drivers/mtd/nand/raw/omap_elm.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Error Location Module
  *
  * Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com/
  */

 #define DRIVER_NAME	"omap-elm"

 #include <linux/platform_device.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/sched.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_data/elm.h>

 #define ELM_SYSCONFIG			0x010
 #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_1		0x404
 #define ELM_SYNDROME_FRAGMENT_2		0x408
 #define ELM_SYNDROME_FRAGMENT_3		0x40c
 #define ELM_SYNDROME_FRAGMENT_4		0x410
 #define ELM_SYNDROME_FRAGMENT_5		0x414
 #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_registers {
 	u32 elm_irqenable;
 	u32 elm_sysconfig;
 	u32 elm_location_config;
 	u32 elm_page_ctrl;
 	u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
 	u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
 };

 struct elm_info {
 	struct device *dev;
 	void __iomem *elm_base;
 	struct completion elm_completion;
 	struct list_head list;
 	enum bch_ecc bch_type;
 	struct elm_registers elm_regs;
 	int ecc_steps;
 	int ecc_syndrome_size;
 };

 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,
 	int ecc_steps, int ecc_step_size, int ecc_syndrome_size)
 {
 	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 -EPROBE_DEFER;
 	}
 	/* ELM cannot detect ECC errors for chunks > 1KB */
 	if (ecc_step_size > ((ELM_ECC_SIZE + 1) / 2)) {
 		dev_err(dev, "unsupported config ecc-size=%d\n", ecc_step_size);
 		return -EINVAL;
 	}
 	/* ELM support 8 error syndrome process */
 	if (ecc_steps > ERROR_VECTOR_MAX) {
 		dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
 		return -EINVAL;
 	}

 	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;
 	info->ecc_steps		= ecc_steps;
 	info->ecc_syndrome_size	= ecc_syndrome_size;

 	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 < info->ecc_steps; 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;
 			switch (info->bch_type) {
 			case BCH8_ECC:
 				/* 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);
 				break;
 			case BCH4_ECC:
 				/* 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);
 				break;
 			case BCH16_ECC:
 				val = cpu_to_be32(*(u32 *) &ecc[22]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[18]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[14]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[10]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[6]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[2]);
 				elm_write_reg(info, offset, val);
 				offset += 4;
 				val = cpu_to_be32(*(u32 *) &ecc[0]) >> 16;
 				elm_write_reg(info, offset, val);
 				break;
 			default:
 				pr_err("invalid config bch_type\n");
 			}
 		}

 		/* Update ecc pointer with ecc byte size */
 		ecc += info->ecc_syndrome_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 < info->ecc_steps; 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 < info->ecc_steps; 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)
 		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);
 	info->elm_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(info->elm_base))
 		return PTR_ERR(info->elm_base);

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

 	pm_runtime_enable(&pdev->dev);
 	if (pm_runtime_get_sync(&pdev->dev) < 0) {
 		ret = -EINVAL;
 		pm_runtime_put_sync(&pdev->dev);
 		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);
 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 /**
  * elm_context_save
  * saves ELM configurations to preserve them across Hardware powered-down
  */
 static int elm_context_save(struct elm_info *info)
 {
 	struct elm_registers *regs = &info->elm_regs;
 	enum bch_ecc bch_type = info->bch_type;
 	u32 offset = 0, i;

 	regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);
 	regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);
 	regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
 	regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);
 	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 		offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 		switch (bch_type) {
 		case BCH16_ECC:
 			regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_6 + offset);
 			regs->elm_syndrome_fragment_5[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_5 + offset);
 			regs->elm_syndrome_fragment_4[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_4 + offset);
 			fallthrough;
 		case BCH8_ECC:
 			regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_3 + offset);
 			regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_2 + offset);
 			fallthrough;
 		case BCH4_ECC:
 			regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_1 + offset);
 			regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_0 + offset);
 			break;
 		default:
 			return -EINVAL;
 		}
 		/* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
 		 * to be saved for all BCH schemes*/
 		regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
 					ELM_SYNDROME_FRAGMENT_6 + offset);
 	}
 	return 0;
 }

 /**
  * elm_context_restore
  * writes configurations saved duing power-down back into ELM registers
  */
 static int elm_context_restore(struct elm_info *info)
 {
 	struct elm_registers *regs = &info->elm_regs;
 	enum bch_ecc bch_type = info->bch_type;
 	u32 offset = 0, i;

 	elm_write_reg(info, ELM_IRQENABLE,	 regs->elm_irqenable);
 	elm_write_reg(info, ELM_SYSCONFIG,	 regs->elm_sysconfig);
 	elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
 	elm_write_reg(info, ELM_PAGE_CTRL,	 regs->elm_page_ctrl);
 	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 		offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 		switch (bch_type) {
 		case BCH16_ECC:
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
 					regs->elm_syndrome_fragment_6[i]);
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_5 + offset,
 					regs->elm_syndrome_fragment_5[i]);
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_4 + offset,
 					regs->elm_syndrome_fragment_4[i]);
 			fallthrough;
 		case BCH8_ECC:
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
 					regs->elm_syndrome_fragment_3[i]);
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
 					regs->elm_syndrome_fragment_2[i]);
 			fallthrough;
 		case BCH4_ECC:
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
 					regs->elm_syndrome_fragment_1[i]);
 			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
 					regs->elm_syndrome_fragment_0[i]);
 			break;
 		default:
 			return -EINVAL;
 		}
 		/* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
 		elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
 					regs->elm_syndrome_fragment_6[i] &
 							 ELM_SYNDROME_VALID);
 	}
 	return 0;
 }

 static int elm_suspend(struct device *dev)
 {
 	struct elm_info *info = dev_get_drvdata(dev);
 	elm_context_save(info);
 	pm_runtime_put_sync(dev);
 	return 0;
 }

 static int elm_resume(struct device *dev)
 {
 	struct elm_info *info = dev_get_drvdata(dev);
 	pm_runtime_get_sync(dev);
 	elm_context_restore(info);
 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);

 #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	= DRIVER_NAME,
 		.of_match_table = of_match_ptr(elm_of_match),
 		.pm	= &elm_pm_ops,
 	},
 	.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:" DRIVER_NAME);
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Error Location Module
	*
	* Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com/
	*/

	#define DRIVER_NAME "omap-elm"

	#include <linux/platform_device.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/of.h>
	#include <linux/sched.h>
	#include <linux/pm_runtime.h>
	#include <linux/platform_data/elm.h>

	#define ELM_SYSCONFIG 0x010
	#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_1 0x404
	#define ELM_SYNDROME_FRAGMENT_2 0x408
	#define ELM_SYNDROME_FRAGMENT_3 0x40c
	#define ELM_SYNDROME_FRAGMENT_4 0x410
	#define ELM_SYNDROME_FRAGMENT_5 0x414
	#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_registers {
	u32 elm_irqenable;
	u32 elm_sysconfig;
	u32 elm_location_config;
	u32 elm_page_ctrl;
	u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
	u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
	};

	struct elm_info {
	struct device *dev;
	void __iomem *elm_base;
	struct completion elm_completion;
	struct list_head list;
	enum bch_ecc bch_type;
	struct elm_registers elm_regs;
	int ecc_steps;
	int ecc_syndrome_size;
	};

	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,
	int ecc_steps, int ecc_step_size, int ecc_syndrome_size)
	{
	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 -EPROBE_DEFER;
	}
	/* ELM cannot detect ECC errors for chunks > 1KB */
	if (ecc_step_size > ((ELM_ECC_SIZE + 1) / 2)) {
	dev_err(dev, "unsupported config ecc-size=%d\n", ecc_step_size);
	return -EINVAL;
	}
	/* ELM support 8 error syndrome process */
	if (ecc_steps > ERROR_VECTOR_MAX) {
	dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
	return -EINVAL;
	}

	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;
	info->ecc_steps = ecc_steps;
	info->ecc_syndrome_size = ecc_syndrome_size;

	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 < info->ecc_steps; 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;
	switch (info->bch_type) {
	case BCH8_ECC:
	/* 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);
	break;
	case BCH4_ECC:
	/* 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);
	break;
	case BCH16_ECC:
	val = cpu_to_be32((u32 ) &ecc[22]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[18]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[14]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[10]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[6]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[2]);
	elm_write_reg(info, offset, val);
	offset += 4;
	val = cpu_to_be32((u32 ) &ecc[0]) >> 16;
	elm_write_reg(info, offset, val);
	break;
	default:
	pr_err("invalid config bch_type\n");
	}
	}

	/* Update ecc pointer with ecc byte size */
	ecc += info->ecc_syndrome_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 < info->ecc_steps; 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 < info->ecc_steps; 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)
	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);
	info->elm_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(info->elm_base))
	return PTR_ERR(info->elm_base);

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

	pm_runtime_enable(&pdev->dev);
	if (pm_runtime_get_sync(&pdev->dev) < 0) {
	ret = -EINVAL;
	pm_runtime_put_sync(&pdev->dev);
	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);
	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	/**
	* elm_context_save
	* saves ELM configurations to preserve them across Hardware powered-down
	*/
	static int elm_context_save(struct elm_info *info)
	{
	struct elm_registers *regs = &info->elm_regs;
	enum bch_ecc bch_type = info->bch_type;
	u32 offset = 0, i;

	regs->elm_irqenable = elm_read_reg(info, ELM_IRQENABLE);
	regs->elm_sysconfig = elm_read_reg(info, ELM_SYSCONFIG);
	regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
	regs->elm_page_ctrl = elm_read_reg(info, ELM_PAGE_CTRL);
	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
	offset = i * SYNDROME_FRAGMENT_REG_SIZE;
	switch (bch_type) {
	case BCH16_ECC:
	regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_6 + offset);
	regs->elm_syndrome_fragment_5[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_5 + offset);
	regs->elm_syndrome_fragment_4[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_4 + offset);
	fallthrough;
	case BCH8_ECC:
	regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_3 + offset);
	regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_2 + offset);
	fallthrough;
	case BCH4_ECC:
	regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_1 + offset);
	regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_0 + offset);
	break;
	default:
	return -EINVAL;
	}
	/* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
	* to be saved for all BCH schemes*/
	regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
	ELM_SYNDROME_FRAGMENT_6 + offset);
	}
	return 0;
	}

	/**
	* elm_context_restore
	* writes configurations saved duing power-down back into ELM registers
	*/
	static int elm_context_restore(struct elm_info *info)
	{
	struct elm_registers *regs = &info->elm_regs;
	enum bch_ecc bch_type = info->bch_type;
	u32 offset = 0, i;

	elm_write_reg(info, ELM_IRQENABLE, regs->elm_irqenable);
	elm_write_reg(info, ELM_SYSCONFIG, regs->elm_sysconfig);
	elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
	elm_write_reg(info, ELM_PAGE_CTRL, regs->elm_page_ctrl);
	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
	offset = i * SYNDROME_FRAGMENT_REG_SIZE;
	switch (bch_type) {
	case BCH16_ECC:
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
	regs->elm_syndrome_fragment_6[i]);
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_5 + offset,
	regs->elm_syndrome_fragment_5[i]);
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_4 + offset,
	regs->elm_syndrome_fragment_4[i]);
	fallthrough;
	case BCH8_ECC:
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
	regs->elm_syndrome_fragment_3[i]);
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
	regs->elm_syndrome_fragment_2[i]);
	fallthrough;
	case BCH4_ECC:
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
	regs->elm_syndrome_fragment_1[i]);
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
	regs->elm_syndrome_fragment_0[i]);
	break;
	default:
	return -EINVAL;
	}
	/* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
	elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
	regs->elm_syndrome_fragment_6[i] &
	ELM_SYNDROME_VALID);
	}
	return 0;
	}

	static int elm_suspend(struct device *dev)
	{
	struct elm_info *info = dev_get_drvdata(dev);
	elm_context_save(info);
	pm_runtime_put_sync(dev);
	return 0;
	}

	static int elm_resume(struct device *dev)
	{
	struct elm_info *info = dev_get_drvdata(dev);
	pm_runtime_get_sync(dev);
	elm_context_restore(info);
	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);

	#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 = DRIVER_NAME,
	.of_match_table = of_match_ptr(elm_of_match),
	.pm = &elm_pm_ops,
	},
	.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:" DRIVER_NAME);
	MODULE_LICENSE("GPL v2");