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>

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 86ce48b..b6a08b2 100644 (file)
--- 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 */