---

yaml
---
r: 310234
b: refs/heads/master
c: 0e618ef
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8d602cf50d3bba864bc1438f486b626df69c87b3
+refs/heads/master: 0e618ef0a6a33cf7ef96c2c824402088dd8ef48c

trunk/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
 

trunk/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)