drivers/mmc/host/sdhci-tegra.c - 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/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/of_gpio.h>
 #include <linux/gpio.h>
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/slot-gpio.h>

 #include <asm/gpio.h>

 #include "sdhci-pltfm.h"

 /* Tegra SDHOST controller vendor register definitions */
 #define SDHCI_TEGRA_VENDOR_MISC_CTRL		0x120
 #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300	0x20

 #define NVQUIRK_FORCE_SDHCI_SPEC_200	BIT(0)
 #define NVQUIRK_ENABLE_BLOCK_GAP_DET	BIT(1)
 #define NVQUIRK_ENABLE_SDHCI_SPEC_300	BIT(2)

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

 struct sdhci_tegra {
 	const struct sdhci_tegra_soc_data *soc_data;
 	int power_gpio;
 };

 static u32 tegra_sdhci_readl(struct sdhci_host *host, int reg)
 {
 	u32 val;

 	if (unlikely(reg == SDHCI_PRESENT_STATE)) {
 		/* Use wp_gpio here instead? */
 		val = readl(host->ioaddr + reg);
 		return val | SDHCI_WRITE_PROTECT;
 	}

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

 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 = pltfm_host->priv;
 	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_writel(struct sdhci_host *host, u32 val, int reg)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = pltfm_host->priv;
 	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_exit(struct sdhci_host *host, u8 mask)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = pltfm_host->priv;
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

 	if (!(mask & SDHCI_RESET_ALL))
 		return;

 	/* Erratum: Enable SDHCI spec v3.00 support */
 	if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300) {
 		u32 misc_ctrl;

 		misc_ctrl = sdhci_readb(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
 		misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
 		sdhci_writeb(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
 	}
 }

 static int tegra_sdhci_buswidth(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);
 	return 0;
 }

 static const struct sdhci_ops tegra_sdhci_ops = {
 	.get_ro     = tegra_sdhci_get_ro,
 	.read_l     = tegra_sdhci_readl,
 	.read_w     = tegra_sdhci_readw,
 	.write_l    = tegra_sdhci_writel,
 	.platform_bus_width = tegra_sdhci_buswidth,
 	.platform_reset_exit = tegra_sdhci_reset_exit,
 };

 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,
 	.ops  = &tegra_sdhci_ops,
 };

 static 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,
 	.ops  = &tegra_sdhci_ops,
 };

 static struct sdhci_tegra_soc_data soc_data_tegra30 = {
 	.pdata = &sdhci_tegra30_pdata,
 	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300,
 };

 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,
 	.ops  = &tegra_sdhci_ops,
 };

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

 static const struct of_device_id sdhci_tegra_dt_match[] = {
 	{ .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 void sdhci_tegra_parse_dt(struct device *dev)
 {
 	struct device_node *np = dev->of_node;
 	struct sdhci_host *host = dev_get_drvdata(dev);
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = pltfm_host->priv;

 	tegra_host->power_gpio = of_get_named_gpio(np, "power-gpios", 0);
 	mmc_of_parse(host->mmc);
 }

 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);
 	if (IS_ERR(host))
 		return PTR_ERR(host);
 	pltfm_host = sdhci_priv(host);

 	tegra_host = devm_kzalloc(&pdev->dev, sizeof(*tegra_host), GFP_KERNEL);
 	if (!tegra_host) {
 		dev_err(mmc_dev(host->mmc), "failed to allocate tegra_host\n");
 		rc = -ENOMEM;
 		goto err_alloc_tegra_host;
 	}
 	tegra_host->soc_data = soc_data;
 	pltfm_host->priv = tegra_host;

 	sdhci_tegra_parse_dt(&pdev->dev);

 	if (gpio_is_valid(tegra_host->power_gpio)) {
 		rc = gpio_request(tegra_host->power_gpio, "sdhci_power");
 		if (rc) {
 			dev_err(mmc_dev(host->mmc),
 				"failed to allocate power gpio\n");
 			goto err_power_req;
 		}
 		gpio_direction_output(tegra_host->power_gpio, 1);
 	}

 	clk = 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;

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

 	return 0;

 err_add_host:
 	clk_disable_unprepare(pltfm_host->clk);
 	clk_put(pltfm_host->clk);
 err_clk_get:
 	if (gpio_is_valid(tegra_host->power_gpio))
 		gpio_free(tegra_host->power_gpio);
 err_power_req:
 err_alloc_tegra_host:
 	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 = pltfm_host->priv;
 	int dead = (readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff);

 	sdhci_remove_host(host, dead);

 	if (gpio_is_valid(tegra_host->power_gpio))
 		gpio_free(tegra_host->power_gpio);

 	clk_disable_unprepare(pltfm_host->clk);
 	clk_put(pltfm_host->clk);

 	sdhci_pltfm_free(pdev);

 	return 0;
 }

 static struct platform_driver sdhci_tegra_driver = {
 	.driver		= {
 		.name	= "sdhci-tegra",
 		.owner	= THIS_MODULE,
 		.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/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/of_gpio.h>
	#include <linux/gpio.h>
	#include <linux/mmc/card.h>
	#include <linux/mmc/host.h>
	#include <linux/mmc/slot-gpio.h>

	#include <asm/gpio.h>

	#include "sdhci-pltfm.h"

	/* Tegra SDHOST controller vendor register definitions */
	#define SDHCI_TEGRA_VENDOR_MISC_CTRL 0x120
	#define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 0x20

	#define NVQUIRK_FORCE_SDHCI_SPEC_200 BIT(0)
	#define NVQUIRK_ENABLE_BLOCK_GAP_DET BIT(1)
	#define NVQUIRK_ENABLE_SDHCI_SPEC_300 BIT(2)

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

	struct sdhci_tegra {
	const struct sdhci_tegra_soc_data *soc_data;
	int power_gpio;
	};

	static u32 tegra_sdhci_readl(struct sdhci_host *host, int reg)
	{
	u32 val;

	if (unlikely(reg == SDHCI_PRESENT_STATE)) {
	/* Use wp_gpio here instead? */
	val = readl(host->ioaddr + reg);
	return val \| SDHCI_WRITE_PROTECT;
	}

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

	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 = pltfm_host->priv;
	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_writel(struct sdhci_host *host, u32 val, int reg)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = pltfm_host->priv;
	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_exit(struct sdhci_host *host, u8 mask)
	{
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = pltfm_host->priv;
	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;

	if (!(mask & SDHCI_RESET_ALL))
	return;

	/* Erratum: Enable SDHCI spec v3.00 support */
	if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300) {
	u32 misc_ctrl;

	misc_ctrl = sdhci_readb(host, SDHCI_TEGRA_VENDOR_MISC_CTRL);
	misc_ctrl \|= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
	sdhci_writeb(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
	}
	}

	static int tegra_sdhci_buswidth(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);
	return 0;
	}

	static const struct sdhci_ops tegra_sdhci_ops = {
	.get_ro = tegra_sdhci_get_ro,
	.read_l = tegra_sdhci_readl,
	.read_w = tegra_sdhci_readw,
	.write_l = tegra_sdhci_writel,
	.platform_bus_width = tegra_sdhci_buswidth,
	.platform_reset_exit = tegra_sdhci_reset_exit,
	};

	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,
	.ops = &tegra_sdhci_ops,
	};

	static 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,
	.ops = &tegra_sdhci_ops,
	};

	static struct sdhci_tegra_soc_data soc_data_tegra30 = {
	.pdata = &sdhci_tegra30_pdata,
	.nvquirks = NVQUIRK_ENABLE_SDHCI_SPEC_300,
	};

	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,
	.ops = &tegra_sdhci_ops,
	};

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

	static const struct of_device_id sdhci_tegra_dt_match[] = {
	{ .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 void sdhci_tegra_parse_dt(struct device *dev)
	{
	struct device_node *np = dev->of_node;
	struct sdhci_host *host = dev_get_drvdata(dev);
	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
	struct sdhci_tegra *tegra_host = pltfm_host->priv;

	tegra_host->power_gpio = of_get_named_gpio(np, "power-gpios", 0);
	mmc_of_parse(host->mmc);
	}

	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);
	if (IS_ERR(host))
	return PTR_ERR(host);
	pltfm_host = sdhci_priv(host);

	tegra_host = devm_kzalloc(&pdev->dev, sizeof(*tegra_host), GFP_KERNEL);
	if (!tegra_host) {
	dev_err(mmc_dev(host->mmc), "failed to allocate tegra_host\n");
	rc = -ENOMEM;
	goto err_alloc_tegra_host;
	}
	tegra_host->soc_data = soc_data;
	pltfm_host->priv = tegra_host;

	sdhci_tegra_parse_dt(&pdev->dev);

	if (gpio_is_valid(tegra_host->power_gpio)) {
	rc = gpio_request(tegra_host->power_gpio, "sdhci_power");
	if (rc) {
	dev_err(mmc_dev(host->mmc),
	"failed to allocate power gpio\n");
	goto err_power_req;
	}
	gpio_direction_output(tegra_host->power_gpio, 1);
	}

	clk = 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;

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

	return 0;

	err_add_host:
	clk_disable_unprepare(pltfm_host->clk);
	clk_put(pltfm_host->clk);
	err_clk_get:
	if (gpio_is_valid(tegra_host->power_gpio))
	gpio_free(tegra_host->power_gpio);
	err_power_req:
	err_alloc_tegra_host:
	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 = pltfm_host->priv;
	int dead = (readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff);

	sdhci_remove_host(host, dead);

	if (gpio_is_valid(tegra_host->power_gpio))
	gpio_free(tegra_host->power_gpio);

	clk_disable_unprepare(pltfm_host->clk);
	clk_put(pltfm_host->clk);

	sdhci_pltfm_free(pdev);

	return 0;
	}

	static struct platform_driver sdhci_tegra_driver = {
	.driver = {
	.name = "sdhci-tegra",
	.owner = THIS_MODULE,
	.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");