drivers/mmc/host/sdhci-bcm-kona.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2013 Broadcom Corporation
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation version 2.
  *
  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  * kind, whether express or implied; without even the implied warranty
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/highmem.h>
 #include <linux/platform_device.h>
 #include <linux/mmc/host.h>
 #include <linux/io.h>
 #include <linux/gpio.h>
 #include <linux/clk.h>
 #include <linux/regulator/consumer.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/mmc/slot-gpio.h>

 #include "sdhci-pltfm.h"
 #include "sdhci.h"

 #define SDHCI_SOFT_RESET			0x01000000
 #define KONA_SDHOST_CORECTRL			0x8000
 #define KONA_SDHOST_CD_PINCTRL			0x00000008
 #define KONA_SDHOST_STOP_HCLK			0x00000004
 #define KONA_SDHOST_RESET			0x00000002
 #define KONA_SDHOST_EN				0x00000001

 #define KONA_SDHOST_CORESTAT			0x8004
 #define KONA_SDHOST_WP				0x00000002
 #define KONA_SDHOST_CD_SW			0x00000001

 #define KONA_SDHOST_COREIMR			0x8008
 #define KONA_SDHOST_IP				0x00000001

 #define KONA_SDHOST_COREISR			0x800C
 #define KONA_SDHOST_COREIMSR			0x8010
 #define KONA_SDHOST_COREDBG1			0x8014
 #define KONA_SDHOST_COREGPO_MASK		0x8018

 #define SD_DETECT_GPIO_DEBOUNCE_128MS		128

 #define KONA_MMC_AUTOSUSPEND_DELAY		(50)

 struct sdhci_bcm_kona_dev {
 	struct mutex	write_lock; /* protect back to back writes */
 	struct clk	*external_clk;
 };


 static int sdhci_bcm_kona_sd_reset(struct sdhci_host *host)
 {
 	unsigned int val;
 	unsigned long timeout;

 	/* This timeout should be sufficent for core to reset */
 	timeout = jiffies + msecs_to_jiffies(100);

 	/* reset the host using the top level reset */
 	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
 	val |= KONA_SDHOST_RESET;
 	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);

 	while (!(sdhci_readl(host, KONA_SDHOST_CORECTRL) & KONA_SDHOST_RESET)) {
 		if (time_is_before_jiffies(timeout)) {
 			pr_err("Error: sd host is stuck in reset!!!\n");
 			return -EFAULT;
 		}
 	}

 	/* bring the host out of reset */
 	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
 	val &= ~KONA_SDHOST_RESET;

 	/*
 	 * Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
 	 * Back-to-Back writes to same register needs delay when SD bus clock
 	 * is very low w.r.t AHB clock, mainly during boot-time and during card
 	 * insert-removal.
 	 */
 	usleep_range(1000, 5000);
 	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);

 	return 0;
 }

 static void sdhci_bcm_kona_sd_init(struct sdhci_host *host)
 {
 	unsigned int val;

 	/* enable the interrupt from the IP core */
 	val = sdhci_readl(host, KONA_SDHOST_COREIMR);
 	val |= KONA_SDHOST_IP;
 	sdhci_writel(host, val, KONA_SDHOST_COREIMR);

 	/* Enable the AHB clock gating module to the host */
 	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
 	val |= KONA_SDHOST_EN;

 	/*
 	 * Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
 	 * Back-to-Back writes to same register needs delay when SD bus clock
 	 * is very low w.r.t AHB clock, mainly during boot-time and during card
 	 * insert-removal.
 	 */
 	usleep_range(1000, 5000);
 	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);
 }

 /*
  * Software emulation of the SD card insertion/removal. Set insert=1 for insert
  * and insert=0 for removal. The card detection is done by GPIO. For Broadcom
  * IP to function properly the bit 0 of CORESTAT register needs to be set/reset
  * to generate the CD IRQ handled in sdhci.c which schedules card_tasklet.
  */
 static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
 {
 	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
 	struct sdhci_bcm_kona_dev *kona_dev = sdhci_pltfm_priv(pltfm_priv);
 	u32 val;

 	/*
 	 * Back-to-Back register write needs a delay of min 10uS.
 	 * Back-to-Back writes to same register needs delay when SD bus clock
 	 * is very low w.r.t AHB clock, mainly during boot-time and during card
 	 * insert-removal.
 	 * We keep 20uS
 	 */
 	mutex_lock(&kona_dev->write_lock);
 	udelay(20);
 	val = sdhci_readl(host, KONA_SDHOST_CORESTAT);

 	if (insert) {
 		int ret;

 		ret = mmc_gpio_get_ro(host->mmc);
 		if (ret >= 0)
 			val = (val & ~KONA_SDHOST_WP) |
 				((ret) ? KONA_SDHOST_WP : 0);

 		val |= KONA_SDHOST_CD_SW;
 		sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
 	} else {
 		val &= ~KONA_SDHOST_CD_SW;
 		sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
 	}
 	mutex_unlock(&kona_dev->write_lock);

 	return 0;
 }

 /*
  * SD card interrupt event callback
  */
 static void sdhci_bcm_kona_card_event(struct sdhci_host *host)
 {
 	if (mmc_gpio_get_cd(host->mmc) > 0) {
 		dev_dbg(mmc_dev(host->mmc),
 			"card inserted\n");
 		sdhci_bcm_kona_sd_card_emulate(host, 1);
 	} else {
 		dev_dbg(mmc_dev(host->mmc),
 			"card removed\n");
 		sdhci_bcm_kona_sd_card_emulate(host, 0);
 	}
 }

 /*
  * Get the base clock. Use central clock source for now. Not sure if different
  * clock speed to each dev is allowed
  */
 static unsigned int sdhci_bcm_kona_get_max_clk(struct sdhci_host *host)
 {
 	struct sdhci_bcm_kona_dev *kona_dev;
 	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
 	kona_dev = sdhci_pltfm_priv(pltfm_priv);

 	return host->mmc->f_max;
 }

 static unsigned int sdhci_bcm_kona_get_timeout_clock(struct sdhci_host *host)
 {
 	return sdhci_bcm_kona_get_max_clk(host);
 }

 static void sdhci_bcm_kona_init_74_clocks(struct sdhci_host *host,
 				u8 power_mode)
 {
 	/*
 	 *  JEDEC and SD spec specify supplying 74 continuous clocks to
 	 * device after power up. With minimum bus (100KHz) that
 	 * that translates to 740us
 	 */
 	if (power_mode != MMC_POWER_OFF)
 		udelay(740);
 }

 static struct sdhci_ops sdhci_bcm_kona_ops = {
 	.set_clock = sdhci_set_clock,
 	.get_max_clock = sdhci_bcm_kona_get_max_clk,
 	.get_timeout_clock = sdhci_bcm_kona_get_timeout_clock,
 	.platform_send_init_74_clocks = sdhci_bcm_kona_init_74_clocks,
 	.set_bus_width = sdhci_set_bus_width,
 	.reset = sdhci_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
 	.card_event = sdhci_bcm_kona_card_event,
 };

 static struct sdhci_pltfm_data sdhci_pltfm_data_kona = {
 	.ops    = &sdhci_bcm_kona_ops,
 	.quirks = SDHCI_QUIRK_NO_CARD_NO_RESET |
 		SDHCI_QUIRK_BROKEN_TIMEOUT_VAL | SDHCI_QUIRK_32BIT_DMA_ADDR |
 		SDHCI_QUIRK_32BIT_DMA_SIZE | SDHCI_QUIRK_32BIT_ADMA_SIZE |
 		SDHCI_QUIRK_FORCE_BLK_SZ_2048 |
 		SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 };

 static struct __initconst of_device_id sdhci_bcm_kona_of_match[] = {
 	{ .compatible = "brcm,kona-sdhci"},
 	{ .compatible = "bcm,kona-sdhci"}, /* deprecated name */
 	{}
 };
 MODULE_DEVICE_TABLE(of, sdhci_bcm_kona_of_match);

 static int sdhci_bcm_kona_probe(struct platform_device *pdev)
 {
 	struct sdhci_bcm_kona_dev *kona_dev = NULL;
 	struct sdhci_pltfm_host *pltfm_priv;
 	struct device *dev = &pdev->dev;
 	struct sdhci_host *host;
 	int ret;

 	ret = 0;

 	host = sdhci_pltfm_init(pdev, &sdhci_pltfm_data_kona,
 			sizeof(*kona_dev));
 	if (IS_ERR(host))
 		return PTR_ERR(host);

 	dev_dbg(dev, "%s: inited. IOADDR=%p\n", __func__, host->ioaddr);

 	pltfm_priv = sdhci_priv(host);

 	kona_dev = sdhci_pltfm_priv(pltfm_priv);
 	mutex_init(&kona_dev->write_lock);

 	mmc_of_parse(host->mmc);

 	if (!host->mmc->f_max) {
 		dev_err(&pdev->dev, "Missing max-freq for SDHCI cfg\n");
 		ret = -ENXIO;
 		goto err_pltfm_free;
 	}

 	/* Get and enable the external clock */
 	kona_dev->external_clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(kona_dev->external_clk)) {
 		dev_err(dev, "Failed to get external clock\n");
 		ret = PTR_ERR(kona_dev->external_clk);
 		goto err_pltfm_free;
 	}

 	if (clk_set_rate(kona_dev->external_clk, host->mmc->f_max) != 0) {
 		dev_err(dev, "Failed to set rate external clock\n");
 		goto err_pltfm_free;
 	}

 	if (clk_prepare_enable(kona_dev->external_clk) != 0) {
 		dev_err(dev, "Failed to enable external clock\n");
 		goto err_pltfm_free;
 	}

 	dev_dbg(dev, "non-removable=%c\n",
 		(host->mmc->caps & MMC_CAP_NONREMOVABLE) ? 'Y' : 'N');
 	dev_dbg(dev, "cd_gpio %c, wp_gpio %c\n",
 		(mmc_gpio_get_cd(host->mmc) != -ENOSYS) ? 'Y' : 'N',
 		(mmc_gpio_get_ro(host->mmc) != -ENOSYS) ? 'Y' : 'N');

 	if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
 		host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;

 	dev_dbg(dev, "is_8bit=%c\n",
 		(host->mmc->caps | MMC_CAP_8_BIT_DATA) ? 'Y' : 'N');

 	ret = sdhci_bcm_kona_sd_reset(host);
 	if (ret)
 		goto err_clk_disable;

 	sdhci_bcm_kona_sd_init(host);

 	ret = sdhci_add_host(host);
 	if (ret) {
 		dev_err(dev, "Failed sdhci_add_host\n");
 		goto err_reset;
 	}

 	/* if device is eMMC, emulate card insert right here */
 	if (host->mmc->caps & MMC_CAP_NONREMOVABLE) {
 		ret = sdhci_bcm_kona_sd_card_emulate(host, 1);
 		if (ret) {
 			dev_err(dev,
 				"unable to emulate card insertion\n");
 			goto err_remove_host;
 		}
 	}
 	/*
 	 * Since the card detection GPIO interrupt is configured to be
 	 * edge sensitive, check the initial GPIO value here, emulate
 	 * only if the card is present
 	 */
 	if (mmc_gpio_get_cd(host->mmc) > 0)
 		sdhci_bcm_kona_sd_card_emulate(host, 1);

 	dev_dbg(dev, "initialized properly\n");
 	return 0;

 err_remove_host:
 	sdhci_remove_host(host, 0);

 err_reset:
 	sdhci_bcm_kona_sd_reset(host);

 err_clk_disable:
 	clk_disable_unprepare(kona_dev->external_clk);

 err_pltfm_free:
 	sdhci_pltfm_free(pdev);

 	dev_err(dev, "Probing of sdhci-pltfm failed: %d\n", ret);
 	return ret;
 }

 static int sdhci_bcm_kona_remove(struct platform_device *pdev)
 {
 	struct sdhci_host *host = platform_get_drvdata(pdev);
 	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
 	struct sdhci_bcm_kona_dev *kona_dev = sdhci_pltfm_priv(pltfm_priv);
 	int dead = (readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff);

 	sdhci_remove_host(host, dead);

 	clk_disable_unprepare(kona_dev->external_clk);

 	sdhci_pltfm_free(pdev);

 	return 0;
 }

 static struct platform_driver sdhci_bcm_kona_driver = {
 	.driver		= {
 		.name	= "sdhci-kona",
 		.pm	= SDHCI_PLTFM_PMOPS,
 		.of_match_table = sdhci_bcm_kona_of_match,
 	},
 	.probe		= sdhci_bcm_kona_probe,
 	.remove		= sdhci_bcm_kona_remove,
 };
 module_platform_driver(sdhci_bcm_kona_driver);

 MODULE_DESCRIPTION("SDHCI driver for Broadcom Kona platform");
 MODULE_AUTHOR("Broadcom");
 MODULE_LICENSE("GPL v2");
	/*
	* Copyright (C) 2013 Broadcom Corporation
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation version 2.
	*
	* This program is distributed "as is" WITHOUT ANY WARRANTY of any
	* kind, whether express or implied; without even the implied warranty
	* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/highmem.h>
	#include <linux/platform_device.h>
	#include <linux/mmc/host.h>
	#include <linux/io.h>
	#include <linux/gpio.h>
	#include <linux/clk.h>
	#include <linux/regulator/consumer.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/of_gpio.h>
	#include <linux/mmc/slot-gpio.h>

	#include "sdhci-pltfm.h"
	#include "sdhci.h"

	#define SDHCI_SOFT_RESET 0x01000000
	#define KONA_SDHOST_CORECTRL 0x8000
	#define KONA_SDHOST_CD_PINCTRL 0x00000008
	#define KONA_SDHOST_STOP_HCLK 0x00000004
	#define KONA_SDHOST_RESET 0x00000002
	#define KONA_SDHOST_EN 0x00000001

	#define KONA_SDHOST_CORESTAT 0x8004
	#define KONA_SDHOST_WP 0x00000002
	#define KONA_SDHOST_CD_SW 0x00000001

	#define KONA_SDHOST_COREIMR 0x8008
	#define KONA_SDHOST_IP 0x00000001

	#define KONA_SDHOST_COREISR 0x800C
	#define KONA_SDHOST_COREIMSR 0x8010
	#define KONA_SDHOST_COREDBG1 0x8014
	#define KONA_SDHOST_COREGPO_MASK 0x8018

	#define SD_DETECT_GPIO_DEBOUNCE_128MS 128

	#define KONA_MMC_AUTOSUSPEND_DELAY (50)

	struct sdhci_bcm_kona_dev {
	struct mutex write_lock; /* protect back to back writes */
	struct clk *external_clk;
	};


	static int sdhci_bcm_kona_sd_reset(struct sdhci_host *host)
	{
	unsigned int val;
	unsigned long timeout;

	/* This timeout should be sufficent for core to reset */
	timeout = jiffies + msecs_to_jiffies(100);

	/* reset the host using the top level reset */
	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
	val \|= KONA_SDHOST_RESET;
	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);

	while (!(sdhci_readl(host, KONA_SDHOST_CORECTRL) & KONA_SDHOST_RESET)) {
	if (time_is_before_jiffies(timeout)) {
	pr_err("Error: sd host is stuck in reset!!!\n");
	return -EFAULT;
	}
	}

	/* bring the host out of reset */
	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
	val &= ~KONA_SDHOST_RESET;

	/*
	* Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
	* Back-to-Back writes to same register needs delay when SD bus clock
	* is very low w.r.t AHB clock, mainly during boot-time and during card
	* insert-removal.
	*/
	usleep_range(1000, 5000);
	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);

	return 0;
	}

	static void sdhci_bcm_kona_sd_init(struct sdhci_host *host)
	{
	unsigned int val;

	/* enable the interrupt from the IP core */
	val = sdhci_readl(host, KONA_SDHOST_COREIMR);
	val \|= KONA_SDHOST_IP;
	sdhci_writel(host, val, KONA_SDHOST_COREIMR);

	/* Enable the AHB clock gating module to the host */
	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
	val \|= KONA_SDHOST_EN;

	/*
	* Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
	* Back-to-Back writes to same register needs delay when SD bus clock
	* is very low w.r.t AHB clock, mainly during boot-time and during card
	* insert-removal.
	*/
	usleep_range(1000, 5000);
	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);
	}

	/*
	* Software emulation of the SD card insertion/removal. Set insert=1 for insert
	* and insert=0 for removal. The card detection is done by GPIO. For Broadcom
	* IP to function properly the bit 0 of CORESTAT register needs to be set/reset
	* to generate the CD IRQ handled in sdhci.c which schedules card_tasklet.
	*/
	static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
	{
	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
	struct sdhci_bcm_kona_dev *kona_dev = sdhci_pltfm_priv(pltfm_priv);
	u32 val;

	/*
	* Back-to-Back register write needs a delay of min 10uS.
	* Back-to-Back writes to same register needs delay when SD bus clock
	* is very low w.r.t AHB clock, mainly during boot-time and during card
	* insert-removal.
	* We keep 20uS
	*/
	mutex_lock(&kona_dev->write_lock);
	udelay(20);
	val = sdhci_readl(host, KONA_SDHOST_CORESTAT);

	if (insert) {
	int ret;

	ret = mmc_gpio_get_ro(host->mmc);
	if (ret >= 0)
	val = (val & ~KONA_SDHOST_WP) \|
	((ret) ? KONA_SDHOST_WP : 0);

	val \|= KONA_SDHOST_CD_SW;
	sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
	} else {
	val &= ~KONA_SDHOST_CD_SW;
	sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
	}
	mutex_unlock(&kona_dev->write_lock);

	return 0;
	}

	/*
	* SD card interrupt event callback
	*/
	static void sdhci_bcm_kona_card_event(struct sdhci_host *host)
	{
	if (mmc_gpio_get_cd(host->mmc) > 0) {
	dev_dbg(mmc_dev(host->mmc),
	"card inserted\n");
	sdhci_bcm_kona_sd_card_emulate(host, 1);
	} else {
	dev_dbg(mmc_dev(host->mmc),
	"card removed\n");
	sdhci_bcm_kona_sd_card_emulate(host, 0);
	}
	}

	/*
	* Get the base clock. Use central clock source for now. Not sure if different
	* clock speed to each dev is allowed
	*/
	static unsigned int sdhci_bcm_kona_get_max_clk(struct sdhci_host *host)
	{
	struct sdhci_bcm_kona_dev *kona_dev;
	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
	kona_dev = sdhci_pltfm_priv(pltfm_priv);

	return host->mmc->f_max;
	}

	static unsigned int sdhci_bcm_kona_get_timeout_clock(struct sdhci_host *host)
	{
	return sdhci_bcm_kona_get_max_clk(host);
	}

	static void sdhci_bcm_kona_init_74_clocks(struct sdhci_host *host,
	u8 power_mode)
	{
	/*
	* JEDEC and SD spec specify supplying 74 continuous clocks to
	* device after power up. With minimum bus (100KHz) that
	* that translates to 740us
	*/
	if (power_mode != MMC_POWER_OFF)
	udelay(740);
	}

	static struct sdhci_ops sdhci_bcm_kona_ops = {
	.set_clock = sdhci_set_clock,
	.get_max_clock = sdhci_bcm_kona_get_max_clk,
	.get_timeout_clock = sdhci_bcm_kona_get_timeout_clock,
	.platform_send_init_74_clocks = sdhci_bcm_kona_init_74_clocks,
	.set_bus_width = sdhci_set_bus_width,
	.reset = sdhci_reset,
	.set_uhs_signaling = sdhci_set_uhs_signaling,
	.card_event = sdhci_bcm_kona_card_event,
	};

	static struct sdhci_pltfm_data sdhci_pltfm_data_kona = {
	.ops = &sdhci_bcm_kona_ops,
	.quirks = SDHCI_QUIRK_NO_CARD_NO_RESET \|
	SDHCI_QUIRK_BROKEN_TIMEOUT_VAL \| SDHCI_QUIRK_32BIT_DMA_ADDR \|
	SDHCI_QUIRK_32BIT_DMA_SIZE \| SDHCI_QUIRK_32BIT_ADMA_SIZE \|
	SDHCI_QUIRK_FORCE_BLK_SZ_2048 \|
	SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
	};

	static struct __initconst of_device_id sdhci_bcm_kona_of_match[] = {
	{ .compatible = "brcm,kona-sdhci"},
	{ .compatible = "bcm,kona-sdhci"}, /* deprecated name */
	{}
	};
	MODULE_DEVICE_TABLE(of, sdhci_bcm_kona_of_match);

	static int sdhci_bcm_kona_probe(struct platform_device *pdev)
	{
	struct sdhci_bcm_kona_dev *kona_dev = NULL;
	struct sdhci_pltfm_host *pltfm_priv;
	struct device *dev = &pdev->dev;
	struct sdhci_host *host;
	int ret;

	ret = 0;

	host = sdhci_pltfm_init(pdev, &sdhci_pltfm_data_kona,
	sizeof(*kona_dev));
	if (IS_ERR(host))
	return PTR_ERR(host);

	dev_dbg(dev, "%s: inited. IOADDR=%p\n", __func__, host->ioaddr);

	pltfm_priv = sdhci_priv(host);

	kona_dev = sdhci_pltfm_priv(pltfm_priv);
	mutex_init(&kona_dev->write_lock);

	mmc_of_parse(host->mmc);

	if (!host->mmc->f_max) {
	dev_err(&pdev->dev, "Missing max-freq for SDHCI cfg\n");
	ret = -ENXIO;
	goto err_pltfm_free;
	}

	/* Get and enable the external clock */
	kona_dev->external_clk = devm_clk_get(dev, NULL);
	if (IS_ERR(kona_dev->external_clk)) {
	dev_err(dev, "Failed to get external clock\n");
	ret = PTR_ERR(kona_dev->external_clk);
	goto err_pltfm_free;
	}

	if (clk_set_rate(kona_dev->external_clk, host->mmc->f_max) != 0) {
	dev_err(dev, "Failed to set rate external clock\n");
	goto err_pltfm_free;
	}

	if (clk_prepare_enable(kona_dev->external_clk) != 0) {
	dev_err(dev, "Failed to enable external clock\n");
	goto err_pltfm_free;
	}

	dev_dbg(dev, "non-removable=%c\n",
	(host->mmc->caps & MMC_CAP_NONREMOVABLE) ? 'Y' : 'N');
	dev_dbg(dev, "cd_gpio %c, wp_gpio %c\n",
	(mmc_gpio_get_cd(host->mmc) != -ENOSYS) ? 'Y' : 'N',
	(mmc_gpio_get_ro(host->mmc) != -ENOSYS) ? 'Y' : 'N');

	if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
	host->quirks \|= SDHCI_QUIRK_BROKEN_CARD_DETECTION;

	dev_dbg(dev, "is_8bit=%c\n",
	(host->mmc->caps \| MMC_CAP_8_BIT_DATA) ? 'Y' : 'N');

	ret = sdhci_bcm_kona_sd_reset(host);
	if (ret)
	goto err_clk_disable;

	sdhci_bcm_kona_sd_init(host);

	ret = sdhci_add_host(host);
	if (ret) {
	dev_err(dev, "Failed sdhci_add_host\n");
	goto err_reset;
	}

	/* if device is eMMC, emulate card insert right here */
	if (host->mmc->caps & MMC_CAP_NONREMOVABLE) {
	ret = sdhci_bcm_kona_sd_card_emulate(host, 1);
	if (ret) {
	dev_err(dev,
	"unable to emulate card insertion\n");
	goto err_remove_host;
	}
	}
	/*
	* Since the card detection GPIO interrupt is configured to be
	* edge sensitive, check the initial GPIO value here, emulate
	* only if the card is present
	*/
	if (mmc_gpio_get_cd(host->mmc) > 0)
	sdhci_bcm_kona_sd_card_emulate(host, 1);

	dev_dbg(dev, "initialized properly\n");
	return 0;

	err_remove_host:
	sdhci_remove_host(host, 0);

	err_reset:
	sdhci_bcm_kona_sd_reset(host);

	err_clk_disable:
	clk_disable_unprepare(kona_dev->external_clk);

	err_pltfm_free:
	sdhci_pltfm_free(pdev);

	dev_err(dev, "Probing of sdhci-pltfm failed: %d\n", ret);
	return ret;
	}

	static int sdhci_bcm_kona_remove(struct platform_device *pdev)
	{
	struct sdhci_host *host = platform_get_drvdata(pdev);
	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
	struct sdhci_bcm_kona_dev *kona_dev = sdhci_pltfm_priv(pltfm_priv);
	int dead = (readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff);

	sdhci_remove_host(host, dead);

	clk_disable_unprepare(kona_dev->external_clk);

	sdhci_pltfm_free(pdev);

	return 0;
	}

	static struct platform_driver sdhci_bcm_kona_driver = {
	.driver = {
	.name = "sdhci-kona",
	.pm = SDHCI_PLTFM_PMOPS,
	.of_match_table = sdhci_bcm_kona_of_match,
	},
	.probe = sdhci_bcm_kona_probe,
	.remove = sdhci_bcm_kona_remove,
	};
	module_platform_driver(sdhci_bcm_kona_driver);

	MODULE_DESCRIPTION("SDHCI driver for Broadcom Kona platform");
	MODULE_AUTHOR("Broadcom");
	MODULE_LICENSE("GPL v2");