mtd: nand: omap: ecc.calculate: refactor omap_calculate_ecc_bch for BCHx_HW ecc-scheme

OMAP NAND driver supports multiple flavours of BCH4 and BCH8 ECC algorithms.
+------+------------------------------------+---------------+---------------+
| Algo | ECC scheme                         |ECC calculation|Error detection|
+------+------------------------------------+---------------+---------------+
|      |OMAP_ECC_BCH4_CODE_HW_DETECTION_SW  |H/W (GPMC)     |S/W            |
| BCH4 |OMAP_ECC_BCH4_CODE_HW               |H/W (GPMC)     |H/W (ELM)      |
+------+------------------------------------+---------------+---------------+
|      |OMAP_ECC_BCH8_CODE_HW_DETECTION_SW  |H/W (GPMC)     |S/W            |
| BCH8 |OMAP_ECC_BCH8_CODE_HW               |H/W (GPMC)     |H/W (ELM)      |
+------+------------------------------------+---------------+---------------+

This patch refactors omap_calculate_ecc_bch() so that
 - separate out ecc-scheme specific code so that common-code can be reused
   between different implementations of same ECC algorithm.
 - new ecc-schemes can be added with ease in future.

Tested-by: Stefan Roese <sr@denx.de>
Signed-off-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 35 insertions, 33 deletions

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 4b98ee52e5e1..2ccd557bf77d 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -1219,33 +1219,25 @@ static int omap3_calculate_ecc_bch8(struct mtd_info *mtd, const u_char *dat,
  * Support calculating of BCH4/8 ecc vectors for the page
  */
 static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
-                                        const u_char *dat, u_char *ecc_code)
+                                        const u_char *dat, u_char *ecc_calc)
 {
         struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                    mtd);
+        int eccbytes    = info->nand.ecc.bytes;
+        struct gpmc_nand_regs   *gpmc_regs = &info->reg;
+        u8 *ecc_code;
         unsigned long nsectors, bch_val1, bch_val2, bch_val3, bch_val4;
-        int i, eccbchtsel;
+        int i;
 
         nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;
-        /*
-         * find BCH scheme used
-         * 0 -> BCH4
-         * 1 -> BCH8
-         */
-        eccbchtsel = ((readl(info->reg.gpmc_ecc_config) >> 12) & 0x3);
-
         for (i = 0; i < nsectors; i++) {
-
-                /* Read hw-computed remainder */
-                bch_val1 = readl(info->reg.gpmc_bch_result0[i]);
-                bch_val2 = readl(info->reg.gpmc_bch_result1[i]);
-                if (eccbchtsel) {
-                        bch_val3 = readl(info->reg.gpmc_bch_result2[i]);
-                        bch_val4 = readl(info->reg.gpmc_bch_result3[i]);
-                }
-
-                if (eccbchtsel) {
-                        /* BCH8 ecc scheme */
+                ecc_code = ecc_calc;
+                switch (info->ecc_opt) {
+                case OMAP_ECC_BCH8_CODE_HW:
+                        bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
+                        bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
+                        bch_val3 = readl(gpmc_regs->gpmc_bch_result2[i]);
+                        bch_val4 = readl(gpmc_regs->gpmc_bch_result3[i]);
                         *ecc_code++ = (bch_val4 & 0xFF);
                         *ecc_code++ = ((bch_val3 >> 24) & 0xFF);
                         *ecc_code++ = ((bch_val3 >> 16) & 0xFF);
@@ -1259,14 +1251,10 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
                         *ecc_code++ = ((bch_val1 >> 16) & 0xFF);
                         *ecc_code++ = ((bch_val1 >> 8) & 0xFF);
                         *ecc_code++ = (bch_val1 & 0xFF);
-                        /*
-                         * Setting 14th byte to zero to handle
-                         * erased page & maintain compatibility
-                         * with RBL
-                         */
-                        *ecc_code++ = 0x0;
-                } else {
-                        /* BCH4 ecc scheme */
+                        break;
+                case OMAP_ECC_BCH4_CODE_HW:
+                        bch_val1 = readl(gpmc_regs->gpmc_bch_result0[i]);
+                        bch_val2 = readl(gpmc_regs->gpmc_bch_result1[i]);
                         *ecc_code++ = ((bch_val2 >> 12) & 0xFF);
                         *ecc_code++ = ((bch_val2 >> 4) & 0xFF);
                         *ecc_code++ = ((bch_val2 & 0xF) << 4) |
@@ -1275,12 +1263,26 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
                         *ecc_code++ = ((bch_val1 >> 12) & 0xFF);
                         *ecc_code++ = ((bch_val1 >> 4) & 0xFF);
                         *ecc_code++ = ((bch_val1 & 0xF) << 4);
-                        /*
-                         * Setting 8th byte to zero to handle
-                         * erased page
-                         */
-                        *ecc_code++ = 0x0;
+                        break;
+                default:
+                        return -EINVAL;
                 }
+
+                /* ECC scheme specific syndrome customizations */
+                switch (info->ecc_opt) {
+                case OMAP_ECC_BCH4_CODE_HW:
+                        /* Set  8th ECC byte as 0x0 for ROM compatibility */
+                        ecc_calc[eccbytes - 1] = 0x0;
+                        break;
+                case OMAP_ECC_BCH8_CODE_HW:
+                        /* Set 14th ECC byte as 0x0 for ROM compatibility */
+                        ecc_calc[eccbytes - 1] = 0x0;
+                        break;
+                default:
+                        return -EINVAL;
+                }
+
+        ecc_calc += eccbytes;
         }
 
         return 0;