[PATCH] NAND hardware ECC controller on at91sam9263 / at91sam9260
Richard Genoud
richard.genoud at gmail.com
Wed Apr 23 13:51:14 EDT 2008
This is a patch to use the hardware ECC controller of
the AT91SAM9260 and AT91SAM9263 for the AT91 nand.
On AT91 NAND, there's now a choice between ECC soft,
ECC hard or no ECC (for debug).
It has been tested on AT91SAM9263 with 8 bits large
and small page NAND.
kernel version : 2.6.25 linux-mtd master tree
Signed-off-by: Richard Genoud <richard.genoud at gmail.com>
---
drivers/mtd/nand/Kconfig | 41 ++++
drivers/mtd/nand/at91_nand.c | 361 +++++++++++++++++++++++++++++-
2 files changed, 397 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-at91/at91sam9260_devices.c b/arch/arm/mach-at91/at91sam9260_devices.c
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index dcbb0de..5076faf 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -278,6 +278,47 @@ config MTD_NAND_AT91
help
Enables support for NAND Flash / Smart Media Card interface
on Atmel AT91 processors.
+choice
+ prompt "ECC management for NAND Flash / SmartMedia on AT91"
+ depends on MTD_NAND_AT91
+
+config MTD_NAND_AT91_ECC_HW
+ bool "Hardware ECC"
+ depends on ARCH_AT91SAM9263 || ARCH_AT91SAM9260
+ help
+ Uses hardware ECC provided by the at91sam9260/at91sam9263 chip
+ instead of software ECC.
+ The hardware ECC controller is capable of single bit error
+ correction and 2-bit random detection per page.
+
+ NB : hardware and software ECC schemes are incompatible.
+ If you switch from one to another, you'll have to erase your
+ mtd partition.
+
+ If unsure, say Y
+
+config MTD_NAND_AT91_ECC_SOFT
+ bool "Software ECC"
+ help
+ Uses software ECC.
+
+ NB : hardware and software ECC schemes are incompatible.
+ If you switch from one to another, you'll have to erase your
+ mtd partition.
+
+config MTD_NAND_AT91_ECC_NONE
+ bool "No ECC (testing only, DANGEROUS)"
+ depends on DEBUG_KERNEL
+ help
+ No ECC will be used.
+ It's not a good idea and it should be reserved for testing
+ purpose only.
+
+ If unsure, say N
+
+ endchoice
+
+endchoice
config MTD_NAND_PXA3xx
bool "Support for NAND flash devices on PXA3xx"
diff --git a/drivers/mtd/nand/at91_nand.c b/drivers/mtd/nand/at91_nand.c
index 463632e..c3eb203 100644
--- a/drivers/mtd/nand/at91_nand.c
+++ b/drivers/mtd/nand/at91_nand.c
@@ -9,6 +9,15 @@
* Derived from drivers/mtd/spia.c
* Copyright (C) 2000 Steven J. Hill (sjhill at cotw.com)
*
+ *
+ * Add Hardware ECC support for AT91SAM9260 / AT91SAM9263
+ * Richard Genoud (richard.genoud at gmail.com), Adeneo Copyright (C) 2007
+ *
+ * Derived from Das U-Boot source code
+ * (u-boot-1.1.5/board/atmel/at91sam9263ek/nand.c)
+ * (C) Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
+ *
+ *
* 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.
@@ -29,11 +38,59 @@
#include <asm/arch/board.h>
#include <asm/arch/gpio.h>
+#ifdef CONFIG_MTD_NAND_AT91_ECC_HW
+#define hard_ecc 1
+#else
+#define hard_ecc 0
+#endif
+
+#ifdef CONFIG_MTD_NAND_AT91_ECC_NONE
+#define no_ecc 1
+#else
+#define no_ecc 0
+#endif
+
+/* Register access macros */
+#define ecc_readl(add, reg) \
+ __raw_readl(add + AT91_ECC_##reg)
+#define ecc_writel(add, reg, value) \
+ __raw_writel((value), add + AT91_ECC_##reg)
+
+#include <asm/arch/at91_ecc.h> /* AT91SAM9260/3 ECC registers */
+
+/* oob layout for large page size
+ * bad block info is on bytes 0 and 1
+ * the bytes have to be consecutives to avoid
+ * several NAND_CMD_RNDOUT during read
+ */
+static struct nand_ecclayout at91_oobinfo_large = {
+ .eccbytes = 4,
+ .eccpos = {60, 61, 62, 63},
+ .oobfree = {
+ {2, 58}
+ },
+};
+
+/* oob layout for small page size
+ * bad block info is on bytes 4 and 5
+ * the bytes have to be consecutives to avoid
+ * several NAND_CMD_RNDOUT during read
+ */
+static struct nand_ecclayout at91_oobinfo_small = {
+ .eccbytes = 4,
+ .eccpos = {0, 1, 2, 3},
+ .oobfree = {
+ {6, 10}
+ },
+};
+
struct at91_nand_host {
struct nand_chip nand_chip;
struct mtd_info mtd;
void __iomem *io_base;
struct at91_nand_data *board;
+ struct device *dev;
+ void __iomem *ecc;
};
/*
@@ -82,6 +139,215 @@ static void at91_nand_disable(struct at91_nand_host *host)
at91_set_gpio_value(host->board->enable_pin, 1);
}
+/*
+ * write oob for small pages
+ */
+static int at91_nand_write_oob_512(struct mtd_info *mtd,
+ struct nand_chip *chip, int page)
+{
+ int chunk = chip->ecc.bytes + chip->ecc.prepad + chip->ecc.postpad;
+ int eccsize = chip->ecc.size, length = mtd->oobsize;
+ int len, pos, status = 0;
+ const uint8_t *bufpoi = chip->oob_poi;
+
+ pos = eccsize + chunk;
+
+ chip->cmdfunc(mtd, NAND_CMD_SEQIN, pos, page);
+ len = min_t(int, length, chunk);
+ chip->write_buf(mtd, bufpoi, len);
+ bufpoi += len;
+ length -= len;
+ if (length > 0)
+ chip->write_buf(mtd, bufpoi, length);
+
+ chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+ status = chip->waitfunc(mtd, chip);
+
+ return status & NAND_STATUS_FAIL ? -EIO : 0;
+
+}
+
+/*
+ * read oob for small pages
+ */
+static int at91_nand_read_oob_512(struct mtd_info *mtd,
+ struct nand_chip *chip, int page, int sndcmd)
+{
+ if (sndcmd) {
+ chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
+ sndcmd = 0;
+ }
+ chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
+ return sndcmd;
+}
+
+/*
+ * Calculate HW ECC
+ *
+ * function called after a write
+ *
+ * mtd: MTD block structure
+ * dat: raw data (unused)
+ * ecc_code: buffer for ECC
+ */
+static int at91_nand_calculate(struct mtd_info *mtd,
+ const u_char *dat, unsigned char *ecc_code)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+ struct at91_nand_host *host = nand_chip->priv;
+ uint32_t *eccpos = nand_chip->ecc.layout->eccpos;
+ unsigned int ecc_value;
+
+ /* get the first 2 ECC bytes */
+ ecc_value = ecc_readl(host->ecc, PR) & AT91_ECC_PARITY;
+
+ ecc_code[eccpos[0]] = ecc_value & 0xFF;
+ ecc_code[eccpos[1]] = (ecc_value >> 8) & 0xFF;
+
+ /* get the last 2 ECC bytes */
+ ecc_value = ecc_readl(host->ecc, NPR) & AT91_ECC_NPARITY;
+
+ ecc_code[eccpos[2]] = ecc_value & 0xFF;
+ ecc_code[eccpos[3]] = (ecc_value >> 8) & 0xFF;
+
+ return 0;
+}
+
+/*
+ * HW ECC read page function
+ *
+ * mtd: mtd info structure
+ * chip: nand chip info structure
+ * buf: buffer to store read data
+ */
+static int at91_nand_read_page(struct mtd_info *mtd,
+ struct nand_chip *chip, uint8_t *buf)
+{
+ int eccsize = chip->ecc.size;
+ int eccbytes = chip->ecc.bytes;
+ uint32_t *eccpos = chip->ecc.layout->eccpos;
+ uint8_t *p = buf;
+ uint8_t *oob = chip->oob_poi;
+ uint8_t *ecc_pos;
+ int stat;
+
+ /* read the page */
+ chip->read_buf(mtd, p, eccsize);
+
+ /* move to ECC position if needed */
+ if (eccpos[0] != 0) {
+ /* This only works on large pages
+ * because the ECC controller waits for
+ * NAND_CMD_RNDOUTSTART after the
+ * NAND_CMD_RNDOUT.
+ * anyway, for small pages, the eccpos[0] == 0
+ */
+ chip->cmdfunc(mtd, NAND_CMD_RNDOUT,
+ mtd->writesize + eccpos[0], -1);
+ }
+
+ /* the ECC controller needs to read the ECC just after the data */
+ ecc_pos = oob + eccpos[0];
+ chip->read_buf(mtd, ecc_pos, eccbytes);
+
+ /* check if there's an error */
+ stat = chip->ecc.correct(mtd, p, oob, NULL);
+
+ if (stat < 0)
+ mtd->ecc_stats.failed++;
+ else
+ mtd->ecc_stats.corrected += stat;
+
+ /* get back to oob start (end of page) */
+ chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize, -1);
+
+ /* read the oob */
+ chip->read_buf(mtd, oob, mtd->oobsize);
+
+ return 0;
+}
+
+/*
+ * HW ECC Correction
+ *
+ * function called after a read
+ *
+ * mtd: MTD block structure
+ * dat: raw data read from the chip
+ * read_ecc: ECC from the chip (unused)
+ * isnull: unused
+ *
+ * Detect and correct a 1 bit error for a page
+ */
+static int at91_nand_correct(struct mtd_info *mtd, u_char *dat,
+ u_char *read_ecc, u_char *isnull)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+ struct at91_nand_host *host = nand_chip->priv;
+ unsigned int ecc_status;
+ unsigned int ecc_word, ecc_bit;
+
+ /* get the status from the Status Register */
+ ecc_status = ecc_readl(host->ecc, SR);
+
+ /* if there's no error */
+ if (likely(!(ecc_status & AT91_ECC_RECERR)))
+ return 0;
+
+ /* get error bit offset (4 bits) */
+ ecc_bit = ecc_readl(host->ecc, PR) & AT91_ECC_BITADDR;
+ /* get word address (12 bits) */
+ ecc_word = ecc_readl(host->ecc, PR) & AT91_ECC_WORDADDR;
+ ecc_word >>= 4;
+
+ /* if there are multiple errors */
+ if (ecc_status & AT91_ECC_MULERR) {
+ /* check if it is a freshly erased block
+ * (filled with 0xff) */
+ if ((ecc_bit == AT91_ECC_BITADDR)
+ && (ecc_word == (AT91_ECC_WORDADDR >> 4))) {
+ /* the block has just been erased, return OK */
+ return 0;
+ }
+ /* it doesn't seems to be a freshly
+ * erased block.
+ * We can't correct so many errors */
+ dev_dbg(host->dev, "at91_nand : multiple errors detected."
+ " Unable to correct.\n");
+ return -EIO;
+ }
+
+ /* if there's a single bit error : we can correct it */
+ if (ecc_status & AT91_ECC_ECCERR) {
+ /* there's nothing much to do here.
+ * the bit error is on the ECC itself.
+ */
+ dev_dbg(host->dev, "at91_nand : one bit error on ECC code."
+ " Nothing to correct\n");
+ return 0;
+ }
+
+ dev_dbg(host->dev, "at91_nand : one bit error on data."
+ " (word offset in the page :"
+ " 0x%x bit offset : 0x%x)\n",
+ ecc_word, ecc_bit);
+ /* correct the error */
+ if (nand_chip->options & NAND_BUSWIDTH_16) {
+ /* 16 bits words */
+ ((unsigned short *) dat)[ecc_word] ^= (1 << ecc_bit);
+ } else {
+ /* 8 bits words */
+ dat[ecc_word] ^= (1 << ecc_bit);
+ }
+ dev_dbg(host->dev, "at91_nand : error corrected\n");
+ return 1;
+}
+
+/*
+ * Enable HW ECC : unsused
+ */
+static void at91_nand_hwctl(struct mtd_info *mtd, int mode) { ; }
+
#ifdef CONFIG_MTD_PARTITIONS
static const char *part_probes[] = { "cmdlinepart", NULL };
#endif
@@ -94,6 +360,8 @@ static int __init at91_nand_probe(struct platform_device *pdev)
struct at91_nand_host *host;
struct mtd_info *mtd;
struct nand_chip *nand_chip;
+ struct resource *regs;
+ struct resource *mem;
int res;
#ifdef CONFIG_MTD_PARTITIONS
@@ -108,8 +376,13 @@ static int __init at91_nand_probe(struct platform_device *pdev)
return -ENOMEM;
}
- host->io_base = ioremap(pdev->resource[0].start,
- pdev->resource[0].end - pdev->resource[0].start + 1);
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!mem) {
+ printk(KERN_ERR "at91_nand: can't get I/O resource mem\n");
+ return -ENXIO;
+ }
+
+ host->io_base = ioremap(mem->start, mem->end - mem->start + 1);
if (host->io_base == NULL) {
printk(KERN_ERR "at91_nand: ioremap failed\n");
kfree(host);
@@ -119,6 +392,7 @@ static int __init at91_nand_probe(struct platform_device *pdev)
mtd = &host->mtd;
nand_chip = &host->nand_chip;
host->board = pdev->dev.platform_data;
+ host->dev = &pdev->dev;
nand_chip->priv = host; /* link the private data structures */
mtd->priv = nand_chip;
@@ -132,7 +406,32 @@ static int __init at91_nand_probe(struct platform_device *pdev)
if (host->board->rdy_pin)
nand_chip->dev_ready = at91_nand_device_ready;
+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ if (!regs && hard_ecc) {
+ printk(KERN_ERR "at91_nand: can't get I/O resource "
+ "regs\nFalling back on software ECC\n");
+ }
+
nand_chip->ecc.mode = NAND_ECC_SOFT; /* enable ECC */
+ if (no_ecc)
+ nand_chip->ecc.mode = NAND_ECC_NONE;
+ if (hard_ecc && regs) {
+ host->ecc = ioremap(regs->start, regs->end - regs->start + 1);
+ if (host->ecc == NULL) {
+ printk(KERN_ERR "at91_nand: ioremap failed\n");
+ res = -EIO;
+ goto err_ecc_ioremap;
+ }
+ nand_chip->ecc.mode = NAND_ECC_HW_SYNDROME;
+ nand_chip->ecc.calculate = at91_nand_calculate;
+ nand_chip->ecc.correct = at91_nand_correct;
+ nand_chip->ecc.hwctl = at91_nand_hwctl;
+ nand_chip->ecc.read_page = at91_nand_read_page;
+ nand_chip->ecc.bytes = 4;
+ nand_chip->ecc.prepad = 0;
+ nand_chip->ecc.postpad = 0;
+ }
+
nand_chip->chip_delay = 20; /* 20us command delay time */
if (host->board->bus_width_16) /* 16-bit bus width */
@@ -149,8 +448,53 @@ static int __init at91_nand_probe(struct platform_device *pdev)
}
}
- /* Scan to find existance of the device */
- if (nand_scan(mtd, 1)) {
+ /* first scan to find the device and get the page size */
+ if (nand_scan_ident(mtd, 1)) {
+ res = -ENXIO;
+ goto out;
+ }
+
+ if (nand_chip->ecc.mode == NAND_ECC_HW_SYNDROME) {
+ /* ECC is calculated for the whole page (1 step) */
+ nand_chip->ecc.size = mtd->writesize;
+
+ /* set ECC page size and oob layout */
+ switch (mtd->writesize) {
+ case 512:
+ nand_chip->ecc.layout = &at91_oobinfo_small;
+ nand_chip->ecc.read_oob = at91_nand_read_oob_512;
+ nand_chip->ecc.write_oob = at91_nand_write_oob_512;
+ ecc_writel(host->ecc, MR, AT91_ECC_PAGESIZE_528);
+ break;
+ case 1024:
+ nand_chip->ecc.layout = &at91_oobinfo_large;
+ ecc_writel(host->ecc, MR, AT91_ECC_PAGESIZE_1056);
+ break;
+ case 2048:
+ nand_chip->ecc.layout = &at91_oobinfo_large;
+ ecc_writel(host->ecc, MR, AT91_ECC_PAGESIZE_2112);
+ break;
+ case 4096:
+ nand_chip->ecc.layout = &at91_oobinfo_large;
+ ecc_writel(host->ecc, MR, AT91_ECC_PAGESIZE_4224);
+ break;
+ default:
+ /* page size not handled by HW ECC */
+ /* switching back to soft ECC */
+ nand_chip->ecc.mode = NAND_ECC_SOFT;
+ nand_chip->ecc.calculate = NULL;
+ nand_chip->ecc.correct = NULL;
+ nand_chip->ecc.hwctl = NULL;
+ nand_chip->ecc.read_page = NULL;
+ nand_chip->ecc.postpad = 0;
+ nand_chip->ecc.prepad = 0;
+ nand_chip->ecc.bytes = 0;
+ break;
+ }
+ }
+
+ /* second phase scan */
+ if (nand_scan_tail(mtd)) {
res = -ENXIO;
goto out;
}
@@ -179,9 +523,15 @@ static int __init at91_nand_probe(struct platform_device *pdev)
if (!res)
return res;
+#ifdef CONFIG_MTD_PARTITIONS
release:
+#endif
nand_release(mtd);
+
out:
+ iounmap(host->ecc);
+
+err_ecc_ioremap:
at91_nand_disable(host);
platform_set_drvdata(pdev, NULL);
iounmap(host->io_base);
@@ -202,6 +552,7 @@ static int __devexit at91_nand_remove(struct platform_device *pdev)
at91_nand_disable(host);
iounmap(host->io_base);
+ iounmap(host->ecc);
kfree(host);
return 0;
@@ -233,5 +584,5 @@ module_exit(at91_nand_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rick Bronson");
-MODULE_DESCRIPTION("NAND/SmartMedia driver for AT91RM9200");
+MODULE_DESCRIPTION("NAND/SmartMedia driver for AT91RM9200 / AT91SAM9");
MODULE_ALIAS("platform:at91_nand");
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