mtd: devices: elm: Add support for ELM error correction

Error location module

Required properties:

- compatible: Must be "ti,am33xx-elm"

- reg: physical base address and size of the registers map.

- interrupts: Interrupt number for the elm.

Optional properties:

- ti,hwmods: Name of the hwmod associated to the elm

Example:

elm: elm@0 {

	compatible	= "ti,am33xx-elm";

	reg = <0x48080000 0x2000>;

	interrupts = <4>;

};

obj-$(CONFIG_MTD_BLOCK2MTD)	+= block2mtd.o

obj-$(CONFIG_MTD_DATAFLASH)	+= mtd_dataflash.o

obj-$(CONFIG_MTD_M25P80)	+= m25p80.o

obj-$(CONFIG_MTD_NAND_OMAP_BCH)	+= elm.o

obj-$(CONFIG_MTD_SPEAR_SMI)	+= spear_smi.o

obj-$(CONFIG_MTD_SST25L)	+= sst25l.o

obj-$(CONFIG_MTD_BCM47XXSFLASH)	+= bcm47xxsflash.o

CFLAGS_docg3.o			+= -I$(src)

/*

 * 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

 */

void elm_config(struct device *dev, enum bch_ecc bch_type)

{

	u32 reg_val;

	struct elm_info *info = dev_get_drvdata(dev);

	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;

}

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,am33xx-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");

/*

 * BCH 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.

 *

 */

#ifndef __ELM_H

#define __ELM_H

enum bch_ecc {

	BCH4_ECC = 0,

	BCH8_ECC,

};

/* ELM support 8 error syndrome process */

#define ERROR_VECTOR_MAX		8

#define BCH8_ECC_OOB_BYTES		13

#define BCH4_ECC_OOB_BYTES		7

/* RBL requires 14 byte even though BCH8 uses only 13 byte */

#define BCH8_SIZE			(BCH8_ECC_OOB_BYTES + 1)

#define BCH4_SIZE			(BCH4_ECC_OOB_BYTES)

/**

 * struct elm_errorvec - error vector for elm

 * @error_reported:		set true for vectors error is reported

 * @error_uncorrectable:	number of uncorrectable errors

 * @error_count:		number of correctable errors in the sector

 * @error_loc:			buffer for error location

 *

 */

struct elm_errorvec {

	bool error_reported;

	bool error_uncorrectable;

	int error_count;

	int error_loc[ERROR_VECTOR_MAX];

};

void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,

		struct elm_errorvec *err_vec);

void elm_config(struct device *dev, enum bch_ecc bch_type);

#endif /* __ELM_H */