drivers/mtd/devices/elm.c - maze/linux - Git at Google

 /*
  * Error Location Module
  *
  * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
  *
  * 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; either version 2 of the License, or
  * (at your option) any later version.
  *
  * 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/platform_device.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_data/elm.h>

 #define ELM_IRQSTATUS			0x018
 #define ELM_IRQENABLE			0x01c
 #define ELM_LOCATION_CONFIG		0x020
 #define ELM_PAGE_CTRL			0x080
 #define ELM_SYNDROME_FRAGMENT_0		0x400
 #define ELM_SYNDROME_FRAGMENT_6		0x418
 #define ELM_LOCATION_STATUS		0x800
 #define ELM_ERROR_LOCATION_0		0x880

 /* ELM Interrupt Status Register */
 #define INTR_STATUS_PAGE_VALID		BIT(8)

 /* ELM Interrupt Enable Register */
 #define INTR_EN_PAGE_MASK		BIT(8)

 /* ELM Location Configuration Register */
 #define ECC_BCH_LEVEL_MASK		0x3

 /* ELM syndrome */
 #define ELM_SYNDROME_VALID		BIT(16)

 /* ELM_LOCATION_STATUS Register */
 #define ECC_CORRECTABLE_MASK		BIT(8)
 #define ECC_NB_ERRORS_MASK		0x1f

 /* ELM_ERROR_LOCATION_0-15 Registers */
 #define ECC_ERROR_LOCATION_MASK		0x1fff

 #define ELM_ECC_SIZE			0x7ff

 #define SYNDROME_FRAGMENT_REG_SIZE	0x40
 #define ERROR_LOCATION_SIZE		0x100

 struct elm_info {
 	struct device *dev;
 	void __iomem *elm_base;
 	struct completion elm_completion;
 	struct list_head list;
 	enum bch_ecc bch_type;
 };

 static LIST_HEAD(elm_devices);

 static void elm_write_reg(struct elm_info *info, int offset, u32 val)
 {
 	writel(val, info->elm_base + offset);
 }

 static u32 elm_read_reg(struct elm_info *info, int offset)
 {
 	return readl(info->elm_base + offset);
 }

 /**
  * elm_config - Configure ELM module
  * @dev:	ELM device
  * @bch_type:	Type of BCH ecc
  */
 int elm_config(struct device *dev, enum bch_ecc bch_type)
 {
 	u32 reg_val;
 	struct elm_info *info = dev_get_drvdata(dev);

 	if (!info) {
 		dev_err(dev, "Unable to configure elm - device not probed?\n");
 		return -ENODEV;
 	}

 	reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
 	elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
 	info->bch_type = bch_type;

 	return 0;
 }
 EXPORT_SYMBOL(elm_config);

 /**
  * elm_configure_page_mode - Enable/Disable page mode
  * @info:	elm info
  * @index:	index number of syndrome fragment vector
  * @enable:	enable/disable flag for page mode
  *
  * Enable page mode for syndrome fragment index
  */
 static void elm_configure_page_mode(struct elm_info *info, int index,
 		bool enable)
 {
 	u32 reg_val;

 	reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
 	if (enable)
 		reg_val |= BIT(index);	/* enable page mode */
 	else
 		reg_val &= ~BIT(index);	/* disable page mode */

 	elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
 }

 /**
  * elm_load_syndrome - Load ELM syndrome reg
  * @info:	elm info
  * @err_vec:	elm error vectors
  * @ecc:	buffer with calculated ecc
  *
  * Load syndrome fragment registers with calculated ecc in reverse order.
  */
 static void elm_load_syndrome(struct elm_info *info,
 		struct elm_errorvec *err_vec, u8 *ecc)
 {
 	int i, offset;
 	u32 val;

 	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

 		/* Check error reported */
 		if (err_vec[i].error_reported) {
 			elm_configure_page_mode(info, i, true);
 			offset = ELM_SYNDROME_FRAGMENT_0 +
 				SYNDROME_FRAGMENT_REG_SIZE * i;

 			/* BCH8 */
 			if (info->bch_type) {

 				/* syndrome fragment 0 = ecc[9-12B] */
 				val = cpu_to_be32(*(u32 *) &ecc[9]);
 				elm_write_reg(info, offset, val);

 				/* syndrome fragment 1 = ecc[5-8B] */
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[5]);
 				elm_write_reg(info, offset, val);

 				/* syndrome fragment 2 = ecc[1-4B] */
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[1]);
 				elm_write_reg(info, offset, val);

 				/* syndrome fragment 3 = ecc[0B] */
 				offset += 4;
 				val = ecc[0];
 				elm_write_reg(info, offset, val);
 			} else {
 				/* syndrome fragment 0 = ecc[20-52b] bits */
 				val = (cpu_to_be32(*(u32 *) &ecc[3]) >> 4) |
 					((ecc[2] & 0xf) << 28);
 				elm_write_reg(info, offset, val);

 				/* syndrome fragment 1 = ecc[0-20b] bits */
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[0]) >> 12;
 				elm_write_reg(info, offset, val);
 			}
 		}

 		/* Update ecc pointer with ecc byte size */
 		ecc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
 	}
 }

 /**
  * elm_start_processing - start elm syndrome processing
  * @info:	elm info
  * @err_vec:	elm error vectors
  *
  * Set syndrome valid bit for syndrome fragment registers for which
  * elm syndrome fragment registers are loaded. This enables elm module
  * to start processing syndrome vectors.
  */
 static void elm_start_processing(struct elm_info *info,
 		struct elm_errorvec *err_vec)
 {
 	int i, offset;
 	u32 reg_val;

 	/*
 	 * Set syndrome vector valid, so that ELM module
 	 * will process it for vectors error is reported
 	 */
 	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 		if (err_vec[i].error_reported) {
 			offset = ELM_SYNDROME_FRAGMENT_6 +
 				SYNDROME_FRAGMENT_REG_SIZE * i;
 			reg_val = elm_read_reg(info, offset);
 			reg_val |= ELM_SYNDROME_VALID;
 			elm_write_reg(info, offset, reg_val);
 		}
 	}
 }

 /**
  * elm_error_correction - locate correctable error position
  * @info:	elm info
  * @err_vec:	elm error vectors
  *
  * On completion of processing by elm module, error location status
  * register updated with correctable/uncorrectable error information.
  * In case of correctable errors, number of errors located from
  * elm location status register & read the positions from
  * elm error location register.
  */
 static void elm_error_correction(struct elm_info *info,
 		struct elm_errorvec *err_vec)
 {
 	int i, j, errors = 0;
 	int offset;
 	u32 reg_val;

 	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

 		/* Check error reported */
 		if (err_vec[i].error_reported) {
 			offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
 			reg_val = elm_read_reg(info, offset);

 			/* Check correctable error or not */
 			if (reg_val & ECC_CORRECTABLE_MASK) {
 				offset = ELM_ERROR_LOCATION_0 +
 					ERROR_LOCATION_SIZE * i;

 				/* Read count of correctable errors */
 				err_vec[i].error_count = reg_val &
 					ECC_NB_ERRORS_MASK;

 				/* Update the error locations in error vector */
 				for (j = 0; j < err_vec[i].error_count; j++) {

 					reg_val = elm_read_reg(info, offset);
 					err_vec[i].error_loc[j] = reg_val &
 						ECC_ERROR_LOCATION_MASK;

 					/* Update error location register */
 					offset += 4;
 				}

 				errors += err_vec[i].error_count;
 			} else {
 				err_vec[i].error_uncorrectable = true;
 			}

 			/* Clearing interrupts for processed error vectors */
 			elm_write_reg(info, ELM_IRQSTATUS, BIT(i));

 			/* Disable page mode */
 			elm_configure_page_mode(info, i, false);
 		}
 	}
 }

 /**
  * elm_decode_bch_error_page - Locate error position
  * @dev:	device pointer
  * @ecc_calc:	calculated ECC bytes from GPMC
  * @err_vec:	elm error vectors
  *
  * Called with one or more error reported vectors & vectors with
  * error reported is updated in err_vec[].error_reported
  */
 void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
 		struct elm_errorvec *err_vec)
 {
 	struct elm_info *info = dev_get_drvdata(dev);
 	u32 reg_val;

 	/* Enable page mode interrupt */
 	reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 	elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
 	elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);

 	/* Load valid ecc byte to syndrome fragment register */
 	elm_load_syndrome(info, err_vec, ecc_calc);

 	/* Enable syndrome processing for which syndrome fragment is updated */
 	elm_start_processing(info, err_vec);

 	/* Wait for ELM module to finish locating error correction */
 	wait_for_completion(&info->elm_completion);

 	/* Disable page mode interrupt */
 	reg_val = elm_read_reg(info, ELM_IRQENABLE);
 	elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
 	elm_error_correction(info, err_vec);
 }
 EXPORT_SYMBOL(elm_decode_bch_error_page);

 static irqreturn_t elm_isr(int this_irq, void *dev_id)
 {
 	u32 reg_val;
 	struct elm_info *info = dev_id;

 	reg_val = elm_read_reg(info, ELM_IRQSTATUS);

 	/* All error vectors processed */
 	if (reg_val & INTR_STATUS_PAGE_VALID) {
 		elm_write_reg(info, ELM_IRQSTATUS,
 				reg_val & INTR_STATUS_PAGE_VALID);
 		complete(&info->elm_completion);
 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static int elm_probe(struct platform_device *pdev)
 {
 	int ret = 0;
 	struct resource *res, *irq;
 	struct elm_info *info;

 	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info) {
 		dev_err(&pdev->dev, "failed to allocate memory\n");
 		return -ENOMEM;
 	}

 	info->dev = &pdev->dev;

 	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	if (!irq) {
 		dev_err(&pdev->dev, "no irq resource defined\n");
 		return -ENODEV;
 	}

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(&pdev->dev, "no memory resource defined\n");
 		return -ENODEV;
 	}

 	info->elm_base = devm_request_and_ioremap(&pdev->dev, res);
 	if (!info->elm_base)
 		return -EADDRNOTAVAIL;

 	ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
 			pdev->name, info);
 	if (ret) {
 		dev_err(&pdev->dev, "failure requesting irq %i\n", irq->start);
 		return ret;
 	}

 	pm_runtime_enable(&pdev->dev);
 	if (pm_runtime_get_sync(&pdev->dev)) {
 		ret = -EINVAL;
 		pm_runtime_disable(&pdev->dev);
 		dev_err(&pdev->dev, "can't enable clock\n");
 		return ret;
 	}

 	init_completion(&info->elm_completion);
 	INIT_LIST_HEAD(&info->list);
 	list_add(&info->list, &elm_devices);
 	platform_set_drvdata(pdev, info);
 	return ret;
 }

 static int elm_remove(struct platform_device *pdev)
 {
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	platform_set_drvdata(pdev, NULL);
 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id elm_of_match[] = {
 	{ .compatible = "ti,am3352-elm" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, elm_of_match);
 #endif

 static struct platform_driver elm_driver = {
 	.driver	= {
 		.name	= "elm",
 		.owner	= THIS_MODULE,
 		.of_match_table = of_match_ptr(elm_of_match),
 	},
 	.probe	= elm_probe,
 	.remove	= elm_remove,
 };

 module_platform_driver(elm_driver);

 MODULE_DESCRIPTION("ELM driver for BCH error correction");
 MODULE_AUTHOR("Texas Instruments");
 MODULE_ALIAS("platform: elm");
 MODULE_LICENSE("GPL v2");
	/*
	* Error Location Module
	*
	* Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
	*
	* 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; either version 2 of the License, or
	* (at your option) any later version.
	*
	* 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/platform_device.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/of.h>
	#include <linux/pm_runtime.h>
	#include <linux/platform_data/elm.h>

	#define ELM_IRQSTATUS 0x018
	#define ELM_IRQENABLE 0x01c
	#define ELM_LOCATION_CONFIG 0x020
	#define ELM_PAGE_CTRL 0x080
	#define ELM_SYNDROME_FRAGMENT_0 0x400
	#define ELM_SYNDROME_FRAGMENT_6 0x418
	#define ELM_LOCATION_STATUS 0x800
	#define ELM_ERROR_LOCATION_0 0x880

	/* ELM Interrupt Status Register */
	#define INTR_STATUS_PAGE_VALID BIT(8)

	/* ELM Interrupt Enable Register */
	#define INTR_EN_PAGE_MASK BIT(8)

	/* ELM Location Configuration Register */
	#define ECC_BCH_LEVEL_MASK 0x3

	/* ELM syndrome */
	#define ELM_SYNDROME_VALID BIT(16)

	/* ELM_LOCATION_STATUS Register */
	#define ECC_CORRECTABLE_MASK BIT(8)
	#define ECC_NB_ERRORS_MASK 0x1f

	/* ELM_ERROR_LOCATION_0-15 Registers */
	#define ECC_ERROR_LOCATION_MASK 0x1fff

	#define ELM_ECC_SIZE 0x7ff

	#define SYNDROME_FRAGMENT_REG_SIZE 0x40
	#define ERROR_LOCATION_SIZE 0x100

	struct elm_info {
	struct device *dev;
	void __iomem *elm_base;
	struct completion elm_completion;
	struct list_head list;
	enum bch_ecc bch_type;
	};

	static LIST_HEAD(elm_devices);

	static void elm_write_reg(struct elm_info *info, int offset, u32 val)
	{
	writel(val, info->elm_base + offset);
	}

	static u32 elm_read_reg(struct elm_info *info, int offset)
	{
	return readl(info->elm_base + offset);
	}

	/**
	* elm_config - Configure ELM module
	* @dev: ELM device
	* @bch_type: Type of BCH ecc
	*/
	int elm_config(struct device *dev, enum bch_ecc bch_type)
	{
	u32 reg_val;
	struct elm_info *info = dev_get_drvdata(dev);

	if (!info) {
	dev_err(dev, "Unable to configure elm - device not probed?\n");
	return -ENODEV;
	}

	reg_val = (bch_type & ECC_BCH_LEVEL_MASK) \| (ELM_ECC_SIZE << 16);
	elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
	info->bch_type = bch_type;

	return 0;
	}
	EXPORT_SYMBOL(elm_config);

	/**
	* elm_configure_page_mode - Enable/Disable page mode
	* @info: elm info
	* @index: index number of syndrome fragment vector
	* @enable: enable/disable flag for page mode
	*
	* Enable page mode for syndrome fragment index
	*/
	static void elm_configure_page_mode(struct elm_info *info, int index,
	bool enable)
	{
	u32 reg_val;

	reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
	if (enable)
	reg_val \|= BIT(index); /* enable page mode */
	else
	reg_val &= ~BIT(index); /* disable page mode */

	elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
	}

	/**
	* elm_load_syndrome - Load ELM syndrome reg
	* @info: elm info
	* @err_vec: elm error vectors
	* @ecc: buffer with calculated ecc
	*
	* Load syndrome fragment registers with calculated ecc in reverse order.
	*/
	static void elm_load_syndrome(struct elm_info *info,
	struct elm_errorvec err_vec, u8 ecc)
	{
	int i, offset;
	u32 val;

	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

	/* Check error reported */
	if (err_vec[i].error_reported) {
	elm_configure_page_mode(info, i, true);
	offset = ELM_SYNDROME_FRAGMENT_0 +
	SYNDROME_FRAGMENT_REG_SIZE * i;

	/* BCH8 */
	if (info->bch_type) {

	/* syndrome fragment 0 = ecc[9-12B] */
	val = cpu_to_be32((u32 ) &ecc[9]);
	elm_write_reg(info, offset, val);

	/* syndrome fragment 1 = ecc[5-8B] */
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[5]);
	elm_write_reg(info, offset, val);

	/* syndrome fragment 2 = ecc[1-4B] */
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[1]);
	elm_write_reg(info, offset, val);

	/* syndrome fragment 3 = ecc[0B] */
	offset += 4;
	val = ecc[0];
	elm_write_reg(info, offset, val);
	} else {
	/* syndrome fragment 0 = ecc[20-52b] bits */
	val = (cpu_to_be32((u32 ) &ecc[3]) >> 4) \|
	((ecc[2] & 0xf) << 28);
	elm_write_reg(info, offset, val);

	/* syndrome fragment 1 = ecc[0-20b] bits */
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[0]) >> 12;
	elm_write_reg(info, offset, val);
	}
	}

	/* Update ecc pointer with ecc byte size */
	ecc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
	}
	}

	/**
	* elm_start_processing - start elm syndrome processing
	* @info: elm info
	* @err_vec: elm error vectors
	*
	* Set syndrome valid bit for syndrome fragment registers for which
	* elm syndrome fragment registers are loaded. This enables elm module
	* to start processing syndrome vectors.
	*/
	static void elm_start_processing(struct elm_info *info,
	struct elm_errorvec *err_vec)
	{
	int i, offset;
	u32 reg_val;

	/*
	* Set syndrome vector valid, so that ELM module
	* will process it for vectors error is reported
	*/
	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
	if (err_vec[i].error_reported) {
	offset = ELM_SYNDROME_FRAGMENT_6 +
	SYNDROME_FRAGMENT_REG_SIZE * i;
	reg_val = elm_read_reg(info, offset);
	reg_val \|= ELM_SYNDROME_VALID;
	elm_write_reg(info, offset, reg_val);
	}
	}
	}

	/**
	* elm_error_correction - locate correctable error position
	* @info: elm info
	* @err_vec: elm error vectors
	*
	* On completion of processing by elm module, error location status
	* register updated with correctable/uncorrectable error information.
	* In case of correctable errors, number of errors located from
	* elm location status register & read the positions from
	* elm error location register.
	*/
	static void elm_error_correction(struct elm_info *info,
	struct elm_errorvec *err_vec)
	{
	int i, j, errors = 0;
	int offset;
	u32 reg_val;

	for (i = 0; i < ERROR_VECTOR_MAX; i++) {

	/* Check error reported */
	if (err_vec[i].error_reported) {
	offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
	reg_val = elm_read_reg(info, offset);

	/* Check correctable error or not */
	if (reg_val & ECC_CORRECTABLE_MASK) {
	offset = ELM_ERROR_LOCATION_0 +
	ERROR_LOCATION_SIZE * i;

	/* Read count of correctable errors */
	err_vec[i].error_count = reg_val &
	ECC_NB_ERRORS_MASK;

	/* Update the error locations in error vector */
	for (j = 0; j < err_vec[i].error_count; j++) {

	reg_val = elm_read_reg(info, offset);
	err_vec[i].error_loc[j] = reg_val &
	ECC_ERROR_LOCATION_MASK;

	/* Update error location register */
	offset += 4;
	}

	errors += err_vec[i].error_count;
	} else {
	err_vec[i].error_uncorrectable = true;
	}

	/* Clearing interrupts for processed error vectors */
	elm_write_reg(info, ELM_IRQSTATUS, BIT(i));

	/* Disable page mode */
	elm_configure_page_mode(info, i, false);
	}
	}
	}

	/**
	* elm_decode_bch_error_page - Locate error position
	* @dev: device pointer
	* @ecc_calc: calculated ECC bytes from GPMC
	* @err_vec: elm error vectors
	*
	* Called with one or more error reported vectors & vectors with
	* error reported is updated in err_vec[].error_reported
	*/
	void elm_decode_bch_error_page(struct device dev, u8 ecc_calc,
	struct elm_errorvec *err_vec)
	{
	struct elm_info *info = dev_get_drvdata(dev);
	u32 reg_val;

	/* Enable page mode interrupt */
	reg_val = elm_read_reg(info, ELM_IRQSTATUS);
	elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
	elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);

	/* Load valid ecc byte to syndrome fragment register */
	elm_load_syndrome(info, err_vec, ecc_calc);

	/* Enable syndrome processing for which syndrome fragment is updated */
	elm_start_processing(info, err_vec);

	/* Wait for ELM module to finish locating error correction */
	wait_for_completion(&info->elm_completion);

	/* Disable page mode interrupt */
	reg_val = elm_read_reg(info, ELM_IRQENABLE);
	elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
	elm_error_correction(info, err_vec);
	}
	EXPORT_SYMBOL(elm_decode_bch_error_page);

	static irqreturn_t elm_isr(int this_irq, void *dev_id)
	{
	u32 reg_val;
	struct elm_info *info = dev_id;

	reg_val = elm_read_reg(info, ELM_IRQSTATUS);

	/* All error vectors processed */
	if (reg_val & INTR_STATUS_PAGE_VALID) {
	elm_write_reg(info, ELM_IRQSTATUS,
	reg_val & INTR_STATUS_PAGE_VALID);
	complete(&info->elm_completion);
	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static int elm_probe(struct platform_device *pdev)
	{
	int ret = 0;
	struct resource res, irq;
	struct elm_info *info;

	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
	if (!info) {
	dev_err(&pdev->dev, "failed to allocate memory\n");
	return -ENOMEM;
	}

	info->dev = &pdev->dev;

	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (!irq) {
	dev_err(&pdev->dev, "no irq resource defined\n");
	return -ENODEV;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(&pdev->dev, "no memory resource defined\n");
	return -ENODEV;
	}

	info->elm_base = devm_request_and_ioremap(&pdev->dev, res);
	if (!info->elm_base)
	return -EADDRNOTAVAIL;

	ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
	pdev->name, info);
	if (ret) {
	dev_err(&pdev->dev, "failure requesting irq %i\n", irq->start);
	return ret;
	}

	pm_runtime_enable(&pdev->dev);
	if (pm_runtime_get_sync(&pdev->dev)) {
	ret = -EINVAL;
	pm_runtime_disable(&pdev->dev);
	dev_err(&pdev->dev, "can't enable clock\n");
	return ret;
	}

	init_completion(&info->elm_completion);
	INIT_LIST_HEAD(&info->list);
	list_add(&info->list, &elm_devices);
	platform_set_drvdata(pdev, info);
	return ret;
	}

	static int elm_remove(struct platform_device *pdev)
	{
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);
	platform_set_drvdata(pdev, NULL);
	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id elm_of_match[] = {
	{ .compatible = "ti,am3352-elm" },
	{},
	};
	MODULE_DEVICE_TABLE(of, elm_of_match);
	#endif

	static struct platform_driver elm_driver = {
	.driver = {
	.name = "elm",
	.owner = THIS_MODULE,
	.of_match_table = of_match_ptr(elm_of_match),
	},
	.probe = elm_probe,
	.remove = elm_remove,
	};

	module_platform_driver(elm_driver);

	MODULE_DESCRIPTION("ELM driver for BCH error correction");
	MODULE_AUTHOR("Texas Instruments");
	MODULE_ALIAS("platform: elm");
	MODULE_LICENSE("GPL v2");