OMAP NAND driver support multiple ECC scheme, which can used in following
different flavours, depending on in-build Hardware engines supported by SoC.

+---------------------------------------+---------------+---------------+
| ECC scheme                            |ECC calculation|Error detection|
+---------------------------------------+---------------+---------------+
|OMAP_ECC_HAM1_CODE_HW                  |H/W (GPMC)     |S/W            |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW_DETECTION_SW     |H/W (GPMC)     |S/W            |
|(requires CONFIG_MTD_NAND_ECC_BCH)     |               |               |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW                  |H/W (GPMC)     |H/W (ELM)      |
|(requires CONFIG_MTD_NAND_OMAP_BCH &&  |               |               |
| ti,elm-id in DT)                      |               |               |
+---------------------------------------+---------------+---------------+
To optimize footprint of omap2-nand driver, selection of some ECC schemes
also require enabling following Kconfigs, in addition to setting appropriate
DT bindings
- Kconfig:CONFIG_MTD_NAND_ECC_BCH        enables S/W based BCH ECC algorithm
- Kconfig:CONFIG_MTD_NAND_OMAP_BCH       enables H/W based BCH ECC algorithm

This patch
- separates the configurations code for each ECC schemes
- fixes dependency issues based on Kconfig options
- updates ELM device detection in is_elm_present()
- cleans redundant code

Signed-off-by: Pekon Gupta <pe...@ti.com>
---
 drivers/mtd/nand/omap2.c | 450 +++++++++++++++++++++++------------------------
 1 file changed, 220 insertions(+), 230 deletions(-)

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 8d521aa..fb96251 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -25,8 +25,10 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 
-#ifdef CONFIG_MTD_NAND_OMAP_BCH
+#ifdef CONFIG_MTD_NAND_ECC_BCH
 #include <linux/bch.h>
+#endif
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
 #include <linux/platform_data/elm.h>
 #endif
 
@@ -141,6 +143,9 @@
 #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
 static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,
        0xac, 0x6b, 0xff, 0x99, 0x7b};
@@ -182,14 +187,11 @@ struct omap_nand_info {
        u_char                          *buf;
        int                                     buf_len;
        struct gpmc_nand_regs           reg;
-
-#ifdef CONFIG_MTD_NAND_OMAP_BCH
-       struct bch_control             *bch;
-       struct nand_ecclayout           ecclayout;
+       /* fields specific for BCHx_HW ECC scheme */
+       struct bch_control              *bch;
        bool                            is_elm_used;
        struct device                   *elm_dev;
        struct device_node              *of_node;
-#endif
 };
 
 /**
@@ -1058,8 +1060,7 @@ static int omap_dev_ready(struct mtd_info *mtd)
        }
 }
 
-#ifdef CONFIG_MTD_NAND_OMAP_BCH
-
+#if defined(CONFIG_MTD_NAND_ECC_BCH) || defined(CONFIG_MTD_NAND_OMAP_BCH)
 /**
  * omap3_enable_hwecc_bch - Program OMAP3 GPMC to perform BCH ECC correction
  * @mtd: MTD device structure
@@ -1140,7 +1141,9 @@ static void omap3_enable_hwecc_bch(struct mtd_info *mtd, 
int mode)
        /* Clear ecc and enable bits */
        writel(ECCCLEAR | ECC1, info->reg.gpmc_ecc_control);
 }
+#endif
 
+#ifdef CONFIG_MTD_NAND_ECC_BCH
 /**
  * omap3_calculate_ecc_bch4 - Generate 7 bytes of ECC bytes
  * @mtd: MTD device structure
@@ -1225,7 +1228,9 @@ static int omap3_calculate_ecc_bch8(struct mtd_info *mtd, 
const u_char *dat,
 
        return 0;
 }
+#endif /* CONFIG_MTD_NAND_ECC_BCH */
 
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
 /**
  * omap3_calculate_ecc_bch - Generate bytes of ECC bytes
  * @mtd:       MTD device structure
@@ -1517,7 +1522,9 @@ static int omap_elm_correct_data(struct mtd_info *mtd, 
u_char *data,
 
        return stat;
 }
+#endif /* CONFIG_MTD_NAND_OMAP_BCH */
 
+#ifdef CONFIG_MTD_NAND_ECC_BCH
 /**
  * omap3_correct_data_bch - Decode received data and correct errors
  * @mtd: MTD device structure
@@ -1549,7 +1556,9 @@ static int omap3_correct_data_bch(struct mtd_info *mtd, 
u_char *data,
        }
        return count;
 }
+#endif /* CONFIG_MTD_NAND_ECC_BCH */
 
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
 /**
  * omap_write_page_bch - BCH ecc based write page function for entire page
  * @mtd:               mtd info structure
@@ -1637,197 +1646,68 @@ static int omap_read_page_bch(struct mtd_info *mtd, 
struct nand_chip *chip,
 }
 
 /**
- * omap3_free_bch - Release BCH ecc resources
- * @mtd: MTD device structure
+ * is_elm_present - checks for presence of ELM module by scanning DT nodes
+ * @omap_nand_info: NAND device structure containing platform data
+ * @bch_type: 0x0=BCH4, 0x1=BCH8, 0x2=BCH16
  */
-static void omap3_free_bch(struct mtd_info *mtd)
+static int is_elm_present(struct omap_nand_info *info,
+                       struct device_node *elm_node, enum bch_ecc bch_type)
 {
-       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 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 = BCH8_MAX_ERROR;
-#else
-       const int hw_errors = BCH4_MAX_ERROR;
-#endif
-       enum bch_ecc bch_type;
-       const __be32 *parp;
-       int lenp;
-       struct device_node *elm_node;
-
-       info->bch = NULL;
-
-       max_errors = (ecc_opt == OMAP_ECC_BCH8_CODE_HW) ?
-               BCH8_MAX_ERROR : BCH4_MAX_ERROR;
-       if (max_errors != hw_errors) {
-               pr_err("cannot configure %d-bit BCH ecc, only %d-bit supported",
-                      max_errors, hw_errors);
-               goto fail;
-       }
-
-       info->nand.ecc.size = 512;
-       info->nand.ecc.hwctl = omap3_enable_hwecc_bch;
-       info->nand.ecc.mode = NAND_ECC_HW;
-       info->nand.ecc.strength = max_errors;
-
-       if (hw_errors == BCH8_MAX_ERROR)
-               bch_type = BCH8_ECC;
-       else
-               bch_type = BCH4_ECC;
-
-       /* Detect availability of ELM module */
-       parp = of_get_property(info->of_node, "elm_id", &lenp);
-       if ((parp == NULL) && (lenp != (sizeof(void *) * 2))) {
-               pr_err("Missing elm_id property, fall back to Software BCH\n");
-               info->is_elm_used = false;
-       } else {
-               struct platform_device *pdev;
-
-               elm_node = of_find_node_by_phandle(be32_to_cpup(parp));
-               pdev = of_find_device_by_node(elm_node);
-               info->elm_dev = &pdev->dev;
-
-               if (elm_config(info->elm_dev, bch_type) == 0)
-                       info->is_elm_used = true;
+       struct platform_device *pdev;
+       info->is_elm_used = false;
+       /* check whether elm-id is passed via DT */
+       if (!elm_node) {
+               pr_err("nand: error: ELM DT node not found\n");
+               return -ENODEV;
        }
-
-       if (info->is_elm_used && (mtd->writesize <= 4096)) {
-
-               if (hw_errors == BCH8_MAX_ERROR)
-                       info->nand.ecc.bytes = BCH8_SIZE;
-               else
-                       info->nand.ecc.bytes = BCH4_SIZE;
-
-               info->nand.ecc.correct = omap_elm_correct_data;
-               info->nand.ecc.calculate = omap3_calculate_ecc_bch;
-               info->nand.ecc.read_page = omap_read_page_bch;
-               info->nand.ecc.write_page = omap_write_page_bch;
-       } else {
-               /*
-                * 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.correct = omap3_correct_data_bch;
-
-               /*
-                * 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.bytes = 13;
-                       info->nand.ecc.calculate = omap3_calculate_ecc_bch8;
-               } else {
-                       info->nand.ecc.bytes = 7;
-                       info->nand.ecc.calculate = omap3_calculate_ecc_bch4;
-               }
+       pdev = of_find_device_by_node(elm_node);
+       /* check whether ELM device is registered */
+       if (!pdev) {
+               pr_err("nand: error: ELM device not found\n");
+               return -ENODEV;
        }
-
-       pr_info("enabling NAND BCH ecc with %d-bit correction\n", max_errors);
+       /* ELM module available, now configure it */
+       info->elm_dev = &pdev->dev;
+       if (elm_config(info->elm_dev, bch_type))
+               return -ENODEV;
+       info->is_elm_used = true;
        return 0;
-fail:
-       omap3_free_bch(mtd);
-       return -1;
 }
+#endif /* CONFIG_MTD_NAND_ECC_BCH */
 
+#ifdef CONFIG_MTD_NAND_ECC_BCH
 /**
- * omap3_init_bch_tail - Build an oob layout for BCH ECC correction.
+ * omap3_free_bch - Release BCH ecc resources
  * @mtd: MTD device structure
  */
-static int omap3_init_bch_tail(struct mtd_info *mtd)
+static void omap3_free_bch(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;
+       if (info->bch) {
+               free_bch(info->bch);
+               info->bch = NULL;
        }
-
-       /* 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(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 */
+#endif /* CONFIG_MTD_NAND_ECC_BCH */
 
 static int omap_nand_probe(struct platform_device *pdev)
 {
        struct omap_nand_info           *info;
        struct omap_nand_platform_data  *pdata;
+       struct mtd_info                 *mtd;
+       struct nand_chip                *nand_chip;
+       struct nand_ecclayout           *ecclayout;
        int                             err;
-       int                             i, offset;
-       dma_cap_mask_t mask;
-       unsigned sig;
+       int                             i;
+       dma_cap_mask_t                  mask;
+       unsigned                        sig;
        struct resource                 *res;
        struct mtd_part_parser_data     ppdata = {};
 
@@ -1846,20 +1726,18 @@ static int omap_nand_probe(struct platform_device *pdev)
        spin_lock_init(&info->controller.lock);
        init_waitqueue_head(&info->controller.wq);
 
-       info->pdev = pdev;
-
+       mtd                     = &info->mtd;
+       mtd->name               = dev_name(&pdev->dev);
+       mtd->owner              = THIS_MODULE;
+       mtd->priv               = &info->nand;
+       nand_chip               = &info->nand;
+       info->pdev              = pdev;
        info->gpmc_cs           = pdata->cs;
        info->reg               = pdata->reg;
+       info->bch               = NULL;
 
-       info->mtd.priv          = &info->nand;
-       info->mtd.name          = dev_name(&pdev->dev);
-       info->mtd.owner         = THIS_MODULE;
-
-       info->nand.options      = pdata->devsize;
-       info->nand.options      |= NAND_SKIP_BBTSCAN;
-#ifdef CONFIG_MTD_NAND_OMAP_BCH
+       nand_chip->options      |= NAND_SKIP_BBTSCAN | NAND_BUSWIDTH_AUTO;
        info->of_node           = pdata->of_node;
-#endif
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res == NULL) {
@@ -1903,6 +1781,30 @@ static int omap_nand_probe(struct platform_device *pdev)
                info->nand.chip_delay = 50;
        }
 
+       /* scan NAND device conncted to controller */
+       if (nand_scan_ident(mtd, 1, NULL)) {
+               err = -ENXIO;
+               goto out_release_mem_region;
+       }
+       pr_info("%s: detected %s NAND flash\n", DRIVER_NAME,
+                       (nand_chip->options & NAND_BUSWIDTH_16) ? "x16" : "x8");
+       if ((nand_chip->options & NAND_BUSWIDTH_16) !=
+                       (pdata->devsize & NAND_BUSWIDTH_16)) {
+               pr_err("%s: but incorrectly configured as %s", DRIVER_NAME,
+                       (pdata->devsize & NAND_BUSWIDTH_16) ? "x16" : "x8");
+               err = -EINVAL;
+               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;
+       }
+
+       /* populate read & write API based on xfer_type selected */
        switch (pdata->xfer_type) {
        case NAND_OMAP_PREFETCH_POLLED:
                info->nand.read_buf   = omap_read_buf_pref;
@@ -1992,61 +1894,148 @@ static int omap_nand_probe(struct platform_device 
*pdev)
                goto out_release_mem_region;
        }
 
-       /* select the ecc type */
-       if (pdata->ecc_opt == OMAP_ECC_HAM1_CODE_HW) {
-               info->nand.ecc.bytes            = 3;
-               info->nand.ecc.size             = 512;
-               info->nand.ecc.strength         = 1;
-               info->nand.ecc.calculate        = omap_calculate_ecc;
-               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) {
+       /* 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");
+               nand_chip->ecc.mode             = NAND_ECC_HW;
+               nand_chip->ecc.bytes            = 3;
+               nand_chip->ecc.size             = 512;
+               nand_chip->ecc.strength         = 1;
+               nand_chip->ecc.calculate        = omap_calculate_ecc;
+               nand_chip->ecc.hwctl            = omap_enable_hwecc;
+               nand_chip->ecc.correct          = omap_correct_data;
+               /* define custom 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:
+#ifdef CONFIG_MTD_NAND_ECC_BCH
+               pr_info("nand: using OMAP_ECC_BCH4_CODE_HW_DETECTION_SW\n");
+               nand_chip->ecc.mode             = NAND_ECC_HW;
+               nand_chip->ecc.size             = 512;
+               nand_chip->ecc.bytes            = 7;
+               nand_chip->ecc.strength         = 4;
+               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 custom 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,
+                                       OMAP_ECC_BCH8_POLYNOMIAL);
+               if (!info->bch) {
+                       pr_err("nand: error: unable to use s/w BCH library\n");
                        err = -EINVAL;
-                       goto out_release_mem_region;
                }
-       }
+               break;
+#else
+               pr_err("nand: error: CONFIG_MTD_NAND_ECC_BCH not enabled\n");
+               err = -EINVAL;
+               goto out_release_mem_region;
+#endif
 
-       /* DIP switches on some boards change between 8 and 16 bit
-        * bus widths for flash.  Try the other width if the first try fails.
-        */
-       if (nand_scan_ident(&info->mtd, 1, NULL)) {
-               info->nand.options ^= NAND_BUSWIDTH_16;
-               if (nand_scan_ident(&info->mtd, 1, NULL)) {
-                       err = -ENXIO;
+       case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
+#ifdef CONFIG_MTD_NAND_ECC_BCH
+               pr_info("nand: using OMAP_ECC_BCH8_CODE_HW_DETECTION_SW\n");
+               nand_chip->ecc.mode             = NAND_ECC_HW;
+               nand_chip->ecc.size             = 512;
+               nand_chip->ecc.bytes            = 13;
+               nand_chip->ecc.strength         = 8;
+               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 custom 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,
+                                       OMAP_ECC_BCH8_POLYNOMIAL);
+               if (!info->bch) {
+                       pr_err("nand: error: unable to use s/w BCH library\n");
+                       err = -EINVAL;
                        goto out_release_mem_region;
                }
-       }
-
-       /* rom code layout */
-       if (pdata->ecc_opt == OMAP_ECC_HAM1_CODE_HW) {
+               break;
+#else
+               pr_err("nand: error: CONFIG_MTD_NAND_ECC_BCH not enabled\n");
+               err = -EINVAL;
+               goto out_release_mem_region;
+#endif
 
-               if (info->nand.options & NAND_BUSWIDTH_16)
-                       offset = 2;
-               else {
-                       offset = 1;
-                       info->nand.badblock_pattern = &bb_descrip_flashbased;
-               }
-               omap_oobinfo.eccbytes = 3 * (info->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 = info->mtd.oobsize -
-                                       (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;
+       case OMAP_ECC_BCH8_CODE_HW:
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+               pr_info("nand: using OMAP_ECC_BCH8_CODE_HW ECC scheme\n");
+               nand_chip->ecc.mode             = NAND_ECC_HW;
+               nand_chip->ecc.size             = 512;
+               /* 14th bit is kept reserved for ROM-code compatibility */
+               nand_chip->ecc.bytes            = 13 + 1;
+               nand_chip->ecc.strength         = 8;
+               nand_chip->ecc.hwctl            = omap3_enable_hwecc_bch;
+               nand_chip->ecc.correct          = omap_elm_correct_data;
+               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;
+               /* This ECC scheme requires ELM H/W block */
+               if (is_elm_present(info, pdata->elm_of_node, BCH8_ECC) < 0) {
+                       pr_err("nand: error: could not initialize ELM\n");
                        goto out_release_mem_region;
                }
+               /* define custom 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");
+               err = -EINVAL;
+               goto out_release_mem_region;
+#endif
+
+       default:
+               pr_err("nand: error: invalid or unsupported ECC scheme\n");
+               err = -EINVAL;
+               goto out_release_mem_region;
+       }
+
+       /* populate remaining info for custom ecc layout */
+       pr_info("%s: using custom ecc layout\n", DRIVER_NAME);
+       ecclayout->oobfree->length = mtd->oobsize - BADBLOCK_MARKER_LENGTH
+                                               - ecclayout->eccbytes;
+       if (!(nand_chip->options & NAND_BUSWIDTH_16))
+               nand_chip->badblock_pattern = &bb_descrip_flashbased;
+       for (i = 1; i < ecclayout->eccbytes; i++)
+               ecclayout->eccpos[i] = ecclayout->eccpos[0] + i;
+       /* check if NAND OOBSIZE meets ECC scheme requirement */
+       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 */
@@ -2072,6 +2061,7 @@ out_release_mem_region:
                free_irq(info->gpmc_irq_fifo, info);
        release_mem_region(info->phys_base, info->mem_size);
 out_free_info:
+       omap3_free_bch(&info->mtd);
        kfree(info);
 
        return err;
-- 
1.8.1

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