mtd: nand: pxa3xx: Add driver-specific ECC BCH support

This commit adds the BCH ECC support available in NFCv2 controller.
Depending on the detected required strength the respective ECC layout
is selected.

This commit adds an empty ECC layout, since support to access large
pages is first required. Once that support is added, a proper ECC
layout will be added as well.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index 84a6c649100c163390c8bc2c3235f7b5fd083bbf..5062eddad834871b9686921fc42908c081e1a3cf 100644 (file)
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -58,6 +58,7 @@
 #define NDPCR          (0x18) /* Page Count Register */
 #define NDBDR0         (0x1C) /* Bad Block Register 0 */
 #define NDBDR1         (0x20) /* Bad Block Register 1 */
+#define NDECCCTRL      (0x28) /* ECC control */
 #define NDDB           (0x40) /* Data Buffer */
 #define NDCB0          (0x48) /* Command Buffer0 */
 #define NDCB1          (0x4C) /* Command Buffer1 */
@@ -198,6 +199,7 @@ struct pxa3xx_nand_info {
 
        int                     cs;
        int                     use_ecc;        /* use HW ECC ? */
+       int                     ecc_bch;        /* using BCH ECC? */
        int                     use_dma;        /* use DMA ? */
        int                     use_spare;      /* use spare ? */
        int                     need_wait;
@@ -205,6 +207,8 @@ struct pxa3xx_nand_info {
        unsigned int            fifo_size;      /* max. data size in the FIFO */
        unsigned int            data_size;      /* data to be read from FIFO */
        unsigned int            oob_size;
+       unsigned int            spare_size;
+       unsigned int            ecc_size;
        int                     retcode;
 
        /* cached register value */
@@ -335,19 +339,12 @@ static void pxa3xx_set_datasize(struct pxa3xx_nand_info *info)
        int oob_enable = info->reg_ndcr & NDCR_SPARE_EN;
 
        info->data_size = info->fifo_size;
-       if (!oob_enable) {
-               info->oob_size = 0;
+       if (!oob_enable)
                return;
-       }
 
-       switch (info->fifo_size) {
-       case 2048:
-               info->oob_size = (info->use_ecc) ? 40 : 64;
-               break;
-       case 512:
-               info->oob_size = (info->use_ecc) ? 8 : 16;
-               break;
-       }
+       info->oob_size = info->spare_size;
+       if (!info->use_ecc)
+               info->oob_size += info->ecc_size;
 }
 
 /**
@@ -362,10 +359,15 @@ static void pxa3xx_nand_start(struct pxa3xx_nand_info *info)
 
        ndcr = info->reg_ndcr;
 
-       if (info->use_ecc)
+       if (info->use_ecc) {
                ndcr |= NDCR_ECC_EN;
-       else
+               if (info->ecc_bch)
+                       nand_writel(info, NDECCCTRL, 0x1);
+       } else {
                ndcr &= ~NDCR_ECC_EN;
+               if (info->ecc_bch)
+                       nand_writel(info, NDECCCTRL, 0x0);
+       }
 
        if (info->use_dma)
                ndcr |= NDCR_DMA_EN;
@@ -1067,6 +1069,41 @@ static int pxa3xx_nand_sensing(struct pxa3xx_nand_info *info)
        return 0;
 }
 
+static int pxa_ecc_init(struct pxa3xx_nand_info *info,
+                       struct nand_ecc_ctrl *ecc,
+                       int strength, int page_size)
+{
+       /*
+        * We don't use strength here as the PXA variant
+        * is used with non-ONFI compliant devices.
+        */
+       if (page_size == 2048) {
+               info->spare_size = 40;
+               info->ecc_size = 24;
+               ecc->mode = NAND_ECC_HW;
+               ecc->size = 512;
+               ecc->strength = 1;
+               return 1;
+
+       } else if (page_size == 512) {
+               info->spare_size = 8;
+               info->ecc_size = 8;
+               ecc->mode = NAND_ECC_HW;
+               ecc->size = 512;
+               ecc->strength = 1;
+               return 1;
+       }
+       return 0;
+}
+
+static int armada370_ecc_init(struct pxa3xx_nand_info *info,
+                             struct nand_ecc_ctrl *ecc,
+                             int strength, int page_size)
+{
+       /* Unimplemented yet */
+       return 0;
+}
+
 static int pxa3xx_nand_scan(struct mtd_info *mtd)
 {
        struct pxa3xx_nand_host *host = mtd->priv;
@@ -1137,13 +1174,13 @@ static int pxa3xx_nand_scan(struct mtd_info *mtd)
        pxa3xx_flash_ids[1].name = NULL;
        def = pxa3xx_flash_ids;
 KEEP_CONFIG:
-       chip->ecc.mode = NAND_ECC_HW;
-       chip->ecc.size = info->fifo_size;
-       chip->ecc.strength = 1;
-
        if (info->reg_ndcr & NDCR_DWIDTH_M)
                chip->options |= NAND_BUSWIDTH_16;
 
+       /* Device detection must be done with ECC disabled */
+       if (info->variant == PXA3XX_NAND_VARIANT_ARMADA370)
+               nand_writel(info, NDECCCTRL, 0x0);
+
        if (nand_scan_ident(mtd, 1, def))
                return -ENODEV;
 
@@ -1158,6 +1195,21 @@ KEEP_CONFIG:
                chip->bbt_md = &bbt_mirror_descr;
        }
 
+       if (info->variant == PXA3XX_NAND_VARIANT_ARMADA370)
+               ret = armada370_ecc_init(info, &chip->ecc,
+                                  chip->ecc_strength_ds,
+                                  mtd->writesize);
+       else
+               ret = pxa_ecc_init(info, &chip->ecc,
+                                  chip->ecc_strength_ds,
+                                  mtd->writesize);
+       if (!ret) {
+               dev_err(&info->pdev->dev,
+                       "ECC strength %d at page size %d is not supported\n",
+                       chip->ecc_strength_ds, mtd->writesize);
+               return -ENODEV;
+       }
+
        /* calculate addressing information */
        if (mtd->writesize >= 2048)
                host->col_addr_cycles = 2;