mtd: nand: omap: clean-up ecc layout for BCH ecc schemes

In current implementation omap3_init_bch_tail() is a common function to
define ecc layout for different BCHx ecc schemes.This patch:
(1) removes omap3_init_bch_tail() and defines ecc layout for individual
    ecc-schemes along with populating their nand_chip->ecc data in
    omap_nand_probe(). This improves the readability and scalability of
    code for add new ecc schemes in future.
(2) removes 'struct nand_bbt_descr bb_descrip_flashbased' because default
    nand_bbt_descr in nand_bbt.c matches the same (.len=1 for x8 devices).
(3) add the check to see if NAND device has enough OOB/Spare bytes to
    store ECC signature of whole page, as defined by ecc-scheme.

Signed-off-by: Pekon Gupta <pekon@ti.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 62 insertions, 99 deletions

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 86ce48b2c47a..b6a08b23853b 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -139,6 +139,7 @@
 #define BCH_ECC_SIZE0           0x0     /* ecc_size0 = 0, no oob protection */
 #define BCH_ECC_SIZE1           0x20    /* ecc_size1 = 32 */
 
+#define BADBLOCK_MARKER_LENGTH          2
 #define OMAP_ECC_BCH8_POLYNOMIAL        0x201b
 
 #ifdef CONFIG_MTD_NAND_OMAP_BCH
@@ -149,17 +150,6 @@ static u_char bch4_vector[] = {0x00, 0x6b, 0x31, 0xdd, 0x41, 0xbc, 0x10};
 
 /* oob info generated runtime depending on ecc algorithm and layout selected */
 static struct nand_ecclayout omap_oobinfo;
-/* Define some generic bad / good block scan pattern which are used
- * while scanning a device for factory marked good / bad blocks
- */
-static uint8_t scan_ff_pattern[] = { 0xff };
-static struct nand_bbt_descr bb_descrip_flashbased = {
-        .options = NAND_BBT_SCANALLPAGES,
-        .offs = 0,
-        .len = 1,
-        .pattern = scan_ff_pattern,
-};
-
 
 struct omap_nand_info {
         struct nand_hw_control          controller;
@@ -184,7 +174,6 @@ struct omap_nand_info {
         struct gpmc_nand_regs           reg;
         /* fields specific for BCHx_HW ECC scheme */
         struct bch_control             *bch;
-        struct nand_ecclayout           ecclayout;
         bool                            is_elm_used;
         struct device                   *elm_dev;
         struct device_node              *of_node;
@@ -1686,65 +1675,8 @@ static void omap3_free_bch(struct mtd_info *mtd)
         }
 }
 
-/**
- * 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, offset;
-        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;
-        }
-
-        /* ECC layout compatible with RBL for BCH8 */
-        if (info->is_elm_used && (info->nand.ecc.bytes == BCH8_SIZE))
-                offset = 2;
-        else
-                offset = mtd->oobsize - layout->eccbytes;
-
-        /* put ecc bytes at oob tail */
-        for (i = 0; i < layout->eccbytes; i++)
-                layout->eccpos[i] = offset + i;
-
-        if (info->is_elm_used && (info->nand.ecc.bytes == BCH8_SIZE))
-                layout->oobfree[0].offset = 2 + layout->eccbytes * steps;
-        else
-                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_tail(struct mtd_info *mtd)
-{
-        return -1;
-}
+
 static void omap3_free_bch(struct mtd_info *mtd)
 {
 }
@@ -1756,8 +1688,9 @@ static int omap_nand_probe(struct platform_device *pdev)
         struct omap_nand_platform_data  *pdata;
         struct mtd_info                 *mtd;
         struct nand_chip                *nand_chip;
+        struct nand_ecclayout           *ecclayout;
         int                             err;
-        int                             i, offset;
+        int                             i;
         dma_cap_mask_t                  mask;
         unsigned                        sig;
         struct resource                 *res;
@@ -1840,6 +1773,13 @@ static int omap_nand_probe(struct platform_device *pdev)
                 goto out_release_mem_region;
         }
 
+        /* check for small page devices */
+        if ((mtd->oobsize < 64) && (pdata->ecc_opt != OMAP_ECC_HAM1_CODE_HW)) {
+                pr_err("small page devices are not supported\n");
+                err = -EINVAL;
+                goto out_release_mem_region;
+        }
+
         /* re-populate low-level callbacks based on xfer modes */
         switch (pdata->xfer_type) {
         case NAND_OMAP_PREFETCH_POLLED:
@@ -1931,6 +1871,8 @@ static int omap_nand_probe(struct platform_device *pdev)
         }
 
         /* populate MTD interface based on ECC scheme */
+        nand_chip->ecc.layout   = &omap_oobinfo;
+        ecclayout               = &omap_oobinfo;
         switch (pdata->ecc_opt) {
         case OMAP_ECC_HAM1_CODE_HW:
                 pr_info("nand: using OMAP_ECC_HAM1_CODE_HW\n");
@@ -1941,6 +1883,16 @@ static int omap_nand_probe(struct platform_device *pdev)
                 nand_chip->ecc.calculate        = omap_calculate_ecc;
                 nand_chip->ecc.hwctl            = omap_enable_hwecc;
                 nand_chip->ecc.correct          = omap_correct_data;
+                /* define ECC layout */
+                ecclayout->eccbytes             = nand_chip->ecc.bytes *
+                                                        (mtd->writesize /
+                                                        nand_chip->ecc.size);
+                if (nand_chip->options & NAND_BUSWIDTH_16)
+                        ecclayout->eccpos[0]    = BADBLOCK_MARKER_LENGTH;
+                else
+                        ecclayout->eccpos[0]    = 1;
+                ecclayout->oobfree->offset      = ecclayout->eccpos[0] +
+                                                        ecclayout->eccbytes;
                 break;
 
         case OMAP_ECC_BCH4_CODE_HW_DETECTION_SW:
@@ -1953,6 +1905,13 @@ static int omap_nand_probe(struct platform_device *pdev)
                 nand_chip->ecc.hwctl            = omap3_enable_hwecc_bch;
                 nand_chip->ecc.correct          = omap3_correct_data_bch;
                 nand_chip->ecc.calculate        = omap3_calculate_ecc_bch4;
+                /* define ECC layout */
+                ecclayout->eccbytes             = nand_chip->ecc.bytes *
+                                                        (mtd->writesize /
+                                                        nand_chip->ecc.size);
+                ecclayout->eccpos[0]            = BADBLOCK_MARKER_LENGTH;
+                ecclayout->oobfree->offset      = ecclayout->eccpos[0] +
+                                                        ecclayout->eccbytes;
                 /* software bch library is used for locating errors */
                 info->bch = init_bch(nand_chip->ecc.bytes,
                                         nand_chip->ecc.strength,
@@ -1981,6 +1940,13 @@ static int omap_nand_probe(struct platform_device *pdev)
                 nand_chip->ecc.calculate        = omap3_calculate_ecc_bch;
                 nand_chip->ecc.read_page        = omap_read_page_bch;
                 nand_chip->ecc.write_page       = omap_write_page_bch;
+                /* define ECC layout */
+                ecclayout->eccbytes             = nand_chip->ecc.bytes *
+                                                        (mtd->writesize /
+                                                        nand_chip->ecc.size);
+                ecclayout->eccpos[0]            = BADBLOCK_MARKER_LENGTH;
+                ecclayout->oobfree->offset      = ecclayout->eccpos[0] +
+                                                        ecclayout->eccbytes;
                 /* This ECC scheme requires ELM H/W block */
                 if (is_elm_present(info, pdata->elm_of_node, BCH4_ECC) < 0) {
                         pr_err("nand: error: could not initialize ELM\n");
@@ -2004,6 +1970,13 @@ static int omap_nand_probe(struct platform_device *pdev)
                 nand_chip->ecc.hwctl            = omap3_enable_hwecc_bch;
                 nand_chip->ecc.correct          = omap3_correct_data_bch;
                 nand_chip->ecc.calculate        = omap3_calculate_ecc_bch8;
+                /* define ECC layout */
+                ecclayout->eccbytes             = nand_chip->ecc.bytes *
+                                                        (mtd->writesize /
+                                                        nand_chip->ecc.size);
+                ecclayout->eccpos[0]            = BADBLOCK_MARKER_LENGTH;
+                ecclayout->oobfree->offset      = ecclayout->eccpos[0] +
+                                                        ecclayout->eccbytes;
                 /* software bch library is used for locating errors */
                 info->bch = init_bch(nand_chip->ecc.bytes,
                                         nand_chip->ecc.strength,
@@ -2038,6 +2011,13 @@ static int omap_nand_probe(struct platform_device *pdev)
                         pr_err("nand: error: could not initialize ELM\n");
                         goto out_release_mem_region;
                 }
+                /* define ECC layout */
+                ecclayout->eccbytes             = nand_chip->ecc.bytes *
+                                                        (mtd->writesize /
+                                                        nand_chip->ecc.size);
+                ecclayout->eccpos[0]            = BADBLOCK_MARKER_LENGTH;
+                ecclayout->oobfree->offset      = ecclayout->eccpos[0] +
+                                                        ecclayout->eccbytes;
                 break;
 #else
                 pr_err("nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled\n");
@@ -2051,34 +2031,17 @@ static int omap_nand_probe(struct platform_device *pdev)
                 goto out_release_mem_region;
         }
 
-        /* rom code layout */
-        if (pdata->ecc_opt == OMAP_ECC_HAM1_CODE_HW) {
-
-                if (nand_chip->options & NAND_BUSWIDTH_16) {
-                        offset = 2;
-                } else {
-                        offset = 1;
-                        nand_chip->badblock_pattern = &bb_descrip_flashbased;
-                }
-                omap_oobinfo.eccbytes = 3 * (mtd->writesize / 512);
-                for (i = 0; i < omap_oobinfo.eccbytes; i++)
-                        omap_oobinfo.eccpos[i] = i+offset;
-
-                omap_oobinfo.oobfree->offset = offset + omap_oobinfo.eccbytes;
-                omap_oobinfo.oobfree->length = mtd->oobsize -
-                                        (offset + omap_oobinfo.eccbytes);
-
-                nand_chip->ecc.layout = &omap_oobinfo;
-        } else if ((pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) ||
-                   (pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW_DETECTION_SW) ||
-                   (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW_DETECTION_SW) ||
-                   (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW)) {
-                /* build OOB layout for BCH ECC correction */
-                err = omap3_init_bch_tail(mtd);
-                if (err) {
-                        err = -EINVAL;
-                        goto out_release_mem_region;
-                }
+        /* populate remaining ECC layout data */
+        ecclayout->oobfree->length = mtd->oobsize - (BADBLOCK_MARKER_LENGTH +
+                                                        ecclayout->eccbytes);
+        for (i = 1; i < ecclayout->eccbytes; i++)
+                ecclayout->eccpos[i] = ecclayout->eccpos[0] + i;
+        /* check if NAND device's OOB is enough to store ECC signatures */
+        if (mtd->oobsize < (ecclayout->eccbytes + BADBLOCK_MARKER_LENGTH)) {
+                pr_err("not enough OOB bytes required = %d, available=%d\n",
+                                           ecclayout->eccbytes, mtd->oobsize);
+                err = -EINVAL;
+                goto out_release_mem_region;
         }
 
         /* second phase scan */