xref: /openbmc/linux/drivers/mmc/host/sdhci-tegra.c (revision 711aab1d)
1 /*
2  * Copyright (C) 2010 Google, Inc.
3  *
4  * This software is licensed under the terms of the GNU General Public
5  * License version 2, as published by the Free Software Foundation, and
6  * may be copied, distributed, and modified under those terms.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  */
14 
15 #include <linux/delay.h>
16 #include <linux/err.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/platform_device.h>
20 #include <linux/clk.h>
21 #include <linux/io.h>
22 #include <linux/of.h>
23 #include <linux/of_device.h>
24 #include <linux/reset.h>
25 #include <linux/mmc/card.h>
26 #include <linux/mmc/host.h>
27 #include <linux/mmc/mmc.h>
28 #include <linux/mmc/slot-gpio.h>
29 #include <linux/gpio/consumer.h>
30 
31 #include "sdhci-pltfm.h"
32 
33 /* Tegra SDHOST controller vendor register definitions */
34 #define SDHCI_TEGRA_VENDOR_CLOCK_CTRL			0x100
35 #define SDHCI_CLOCK_CTRL_TAP_MASK			0x00ff0000
36 #define SDHCI_CLOCK_CTRL_TAP_SHIFT			16
37 #define SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE		BIT(5)
38 #define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE		BIT(3)
39 #define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE	BIT(2)
40 
41 #define SDHCI_TEGRA_VENDOR_MISC_CTRL		0x120
42 #define SDHCI_MISC_CTRL_ENABLE_SDR104		0x8
43 #define SDHCI_MISC_CTRL_ENABLE_SDR50		0x10
44 #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300	0x20
45 #define SDHCI_MISC_CTRL_ENABLE_DDR50		0x200
46 
47 #define SDHCI_TEGRA_AUTO_CAL_CONFIG		0x1e4
48 #define SDHCI_AUTO_CAL_START			BIT(31)
49 #define SDHCI_AUTO_CAL_ENABLE			BIT(29)
50 
51 #define NVQUIRK_FORCE_SDHCI_SPEC_200	BIT(0)
52 #define NVQUIRK_ENABLE_BLOCK_GAP_DET	BIT(1)
53 #define NVQUIRK_ENABLE_SDHCI_SPEC_300	BIT(2)
54 #define NVQUIRK_ENABLE_SDR50		BIT(3)
55 #define NVQUIRK_ENABLE_SDR104		BIT(4)
56 #define NVQUIRK_ENABLE_DDR50		BIT(5)
57 #define NVQUIRK_HAS_PADCALIB		BIT(6)
58 
59 struct sdhci_tegra_soc_data {
60 	const struct sdhci_pltfm_data *pdata;
61 	u32 nvquirks;
62 };
63 
64 struct sdhci_tegra {
65 	const struct sdhci_tegra_soc_data *soc_data;
66 	struct gpio_desc *power_gpio;
67 	bool ddr_signaling;
68 	bool pad_calib_required;
69 
70 	struct reset_control *rst;
71 };
72 
73 static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
74 {
75 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
76 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
77 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
78 
79 	if (unlikely((soc_data->nvquirks & NVQUIRK_FORCE_SDHCI_SPEC_200) &&
80 			(reg == SDHCI_HOST_VERSION))) {
81 		/* Erratum: Version register is invalid in HW. */
82 		return SDHCI_SPEC_200;
83 	}
84 
85 	return readw(host->ioaddr + reg);
86 }
87 
88 static void tegra_sdhci_writew(struct sdhci_host *host, u16 val, int reg)
89 {
90 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
91 
92 	switch (reg) {
93 	case SDHCI_TRANSFER_MODE:
94 		/*
95 		 * Postpone this write, we must do it together with a
96 		 * command write that is down below.
97 		 */
98 		pltfm_host->xfer_mode_shadow = val;
99 		return;
100 	case SDHCI_COMMAND:
101 		writel((val << 16) | pltfm_host->xfer_mode_shadow,
102 			host->ioaddr + SDHCI_TRANSFER_MODE);
103 		return;
104 	}
105 
106 	writew(val, host->ioaddr + reg);
107 }
108 
109 static void tegra_sdhci_writel(struct sdhci_host *host, u32 val, int reg)
110 {
111 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
112 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
113 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
114 
115 	/* Seems like we're getting spurious timeout and crc errors, so
116 	 * disable signalling of them. In case of real errors software
117 	 * timers should take care of eventually detecting them.
118 	 */
119 	if (unlikely(reg == SDHCI_SIGNAL_ENABLE))
120 		val &= ~(SDHCI_INT_TIMEOUT|SDHCI_INT_CRC);
121 
122 	writel(val, host->ioaddr + reg);
123 
124 	if (unlikely((soc_data->nvquirks & NVQUIRK_ENABLE_BLOCK_GAP_DET) &&
125 			(reg == SDHCI_INT_ENABLE))) {
126 		/* Erratum: Must enable block gap interrupt detection */
127 		u8 gap_ctrl = readb(host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
128 		if (val & SDHCI_INT_CARD_INT)
129 			gap_ctrl |= 0x8;
130 		else
131 			gap_ctrl &= ~0x8;
132 		writeb(gap_ctrl, host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
133 	}
134 }
135 
136 static unsigned int tegra_sdhci_get_ro(struct sdhci_host *host)
137 {
138 	return mmc_gpio_get_ro(host->mmc);
139 }
140 
141 static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
142 {
143 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
144 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
145 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
146 	u32 misc_ctrl, clk_ctrl;
147 
148 	sdhci_reset(host, mask);
149 
150 	if (!(mask & SDHCI_RESET_ALL))
151 		return;
152 
153 	misc_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
154 	clk_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
155 
156 	misc_ctrl &= ~(SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 |
157 		       SDHCI_MISC_CTRL_ENABLE_SDR50 |
158 		       SDHCI_MISC_CTRL_ENABLE_DDR50 |
159 		       SDHCI_MISC_CTRL_ENABLE_SDR104);
160 
161 	clk_ctrl &= ~SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE;
162 
163 	/*
164 	 * If the board does not define a regulator for the SDHCI
165 	 * IO voltage, then don't advertise support for UHS modes
166 	 * even if the device supports it because the IO voltage
167 	 * cannot be configured.
168 	 */
169 	if (!IS_ERR(host->mmc->supply.vqmmc)) {
170 		/* Erratum: Enable SDHCI spec v3.00 support */
171 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300)
172 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
173 		/* Advertise UHS modes as supported by host */
174 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR50)
175 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR50;
176 		if (soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
177 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_DDR50;
178 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR104)
179 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR104;
180 		if (soc_data->nvquirks & SDHCI_MISC_CTRL_ENABLE_SDR50)
181 			clk_ctrl |= SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE;
182 	}
183 
184 	sdhci_writel(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
185 	sdhci_writel(host, clk_ctrl, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
186 
187 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
188 		tegra_host->pad_calib_required = true;
189 
190 	tegra_host->ddr_signaling = false;
191 }
192 
193 static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
194 {
195 	u32 val;
196 
197 	mdelay(1);
198 
199 	val = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
200 	val |= SDHCI_AUTO_CAL_ENABLE | SDHCI_AUTO_CAL_START;
201 	sdhci_writel(host,val, SDHCI_TEGRA_AUTO_CAL_CONFIG);
202 }
203 
204 static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
205 {
206 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
207 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
208 	unsigned long host_clk;
209 
210 	if (!clock)
211 		return sdhci_set_clock(host, clock);
212 
213 	host_clk = tegra_host->ddr_signaling ? clock * 2 : clock;
214 	clk_set_rate(pltfm_host->clk, host_clk);
215 	host->max_clk = clk_get_rate(pltfm_host->clk);
216 
217 	sdhci_set_clock(host, clock);
218 
219 	if (tegra_host->pad_calib_required) {
220 		tegra_sdhci_pad_autocalib(host);
221 		tegra_host->pad_calib_required = false;
222 	}
223 }
224 
225 static void tegra_sdhci_set_uhs_signaling(struct sdhci_host *host,
226 					  unsigned timing)
227 {
228 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
229 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
230 
231 	if (timing == MMC_TIMING_UHS_DDR50)
232 		tegra_host->ddr_signaling = true;
233 
234 	return sdhci_set_uhs_signaling(host, timing);
235 }
236 
237 static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host)
238 {
239 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
240 
241 	/*
242 	 * DDR modes require the host to run at double the card frequency, so
243 	 * the maximum rate we can support is half of the module input clock.
244 	 */
245 	return clk_round_rate(pltfm_host->clk, UINT_MAX) / 2;
246 }
247 
248 static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap)
249 {
250 	u32 reg;
251 
252 	reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
253 	reg &= ~SDHCI_CLOCK_CTRL_TAP_MASK;
254 	reg |= tap << SDHCI_CLOCK_CTRL_TAP_SHIFT;
255 	sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
256 }
257 
258 static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
259 {
260 	unsigned int min, max;
261 
262 	/*
263 	 * Start search for minimum tap value at 10, as smaller values are
264 	 * may wrongly be reported as working but fail at higher speeds,
265 	 * according to the TRM.
266 	 */
267 	min = 10;
268 	while (min < 255) {
269 		tegra_sdhci_set_tap(host, min);
270 		if (!mmc_send_tuning(host->mmc, opcode, NULL))
271 			break;
272 		min++;
273 	}
274 
275 	/* Find the maximum tap value that still passes. */
276 	max = min + 1;
277 	while (max < 255) {
278 		tegra_sdhci_set_tap(host, max);
279 		if (mmc_send_tuning(host->mmc, opcode, NULL)) {
280 			max--;
281 			break;
282 		}
283 		max++;
284 	}
285 
286 	/* The TRM states the ideal tap value is at 75% in the passing range. */
287 	tegra_sdhci_set_tap(host, min + ((max - min) * 3 / 4));
288 
289 	return mmc_send_tuning(host->mmc, opcode, NULL);
290 }
291 
292 static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
293 {
294 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
295 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
296 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
297 
298 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
299 		tegra_host->pad_calib_required = true;
300 }
301 
302 static const struct sdhci_ops tegra_sdhci_ops = {
303 	.get_ro     = tegra_sdhci_get_ro,
304 	.read_w     = tegra_sdhci_readw,
305 	.write_l    = tegra_sdhci_writel,
306 	.set_clock  = tegra_sdhci_set_clock,
307 	.set_bus_width = sdhci_set_bus_width,
308 	.reset      = tegra_sdhci_reset,
309 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
310 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
311 	.voltage_switch = tegra_sdhci_voltage_switch,
312 	.get_max_clock = tegra_sdhci_get_max_clock,
313 };
314 
315 static const struct sdhci_pltfm_data sdhci_tegra20_pdata = {
316 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
317 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
318 		  SDHCI_QUIRK_NO_HISPD_BIT |
319 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
320 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
321 	.ops  = &tegra_sdhci_ops,
322 };
323 
324 static const struct sdhci_tegra_soc_data soc_data_tegra20 = {
325 	.pdata = &sdhci_tegra20_pdata,
326 	.nvquirks = NVQUIRK_FORCE_SDHCI_SPEC_200 |
327 		    NVQUIRK_ENABLE_BLOCK_GAP_DET,
328 };
329 
330 static const struct sdhci_pltfm_data sdhci_tegra30_pdata = {
331 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
332 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
333 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
334 		  SDHCI_QUIRK_NO_HISPD_BIT |
335 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
336 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
337 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
338 	.ops  = &tegra_sdhci_ops,
339 };
340 
341 static const struct sdhci_tegra_soc_data soc_data_tegra30 = {
342 	.pdata = &sdhci_tegra30_pdata,
343 	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300 |
344 		    NVQUIRK_ENABLE_SDR50 |
345 		    NVQUIRK_ENABLE_SDR104 |
346 		    NVQUIRK_HAS_PADCALIB,
347 };
348 
349 static const struct sdhci_ops tegra114_sdhci_ops = {
350 	.get_ro     = tegra_sdhci_get_ro,
351 	.read_w     = tegra_sdhci_readw,
352 	.write_w    = tegra_sdhci_writew,
353 	.write_l    = tegra_sdhci_writel,
354 	.set_clock  = tegra_sdhci_set_clock,
355 	.set_bus_width = sdhci_set_bus_width,
356 	.reset      = tegra_sdhci_reset,
357 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
358 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
359 	.voltage_switch = tegra_sdhci_voltage_switch,
360 	.get_max_clock = tegra_sdhci_get_max_clock,
361 };
362 
363 static const struct sdhci_pltfm_data sdhci_tegra114_pdata = {
364 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
365 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
366 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
367 		  SDHCI_QUIRK_NO_HISPD_BIT |
368 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
369 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
370 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
371 	.ops  = &tegra114_sdhci_ops,
372 };
373 
374 static const struct sdhci_tegra_soc_data soc_data_tegra114 = {
375 	.pdata = &sdhci_tegra114_pdata,
376 };
377 
378 static const struct sdhci_pltfm_data sdhci_tegra124_pdata = {
379 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
380 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
381 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
382 		  SDHCI_QUIRK_NO_HISPD_BIT |
383 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
384 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
385 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
386 		   /*
387 		    * The TRM states that the SD/MMC controller found on
388 		    * Tegra124 can address 34 bits (the maximum supported by
389 		    * the Tegra memory controller), but tests show that DMA
390 		    * to or from above 4 GiB doesn't work. This is possibly
391 		    * caused by missing programming, though it's not obvious
392 		    * what sequence is required. Mark 64-bit DMA broken for
393 		    * now to fix this for existing users (e.g. Nyan boards).
394 		    */
395 		   SDHCI_QUIRK2_BROKEN_64_BIT_DMA,
396 	.ops  = &tegra114_sdhci_ops,
397 };
398 
399 static const struct sdhci_tegra_soc_data soc_data_tegra124 = {
400 	.pdata = &sdhci_tegra124_pdata,
401 };
402 
403 static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
404 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
405 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
406 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
407 		  SDHCI_QUIRK_NO_HISPD_BIT |
408 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
409 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
410 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
411 	.ops  = &tegra114_sdhci_ops,
412 };
413 
414 static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
415 	.pdata = &sdhci_tegra210_pdata,
416 };
417 
418 static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
419 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
420 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
421 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
422 		  SDHCI_QUIRK_NO_HISPD_BIT |
423 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
424 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
425 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
426 	.ops  = &tegra114_sdhci_ops,
427 };
428 
429 static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
430 	.pdata = &sdhci_tegra186_pdata,
431 };
432 
433 static const struct of_device_id sdhci_tegra_dt_match[] = {
434 	{ .compatible = "nvidia,tegra186-sdhci", .data = &soc_data_tegra186 },
435 	{ .compatible = "nvidia,tegra210-sdhci", .data = &soc_data_tegra210 },
436 	{ .compatible = "nvidia,tegra124-sdhci", .data = &soc_data_tegra124 },
437 	{ .compatible = "nvidia,tegra114-sdhci", .data = &soc_data_tegra114 },
438 	{ .compatible = "nvidia,tegra30-sdhci", .data = &soc_data_tegra30 },
439 	{ .compatible = "nvidia,tegra20-sdhci", .data = &soc_data_tegra20 },
440 	{}
441 };
442 MODULE_DEVICE_TABLE(of, sdhci_tegra_dt_match);
443 
444 static int sdhci_tegra_probe(struct platform_device *pdev)
445 {
446 	const struct of_device_id *match;
447 	const struct sdhci_tegra_soc_data *soc_data;
448 	struct sdhci_host *host;
449 	struct sdhci_pltfm_host *pltfm_host;
450 	struct sdhci_tegra *tegra_host;
451 	struct clk *clk;
452 	int rc;
453 
454 	match = of_match_device(sdhci_tegra_dt_match, &pdev->dev);
455 	if (!match)
456 		return -EINVAL;
457 	soc_data = match->data;
458 
459 	host = sdhci_pltfm_init(pdev, soc_data->pdata, sizeof(*tegra_host));
460 	if (IS_ERR(host))
461 		return PTR_ERR(host);
462 	pltfm_host = sdhci_priv(host);
463 
464 	tegra_host = sdhci_pltfm_priv(pltfm_host);
465 	tegra_host->ddr_signaling = false;
466 	tegra_host->pad_calib_required = false;
467 	tegra_host->soc_data = soc_data;
468 
469 	rc = mmc_of_parse(host->mmc);
470 	if (rc)
471 		goto err_parse_dt;
472 
473 	if (tegra_host->soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
474 		host->mmc->caps |= MMC_CAP_1_8V_DDR;
475 
476 	tegra_host->power_gpio = devm_gpiod_get_optional(&pdev->dev, "power",
477 							 GPIOD_OUT_HIGH);
478 	if (IS_ERR(tegra_host->power_gpio)) {
479 		rc = PTR_ERR(tegra_host->power_gpio);
480 		goto err_power_req;
481 	}
482 
483 	clk = devm_clk_get(mmc_dev(host->mmc), NULL);
484 	if (IS_ERR(clk)) {
485 		dev_err(mmc_dev(host->mmc), "clk err\n");
486 		rc = PTR_ERR(clk);
487 		goto err_clk_get;
488 	}
489 	clk_prepare_enable(clk);
490 	pltfm_host->clk = clk;
491 
492 	tegra_host->rst = devm_reset_control_get_exclusive(&pdev->dev,
493 							   "sdhci");
494 	if (IS_ERR(tegra_host->rst)) {
495 		rc = PTR_ERR(tegra_host->rst);
496 		dev_err(&pdev->dev, "failed to get reset control: %d\n", rc);
497 		goto err_rst_get;
498 	}
499 
500 	rc = reset_control_assert(tegra_host->rst);
501 	if (rc)
502 		goto err_rst_get;
503 
504 	usleep_range(2000, 4000);
505 
506 	rc = reset_control_deassert(tegra_host->rst);
507 	if (rc)
508 		goto err_rst_get;
509 
510 	usleep_range(2000, 4000);
511 
512 	rc = sdhci_add_host(host);
513 	if (rc)
514 		goto err_add_host;
515 
516 	return 0;
517 
518 err_add_host:
519 	reset_control_assert(tegra_host->rst);
520 err_rst_get:
521 	clk_disable_unprepare(pltfm_host->clk);
522 err_clk_get:
523 err_power_req:
524 err_parse_dt:
525 	sdhci_pltfm_free(pdev);
526 	return rc;
527 }
528 
529 static int sdhci_tegra_remove(struct platform_device *pdev)
530 {
531 	struct sdhci_host *host = platform_get_drvdata(pdev);
532 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
533 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
534 
535 	sdhci_remove_host(host, 0);
536 
537 	reset_control_assert(tegra_host->rst);
538 	usleep_range(2000, 4000);
539 	clk_disable_unprepare(pltfm_host->clk);
540 
541 	sdhci_pltfm_free(pdev);
542 
543 	return 0;
544 }
545 
546 static struct platform_driver sdhci_tegra_driver = {
547 	.driver		= {
548 		.name	= "sdhci-tegra",
549 		.of_match_table = sdhci_tegra_dt_match,
550 		.pm	= &sdhci_pltfm_pmops,
551 	},
552 	.probe		= sdhci_tegra_probe,
553 	.remove		= sdhci_tegra_remove,
554 };
555 
556 module_platform_driver(sdhci_tegra_driver);
557 
558 MODULE_DESCRIPTION("SDHCI driver for Tegra");
559 MODULE_AUTHOR("Google, Inc.");
560 MODULE_LICENSE("GPL v2");
561