[PATCH 2/4] mtd: devices: elm: Add support for ELM error correction
From: Philip, Avinash
Date: Wed Oct 03 2012 - 10:52:15 EST
Platforms containing the ELM module can be used to correct errors
reported by BCH 4, 8 & 16 bit ECC scheme. For now only 4 & 8 bit
support is added.
Signed-off-by: Philip, Avinash <avinashphilip@xxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
---
:000000 100644 0000000... b88ee83... A Documentation/devicetree/bindings/mtd/elm.txt
:100644 100644 395733a... 0f6a94b... M drivers/mtd/devices/Makefile
:000000 100644 0000000... 802b572... A drivers/mtd/devices/elm.c
:000000 100644 0000000... eb53163... A include/linux/platform_data/elm.h
Documentation/devicetree/bindings/mtd/elm.txt | 18 +
drivers/mtd/devices/Makefile | 4 +-
drivers/mtd/devices/elm.c | 440 +++++++++++++++++++++++++
include/linux/platform_data/elm.h | 60 ++++
4 files changed, 521 insertions(+), 1 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/elm.txt b/Documentation/devicetree/bindings/mtd/elm.txt
new file mode 100644
index 0000000..b88ee83
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/elm.txt
@@ -0,0 +1,18 @@
+Error location module
+
+Required properties:
+- compatible: Must be "ti,elm"
+- reg: physical base address and size of the registers map.
+- interrupts: Interrupt number for the elm.
+- interrupt-parent: The parent interrupt controller
+
+Optional properties:
+- ti,hwmods: Name of the hwmod associated to the elm
+
+Example:
+elm: elm@0 {
+ compatible = "ti,elm";
+ reg = <0x48080000 0x2000>;
+ interrupt-parent = <&intc>;
+ interrupts = <4>;
+};
diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
index 395733a..0f6a94b 100644
--- a/drivers/mtd/devices/Makefile
+++ b/drivers/mtd/devices/Makefile
@@ -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-$(CONFIG_MTD_NAND_OMAP2) += elm.o
obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
obj-$(CONFIG_MTD_SST25L) += sst25l.o
obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
-CFLAGS_docg3.o += -I$(src)
\ No newline at end of file
+
+CFLAGS_docg3.o += -I$(src)
diff --git a/drivers/mtd/devices/elm.c b/drivers/mtd/devices/elm.c
new file mode 100644
index 0000000..802b572
--- /dev/null
+++ b/drivers/mtd/devices/elm.c
@@ -0,0 +1,440 @@
+/*
+ * 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
+#define MAX_BCH_ELM_ERROR 16
+#define ELM_FRAGMENT_REG 7
+
+typedef u32 syn_t[ELM_FRAGMENT_REG];
+typedef u32 elm_error_t[MAX_BCH_ELM_ERROR];
+
+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(void *offset, u32 val)
+{
+ writel(val, offset);
+}
+
+static u32 elm_read_reg(void *offset)
+{
+ return readl(offset);
+}
+
+/**
+ * elm_config - Configure ELM module
+ * @info: elm info
+ */
+static void elm_config(struct elm_info *info)
+{
+ u32 reg_val;
+
+ reg_val = (info->bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
+ elm_write_reg(info->elm_base + ELM_LOCATION_CONFIG, reg_val);
+}
+
+/**
+ * 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_base + 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_base + ELM_PAGE_CTRL, reg_val);
+}
+
+static void rearrange_bch4(u8 *syndrome)
+{
+ /*
+ * BCH4 has 52 bit used for ecc, but OOB stored with
+ * nibble 0 appended, removes appended 0 nibble
+ */
+ u64 *dst = (u64 *)syndrome;
+ *dst >>= 4;
+}
+
+/**
+ * elm_reverse_eccdata - Reverse ecc data
+ * @info: elm info
+ * @ecc_data: buffer for calculated ecc
+ * @syndrome: buffer for syndrome polynomial
+ *
+ * ecc_data has to be reversed for syndrome vector
+ */
+static void elm_reverse_eccdata(struct elm_info *info, u8 *ecc_data,
+ u8 *syndrome)
+{
+ int i;
+ int bch_size = info->bch_type ? BCH8_ECC_OOB_BYTES : BCH4_SIZE;
+
+ for (i = 0; i < bch_size; i++)
+ syndrome[bch_size - 1 - i] = ecc_data[i];
+
+ /*
+ * syndrome polynomial to be rearranged for BCH 4 ecc scheme as 52
+ * bits being used and 4 bits being appended in syndrome vector
+ */
+ if (info->bch_type == BCH4_ECC)
+ rearrange_bch4(syndrome);
+}
+
+/**
+ * elm_load_syndrome - Load ELM syndrome reg
+ * @info: elm info
+ * @index: syndrome fragment index
+ * @syndrome: Syndrome polynomial
+ *
+ * Load syndrome fragment registers with syndrome polynomial
+ */
+static void elm_load_syndrome(struct elm_info *info, int index, u8 *syndrome)
+{
+ int i;
+ int max = info->bch_type ? BCH8_SYNDROME_SIZE : BCH4_SYNDROME_SIZE;
+ void *syn_frag_base = info->elm_base + ELM_SYNDROME_FRAGMENT_0;
+ syn_t *syn_fragment;
+ u32 reg_val;
+
+ elm_configure_page_mode(info, index, true);
+ syn_fragment = syn_frag_base + SYNDROME_FRAGMENT_REG_SIZE * index;
+
+ for (i = 0; i < max; i++) {
+ reg_val = syndrome[0] | syndrome[1] << 8 | syndrome[2] << 16 |
+ syndrome[3] << 24;
+ elm_write_reg(*syn_fragment + i, reg_val);
+ /* Update syndrome polynomial pointer */
+ syndrome += 4;
+ }
+}
+
+/**
+ * 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;
+ void *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 = info->elm_base + ELM_SYNDROME_FRAGMENT_6 + i *
+ SYNDROME_FRAGMENT_REG_SIZE;
+ reg_val = elm_read_reg(offset);
+ reg_val |= ELM_SYNDROME_VALID;
+ elm_write_reg(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 these many 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;
+ void *err_loc_base = info->elm_base + ELM_ERROR_LOCATION_0;
+ elm_error_t *err_loc;
+ void *offset;
+ u32 reg_val;
+
+ for (i = 0; i < ERROR_VECTOR_MAX; i++) {
+ /* check error reported */
+ if (err_vec[i].error_reported) {
+ offset = info->elm_base + ELM_LOCATION_STATUS +
+ i * ERROR_LOCATION_SIZE;
+ reg_val = elm_read_reg(offset);
+ /* check correctable error or not */
+ if (reg_val & ECC_CORRECTABLE_MASK) {
+ err_loc = err_loc_base +
+ i * ERROR_LOCATION_SIZE;
+ /* 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(*err_loc + j);
+ err_vec[i].error_loc[j] = reg_val &
+ ECC_ERROR_LOCATION_MASK;
+ }
+
+ errors += err_vec[i].error_count;
+ } else {
+ err_vec[i].error_uncorrectable++;
+ }
+
+ /* clearing interrupts for processed error vectors */
+ elm_write_reg(info->elm_base + ELM_IRQSTATUS, BIT(i));
+
+ /* disable page mode */
+ elm_configure_page_mode(info, i, false);
+ }
+ }
+
+ return;
+}
+
+/**
+ * elm_decode_bch_error_page - Locate error position
+ * @info: elm info
+ * @ecc_calc: calculated ECC bytes from GPMC
+ * @err_vec: elm error vectors
+ *
+ * Called with one or greater reported and is 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)
+{
+ int i;
+ u8 syndrome[BCH_MAX_ECC_BYTES_PER_SECTOR] = {0}, *syn_p;
+ struct elm_info *info = dev_get_drvdata(dev);
+ u32 reg_val;
+
+ /* enable page mode interrupt */
+ reg_val = elm_read_reg(info->elm_base + ELM_IRQSTATUS);
+ elm_write_reg(info->elm_base + ELM_IRQSTATUS,
+ reg_val & INTR_STATUS_PAGE_VALID);
+ elm_write_reg(info->elm_base + ELM_IRQENABLE, INTR_EN_PAGE_MASK);
+
+ syn_p = syndrome;
+ for (i = 0; i < ERROR_VECTOR_MAX; i++) {
+ if (err_vec[i].error_reported) {
+ elm_reverse_eccdata(info, ecc_calc, syn_p);
+ elm_load_syndrome(info, i, syn_p);
+ }
+
+ ecc_calc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
+ syn_p += OOB_SECTOR_SIZE;
+ }
+
+ elm_start_processing(info, err_vec);
+
+ /*
+ * In case of error reported, 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_base + ELM_IRQENABLE);
+ elm_write_reg(info->elm_base + 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_base + ELM_IRQSTATUS);
+
+ /* all error vectors processed */
+ if (reg_val & INTR_STATUS_PAGE_VALID) {
+ elm_write_reg(info->elm_base + ELM_IRQSTATUS,
+ reg_val & INTR_STATUS_PAGE_VALID);
+ complete(&info->elm_completion);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+struct device *elm_request(enum bch_ecc bch_type)
+{
+ struct elm_info *info;
+
+ list_for_each_entry(info, &elm_devices, list) {
+ if (info && info->dev) {
+ info->bch_type = bch_type;
+ elm_config(info);
+ return info->dev;
+ }
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL(elm_request);
+
+static int __devinit 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 __devexit 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,elm" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, elm_of_match);
+#endif
+
+static struct platform_driver elm_driver = {
+ .driver = {
+ .name = "elm",
+ .of_match_table = of_match_ptr(elm_of_match),
+ .owner = THIS_MODULE,
+ },
+ .probe = elm_probe,
+ .remove = __devexit_p(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");
diff --git a/include/linux/platform_data/elm.h b/include/linux/platform_data/elm.h
new file mode 100644
index 0000000..eb53163
--- /dev/null
+++ b/include/linux/platform_data/elm.h
@@ -0,0 +1,60 @@
+/*
+ * 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,
+ BCH16_ECC,
+};
+
+/* ELM support 8 error syndrome process */
+#define ERROR_VECTOR_MAX 8
+#define OOB_SECTOR_SIZE 16
+
+#define BCH_MAX_ECC_BYTES_PER_SECTOR (OOB_SECTOR_SIZE * ERROR_VECTOR_MAX)
+
+#define BCH8_ECC_OOB_BYTES 13
+/* RBL requires 14 byte even though BCH8 uses only 13 byte */
+#define BCH8_SIZE (BCH8_ECC_OOB_BYTES + 1)
+#define BCH4_SIZE 7
+
+#define BCH8_SYNDROME_SIZE 4 /* 13 bytes of ecc */
+#define BCH4_SYNDROME_SIZE 2 /* 7 bytes of ecc */
+
+/**
+ * struct elm_errorvec - error vector for elm
+ * @error_reported: set true for vectors error is reported
+ *
+ * @error_count: number of correctable errors in the sector
+ * @error_uncorrectable: number of uncorrectable errors
+ * @error_loc: buffer for error location
+ *
+ */
+struct elm_errorvec {
+ bool error_reported;
+ int error_count;
+ int error_uncorrectable;
+ int error_loc[ERROR_VECTOR_MAX];
+};
+
+void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
+ struct elm_errorvec *err_vec);
+struct device *elm_request(enum bch_ecc bch_type);
+#endif /* __ELM_H */
--
1.7.0.4
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