drivers/mtd/nand/mtk_ecc.c - kernel/msm-4.9 - Gitiles

 /*
  * MTK ECC controller driver.
  * Copyright (C) 2016  MediaTek Inc.
  * Authors:	Xiaolei Li		<xiaolei.li@mediatek.com>
  *		Jorge Ramirez-Ortiz	<jorge.ramirez-ortiz@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * 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/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/clk.h>
 #include <linux/module.h>
 #include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/mutex.h>

 #include "mtk_ecc.h"

 #define ECC_IDLE_MASK		BIT(0)
 #define ECC_IRQ_EN		BIT(0)
 #define ECC_OP_ENABLE		(1)
 #define ECC_OP_DISABLE		(0)

 #define ECC_ENCCON		(0x00)
 #define ECC_ENCCNFG		(0x04)
 #define		ECC_CNFG_4BIT		(0)
 #define		ECC_CNFG_6BIT		(1)
 #define		ECC_CNFG_8BIT		(2)
 #define		ECC_CNFG_10BIT		(3)
 #define		ECC_CNFG_12BIT		(4)
 #define		ECC_CNFG_14BIT		(5)
 #define		ECC_CNFG_16BIT		(6)
 #define		ECC_CNFG_18BIT		(7)
 #define		ECC_CNFG_20BIT		(8)
 #define		ECC_CNFG_22BIT		(9)
 #define		ECC_CNFG_24BIT		(0xa)
 #define		ECC_CNFG_28BIT		(0xb)
 #define		ECC_CNFG_32BIT		(0xc)
 #define		ECC_CNFG_36BIT		(0xd)
 #define		ECC_CNFG_40BIT		(0xe)
 #define		ECC_CNFG_44BIT		(0xf)
 #define		ECC_CNFG_48BIT		(0x10)
 #define		ECC_CNFG_52BIT		(0x11)
 #define		ECC_CNFG_56BIT		(0x12)
 #define		ECC_CNFG_60BIT		(0x13)
 #define		ECC_MODE_SHIFT		(5)
 #define		ECC_MS_SHIFT		(16)
 #define ECC_ENCDIADDR		(0x08)
 #define ECC_ENCIDLE		(0x0C)
 #define ECC_ENCPAR(x)		(0x10 + (x) * sizeof(u32))
 #define ECC_ENCIRQ_EN		(0x80)
 #define ECC_ENCIRQ_STA		(0x84)
 #define ECC_DECCON		(0x100)
 #define ECC_DECCNFG		(0x104)
 #define		DEC_EMPTY_EN		BIT(31)
 #define		DEC_CNFG_CORRECT	(0x3 << 12)
 #define ECC_DECIDLE		(0x10C)
 #define ECC_DECENUM0		(0x114)
 #define		ERR_MASK		(0x3f)
 #define ECC_DECDONE		(0x124)
 #define ECC_DECIRQ_EN		(0x200)
 #define ECC_DECIRQ_STA		(0x204)

 #define ECC_TIMEOUT		(500000)

 #define ECC_IDLE_REG(op)	((op) == ECC_ENCODE ? ECC_ENCIDLE : ECC_DECIDLE)
 #define ECC_CTL_REG(op)		((op) == ECC_ENCODE ? ECC_ENCCON : ECC_DECCON)
 #define ECC_IRQ_REG(op)		((op) == ECC_ENCODE ? \
 					ECC_ENCIRQ_EN : ECC_DECIRQ_EN)

 struct mtk_ecc {
 	struct device *dev;
 	void __iomem *regs;
 	struct clk *clk;

 	struct completion done;
 	struct mutex lock;
 	u32 sectors;
 };

 static inline void mtk_ecc_wait_idle(struct mtk_ecc *ecc,
 				     enum mtk_ecc_operation op)
 {
 	struct device *dev = ecc->dev;
 	u32 val;
 	int ret;

 	ret = readl_poll_timeout_atomic(ecc->regs + ECC_IDLE_REG(op), val,
 					val & ECC_IDLE_MASK,
 					10, ECC_TIMEOUT);
 	if (ret)
 		dev_warn(dev, "%s NOT idle\n",
 			 op == ECC_ENCODE ? "encoder" : "decoder");
 }

 static irqreturn_t mtk_ecc_irq(int irq, void *id)
 {
 	struct mtk_ecc *ecc = id;
 	enum mtk_ecc_operation op;
 	u32 dec, enc;

 	dec = readw(ecc->regs + ECC_DECIRQ_STA) & ECC_IRQ_EN;
 	if (dec) {
 		op = ECC_DECODE;
 		dec = readw(ecc->regs + ECC_DECDONE);
 		if (dec & ecc->sectors) {
 			ecc->sectors = 0;
 			complete(&ecc->done);
 		} else {
 			return IRQ_HANDLED;
 		}
 	} else {
 		enc = readl(ecc->regs + ECC_ENCIRQ_STA) & ECC_IRQ_EN;
 		if (enc) {
 			op = ECC_ENCODE;
 			complete(&ecc->done);
 		} else {
 			return IRQ_NONE;
 		}
 	}

 	writel(0, ecc->regs + ECC_IRQ_REG(op));

 	return IRQ_HANDLED;
 }

 static void mtk_ecc_config(struct mtk_ecc *ecc, struct mtk_ecc_config *config)
 {
 	u32 ecc_bit = ECC_CNFG_4BIT, dec_sz, enc_sz;
 	u32 reg;

 	switch (config->strength) {
 	case 4:
 		ecc_bit = ECC_CNFG_4BIT;
 		break;
 	case 6:
 		ecc_bit = ECC_CNFG_6BIT;
 		break;
 	case 8:
 		ecc_bit = ECC_CNFG_8BIT;
 		break;
 	case 10:
 		ecc_bit = ECC_CNFG_10BIT;
 		break;
 	case 12:
 		ecc_bit = ECC_CNFG_12BIT;
 		break;
 	case 14:
 		ecc_bit = ECC_CNFG_14BIT;
 		break;
 	case 16:
 		ecc_bit = ECC_CNFG_16BIT;
 		break;
 	case 18:
 		ecc_bit = ECC_CNFG_18BIT;
 		break;
 	case 20:
 		ecc_bit = ECC_CNFG_20BIT;
 		break;
 	case 22:
 		ecc_bit = ECC_CNFG_22BIT;
 		break;
 	case 24:
 		ecc_bit = ECC_CNFG_24BIT;
 		break;
 	case 28:
 		ecc_bit = ECC_CNFG_28BIT;
 		break;
 	case 32:
 		ecc_bit = ECC_CNFG_32BIT;
 		break;
 	case 36:
 		ecc_bit = ECC_CNFG_36BIT;
 		break;
 	case 40:
 		ecc_bit = ECC_CNFG_40BIT;
 		break;
 	case 44:
 		ecc_bit = ECC_CNFG_44BIT;
 		break;
 	case 48:
 		ecc_bit = ECC_CNFG_48BIT;
 		break;
 	case 52:
 		ecc_bit = ECC_CNFG_52BIT;
 		break;
 	case 56:
 		ecc_bit = ECC_CNFG_56BIT;
 		break;
 	case 60:
 		ecc_bit = ECC_CNFG_60BIT;
 		break;
 	default:
 		dev_err(ecc->dev, "invalid strength %d, default to 4 bits\n",
 			config->strength);
 	}

 	if (config->op == ECC_ENCODE) {
 		/* configure ECC encoder (in bits) */
 		enc_sz = config->len << 3;

 		reg = ecc_bit | (config->mode << ECC_MODE_SHIFT);
 		reg |= (enc_sz << ECC_MS_SHIFT);
 		writel(reg, ecc->regs + ECC_ENCCNFG);

 		if (config->mode != ECC_NFI_MODE)
 			writel(lower_32_bits(config->addr),
 			       ecc->regs + ECC_ENCDIADDR);

 	} else {
 		/* configure ECC decoder (in bits) */
 		dec_sz = (config->len << 3) +
 					config->strength * ECC_PARITY_BITS;

 		reg = ecc_bit | (config->mode << ECC_MODE_SHIFT);
 		reg |= (dec_sz << ECC_MS_SHIFT) | DEC_CNFG_CORRECT;
 		reg |= DEC_EMPTY_EN;
 		writel(reg, ecc->regs + ECC_DECCNFG);

 		if (config->sectors)
 			ecc->sectors = 1 << (config->sectors - 1);
 	}
 }

 void mtk_ecc_get_stats(struct mtk_ecc *ecc, struct mtk_ecc_stats *stats,
 		       int sectors)
 {
 	u32 offset, i, err;
 	u32 bitflips = 0;

 	stats->corrected = 0;
 	stats->failed = 0;

 	for (i = 0; i < sectors; i++) {
 		offset = (i >> 2) << 2;
 		err = readl(ecc->regs + ECC_DECENUM0 + offset);
 		err = err >> ((i % 4) * 8);
 		err &= ERR_MASK;
 		if (err == ERR_MASK) {
 			/* uncorrectable errors */
 			stats->failed++;
 			continue;
 		}

 		stats->corrected += err;
 		bitflips = max_t(u32, bitflips, err);
 	}

 	stats->bitflips = bitflips;
 }
 EXPORT_SYMBOL(mtk_ecc_get_stats);

 void mtk_ecc_release(struct mtk_ecc *ecc)
 {
 	clk_disable_unprepare(ecc->clk);
 	put_device(ecc->dev);
 }
 EXPORT_SYMBOL(mtk_ecc_release);

 static void mtk_ecc_hw_init(struct mtk_ecc *ecc)
 {
 	mtk_ecc_wait_idle(ecc, ECC_ENCODE);
 	writew(ECC_OP_DISABLE, ecc->regs + ECC_ENCCON);

 	mtk_ecc_wait_idle(ecc, ECC_DECODE);
 	writel(ECC_OP_DISABLE, ecc->regs + ECC_DECCON);
 }

 static struct mtk_ecc *mtk_ecc_get(struct device_node *np)
 {
 	struct platform_device *pdev;
 	struct mtk_ecc *ecc;

 	pdev = of_find_device_by_node(np);
 	if (!pdev || !platform_get_drvdata(pdev))
 		return ERR_PTR(-EPROBE_DEFER);

 	get_device(&pdev->dev);
 	ecc = platform_get_drvdata(pdev);
 	clk_prepare_enable(ecc->clk);
 	mtk_ecc_hw_init(ecc);

 	return ecc;
 }

 struct mtk_ecc *of_mtk_ecc_get(struct device_node *of_node)
 {
 	struct mtk_ecc *ecc = NULL;
 	struct device_node *np;

 	np = of_parse_phandle(of_node, "ecc-engine", 0);
 	if (np) {
 		ecc = mtk_ecc_get(np);
 		of_node_put(np);
 	}

 	return ecc;
 }
 EXPORT_SYMBOL(of_mtk_ecc_get);

 int mtk_ecc_enable(struct mtk_ecc *ecc, struct mtk_ecc_config *config)
 {
 	enum mtk_ecc_operation op = config->op;
 	int ret;

 	ret = mutex_lock_interruptible(&ecc->lock);
 	if (ret) {
 		dev_err(ecc->dev, "interrupted when attempting to lock\n");
 		return ret;
 	}

 	mtk_ecc_wait_idle(ecc, op);
 	mtk_ecc_config(ecc, config);
 	writew(ECC_OP_ENABLE, ecc->regs + ECC_CTL_REG(op));

 	init_completion(&ecc->done);
 	writew(ECC_IRQ_EN, ecc->regs + ECC_IRQ_REG(op));

 	return 0;
 }
 EXPORT_SYMBOL(mtk_ecc_enable);

 void mtk_ecc_disable(struct mtk_ecc *ecc)
 {
 	enum mtk_ecc_operation op = ECC_ENCODE;

 	/* find out the running operation */
 	if (readw(ecc->regs + ECC_CTL_REG(op)) != ECC_OP_ENABLE)
 		op = ECC_DECODE;

 	/* disable it */
 	mtk_ecc_wait_idle(ecc, op);
 	writew(0, ecc->regs + ECC_IRQ_REG(op));
 	writew(ECC_OP_DISABLE, ecc->regs + ECC_CTL_REG(op));

 	mutex_unlock(&ecc->lock);
 }
 EXPORT_SYMBOL(mtk_ecc_disable);

 int mtk_ecc_wait_done(struct mtk_ecc *ecc, enum mtk_ecc_operation op)
 {
 	int ret;

 	ret = wait_for_completion_timeout(&ecc->done, msecs_to_jiffies(500));
 	if (!ret) {
 		dev_err(ecc->dev, "%s timeout - interrupt did not arrive)\n",
 			(op == ECC_ENCODE) ? "encoder" : "decoder");
 		return -ETIMEDOUT;
 	}

 	return 0;
 }
 EXPORT_SYMBOL(mtk_ecc_wait_done);

 int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config,
 		   u8 *data, u32 bytes)
 {
 	dma_addr_t addr;
 	u32 *p, len, i;
 	int ret = 0;

 	addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE);
 	ret = dma_mapping_error(ecc->dev, addr);
 	if (ret) {
 		dev_err(ecc->dev, "dma mapping error\n");
 		return -EINVAL;
 	}

 	config->op = ECC_ENCODE;
 	config->addr = addr;
 	ret = mtk_ecc_enable(ecc, config);
 	if (ret) {
 		dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
 		return ret;
 	}

 	ret = mtk_ecc_wait_done(ecc, ECC_ENCODE);
 	if (ret)
 		goto timeout;

 	mtk_ecc_wait_idle(ecc, ECC_ENCODE);

 	/* Program ECC bytes to OOB: per sector oob = FDM + ECC + SPARE */
 	len = (config->strength * ECC_PARITY_BITS + 7) >> 3;
 	p = (u32 *)(data + bytes);

 	/* write the parity bytes generated by the ECC back to the OOB region */
 	for (i = 0; i < len; i++)
 		p[i] = readl(ecc->regs + ECC_ENCPAR(i));
 timeout:

 	dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
 	mtk_ecc_disable(ecc);

 	return ret;
 }
 EXPORT_SYMBOL(mtk_ecc_encode);

 void mtk_ecc_adjust_strength(u32 *p)
 {
 	u32 ecc[] = {4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36,
 			40, 44, 48, 52, 56, 60};
 	int i;

 	for (i = 0; i < ARRAY_SIZE(ecc); i++) {
 		if (*p <= ecc[i]) {
 			if (!i)
 				*p = ecc[i];
 			else if (*p != ecc[i])
 				*p = ecc[i - 1];
 			return;
 		}
 	}

 	*p = ecc[ARRAY_SIZE(ecc) - 1];
 }
 EXPORT_SYMBOL(mtk_ecc_adjust_strength);

 static int mtk_ecc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct mtk_ecc *ecc;
 	struct resource *res;
 	int irq, ret;

 	ecc = devm_kzalloc(dev, sizeof(*ecc), GFP_KERNEL);
 	if (!ecc)
 		return -ENOMEM;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	ecc->regs = devm_ioremap_resource(dev, res);
 	if (IS_ERR(ecc->regs)) {
 		dev_err(dev, "failed to map regs: %ld\n", PTR_ERR(ecc->regs));
 		return PTR_ERR(ecc->regs);
 	}

 	ecc->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(ecc->clk)) {
 		dev_err(dev, "failed to get clock: %ld\n", PTR_ERR(ecc->clk));
 		return PTR_ERR(ecc->clk);
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(dev, "failed to get irq\n");
 		return -EINVAL;
 	}

 	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(dev, "failed to set DMA mask\n");
 		return ret;
 	}

 	ret = devm_request_irq(dev, irq, mtk_ecc_irq, 0x0, "mtk-ecc", ecc);
 	if (ret) {
 		dev_err(dev, "failed to request irq\n");
 		return -EINVAL;
 	}

 	ecc->dev = dev;
 	mutex_init(&ecc->lock);
 	platform_set_drvdata(pdev, ecc);
 	dev_info(dev, "probed\n");

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int mtk_ecc_suspend(struct device *dev)
 {
 	struct mtk_ecc *ecc = dev_get_drvdata(dev);

 	clk_disable_unprepare(ecc->clk);

 	return 0;
 }

 static int mtk_ecc_resume(struct device *dev)
 {
 	struct mtk_ecc *ecc = dev_get_drvdata(dev);
 	int ret;

 	ret = clk_prepare_enable(ecc->clk);
 	if (ret) {
 		dev_err(dev, "failed to enable clk\n");
 		return ret;
 	}

 	mtk_ecc_hw_init(ecc);

 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(mtk_ecc_pm_ops, mtk_ecc_suspend, mtk_ecc_resume);
 #endif

 static const struct of_device_id mtk_ecc_dt_match[] = {
 	{ .compatible = "mediatek,mt2701-ecc" },
 	{},
 };

 MODULE_DEVICE_TABLE(of, mtk_ecc_dt_match);

 static struct platform_driver mtk_ecc_driver = {
 	.probe  = mtk_ecc_probe,
 	.driver = {
 		.name  = "mtk-ecc",
 		.of_match_table = of_match_ptr(mtk_ecc_dt_match),
 #ifdef CONFIG_PM_SLEEP
 		.pm = &mtk_ecc_pm_ops,
 #endif
 	},
 };

 module_platform_driver(mtk_ecc_driver);

 MODULE_AUTHOR("Xiaolei Li <xiaolei.li@mediatek.com>");
 MODULE_DESCRIPTION("MTK Nand ECC Driver");
 MODULE_LICENSE("GPL");
	/*
	* MTK ECC controller driver.
	* Copyright (C) 2016 MediaTek Inc.
	* Authors: Xiaolei Li <xiaolei.li@mediatek.com>
	* Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* 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/dma-mapping.h>
	#include <linux/interrupt.h>
	#include <linux/clk.h>
	#include <linux/module.h>
	#include <linux/iopoll.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/mutex.h>

	#include "mtk_ecc.h"

	#define ECC_IDLE_MASK BIT(0)
	#define ECC_IRQ_EN BIT(0)
	#define ECC_OP_ENABLE (1)
	#define ECC_OP_DISABLE (0)

	#define ECC_ENCCON (0x00)
	#define ECC_ENCCNFG (0x04)
	#define ECC_CNFG_4BIT (0)
	#define ECC_CNFG_6BIT (1)
	#define ECC_CNFG_8BIT (2)
	#define ECC_CNFG_10BIT (3)
	#define ECC_CNFG_12BIT (4)
	#define ECC_CNFG_14BIT (5)
	#define ECC_CNFG_16BIT (6)
	#define ECC_CNFG_18BIT (7)
	#define ECC_CNFG_20BIT (8)
	#define ECC_CNFG_22BIT (9)
	#define ECC_CNFG_24BIT (0xa)
	#define ECC_CNFG_28BIT (0xb)
	#define ECC_CNFG_32BIT (0xc)
	#define ECC_CNFG_36BIT (0xd)
	#define ECC_CNFG_40BIT (0xe)
	#define ECC_CNFG_44BIT (0xf)
	#define ECC_CNFG_48BIT (0x10)
	#define ECC_CNFG_52BIT (0x11)
	#define ECC_CNFG_56BIT (0x12)
	#define ECC_CNFG_60BIT (0x13)
	#define ECC_MODE_SHIFT (5)
	#define ECC_MS_SHIFT (16)
	#define ECC_ENCDIADDR (0x08)
	#define ECC_ENCIDLE (0x0C)
	#define ECC_ENCPAR(x) (0x10 + (x) * sizeof(u32))
	#define ECC_ENCIRQ_EN (0x80)
	#define ECC_ENCIRQ_STA (0x84)
	#define ECC_DECCON (0x100)
	#define ECC_DECCNFG (0x104)
	#define DEC_EMPTY_EN BIT(31)
	#define DEC_CNFG_CORRECT (0x3 << 12)
	#define ECC_DECIDLE (0x10C)
	#define ECC_DECENUM0 (0x114)
	#define ERR_MASK (0x3f)
	#define ECC_DECDONE (0x124)
	#define ECC_DECIRQ_EN (0x200)
	#define ECC_DECIRQ_STA (0x204)

	#define ECC_TIMEOUT (500000)

	#define ECC_IDLE_REG(op) ((op) == ECC_ENCODE ? ECC_ENCIDLE : ECC_DECIDLE)
	#define ECC_CTL_REG(op) ((op) == ECC_ENCODE ? ECC_ENCCON : ECC_DECCON)
	#define ECC_IRQ_REG(op) ((op) == ECC_ENCODE ? \
	ECC_ENCIRQ_EN : ECC_DECIRQ_EN)

	struct mtk_ecc {
	struct device *dev;
	void __iomem *regs;
	struct clk *clk;

	struct completion done;
	struct mutex lock;
	u32 sectors;
	};

	static inline void mtk_ecc_wait_idle(struct mtk_ecc *ecc,
	enum mtk_ecc_operation op)
	{
	struct device *dev = ecc->dev;
	u32 val;
	int ret;

	ret = readl_poll_timeout_atomic(ecc->regs + ECC_IDLE_REG(op), val,
	val & ECC_IDLE_MASK,
	10, ECC_TIMEOUT);
	if (ret)
	dev_warn(dev, "%s NOT idle\n",
	op == ECC_ENCODE ? "encoder" : "decoder");
	}

	static irqreturn_t mtk_ecc_irq(int irq, void *id)
	{
	struct mtk_ecc *ecc = id;
	enum mtk_ecc_operation op;
	u32 dec, enc;

	dec = readw(ecc->regs + ECC_DECIRQ_STA) & ECC_IRQ_EN;
	if (dec) {
	op = ECC_DECODE;
	dec = readw(ecc->regs + ECC_DECDONE);
	if (dec & ecc->sectors) {
	ecc->sectors = 0;
	complete(&ecc->done);
	} else {
	return IRQ_HANDLED;
	}
	} else {
	enc = readl(ecc->regs + ECC_ENCIRQ_STA) & ECC_IRQ_EN;
	if (enc) {
	op = ECC_ENCODE;
	complete(&ecc->done);
	} else {
	return IRQ_NONE;
	}
	}

	writel(0, ecc->regs + ECC_IRQ_REG(op));

	return IRQ_HANDLED;
	}

	static void mtk_ecc_config(struct mtk_ecc ecc, struct mtk_ecc_config config)
	{
	u32 ecc_bit = ECC_CNFG_4BIT, dec_sz, enc_sz;
	u32 reg;

	switch (config->strength) {
	case 4:
	ecc_bit = ECC_CNFG_4BIT;
	break;
	case 6:
	ecc_bit = ECC_CNFG_6BIT;
	break;
	case 8:
	ecc_bit = ECC_CNFG_8BIT;
	break;
	case 10:
	ecc_bit = ECC_CNFG_10BIT;
	break;
	case 12:
	ecc_bit = ECC_CNFG_12BIT;
	break;
	case 14:
	ecc_bit = ECC_CNFG_14BIT;
	break;
	case 16:
	ecc_bit = ECC_CNFG_16BIT;
	break;
	case 18:
	ecc_bit = ECC_CNFG_18BIT;
	break;
	case 20:
	ecc_bit = ECC_CNFG_20BIT;
	break;
	case 22:
	ecc_bit = ECC_CNFG_22BIT;
	break;
	case 24:
	ecc_bit = ECC_CNFG_24BIT;
	break;
	case 28:
	ecc_bit = ECC_CNFG_28BIT;
	break;
	case 32:
	ecc_bit = ECC_CNFG_32BIT;
	break;
	case 36:
	ecc_bit = ECC_CNFG_36BIT;
	break;
	case 40:
	ecc_bit = ECC_CNFG_40BIT;
	break;
	case 44:
	ecc_bit = ECC_CNFG_44BIT;
	break;
	case 48:
	ecc_bit = ECC_CNFG_48BIT;
	break;
	case 52:
	ecc_bit = ECC_CNFG_52BIT;
	break;
	case 56:
	ecc_bit = ECC_CNFG_56BIT;
	break;
	case 60:
	ecc_bit = ECC_CNFG_60BIT;
	break;
	default:
	dev_err(ecc->dev, "invalid strength %d, default to 4 bits\n",
	config->strength);
	}

	if (config->op == ECC_ENCODE) {
	/* configure ECC encoder (in bits) */
	enc_sz = config->len << 3;

	reg = ecc_bit \| (config->mode << ECC_MODE_SHIFT);
	reg \|= (enc_sz << ECC_MS_SHIFT);
	writel(reg, ecc->regs + ECC_ENCCNFG);

	if (config->mode != ECC_NFI_MODE)
	writel(lower_32_bits(config->addr),
	ecc->regs + ECC_ENCDIADDR);

	} else {
	/* configure ECC decoder (in bits) */
	dec_sz = (config->len << 3) +
	config->strength * ECC_PARITY_BITS;

	reg = ecc_bit \| (config->mode << ECC_MODE_SHIFT);
	reg \|= (dec_sz << ECC_MS_SHIFT) \| DEC_CNFG_CORRECT;
	reg \|= DEC_EMPTY_EN;
	writel(reg, ecc->regs + ECC_DECCNFG);

	if (config->sectors)
	ecc->sectors = 1 << (config->sectors - 1);
	}
	}

	void mtk_ecc_get_stats(struct mtk_ecc ecc, struct mtk_ecc_stats stats,
	int sectors)
	{
	u32 offset, i, err;
	u32 bitflips = 0;

	stats->corrected = 0;
	stats->failed = 0;

	for (i = 0; i < sectors; i++) {
	offset = (i >> 2) << 2;
	err = readl(ecc->regs + ECC_DECENUM0 + offset);
	err = err >> ((i % 4) * 8);
	err &= ERR_MASK;
	if (err == ERR_MASK) {
	/* uncorrectable errors */
	stats->failed++;
	continue;
	}

	stats->corrected += err;
	bitflips = max_t(u32, bitflips, err);
	}

	stats->bitflips = bitflips;
	}
	EXPORT_SYMBOL(mtk_ecc_get_stats);

	void mtk_ecc_release(struct mtk_ecc *ecc)
	{
	clk_disable_unprepare(ecc->clk);
	put_device(ecc->dev);
	}
	EXPORT_SYMBOL(mtk_ecc_release);

	static void mtk_ecc_hw_init(struct mtk_ecc *ecc)
	{
	mtk_ecc_wait_idle(ecc, ECC_ENCODE);
	writew(ECC_OP_DISABLE, ecc->regs + ECC_ENCCON);

	mtk_ecc_wait_idle(ecc, ECC_DECODE);
	writel(ECC_OP_DISABLE, ecc->regs + ECC_DECCON);
	}

	static struct mtk_ecc mtk_ecc_get(struct device_node np)
	{
	struct platform_device *pdev;
	struct mtk_ecc *ecc;

	pdev = of_find_device_by_node(np);
	if (!pdev \|\| !platform_get_drvdata(pdev))
	return ERR_PTR(-EPROBE_DEFER);

	get_device(&pdev->dev);
	ecc = platform_get_drvdata(pdev);
	clk_prepare_enable(ecc->clk);
	mtk_ecc_hw_init(ecc);

	return ecc;
	}

	struct mtk_ecc of_mtk_ecc_get(struct device_node of_node)
	{
	struct mtk_ecc *ecc = NULL;
	struct device_node *np;

	np = of_parse_phandle(of_node, "ecc-engine", 0);
	if (np) {
	ecc = mtk_ecc_get(np);
	of_node_put(np);
	}

	return ecc;
	}
	EXPORT_SYMBOL(of_mtk_ecc_get);

	int mtk_ecc_enable(struct mtk_ecc ecc, struct mtk_ecc_config config)
	{
	enum mtk_ecc_operation op = config->op;
	int ret;

	ret = mutex_lock_interruptible(&ecc->lock);
	if (ret) {
	dev_err(ecc->dev, "interrupted when attempting to lock\n");
	return ret;
	}

	mtk_ecc_wait_idle(ecc, op);
	mtk_ecc_config(ecc, config);
	writew(ECC_OP_ENABLE, ecc->regs + ECC_CTL_REG(op));

	init_completion(&ecc->done);
	writew(ECC_IRQ_EN, ecc->regs + ECC_IRQ_REG(op));

	return 0;
	}
	EXPORT_SYMBOL(mtk_ecc_enable);

	void mtk_ecc_disable(struct mtk_ecc *ecc)
	{
	enum mtk_ecc_operation op = ECC_ENCODE;

	/* find out the running operation */
	if (readw(ecc->regs + ECC_CTL_REG(op)) != ECC_OP_ENABLE)
	op = ECC_DECODE;

	/* disable it */
	mtk_ecc_wait_idle(ecc, op);
	writew(0, ecc->regs + ECC_IRQ_REG(op));
	writew(ECC_OP_DISABLE, ecc->regs + ECC_CTL_REG(op));

	mutex_unlock(&ecc->lock);
	}
	EXPORT_SYMBOL(mtk_ecc_disable);

	int mtk_ecc_wait_done(struct mtk_ecc *ecc, enum mtk_ecc_operation op)
	{
	int ret;

	ret = wait_for_completion_timeout(&ecc->done, msecs_to_jiffies(500));
	if (!ret) {
	dev_err(ecc->dev, "%s timeout - interrupt did not arrive)\n",
	(op == ECC_ENCODE) ? "encoder" : "decoder");
	return -ETIMEDOUT;
	}

	return 0;
	}
	EXPORT_SYMBOL(mtk_ecc_wait_done);

	int mtk_ecc_encode(struct mtk_ecc ecc, struct mtk_ecc_config config,
	u8 *data, u32 bytes)
	{
	dma_addr_t addr;
	u32 *p, len, i;
	int ret = 0;

	addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE);
	ret = dma_mapping_error(ecc->dev, addr);
	if (ret) {
	dev_err(ecc->dev, "dma mapping error\n");
	return -EINVAL;
	}

	config->op = ECC_ENCODE;
	config->addr = addr;
	ret = mtk_ecc_enable(ecc, config);
	if (ret) {
	dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
	return ret;
	}

	ret = mtk_ecc_wait_done(ecc, ECC_ENCODE);
	if (ret)
	goto timeout;

	mtk_ecc_wait_idle(ecc, ECC_ENCODE);

	/* Program ECC bytes to OOB: per sector oob = FDM + ECC + SPARE */
	len = (config->strength * ECC_PARITY_BITS + 7) >> 3;
	p = (u32 *)(data + bytes);

	/* write the parity bytes generated by the ECC back to the OOB region */
	for (i = 0; i < len; i++)
	p[i] = readl(ecc->regs + ECC_ENCPAR(i));
	timeout:

	dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
	mtk_ecc_disable(ecc);

	return ret;
	}
	EXPORT_SYMBOL(mtk_ecc_encode);

	void mtk_ecc_adjust_strength(u32 *p)
	{
	u32 ecc[] = {4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36,
	40, 44, 48, 52, 56, 60};
	int i;

	for (i = 0; i < ARRAY_SIZE(ecc); i++) {
	if (*p <= ecc[i]) {
	if (!i)
	*p = ecc[i];
	else if (*p != ecc[i])
	*p = ecc[i - 1];
	return;
	}
	}

	*p = ecc[ARRAY_SIZE(ecc) - 1];
	}
	EXPORT_SYMBOL(mtk_ecc_adjust_strength);

	static int mtk_ecc_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct mtk_ecc *ecc;
	struct resource *res;
	int irq, ret;

	ecc = devm_kzalloc(dev, sizeof(*ecc), GFP_KERNEL);
	if (!ecc)
	return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	ecc->regs = devm_ioremap_resource(dev, res);
	if (IS_ERR(ecc->regs)) {
	dev_err(dev, "failed to map regs: %ld\n", PTR_ERR(ecc->regs));
	return PTR_ERR(ecc->regs);
	}

	ecc->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(ecc->clk)) {
	dev_err(dev, "failed to get clock: %ld\n", PTR_ERR(ecc->clk));
	return PTR_ERR(ecc->clk);
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(dev, "failed to get irq\n");
	return -EINVAL;
	}

	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
	if (ret) {
	dev_err(dev, "failed to set DMA mask\n");
	return ret;
	}

	ret = devm_request_irq(dev, irq, mtk_ecc_irq, 0x0, "mtk-ecc", ecc);
	if (ret) {
	dev_err(dev, "failed to request irq\n");
	return -EINVAL;
	}

	ecc->dev = dev;
	mutex_init(&ecc->lock);
	platform_set_drvdata(pdev, ecc);
	dev_info(dev, "probed\n");

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int mtk_ecc_suspend(struct device *dev)
	{
	struct mtk_ecc *ecc = dev_get_drvdata(dev);

	clk_disable_unprepare(ecc->clk);

	return 0;
	}

	static int mtk_ecc_resume(struct device *dev)
	{
	struct mtk_ecc *ecc = dev_get_drvdata(dev);
	int ret;

	ret = clk_prepare_enable(ecc->clk);
	if (ret) {
	dev_err(dev, "failed to enable clk\n");
	return ret;
	}

	mtk_ecc_hw_init(ecc);

	return 0;
	}

	static SIMPLE_DEV_PM_OPS(mtk_ecc_pm_ops, mtk_ecc_suspend, mtk_ecc_resume);
	#endif

	static const struct of_device_id mtk_ecc_dt_match[] = {
	{ .compatible = "mediatek,mt2701-ecc" },
	{},
	};

	MODULE_DEVICE_TABLE(of, mtk_ecc_dt_match);

	static struct platform_driver mtk_ecc_driver = {
	.probe = mtk_ecc_probe,
	.driver = {
	.name = "mtk-ecc",
	.of_match_table = of_match_ptr(mtk_ecc_dt_match),
	#ifdef CONFIG_PM_SLEEP
	.pm = &mtk_ecc_pm_ops,
	#endif
	},
	};

	module_platform_driver(mtk_ecc_driver);

	MODULE_AUTHOR("Xiaolei Li <xiaolei.li@mediatek.com>");
	MODULE_DESCRIPTION("MTK Nand ECC Driver");
	MODULE_LICENSE("GPL");