xref: /openbmc/linux/drivers/mmc/host/sdhci-tegra.c (revision 8730046c)
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/mmc/card.h>
25 #include <linux/mmc/host.h>
26 #include <linux/mmc/mmc.h>
27 #include <linux/mmc/slot-gpio.h>
28 #include <linux/gpio/consumer.h>
29 
30 #include "sdhci-pltfm.h"
31 
32 /* Tegra SDHOST controller vendor register definitions */
33 #define SDHCI_TEGRA_VENDOR_CLOCK_CTRL			0x100
34 #define SDHCI_CLOCK_CTRL_TAP_MASK			0x00ff0000
35 #define SDHCI_CLOCK_CTRL_TAP_SHIFT			16
36 #define SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE		BIT(5)
37 #define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE		BIT(3)
38 #define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE	BIT(2)
39 
40 #define SDHCI_TEGRA_VENDOR_MISC_CTRL		0x120
41 #define SDHCI_MISC_CTRL_ENABLE_SDR104		0x8
42 #define SDHCI_MISC_CTRL_ENABLE_SDR50		0x10
43 #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300	0x20
44 #define SDHCI_MISC_CTRL_ENABLE_DDR50		0x200
45 
46 #define SDHCI_TEGRA_AUTO_CAL_CONFIG		0x1e4
47 #define SDHCI_AUTO_CAL_START			BIT(31)
48 #define SDHCI_AUTO_CAL_ENABLE			BIT(29)
49 
50 #define NVQUIRK_FORCE_SDHCI_SPEC_200	BIT(0)
51 #define NVQUIRK_ENABLE_BLOCK_GAP_DET	BIT(1)
52 #define NVQUIRK_ENABLE_SDHCI_SPEC_300	BIT(2)
53 #define NVQUIRK_ENABLE_SDR50		BIT(3)
54 #define NVQUIRK_ENABLE_SDR104		BIT(4)
55 #define NVQUIRK_ENABLE_DDR50		BIT(5)
56 #define NVQUIRK_HAS_PADCALIB		BIT(6)
57 
58 struct sdhci_tegra_soc_data {
59 	const struct sdhci_pltfm_data *pdata;
60 	u32 nvquirks;
61 };
62 
63 struct sdhci_tegra {
64 	const struct sdhci_tegra_soc_data *soc_data;
65 	struct gpio_desc *power_gpio;
66 	bool ddr_signaling;
67 	bool pad_calib_required;
68 };
69 
70 static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
71 {
72 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
73 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
74 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
75 
76 	if (unlikely((soc_data->nvquirks & NVQUIRK_FORCE_SDHCI_SPEC_200) &&
77 			(reg == SDHCI_HOST_VERSION))) {
78 		/* Erratum: Version register is invalid in HW. */
79 		return SDHCI_SPEC_200;
80 	}
81 
82 	return readw(host->ioaddr + reg);
83 }
84 
85 static void tegra_sdhci_writew(struct sdhci_host *host, u16 val, int reg)
86 {
87 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
88 
89 	switch (reg) {
90 	case SDHCI_TRANSFER_MODE:
91 		/*
92 		 * Postpone this write, we must do it together with a
93 		 * command write that is down below.
94 		 */
95 		pltfm_host->xfer_mode_shadow = val;
96 		return;
97 	case SDHCI_COMMAND:
98 		writel((val << 16) | pltfm_host->xfer_mode_shadow,
99 			host->ioaddr + SDHCI_TRANSFER_MODE);
100 		return;
101 	}
102 
103 	writew(val, host->ioaddr + reg);
104 }
105 
106 static void tegra_sdhci_writel(struct sdhci_host *host, u32 val, int reg)
107 {
108 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
109 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
110 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
111 
112 	/* Seems like we're getting spurious timeout and crc errors, so
113 	 * disable signalling of them. In case of real errors software
114 	 * timers should take care of eventually detecting them.
115 	 */
116 	if (unlikely(reg == SDHCI_SIGNAL_ENABLE))
117 		val &= ~(SDHCI_INT_TIMEOUT|SDHCI_INT_CRC);
118 
119 	writel(val, host->ioaddr + reg);
120 
121 	if (unlikely((soc_data->nvquirks & NVQUIRK_ENABLE_BLOCK_GAP_DET) &&
122 			(reg == SDHCI_INT_ENABLE))) {
123 		/* Erratum: Must enable block gap interrupt detection */
124 		u8 gap_ctrl = readb(host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
125 		if (val & SDHCI_INT_CARD_INT)
126 			gap_ctrl |= 0x8;
127 		else
128 			gap_ctrl &= ~0x8;
129 		writeb(gap_ctrl, host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
130 	}
131 }
132 
133 static unsigned int tegra_sdhci_get_ro(struct sdhci_host *host)
134 {
135 	return mmc_gpio_get_ro(host->mmc);
136 }
137 
138 static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
139 {
140 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
141 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
142 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
143 	u32 misc_ctrl, clk_ctrl;
144 
145 	sdhci_reset(host, mask);
146 
147 	if (!(mask & SDHCI_RESET_ALL))
148 		return;
149 
150 	misc_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
151 	clk_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
152 
153 	misc_ctrl &= ~(SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 |
154 		       SDHCI_MISC_CTRL_ENABLE_SDR50 |
155 		       SDHCI_MISC_CTRL_ENABLE_DDR50 |
156 		       SDHCI_MISC_CTRL_ENABLE_SDR104);
157 
158 	clk_ctrl &= ~SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE;
159 
160 	/*
161 	 * If the board does not define a regulator for the SDHCI
162 	 * IO voltage, then don't advertise support for UHS modes
163 	 * even if the device supports it because the IO voltage
164 	 * cannot be configured.
165 	 */
166 	if (!IS_ERR(host->mmc->supply.vqmmc)) {
167 		/* Erratum: Enable SDHCI spec v3.00 support */
168 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300)
169 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
170 		/* Advertise UHS modes as supported by host */
171 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR50)
172 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR50;
173 		if (soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
174 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_DDR50;
175 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR104)
176 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR104;
177 		if (soc_data->nvquirks & SDHCI_MISC_CTRL_ENABLE_SDR50)
178 			clk_ctrl |= SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE;
179 	}
180 
181 	sdhci_writel(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
182 	sdhci_writel(host, clk_ctrl, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
183 
184 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
185 		tegra_host->pad_calib_required = true;
186 
187 	tegra_host->ddr_signaling = false;
188 }
189 
190 static void tegra_sdhci_set_bus_width(struct sdhci_host *host, int bus_width)
191 {
192 	u32 ctrl;
193 
194 	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
195 	if ((host->mmc->caps & MMC_CAP_8_BIT_DATA) &&
196 	    (bus_width == MMC_BUS_WIDTH_8)) {
197 		ctrl &= ~SDHCI_CTRL_4BITBUS;
198 		ctrl |= SDHCI_CTRL_8BITBUS;
199 	} else {
200 		ctrl &= ~SDHCI_CTRL_8BITBUS;
201 		if (bus_width == MMC_BUS_WIDTH_4)
202 			ctrl |= SDHCI_CTRL_4BITBUS;
203 		else
204 			ctrl &= ~SDHCI_CTRL_4BITBUS;
205 	}
206 	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
207 }
208 
209 static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
210 {
211 	u32 val;
212 
213 	mdelay(1);
214 
215 	val = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
216 	val |= SDHCI_AUTO_CAL_ENABLE | SDHCI_AUTO_CAL_START;
217 	sdhci_writel(host,val, SDHCI_TEGRA_AUTO_CAL_CONFIG);
218 }
219 
220 static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
221 {
222 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
223 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
224 	unsigned long host_clk;
225 
226 	if (!clock)
227 		return sdhci_set_clock(host, clock);
228 
229 	host_clk = tegra_host->ddr_signaling ? clock * 2 : clock;
230 	clk_set_rate(pltfm_host->clk, host_clk);
231 	host->max_clk = clk_get_rate(pltfm_host->clk);
232 
233 	sdhci_set_clock(host, clock);
234 
235 	if (tegra_host->pad_calib_required) {
236 		tegra_sdhci_pad_autocalib(host);
237 		tegra_host->pad_calib_required = false;
238 	}
239 }
240 
241 static void tegra_sdhci_set_uhs_signaling(struct sdhci_host *host,
242 					  unsigned timing)
243 {
244 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
245 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
246 
247 	if (timing == MMC_TIMING_UHS_DDR50)
248 		tegra_host->ddr_signaling = true;
249 
250 	return sdhci_set_uhs_signaling(host, timing);
251 }
252 
253 static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host)
254 {
255 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
256 
257 	/*
258 	 * DDR modes require the host to run at double the card frequency, so
259 	 * the maximum rate we can support is half of the module input clock.
260 	 */
261 	return clk_round_rate(pltfm_host->clk, UINT_MAX) / 2;
262 }
263 
264 static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap)
265 {
266 	u32 reg;
267 
268 	reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
269 	reg &= ~SDHCI_CLOCK_CTRL_TAP_MASK;
270 	reg |= tap << SDHCI_CLOCK_CTRL_TAP_SHIFT;
271 	sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
272 }
273 
274 static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
275 {
276 	unsigned int min, max;
277 
278 	/*
279 	 * Start search for minimum tap value at 10, as smaller values are
280 	 * may wrongly be reported as working but fail at higher speeds,
281 	 * according to the TRM.
282 	 */
283 	min = 10;
284 	while (min < 255) {
285 		tegra_sdhci_set_tap(host, min);
286 		if (!mmc_send_tuning(host->mmc, opcode, NULL))
287 			break;
288 		min++;
289 	}
290 
291 	/* Find the maximum tap value that still passes. */
292 	max = min + 1;
293 	while (max < 255) {
294 		tegra_sdhci_set_tap(host, max);
295 		if (mmc_send_tuning(host->mmc, opcode, NULL)) {
296 			max--;
297 			break;
298 		}
299 		max++;
300 	}
301 
302 	/* The TRM states the ideal tap value is at 75% in the passing range. */
303 	tegra_sdhci_set_tap(host, min + ((max - min) * 3 / 4));
304 
305 	return mmc_send_tuning(host->mmc, opcode, NULL);
306 }
307 
308 static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
309 {
310 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
311 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
312 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
313 
314 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
315 		tegra_host->pad_calib_required = true;
316 }
317 
318 static const struct sdhci_ops tegra_sdhci_ops = {
319 	.get_ro     = tegra_sdhci_get_ro,
320 	.read_w     = tegra_sdhci_readw,
321 	.write_l    = tegra_sdhci_writel,
322 	.set_clock  = tegra_sdhci_set_clock,
323 	.set_bus_width = tegra_sdhci_set_bus_width,
324 	.reset      = tegra_sdhci_reset,
325 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
326 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
327 	.voltage_switch = tegra_sdhci_voltage_switch,
328 	.get_max_clock = tegra_sdhci_get_max_clock,
329 };
330 
331 static const struct sdhci_pltfm_data sdhci_tegra20_pdata = {
332 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
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 	.ops  = &tegra_sdhci_ops,
338 };
339 
340 static const struct sdhci_tegra_soc_data soc_data_tegra20 = {
341 	.pdata = &sdhci_tegra20_pdata,
342 	.nvquirks = NVQUIRK_FORCE_SDHCI_SPEC_200 |
343 		    NVQUIRK_ENABLE_BLOCK_GAP_DET,
344 };
345 
346 static const struct sdhci_pltfm_data sdhci_tegra30_pdata = {
347 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
348 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
349 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
350 		  SDHCI_QUIRK_NO_HISPD_BIT |
351 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
352 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
353 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
354 	.ops  = &tegra_sdhci_ops,
355 };
356 
357 static const struct sdhci_tegra_soc_data soc_data_tegra30 = {
358 	.pdata = &sdhci_tegra30_pdata,
359 	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300 |
360 		    NVQUIRK_ENABLE_SDR50 |
361 		    NVQUIRK_ENABLE_SDR104 |
362 		    NVQUIRK_HAS_PADCALIB,
363 };
364 
365 static const struct sdhci_ops tegra114_sdhci_ops = {
366 	.get_ro     = tegra_sdhci_get_ro,
367 	.read_w     = tegra_sdhci_readw,
368 	.write_w    = tegra_sdhci_writew,
369 	.write_l    = tegra_sdhci_writel,
370 	.set_clock  = tegra_sdhci_set_clock,
371 	.set_bus_width = tegra_sdhci_set_bus_width,
372 	.reset      = tegra_sdhci_reset,
373 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
374 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
375 	.voltage_switch = tegra_sdhci_voltage_switch,
376 	.get_max_clock = tegra_sdhci_get_max_clock,
377 };
378 
379 static const struct sdhci_pltfm_data sdhci_tegra114_pdata = {
380 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
381 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
382 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
383 		  SDHCI_QUIRK_NO_HISPD_BIT |
384 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
385 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
386 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
387 	.ops  = &tegra114_sdhci_ops,
388 };
389 
390 static const struct sdhci_tegra_soc_data soc_data_tegra114 = {
391 	.pdata = &sdhci_tegra114_pdata,
392 };
393 
394 static const struct sdhci_pltfm_data sdhci_tegra124_pdata = {
395 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
396 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
397 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
398 		  SDHCI_QUIRK_NO_HISPD_BIT |
399 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
400 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
401 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
402 		   /*
403 		    * The TRM states that the SD/MMC controller found on
404 		    * Tegra124 can address 34 bits (the maximum supported by
405 		    * the Tegra memory controller), but tests show that DMA
406 		    * to or from above 4 GiB doesn't work. This is possibly
407 		    * caused by missing programming, though it's not obvious
408 		    * what sequence is required. Mark 64-bit DMA broken for
409 		    * now to fix this for existing users (e.g. Nyan boards).
410 		    */
411 		   SDHCI_QUIRK2_BROKEN_64_BIT_DMA,
412 	.ops  = &tegra114_sdhci_ops,
413 };
414 
415 static const struct sdhci_tegra_soc_data soc_data_tegra124 = {
416 	.pdata = &sdhci_tegra124_pdata,
417 };
418 
419 static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
420 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
421 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
422 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
423 		  SDHCI_QUIRK_NO_HISPD_BIT |
424 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
425 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
426 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
427 	.ops  = &tegra114_sdhci_ops,
428 };
429 
430 static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
431 	.pdata = &sdhci_tegra210_pdata,
432 };
433 
434 static const struct of_device_id sdhci_tegra_dt_match[] = {
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 	rc = sdhci_add_host(host);
493 	if (rc)
494 		goto err_add_host;
495 
496 	return 0;
497 
498 err_add_host:
499 	clk_disable_unprepare(pltfm_host->clk);
500 err_clk_get:
501 err_power_req:
502 err_parse_dt:
503 	sdhci_pltfm_free(pdev);
504 	return rc;
505 }
506 
507 static struct platform_driver sdhci_tegra_driver = {
508 	.driver		= {
509 		.name	= "sdhci-tegra",
510 		.of_match_table = sdhci_tegra_dt_match,
511 		.pm	= &sdhci_pltfm_pmops,
512 	},
513 	.probe		= sdhci_tegra_probe,
514 	.remove		= sdhci_pltfm_unregister,
515 };
516 
517 module_platform_driver(sdhci_tegra_driver);
518 
519 MODULE_DESCRIPTION("SDHCI driver for Tegra");
520 MODULE_AUTHOR("Google, Inc.");
521 MODULE_LICENSE("GPL v2");
522