drivers/mmc/host/sdhci-tegra.c - arm/linux - Git at Google

 /*
  * Copyright (C) 2010 Google, Inc.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * This program is distributed in the hope that 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.
  *
  */

 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/reset.h>
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/slot-gpio.h>
 #include <linux/gpio/consumer.h>

 #include "sdhci-pltfm.h"

 /* Tegra SDHOST controller vendor register definitions */
 #define SDHCI_TEGRA_VENDOR_CLOCK_CTRL			0x100
 #define SDHCI_CLOCK_CTRL_TAP_MASK			0x00ff0000
 #define SDHCI_CLOCK_CTRL_TAP_SHIFT			16
 #define SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE		BIT(5)
 #define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE		BIT(3)
 #define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE	BIT(2)

 #define SDHCI_TEGRA_VENDOR_MISC_CTRL		0x120
 #define SDHCI_MISC_CTRL_ENABLE_SDR104		0x8
 #define SDHCI_MISC_CTRL_ENABLE_SDR50		0x10
 #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300	0x20
 #define SDHCI_MISC_CTRL_ENABLE_DDR50		0x200

 #define SDHCI_TEGRA_AUTO_CAL_CONFIG		0x1e4
 #define SDHCI_AUTO_CAL_START			BIT(31)
 #define SDHCI_AUTO_CAL_ENABLE			BIT(29)

 #define NVQUIRK_FORCE_SDHCI_SPEC_200	BIT(0)
 #define NVQUIRK_ENABLE_BLOCK_GAP_DET	BIT(1)
 #define NVQUIRK_ENABLE_SDHCI_SPEC_300	BIT(2)
 #define NVQUIRK_ENABLE_SDR50		BIT(3)
 #define NVQUIRK_ENABLE_SDR104		BIT(4)
 #define NVQUIRK_ENABLE_DDR50		BIT(5)
 #define NVQUIRK_HAS_PADCALIB		BIT(6)

 struct sdhci_tegra_soc_data {
 	const struct sdhci_pltfm_data *pdata;
 	u32 nvquirks;
 };

 struct sdhci_tegra {
 	const struct sdhci_tegra_soc_data *soc_data;
 	struct gpio_desc *power_gpio;
 	bool ddr_signaling;
 	bool pad_calib_required;

 	struct reset_control *rst;
 };

 static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

 	if (unlikely((soc_data->nvquirks & NVQUIRK_FORCE_SDHCI_SPEC_200) &&
 			(reg == SDHCI_HOST_VERSION))) {
 		/* Erratum: Version register is invalid in HW. */
 		return SDHCI_SPEC_200;
 	}

 	return readw(host->ioaddr + reg);
 }

 static void tegra_sdhci_writew(struct sdhci_host *host, u16 val, int reg)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);

 	switch (reg) {
 	case SDHCI_TRANSFER_MODE:
 		/*
 		 * Postpone this write, we must do it together with a
 		 * command write that is down below.
 		 */
 		pltfm_host->xfer_mode_shadow = val;
 		return;
 	case SDHCI_COMMAND:
 		writel((val << 16) | pltfm_host->xfer_mode_shadow,
 			host->ioaddr + SDHCI_TRANSFER_MODE);
 		return;
 	}

 	writew(val, host->ioaddr + reg);
 }

 static void tegra_sdhci_writel(struct sdhci_host *host, u32 val, int reg)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

 	/* Seems like we're getting spurious timeout and crc errors, so
 	 * disable signalling of them. In case of real errors software
 	 * timers should take care of eventually detecting them.
 	 */
 	if (unlikely(reg == SDHCI_SIGNAL_ENABLE))
 		val &= ~(SDHCI_INT_TIMEOUT|SDHCI_INT_CRC);

 	writel(val, host->ioaddr + reg);

 	if (unlikely((soc_data->nvquirks & NVQUIRK_ENABLE_BLOCK_GAP_DET) &&
 			(reg == SDHCI_INT_ENABLE))) {
 		/* Erratum: Must enable block gap interrupt detection */
 		u8 gap_ctrl = readb(host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
 		if (val & SDHCI_INT_CARD_INT)
 			gap_ctrl |= 0x8;
 		else
 			gap_ctrl &= ~0x8;
 		writeb(gap_ctrl, host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
 	}
 }

 static unsigned int tegra_sdhci_get_ro(struct sdhci_host *host)
 {
 	return mmc_gpio_get_ro(host->mmc);
 }

 static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
 	u32 misc_ctrl, clk_ctrl;

 	sdhci_reset(host, mask);

 	if (!(mask & SDHCI_RESET_ALL))
 		return;

 	misc_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
 	clk_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);

 	misc_ctrl &= ~(SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 |
 		       SDHCI_MISC_CTRL_ENABLE_SDR50 |
 		       SDHCI_MISC_CTRL_ENABLE_DDR50 |
 		       SDHCI_MISC_CTRL_ENABLE_SDR104);

 	clk_ctrl &= ~SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE;

 	/*
 	 * If the board does not define a regulator for the SDHCI
 	 * IO voltage, then don't advertise support for UHS modes
 	 * even if the device supports it because the IO voltage
 	 * cannot be configured.
 	 */
 	if (!IS_ERR(host->mmc->supply.vqmmc)) {
 		/* Erratum: Enable SDHCI spec v3.00 support */
 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300)
 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
 		/* Advertise UHS modes as supported by host */
 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR50)
 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR50;
 		if (soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_DDR50;
 		if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR104)
 			misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDR104;
 		if (soc_data->nvquirks & SDHCI_MISC_CTRL_ENABLE_SDR50)
 			clk_ctrl |= SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE;
 	}

 	sdhci_writel(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
 	sdhci_writel(host, clk_ctrl, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);

 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
 		tegra_host->pad_calib_required = true;

 	tegra_host->ddr_signaling = false;
 }

 static void tegra_sdhci_set_bus_width(struct sdhci_host *host, int bus_width)
 {
 	u32 ctrl;

 	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
 	if ((host->mmc->caps & MMC_CAP_8_BIT_DATA) &&
 	    (bus_width == MMC_BUS_WIDTH_8)) {
 		ctrl &= ~SDHCI_CTRL_4BITBUS;
 		ctrl |= SDHCI_CTRL_8BITBUS;
 	} else {
 		ctrl &= ~SDHCI_CTRL_8BITBUS;
 		if (bus_width == MMC_BUS_WIDTH_4)
 			ctrl |= SDHCI_CTRL_4BITBUS;
 		else
 			ctrl &= ~SDHCI_CTRL_4BITBUS;
 	}
 	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
 }

 static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
 {
 	u32 val;

 	mdelay(1);

 	val = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
 	val |= SDHCI_AUTO_CAL_ENABLE | SDHCI_AUTO_CAL_START;
 	sdhci_writel(host,val, SDHCI_TEGRA_AUTO_CAL_CONFIG);
 }

 static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	unsigned long host_clk;

 	if (!clock)
 		return sdhci_set_clock(host, clock);

 	host_clk = tegra_host->ddr_signaling ? clock * 2 : clock;
 	clk_set_rate(pltfm_host->clk, host_clk);
 	host->max_clk = clk_get_rate(pltfm_host->clk);

 	sdhci_set_clock(host, clock);

 	if (tegra_host->pad_calib_required) {
 		tegra_sdhci_pad_autocalib(host);
 		tegra_host->pad_calib_required = false;
 	}
 }

 static void tegra_sdhci_set_uhs_signaling(struct sdhci_host *host,
 					  unsigned timing)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);

 	if (timing == MMC_TIMING_UHS_DDR50)
 		tegra_host->ddr_signaling = true;

 	return sdhci_set_uhs_signaling(host, timing);
 }

 static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);

 	/*
 	 * DDR modes require the host to run at double the card frequency, so
 	 * the maximum rate we can support is half of the module input clock.
 	 */
 	return clk_round_rate(pltfm_host->clk, UINT_MAX) / 2;
 }

 static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap)
 {
 	u32 reg;

 	reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
 	reg &= ~SDHCI_CLOCK_CTRL_TAP_MASK;
 	reg |= tap << SDHCI_CLOCK_CTRL_TAP_SHIFT;
 	sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
 }

 static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
 {
 	unsigned int min, max;

 	/*
 	 * Start search for minimum tap value at 10, as smaller values are
 	 * may wrongly be reported as working but fail at higher speeds,
 	 * according to the TRM.
 	 */
 	min = 10;
 	while (min < 255) {
 		tegra_sdhci_set_tap(host, min);
 		if (!mmc_send_tuning(host->mmc, opcode, NULL))
 			break;
 		min++;
 	}

 	/* Find the maximum tap value that still passes. */
 	max = min + 1;
 	while (max < 255) {
 		tegra_sdhci_set_tap(host, max);
 		if (mmc_send_tuning(host->mmc, opcode, NULL)) {
 			max--;
 			break;
 		}
 		max++;
 	}

 	/* The TRM states the ideal tap value is at 75% in the passing range. */
 	tegra_sdhci_set_tap(host, min + ((max - min) * 3 / 4));

 	return mmc_send_tuning(host->mmc, opcode, NULL);
 }

 static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

 	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
 		tegra_host->pad_calib_required = true;
 }

 static const struct sdhci_ops tegra_sdhci_ops = {
 	.get_ro     = tegra_sdhci_get_ro,
 	.read_w     = tegra_sdhci_readw,
 	.write_l    = tegra_sdhci_writel,
 	.set_clock  = tegra_sdhci_set_clock,
 	.set_bus_width = tegra_sdhci_set_bus_width,
 	.reset      = tegra_sdhci_reset,
 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
 	.voltage_switch = tegra_sdhci_voltage_switch,
 	.get_max_clock = tegra_sdhci_get_max_clock,
 };

 static const struct sdhci_pltfm_data sdhci_tegra20_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.ops  = &tegra_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra20 = {
 	.pdata = &sdhci_tegra20_pdata,
 	.nvquirks = NVQUIRK_FORCE_SDHCI_SPEC_200 |
 		    NVQUIRK_ENABLE_BLOCK_GAP_DET,
 };

 static const struct sdhci_pltfm_data sdhci_tegra30_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
 	.ops  = &tegra_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra30 = {
 	.pdata = &sdhci_tegra30_pdata,
 	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300 |
 		    NVQUIRK_ENABLE_SDR50 |
 		    NVQUIRK_ENABLE_SDR104 |
 		    NVQUIRK_HAS_PADCALIB,
 };

 static const struct sdhci_ops tegra114_sdhci_ops = {
 	.get_ro     = tegra_sdhci_get_ro,
 	.read_w     = tegra_sdhci_readw,
 	.write_w    = tegra_sdhci_writew,
 	.write_l    = tegra_sdhci_writel,
 	.set_clock  = tegra_sdhci_set_clock,
 	.set_bus_width = tegra_sdhci_set_bus_width,
 	.reset      = tegra_sdhci_reset,
 	.platform_execute_tuning = tegra_sdhci_execute_tuning,
 	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
 	.voltage_switch = tegra_sdhci_voltage_switch,
 	.get_max_clock = tegra_sdhci_get_max_clock,
 };

 static const struct sdhci_pltfm_data sdhci_tegra114_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
 	.ops  = &tegra114_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra114 = {
 	.pdata = &sdhci_tegra114_pdata,
 };

 static const struct sdhci_pltfm_data sdhci_tegra124_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
 		   /*
 		    * The TRM states that the SD/MMC controller found on
 		    * Tegra124 can address 34 bits (the maximum supported by
 		    * the Tegra memory controller), but tests show that DMA
 		    * to or from above 4 GiB doesn't work. This is possibly
 		    * caused by missing programming, though it's not obvious
 		    * what sequence is required. Mark 64-bit DMA broken for
 		    * now to fix this for existing users (e.g. Nyan boards).
 		    */
 		   SDHCI_QUIRK2_BROKEN_64_BIT_DMA,
 	.ops  = &tegra114_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra124 = {
 	.pdata = &sdhci_tegra124_pdata,
 };

 static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
 	.ops  = &tegra114_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
 	.pdata = &sdhci_tegra210_pdata,
 };

 static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
 	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 		  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 		  SDHCI_QUIRK_SINGLE_POWER_WRITE |
 		  SDHCI_QUIRK_NO_HISPD_BIT |
 		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
 		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
 	.ops  = &tegra114_sdhci_ops,
 };

 static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
 	.pdata = &sdhci_tegra186_pdata,
 };

 static const struct of_device_id sdhci_tegra_dt_match[] = {
 	{ .compatible = "nvidia,tegra186-sdhci", .data = &soc_data_tegra186 },
 	{ .compatible = "nvidia,tegra210-sdhci", .data = &soc_data_tegra210 },
 	{ .compatible = "nvidia,tegra124-sdhci", .data = &soc_data_tegra124 },
 	{ .compatible = "nvidia,tegra114-sdhci", .data = &soc_data_tegra114 },
 	{ .compatible = "nvidia,tegra30-sdhci", .data = &soc_data_tegra30 },
 	{ .compatible = "nvidia,tegra20-sdhci", .data = &soc_data_tegra20 },
 	{}
 };
 MODULE_DEVICE_TABLE(of, sdhci_tegra_dt_match);

 static int sdhci_tegra_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	const struct sdhci_tegra_soc_data *soc_data;
 	struct sdhci_host *host;
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_tegra *tegra_host;
 	struct clk *clk;
 	int rc;

 	match = of_match_device(sdhci_tegra_dt_match, &pdev->dev);
 	if (!match)
 		return -EINVAL;
 	soc_data = match->data;

 	host = sdhci_pltfm_init(pdev, soc_data->pdata, sizeof(*tegra_host));
 	if (IS_ERR(host))
 		return PTR_ERR(host);
 	pltfm_host = sdhci_priv(host);

 	tegra_host = sdhci_pltfm_priv(pltfm_host);
 	tegra_host->ddr_signaling = false;
 	tegra_host->pad_calib_required = false;
 	tegra_host->soc_data = soc_data;

 	rc = mmc_of_parse(host->mmc);
 	if (rc)
 		goto err_parse_dt;

 	if (tegra_host->soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
 		host->mmc->caps |= MMC_CAP_1_8V_DDR;

 	tegra_host->power_gpio = devm_gpiod_get_optional(&pdev->dev, "power",
 							 GPIOD_OUT_HIGH);
 	if (IS_ERR(tegra_host->power_gpio)) {
 		rc = PTR_ERR(tegra_host->power_gpio);
 		goto err_power_req;
 	}

 	clk = devm_clk_get(mmc_dev(host->mmc), NULL);
 	if (IS_ERR(clk)) {
 		dev_err(mmc_dev(host->mmc), "clk err\n");
 		rc = PTR_ERR(clk);
 		goto err_clk_get;
 	}
 	clk_prepare_enable(clk);
 	pltfm_host->clk = clk;

 	tegra_host->rst = devm_reset_control_get(&pdev->dev, "sdhci");
 	if (IS_ERR(tegra_host->rst)) {
 		rc = PTR_ERR(tegra_host->rst);
 		dev_err(&pdev->dev, "failed to get reset control: %d\n", rc);
 		goto err_rst_get;
 	}

 	rc = reset_control_assert(tegra_host->rst);
 	if (rc)
 		goto err_rst_get;

 	usleep_range(2000, 4000);

 	rc = reset_control_deassert(tegra_host->rst);
 	if (rc)
 		goto err_rst_get;

 	usleep_range(2000, 4000);

 	rc = sdhci_add_host(host);
 	if (rc)
 		goto err_add_host;

 	return 0;

 err_add_host:
 	reset_control_assert(tegra_host->rst);
 err_rst_get:
 	clk_disable_unprepare(pltfm_host->clk);
 err_clk_get:
 err_power_req:
 err_parse_dt:
 	sdhci_pltfm_free(pdev);
 	return rc;
 }

 static int sdhci_tegra_remove(struct platform_device *pdev)
 {
 	struct sdhci_host *host = platform_get_drvdata(pdev);
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);

 	sdhci_remove_host(host, 0);

 	reset_control_assert(tegra_host->rst);
 	usleep_range(2000, 4000);
 	clk_disable_unprepare(pltfm_host->clk);

 	sdhci_pltfm_free(pdev);

 	return 0;
 }

 static struct platform_driver sdhci_tegra_driver = {
 	.driver		= {
 		.name	= "sdhci-tegra",
 		.of_match_table = sdhci_tegra_dt_match,
 		.pm	= &sdhci_pltfm_pmops,
 	},
 	.probe		= sdhci_tegra_probe,
 	.remove		= sdhci_tegra_remove,
 };

 module_platform_driver(sdhci_tegra_driver);

 MODULE_DESCRIPTION("SDHCI driver for Tegra");
 MODULE_AUTHOR("Google, Inc.");
 MODULE_LICENSE("GPL v2");
	/*
	* Copyright (C) 2010 Google, Inc.
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* This program is distributed in the hope that 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.
	*
	*/

	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/platform_device.h>
	#include <linux/clk.h>
	#include <linux/io.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/reset.h>
	#include <linux/mmc/card.h>
	#include <linux/mmc/host.h>
	#include <linux/mmc/mmc.h>
	#include <linux/mmc/slot-gpio.h>
	#include <linux/gpio/consumer.h>

	#include "sdhci-pltfm.h"

	/* Tegra SDHOST controller vendor register definitions */
	#define SDHCI_TEGRA_VENDOR_CLOCK_CTRL 0x100
	#define SDHCI_CLOCK_CTRL_TAP_MASK 0x00ff0000
	#define SDHCI_CLOCK_CTRL_TAP_SHIFT 16
	#define SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE BIT(5)
	#define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE BIT(3)
	#define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE BIT(2)

	#define SDHCI_TEGRA_VENDOR_MISC_CTRL 0x120
	#define SDHCI_MISC_CTRL_ENABLE_SDR104 0x8
	#define SDHCI_MISC_CTRL_ENABLE_SDR50 0x10
	#define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 0x20
	#define SDHCI_MISC_CTRL_ENABLE_DDR50 0x200

	#define SDHCI_TEGRA_AUTO_CAL_CONFIG 0x1e4
	#define SDHCI_AUTO_CAL_START BIT(31)
	#define SDHCI_AUTO_CAL_ENABLE BIT(29)

	#define NVQUIRK_FORCE_SDHCI_SPEC_200 BIT(0)
	#define NVQUIRK_ENABLE_BLOCK_GAP_DET BIT(1)
	#define NVQUIRK_ENABLE_SDHCI_SPEC_300 BIT(2)
	#define NVQUIRK_ENABLE_SDR50 BIT(3)
	#define NVQUIRK_ENABLE_SDR104 BIT(4)
	#define NVQUIRK_ENABLE_DDR50 BIT(5)
	#define NVQUIRK_HAS_PADCALIB BIT(6)

	struct sdhci_tegra_soc_data {
	const struct sdhci_pltfm_data *pdata;
	u32 nvquirks;
	};

	struct sdhci_tegra {
	const struct sdhci_tegra_soc_data *soc_data;
	struct gpio_desc *power_gpio;
	bool ddr_signaling;
	bool pad_calib_required;

	struct reset_control *rst;
	};

	static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

	if (unlikely((soc_data->nvquirks & NVQUIRK_FORCE_SDHCI_SPEC_200) &&
	(reg == SDHCI_HOST_VERSION))) {
	/* Erratum: Version register is invalid in HW. */
	return SDHCI_SPEC_200;
	}

	return readw(host->ioaddr + reg);
	}

	static void tegra_sdhci_writew(struct sdhci_host *host, u16 val, int reg)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);

	switch (reg) {
	case SDHCI_TRANSFER_MODE:
	/*
	* Postpone this write, we must do it together with a
	* command write that is down below.
	*/
	pltfm_host->xfer_mode_shadow = val;
	return;
	case SDHCI_COMMAND:
	writel((val << 16) \| pltfm_host->xfer_mode_shadow,
	host->ioaddr + SDHCI_TRANSFER_MODE);
	return;
	}

	writew(val, host->ioaddr + reg);
	}

	static void tegra_sdhci_writel(struct sdhci_host *host, u32 val, int reg)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

	/* Seems like we're getting spurious timeout and crc errors, so
	* disable signalling of them. In case of real errors software
	* timers should take care of eventually detecting them.
	*/
	if (unlikely(reg == SDHCI_SIGNAL_ENABLE))
	val &= ~(SDHCI_INT_TIMEOUT\|SDHCI_INT_CRC);

	writel(val, host->ioaddr + reg);

	if (unlikely((soc_data->nvquirks & NVQUIRK_ENABLE_BLOCK_GAP_DET) &&
	(reg == SDHCI_INT_ENABLE))) {
	/* Erratum: Must enable block gap interrupt detection */
	u8 gap_ctrl = readb(host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
	if (val & SDHCI_INT_CARD_INT)
	gap_ctrl \|= 0x8;
	else
	gap_ctrl &= ~0x8;
	writeb(gap_ctrl, host->ioaddr + SDHCI_BLOCK_GAP_CONTROL);
	}
	}

	static unsigned int tegra_sdhci_get_ro(struct sdhci_host *host)
	{
	return mmc_gpio_get_ro(host->mmc);
	}

	static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
	u32 misc_ctrl, clk_ctrl;

	sdhci_reset(host, mask);

	if (!(mask & SDHCI_RESET_ALL))
	return;

	misc_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
	clk_ctrl = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);

	misc_ctrl &= ~(SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 \|
	SDHCI_MISC_CTRL_ENABLE_SDR50 \|
	SDHCI_MISC_CTRL_ENABLE_DDR50 \|
	SDHCI_MISC_CTRL_ENABLE_SDR104);

	clk_ctrl &= ~SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE;

	/*
	* If the board does not define a regulator for the SDHCI
	* IO voltage, then don't advertise support for UHS modes
	* even if the device supports it because the IO voltage
	* cannot be configured.
	*/
	if (!IS_ERR(host->mmc->supply.vqmmc)) {
	/* Erratum: Enable SDHCI spec v3.00 support */
	if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300)
	misc_ctrl \|= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
	/* Advertise UHS modes as supported by host */
	if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR50)
	misc_ctrl \|= SDHCI_MISC_CTRL_ENABLE_SDR50;
	if (soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
	misc_ctrl \|= SDHCI_MISC_CTRL_ENABLE_DDR50;
	if (soc_data->nvquirks & NVQUIRK_ENABLE_SDR104)
	misc_ctrl \|= SDHCI_MISC_CTRL_ENABLE_SDR104;
	if (soc_data->nvquirks & SDHCI_MISC_CTRL_ENABLE_SDR50)
	clk_ctrl \|= SDHCI_CLOCK_CTRL_SDR50_TUNING_OVERRIDE;
	}

	sdhci_writel(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
	sdhci_writel(host, clk_ctrl, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);

	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
	tegra_host->pad_calib_required = true;

	tegra_host->ddr_signaling = false;
	}

	static void tegra_sdhci_set_bus_width(struct sdhci_host *host, int bus_width)
	{
	u32 ctrl;

	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
	if ((host->mmc->caps & MMC_CAP_8_BIT_DATA) &&
	(bus_width == MMC_BUS_WIDTH_8)) {
	ctrl &= ~SDHCI_CTRL_4BITBUS;
	ctrl \|= SDHCI_CTRL_8BITBUS;
	} else {
	ctrl &= ~SDHCI_CTRL_8BITBUS;
	if (bus_width == MMC_BUS_WIDTH_4)
	ctrl \|= SDHCI_CTRL_4BITBUS;
	else
	ctrl &= ~SDHCI_CTRL_4BITBUS;
	}
	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
	}

	static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
	{
	u32 val;

	mdelay(1);

	val = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
	val \|= SDHCI_AUTO_CAL_ENABLE \| SDHCI_AUTO_CAL_START;
	sdhci_writel(host,val, SDHCI_TEGRA_AUTO_CAL_CONFIG);
	}

	static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
	unsigned long host_clk;

	if (!clock)
	return sdhci_set_clock(host, clock);

	host_clk = tegra_host->ddr_signaling ? clock * 2 : clock;
	clk_set_rate(pltfm_host->clk, host_clk);
	host->max_clk = clk_get_rate(pltfm_host->clk);

	sdhci_set_clock(host, clock);

	if (tegra_host->pad_calib_required) {
	tegra_sdhci_pad_autocalib(host);
	tegra_host->pad_calib_required = false;
	}
	}

	static void tegra_sdhci_set_uhs_signaling(struct sdhci_host *host,
	unsigned timing)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);

	if (timing == MMC_TIMING_UHS_DDR50)
	tegra_host->ddr_signaling = true;

	return sdhci_set_uhs_signaling(host, timing);
	}

	static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);

	/*
	* DDR modes require the host to run at double the card frequency, so
	* the maximum rate we can support is half of the module input clock.
	*/
	return clk_round_rate(pltfm_host->clk, UINT_MAX) / 2;
	}

	static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap)
	{
	u32 reg;

	reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
	reg &= ~SDHCI_CLOCK_CTRL_TAP_MASK;
	reg \|= tap << SDHCI_CLOCK_CTRL_TAP_SHIFT;
	sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
	}

	static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
	{
	unsigned int min, max;

	/*
	* Start search for minimum tap value at 10, as smaller values are
	* may wrongly be reported as working but fail at higher speeds,
	* according to the TRM.
	*/
	min = 10;
	while (min < 255) {
	tegra_sdhci_set_tap(host, min);
	if (!mmc_send_tuning(host->mmc, opcode, NULL))
	break;
	min++;
	}

	/* Find the maximum tap value that still passes. */
	max = min + 1;
	while (max < 255) {
	tegra_sdhci_set_tap(host, max);
	if (mmc_send_tuning(host->mmc, opcode, NULL)) {
	max--;
	break;
	}
	max++;
	}

	/* The TRM states the ideal tap value is at 75% in the passing range. */
	tegra_sdhci_set_tap(host, min + ((max - min) * 3 / 4));

	return mmc_send_tuning(host->mmc, opcode, NULL);
	}

	static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
	tegra_host->pad_calib_required = true;
	}

	static const struct sdhci_ops tegra_sdhci_ops = {
	.get_ro = tegra_sdhci_get_ro,
	.read_w = tegra_sdhci_readw,
	.write_l = tegra_sdhci_writel,
	.set_clock = tegra_sdhci_set_clock,
	.set_bus_width = tegra_sdhci_set_bus_width,
	.reset = tegra_sdhci_reset,
	.platform_execute_tuning = tegra_sdhci_execute_tuning,
	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
	.voltage_switch = tegra_sdhci_voltage_switch,
	.get_max_clock = tegra_sdhci_get_max_clock,
	};

	static const struct sdhci_pltfm_data sdhci_tegra20_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.ops = &tegra_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra20 = {
	.pdata = &sdhci_tegra20_pdata,
	.nvquirks = NVQUIRK_FORCE_SDHCI_SPEC_200 \|
	NVQUIRK_ENABLE_BLOCK_GAP_DET,
	};

	static const struct sdhci_pltfm_data sdhci_tegra30_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
	.ops = &tegra_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra30 = {
	.pdata = &sdhci_tegra30_pdata,
	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300 \|
	NVQUIRK_ENABLE_SDR50 \|
	NVQUIRK_ENABLE_SDR104 \|
	NVQUIRK_HAS_PADCALIB,
	};

	static const struct sdhci_ops tegra114_sdhci_ops = {
	.get_ro = tegra_sdhci_get_ro,
	.read_w = tegra_sdhci_readw,
	.write_w = tegra_sdhci_writew,
	.write_l = tegra_sdhci_writel,
	.set_clock = tegra_sdhci_set_clock,
	.set_bus_width = tegra_sdhci_set_bus_width,
	.reset = tegra_sdhci_reset,
	.platform_execute_tuning = tegra_sdhci_execute_tuning,
	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
	.voltage_switch = tegra_sdhci_voltage_switch,
	.get_max_clock = tegra_sdhci_get_max_clock,
	};

	static const struct sdhci_pltfm_data sdhci_tegra114_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
	.ops = &tegra114_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra114 = {
	.pdata = &sdhci_tegra114_pdata,
	};

	static const struct sdhci_pltfm_data sdhci_tegra124_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN \|
	/*
	* The TRM states that the SD/MMC controller found on
	* Tegra124 can address 34 bits (the maximum supported by
	* the Tegra memory controller), but tests show that DMA
	* to or from above 4 GiB doesn't work. This is possibly
	* caused by missing programming, though it's not obvious
	* what sequence is required. Mark 64-bit DMA broken for
	* now to fix this for existing users (e.g. Nyan boards).
	*/
	SDHCI_QUIRK2_BROKEN_64_BIT_DMA,
	.ops = &tegra114_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra124 = {
	.pdata = &sdhci_tegra124_pdata,
	};

	static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
	.ops = &tegra114_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
	.pdata = &sdhci_tegra210_pdata,
	};

	static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
	.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \|
	SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK \|
	SDHCI_QUIRK_SINGLE_POWER_WRITE \|
	SDHCI_QUIRK_NO_HISPD_BIT \|
	SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
	.ops = &tegra114_sdhci_ops,
	};

	static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
	.pdata = &sdhci_tegra186_pdata,
	};

	static const struct of_device_id sdhci_tegra_dt_match[] = {
	{ .compatible = "nvidia,tegra186-sdhci", .data = &soc_data_tegra186 },
	{ .compatible = "nvidia,tegra210-sdhci", .data = &soc_data_tegra210 },
	{ .compatible = "nvidia,tegra124-sdhci", .data = &soc_data_tegra124 },
	{ .compatible = "nvidia,tegra114-sdhci", .data = &soc_data_tegra114 },
	{ .compatible = "nvidia,tegra30-sdhci", .data = &soc_data_tegra30 },
	{ .compatible = "nvidia,tegra20-sdhci", .data = &soc_data_tegra20 },
	{}
	};
	MODULE_DEVICE_TABLE(of, sdhci_tegra_dt_match);

	static int sdhci_tegra_probe(struct platform_device *pdev)
	{
	const struct of_device_id *match;
	const struct sdhci_tegra_soc_data *soc_data;
	struct sdhci_host *host;
	struct sdhci_pltfm_host *pltfm_host;
	struct sdhci_tegra *tegra_host;
	struct clk *clk;
	int rc;

	match = of_match_device(sdhci_tegra_dt_match, &pdev->dev);
	if (!match)
	return -EINVAL;
	soc_data = match->data;

	host = sdhci_pltfm_init(pdev, soc_data->pdata, sizeof(*tegra_host));
	if (IS_ERR(host))
	return PTR_ERR(host);
	pltfm_host = sdhci_priv(host);

	tegra_host = sdhci_pltfm_priv(pltfm_host);
	tegra_host->ddr_signaling = false;
	tegra_host->pad_calib_required = false;
	tegra_host->soc_data = soc_data;

	rc = mmc_of_parse(host->mmc);
	if (rc)
	goto err_parse_dt;

	if (tegra_host->soc_data->nvquirks & NVQUIRK_ENABLE_DDR50)
	host->mmc->caps \|= MMC_CAP_1_8V_DDR;

	tegra_host->power_gpio = devm_gpiod_get_optional(&pdev->dev, "power",
	GPIOD_OUT_HIGH);
	if (IS_ERR(tegra_host->power_gpio)) {
	rc = PTR_ERR(tegra_host->power_gpio);
	goto err_power_req;
	}

	clk = devm_clk_get(mmc_dev(host->mmc), NULL);
	if (IS_ERR(clk)) {
	dev_err(mmc_dev(host->mmc), "clk err\n");
	rc = PTR_ERR(clk);
	goto err_clk_get;
	}
	clk_prepare_enable(clk);
	pltfm_host->clk = clk;

	tegra_host->rst = devm_reset_control_get(&pdev->dev, "sdhci");
	if (IS_ERR(tegra_host->rst)) {
	rc = PTR_ERR(tegra_host->rst);
	dev_err(&pdev->dev, "failed to get reset control: %d\n", rc);
	goto err_rst_get;
	}

	rc = reset_control_assert(tegra_host->rst);
	if (rc)
	goto err_rst_get;

	usleep_range(2000, 4000);

	rc = reset_control_deassert(tegra_host->rst);
	if (rc)
	goto err_rst_get;

	usleep_range(2000, 4000);

	rc = sdhci_add_host(host);
	if (rc)
	goto err_add_host;

	return 0;

	err_add_host:
	reset_control_assert(tegra_host->rst);
	err_rst_get:
	clk_disable_unprepare(pltfm_host->clk);
	err_clk_get:
	err_power_req:
	err_parse_dt:
	sdhci_pltfm_free(pdev);
	return rc;
	}

	static int sdhci_tegra_remove(struct platform_device *pdev)
	{
	struct sdhci_host *host = platform_get_drvdata(pdev);
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);

	sdhci_remove_host(host, 0);

	reset_control_assert(tegra_host->rst);
	usleep_range(2000, 4000);
	clk_disable_unprepare(pltfm_host->clk);

	sdhci_pltfm_free(pdev);

	return 0;
	}

	static struct platform_driver sdhci_tegra_driver = {
	.driver = {
	.name = "sdhci-tegra",
	.of_match_table = sdhci_tegra_dt_match,
	.pm = &sdhci_pltfm_pmops,
	},
	.probe = sdhci_tegra_probe,
	.remove = sdhci_tegra_remove,
	};

	module_platform_driver(sdhci_tegra_driver);

	MODULE_DESCRIPTION("SDHCI driver for Tegra");
	MODULE_AUTHOR("Google, Inc.");
	MODULE_LICENSE("GPL v2");