[PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
From: Philip, Avinash
Date: Thu Nov 29 2012 - 06:47:44 EST
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@xxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
---
Changes since v2:
- Remove __devinit & __devexit annotations
Changes since v1:
- Change build attribute to CONFIG_MTD_NAND_OMAP_BCH
- Reduced indentation using by passing elm_info , offset
to elm_read & elm_write
- Removed syndrome manipulation functions.
:000000 100644 0000000... b88ee83... A Documentation/devicetree/bindings/mtd/elm.txt
:100644 100644 395733a... 369a194... M drivers/mtd/devices/Makefile
:000000 100644 0000000... d2667f3... A drivers/mtd/devices/elm.c
:000000 100644 0000000... d4fce31... A include/linux/platform_data/elm.h
Documentation/devicetree/bindings/mtd/elm.txt | 17 +
drivers/mtd/devices/Makefile | 4 +-
drivers/mtd/devices/elm.c | 418 +++++++++++++++++++++++++
include/linux/platform_data/elm.h | 54 ++++
4 files changed, 493 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 +1,17 @@
+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>;
+ interrupts = <4>;
+};
diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
index 395733a..369a194 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-$(CONFIG_MTD_NAND_OMAP_BCH) += elm.o
obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
obj-$(CONFIG_MTD_SST25L) += sst25l.o
obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
-CFLAGS_docg3.o += -I$(src)
\ No newline at end of file
+
+CFLAGS_docg3.o += -I$(src)
diff --git a/drivers/mtd/devices/elm.c b/drivers/mtd/devices/elm.c
new file mode 100644
index 0000000..d2667f3
--- /dev/null
+++ b/drivers/mtd/devices/elm.c
@@ -0,0 +1,418 @@
+/*
+ * 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
+ * @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_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_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;
+}
+
+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 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,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");
diff --git a/include/linux/platform_data/elm.h b/include/linux/platform_data/elm.h
new file mode 100644
index 0000000..d4fce31
--- /dev/null
+++ b/include/linux/platform_data/elm.h
@@ -0,0 +1,54 @@
+/*
+ * 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_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;
+ 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);
+struct device *elm_request(enum bch_ecc bch_type);
+#endif /* __ELM_H */
--
1.7.0.4
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