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

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The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme
error correction.
For now only 4 & 8 bit support is added

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
This commit is contained in:
Philip Avinash 2013-01-04 13:26:50 +05:30 committed by Artem Bityutskiy
parent c3e4b995e4
commit bf22433575
4 changed files with 476 additions and 1 deletions
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16
Documentation/devicetree/bindings/mtd/elm.txt Normal file
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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>;
};

4
drivers/mtd/devices/Makefile
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@ -17,8 +17,10 @@ obj-$(CONFIG_MTD_LART) += lart.o
obj-$(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$(src)
CFLAGS_docg3.o += -I$(src)

404
drivers/mtd/devices/elm.c Normal file
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/*
* 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");

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include/linux/platform_data/elm.h Normal file
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/*
* 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 */