
452 	struct resource		*r;
453 	int ret;
454 	const struct of_device_id *match;
455 
456 	match = of_match_device(tegra_sflash_of_match, &pdev->dev);
457 	if (!match) {
458 		dev_err(&pdev->dev, "Error: No device match found\n");
459 		return -ENODEV;
460 	}
461 
462 	master = spi_alloc_master(&pdev->dev, sizeof(*tsd));
463 	if (!master) {
464 		dev_err(&pdev->dev, "master allocation failed\n");
465 		return -ENOMEM;
466 	}
467 
468 	/* the spi->mode bits understood by this driver: */
469 	master->mode_bits = SPI_CPOL | SPI_CPHA;
470 	master->setup = tegra_sflash_setup;
471 	master->transfer_one_message = tegra_sflash_transfer_one_message;
472 	master->auto_runtime_pm = true;
473 	master->num_chipselect = MAX_CHIP_SELECT;
474 	master->bus_num = -1;
475 
476 	platform_set_drvdata(pdev, master);
477 	tsd = spi_master_get_devdata(master);
478 	tsd->master = master;
479 	tsd->dev = &pdev->dev;
480 	spin_lock_init(&tsd->lock);
481 
482 	tegra_sflash_parse_dt(tsd);
483 
484 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
485 	tsd->base = devm_ioremap_resource(&pdev->dev, r);
486 	if (IS_ERR(tsd->base)) {
487 		ret = PTR_ERR(tsd->base);
488 		goto exit_free_master;
489 	}
490 
491 	tsd->irq = platform_get_irq(pdev, 0);
492 	ret = request_irq(tsd->irq, tegra_sflash_isr, 0,
493 			dev_name(&pdev->dev), tsd);
494 	if (ret < 0) {
495 		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
496 					tsd->irq);
497 		goto exit_free_master;
498 	}
499 
500 	tsd->clk = devm_clk_get(&pdev->dev, NULL);
501 	if (IS_ERR(tsd->clk)) {
502 		dev_err(&pdev->dev, "can not get clock\n");
503 		ret = PTR_ERR(tsd->clk);
504 		goto exit_free_irq;
505 	}
506 
507 	tsd->rst = devm_reset_control_get(&pdev->dev, "spi");
508 	if (IS_ERR(tsd->rst)) {
509 		dev_err(&pdev->dev, "can not get reset\n");
510 		ret = PTR_ERR(tsd->rst);
511 		goto exit_free_irq;
512 	}
513 
514 	init_completion(&tsd->xfer_completion);
515 	pm_runtime_enable(&pdev->dev);
516 	if (!pm_runtime_enabled(&pdev->dev)) {
517 		ret = tegra_sflash_runtime_resume(&pdev->dev);
518 		if (ret)
519 			goto exit_pm_disable;
520 	}
521 
522 	ret = pm_runtime_get_sync(&pdev->dev);
523 	if (ret < 0) {
524 		dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
525 		goto exit_pm_disable;
526 	}
527 
528 	/* Reset controller */
529 	reset_control_assert(tsd->rst);
530 	udelay(2);
531 	reset_control_deassert(tsd->rst);
532 
533 	tsd->def_command_reg  = SPI_M_S | SPI_CS_SW;
534 	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
535 	pm_runtime_put(&pdev->dev);
536 
537 	master->dev.of_node = pdev->dev.of_node;
538 	ret = devm_spi_register_master(&pdev->dev, master);
539 	if (ret < 0) {
540 		dev_err(&pdev->dev, "can not register to master err %d\n", ret);
541 		goto exit_pm_disable;
542 	}
543 	return ret;
544 
545 exit_pm_disable:
546 	pm_runtime_disable(&pdev->dev);
547 	if (!pm_runtime_status_suspended(&pdev->dev))
548 		tegra_sflash_runtime_suspend(&pdev->dev);
549 exit_free_irq:
550 	free_irq(tsd->irq, tsd);
551 exit_free_master:
552 	spi_master_put(master);
553 	return ret;
554 }
555 
556 static int tegra_sflash_remove(struct platform_device *pdev)
557 {
558 	struct spi_master *master = platform_get_drvdata(pdev);
559 	struct tegra_sflash_data	*tsd = spi_master_get_devdata(master);
560 
561 	free_irq(tsd->irq, tsd);
562 
563 	pm_runtime_disable(&pdev->dev);
564 	if (!pm_runtime_status_suspended(&pdev->dev))
565 		tegra_sflash_runtime_suspend(&pdev->dev);
566 
567 	return 0;
568 }
569 
570 #ifdef CONFIG_PM_SLEEP
571 static int tegra_sflash_suspend(struct device *dev)
572 {
573 	struct spi_master *master = dev_get_drvdata(dev);
574 
575 	return spi_master_suspend(master);
576 }
577 
578 static int tegra_sflash_resume(struct device *dev)
579 {
580 	struct spi_master *master = dev_get_drvdata(dev);
581 	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
582 	int ret;
583 
584 	ret = pm_runtime_get_sync(dev);
585 	if (ret < 0) {
586 		dev_err(dev, "pm runtime failed, e = %d\n", ret);
587 		return ret;
588 	}
589 	tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
590 	pm_runtime_put(dev);
591 
592 	return spi_master_resume(master);
593 }
594 #endif
595 
596 static int tegra_sflash_runtime_suspend(struct device *dev)
597 {
598 	struct spi_master *master = dev_get_drvdata(dev);
599 	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
600 
601 	/* Flush all write which are in PPSB queue by reading back */
602 	tegra_sflash_readl(tsd, SPI_COMMAND);
603 
604 	clk_disable_unprepare(tsd->clk);
605 	return 0;
606 }
607 
608 static int tegra_sflash_runtime_resume(struct device *dev)
609 {
610 	struct spi_master *master = dev_get_drvdata(dev);
611 	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
612 	int ret;
613 
614 	ret = clk_prepare_enable(tsd->clk);
615 	if (ret < 0) {
616 		dev_err(tsd->dev, "clk_prepare failed: %d\n", ret);
617 		return ret;
618 	}
619 	return 0;
620 }
621 
622 static const struct dev_pm_ops slink_pm_ops = {
623 	SET_RUNTIME_PM_OPS(tegra_sflash_runtime_suspend,
624 		tegra_sflash_runtime_resume, NULL)
625 	SET_SYSTEM_SLEEP_PM_OPS(tegra_sflash_suspend, tegra_sflash_resume)
626 };
627 static struct platform_driver tegra_sflash_driver = {
628 	.driver = {
629 		.name		= "spi-tegra-sflash",
630 		.owner		= THIS_MODULE,
631 		.pm		= &slink_pm_ops,
632 		.of_match_table	= tegra_sflash_of_match,
633 	},
634 	.probe =	tegra_sflash_probe,
635 	.remove =	tegra_sflash_remove,
636 };
637 module_platform_driver(tegra_sflash_driver);
638 
639 MODULE_ALIAS("platform:spi-tegra-sflash");
640 MODULE_DESCRIPTION("NVIDIA Tegra20 Serial Flash Controller Driver");
641 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
642 MODULE_LICENSE("GPL v2");
643