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-rw-r--r--drivers/mtd/nand/Kconfig40
-rw-r--r--drivers/mtd/nand/omap2.c245
2 files changed, 285 insertions, 0 deletions
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index bf0a28d513d4..31bb7e5b504a 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -115,6 +115,46 @@ config MTD_NAND_OMAP2
Support for NAND flash on Texas Instruments OMAP2, OMAP3 and OMAP4
platforms.
+config MTD_NAND_OMAP_BCH
+ depends on MTD_NAND && MTD_NAND_OMAP2 && ARCH_OMAP3
+ bool "Enable support for hardware BCH error correction"
+ default n
+ select BCH
+ select BCH_CONST_PARAMS
+ help
+ Support for hardware BCH error correction.
+
+choice
+ prompt "BCH error correction capability"
+ depends on MTD_NAND_OMAP_BCH
+
+config MTD_NAND_OMAP_BCH8
+ bool "8 bits / 512 bytes (recommended)"
+ help
+ Support correcting up to 8 bitflips per 512-byte block.
+ This will use 13 bytes of spare area per 512 bytes of page data.
+ This is the recommended mode, as 4-bit mode does not work
+ on some OMAP3 revisions, due to a hardware bug.
+
+config MTD_NAND_OMAP_BCH4
+ bool "4 bits / 512 bytes"
+ help
+ Support correcting up to 4 bitflips per 512-byte block.
+ This will use 7 bytes of spare area per 512 bytes of page data.
+ Note that this mode does not work on some OMAP3 revisions, due to a
+ hardware bug. Please check your OMAP datasheet before selecting this
+ mode.
+
+endchoice
+
+if MTD_NAND_OMAP_BCH
+config BCH_CONST_M
+ default 13
+config BCH_CONST_T
+ default 4 if MTD_NAND_OMAP_BCH4
+ default 8 if MTD_NAND_OMAP_BCH8
+endif
+
config MTD_NAND_IDS
tristate
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 05d3562ec748..d7f681d0c9b9 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -21,6 +21,10 @@
#include <linux/io.h>
#include <linux/slab.h>
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+#include <linux/bch.h>
+#endif
+
#include <plat/dma.h>
#include <plat/gpmc.h>
#include <plat/nand.h>
@@ -127,6 +131,11 @@ struct omap_nand_info {
} iomode;
u_char *buf;
int buf_len;
+
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+ struct bch_control *bch;
+ struct nand_ecclayout ecclayout;
+#endif
};
/**
@@ -929,6 +938,226 @@ static int omap_dev_ready(struct mtd_info *mtd)
return 1;
}
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+
+/**
+ * omap3_enable_hwecc_bch - Program OMAP3 GPMC to perform BCH ECC correction
+ * @mtd: MTD device structure
+ * @mode: Read/Write mode
+ */
+static void omap3_enable_hwecc_bch(struct mtd_info *mtd, int mode)
+{
+ int nerrors;
+ unsigned int dev_width;
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+ struct nand_chip *chip = mtd->priv;
+
+ nerrors = (info->nand.ecc.bytes == 13) ? 8 : 4;
+ dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;
+ /*
+ * Program GPMC to perform correction on one 512-byte sector at a time.
+ * Using 4 sectors at a time (i.e. ecc.size = 2048) is also possible and
+ * gives a slight (5%) performance gain (but requires additional code).
+ */
+ (void)gpmc_enable_hwecc_bch(info->gpmc_cs, mode, dev_width, 1, nerrors);
+}
+
+/**
+ * omap3_calculate_ecc_bch4 - Generate 7 bytes of ECC bytes
+ * @mtd: MTD device structure
+ * @dat: The pointer to data on which ecc is computed
+ * @ecc_code: The ecc_code buffer
+ */
+static int omap3_calculate_ecc_bch4(struct mtd_info *mtd, const u_char *dat,
+ u_char *ecc_code)
+{
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+ return gpmc_calculate_ecc_bch4(info->gpmc_cs, dat, ecc_code);
+}
+
+/**
+ * omap3_calculate_ecc_bch8 - Generate 13 bytes of ECC bytes
+ * @mtd: MTD device structure
+ * @dat: The pointer to data on which ecc is computed
+ * @ecc_code: The ecc_code buffer
+ */
+static int omap3_calculate_ecc_bch8(struct mtd_info *mtd, const u_char *dat,
+ u_char *ecc_code)
+{
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+ return gpmc_calculate_ecc_bch8(info->gpmc_cs, dat, ecc_code);
+}
+
+/**
+ * omap3_correct_data_bch - Decode received data and correct errors
+ * @mtd: MTD device structure
+ * @data: page data
+ * @read_ecc: ecc read from nand flash
+ * @calc_ecc: ecc read from HW ECC registers
+ */
+static int omap3_correct_data_bch(struct mtd_info *mtd, u_char *data,
+ u_char *read_ecc, u_char *calc_ecc)
+{
+ int i, count;
+ /* cannot correct more than 8 errors */
+ unsigned int errloc[8];
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+
+ count = decode_bch(info->bch, NULL, 512, read_ecc, calc_ecc, NULL,
+ errloc);
+ if (count > 0) {
+ /* correct errors */
+ for (i = 0; i < count; i++) {
+ /* correct data only, not ecc bytes */
+ if (errloc[i] < 8*512)
+ data[errloc[i]/8] ^= 1 << (errloc[i] & 7);
+ pr_debug("corrected bitflip %u\n", errloc[i]);
+ }
+ } else if (count < 0) {
+ pr_err("ecc unrecoverable error\n");
+ }
+ return count;
+}
+
+/**
+ * omap3_free_bch - Release BCH ecc resources
+ * @mtd: MTD device structure
+ */
+static void omap3_free_bch(struct mtd_info *mtd)
+{
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+ if (info->bch) {
+ free_bch(info->bch);
+ info->bch = NULL;
+ }
+}
+
+/**
+ * omap3_init_bch - Initialize BCH ECC
+ * @mtd: MTD device structure
+ * @ecc_opt: OMAP ECC mode (OMAP_ECC_BCH4_CODE_HW or OMAP_ECC_BCH8_CODE_HW)
+ */
+static int omap3_init_bch(struct mtd_info *mtd, int ecc_opt)
+{
+ int ret, max_errors;
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+#ifdef CONFIG_MTD_NAND_OMAP_BCH8
+ const int hw_errors = 8;
+#else
+ const int hw_errors = 4;
+#endif
+ info->bch = NULL;
+
+ max_errors = (ecc_opt == OMAP_ECC_BCH8_CODE_HW) ? 8 : 4;
+ if (max_errors != hw_errors) {
+ pr_err("cannot configure %d-bit BCH ecc, only %d-bit supported",
+ max_errors, hw_errors);
+ goto fail;
+ }
+
+ /* initialize GPMC BCH engine */
+ ret = gpmc_init_hwecc_bch(info->gpmc_cs, 1, max_errors);
+ if (ret)
+ goto fail;
+
+ /* software bch library is only used to detect and locate errors */
+ info->bch = init_bch(13, max_errors, 0x201b /* hw polynomial */);
+ if (!info->bch)
+ goto fail;
+
+ info->nand.ecc.size = 512;
+ info->nand.ecc.hwctl = omap3_enable_hwecc_bch;
+ info->nand.ecc.correct = omap3_correct_data_bch;
+ info->nand.ecc.mode = NAND_ECC_HW;
+
+ /*
+ * The number of corrected errors in an ecc block that will trigger
+ * block scrubbing defaults to the ecc strength (4 or 8).
+ * Set mtd->bitflip_threshold here to define a custom threshold.
+ */
+
+ if (max_errors == 8) {
+ info->nand.ecc.strength = 8;
+ info->nand.ecc.bytes = 13;
+ info->nand.ecc.calculate = omap3_calculate_ecc_bch8;
+ } else {
+ info->nand.ecc.strength = 4;
+ info->nand.ecc.bytes = 7;
+ info->nand.ecc.calculate = omap3_calculate_ecc_bch4;
+ }
+
+ pr_info("enabling NAND BCH ecc with %d-bit correction\n", max_errors);
+ return 0;
+fail:
+ omap3_free_bch(mtd);
+ return -1;
+}
+
+/**
+ * omap3_init_bch_tail - Build an oob layout for BCH ECC correction.
+ * @mtd: MTD device structure
+ */
+static int omap3_init_bch_tail(struct mtd_info *mtd)
+{
+ int i, steps;
+ struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
+ mtd);
+ struct nand_ecclayout *layout = &info->ecclayout;
+
+ /* build oob layout */
+ steps = mtd->writesize/info->nand.ecc.size;
+ layout->eccbytes = steps*info->nand.ecc.bytes;
+
+ /* do not bother creating special oob layouts for small page devices */
+ if (mtd->oobsize < 64) {
+ pr_err("BCH ecc is not supported on small page devices\n");
+ goto fail;
+ }
+
+ /* reserve 2 bytes for bad block marker */
+ if (layout->eccbytes+2 > mtd->oobsize) {
+ pr_err("no oob layout available for oobsize %d eccbytes %u\n",
+ mtd->oobsize, layout->eccbytes);
+ goto fail;
+ }
+
+ /* put ecc bytes at oob tail */
+ for (i = 0; i < layout->eccbytes; i++)
+ layout->eccpos[i] = mtd->oobsize-layout->eccbytes+i;
+
+ layout->oobfree[0].offset = 2;
+ layout->oobfree[0].length = mtd->oobsize-2-layout->eccbytes;
+ info->nand.ecc.layout = layout;
+
+ if (!(info->nand.options & NAND_BUSWIDTH_16))
+ info->nand.badblock_pattern = &bb_descrip_flashbased;
+ return 0;
+fail:
+ omap3_free_bch(mtd);
+ return -1;
+}
+
+#else
+static int omap3_init_bch(struct mtd_info *mtd, int ecc_opt)
+{
+ pr_err("CONFIG_MTD_NAND_OMAP_BCH is not enabled\n");
+ return -1;
+}
+static int omap3_init_bch_tail(struct mtd_info *mtd)
+{
+ return -1;
+}
+static void omap3_free_bch(struct mtd_info *mtd)
+{
+}
+#endif /* CONFIG_MTD_NAND_OMAP_BCH */
+
static int __devinit omap_nand_probe(struct platform_device *pdev)
{
struct omap_nand_info *info;
@@ -1067,6 +1296,13 @@ static int __devinit omap_nand_probe(struct platform_device *pdev)
info->nand.ecc.hwctl = omap_enable_hwecc;
info->nand.ecc.correct = omap_correct_data;
info->nand.ecc.mode = NAND_ECC_HW;
+ } else if ((pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) ||
+ (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW)) {
+ err = omap3_init_bch(&info->mtd, pdata->ecc_opt);
+ if (err) {
+ err = -EINVAL;
+ goto out_release_mem_region;
+ }
}
/* DIP switches on some boards change between 8 and 16 bit
@@ -1098,6 +1334,14 @@ static int __devinit omap_nand_probe(struct platform_device *pdev)
(offset + omap_oobinfo.eccbytes);
info->nand.ecc.layout = &omap_oobinfo;
+ } else if ((pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) ||
+ (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW)) {
+ /* build OOB layout for BCH ECC correction */
+ err = omap3_init_bch_tail(&info->mtd);
+ if (err) {
+ err = -EINVAL;
+ goto out_release_mem_region;
+ }
}
/* second phase scan */
@@ -1126,6 +1370,7 @@ static int omap_nand_remove(struct platform_device *pdev)
struct mtd_info *mtd = platform_get_drvdata(pdev);
struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
mtd);
+ omap3_free_bch(&info->mtd);
platform_set_drvdata(pdev, NULL);
if (info->dma_ch != -1)
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 23:36:32 +0000