mtd: nand: pl35x: Add ECC checking for ondie nand flash

Check status of the operation and increment the correctable or
uncorrectable error counters which is critical for UBI layer to greatly
improve handling of the errors.  In particular it used to trigger migrating
the data to safely off before scrubbing the failing Erase Blocks. Even
uncorrectable errors may often be handled by UBI if it is in a
non-critical page such as Erase Counter header.

Signed-off-by: Andrew Worsley <amworsley@gmail.com>
Reviewed-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

diff --git a/drivers/mtd/nand/pl35x_nand.c b/drivers/mtd/nand/pl35x_nand.c
index 2d9c396864ce8d6a580012a4a10668e817c626dd..ec0b790d05fb7d870d30e0b7692383c97db58ff5 100644 (file)
--- a/drivers/mtd/nand/pl35x_nand.c
+++ b/drivers/mtd/nand/pl35x_nand.c
@@ -444,6 +444,79 @@ static int pl35x_nand_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
        return (status & NAND_STATUS_FAIL) ? -EIO : 0;
 }
 
+/**
+ * pl35x_nand_read_page_ondie - [Intern] read page data with ondie ecc
+ * @mtd:               Pointer to the mtd info structure
+ * @chip:              Pointer to the NAND chip info structure
+ * @buf:               Pointer to the data buffer
+ * @oob_required:      Caller requires OOB data read to chip->oob_poi
+ * @page:              Page number to read
+ *
+ * Return:     Always return zero
+ */
+static int pl35x_nand_read_page_ondie(struct mtd_info *mtd,
+                                     struct nand_chip *chip,
+                                     u8 *buf, int oob_required, int page)
+{
+       unsigned long data_phase_addr;
+       u8 *p;
+       struct pl35x_nand_info *xnand =
+               container_of(chip, struct pl35x_nand_info, chip);
+       unsigned long nand_offset = (unsigned long __force)xnand->nand_base;
+       int status;
+
+       chip->read_buf(mtd, buf, mtd->writesize);
+
+       p = chip->oob_poi;
+       chip->read_buf(mtd, p,
+                       (mtd->oobsize - PL35X_NAND_LAST_TRANSFER_LENGTH));
+       p += (mtd->oobsize - PL35X_NAND_LAST_TRANSFER_LENGTH);
+
+       data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
+       data_phase_addr -= nand_offset;
+       data_phase_addr |= PL35X_NAND_CLEAR_CS;
+       data_phase_addr += nand_offset;
+       chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
+
+       chip->read_buf(mtd, p, PL35X_NAND_LAST_TRANSFER_LENGTH);
+
+       /* Check ECC info */
+       chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
+       status = (int)chip->read_byte(mtd);
+       if (!(status & NAND_STATUS_READY)) {
+               pr_err("%s: page %d status=%#x - transfer not finished!\n",
+                      __func__, page, status);
+               ndelay(100);
+               if (!(status & NAND_STATUS_READY))
+                       return -EIO;
+       }
+/* UnCorrectable Error bitflips. 5+ on our chip */
+#define NAND_UCE_BITS   5
+       if (status & NAND_STATUS_FAIL) {
+               pr_warn("%s: page %d status=%#x - ECC Uncorrectable Error\n",
+                       __func__, page, status);
+               /*
+                * Note: don't return -EIO which means no data and is fatal
+                * during a filesystem mount.
+                * Instead return NAND_UCE_BITS bitflips and increment
+                * the uncorrectable error count. This allows the layer above
+                * (such as UBI) to know data is present but corrupt and to
+                * be safely manage if its only a EC or VI page.
+                */
+               mtd->ecc_stats.failed++;
+               return NAND_UCE_BITS;
+       }
+#define NAND_STATUS_ECC_COR BIT(3) /* Correctable error */
+       if (status & NAND_STATUS_ECC_COR) {
+               pr_info("%s: page %d status=%#x - ECC Correctable error\n",
+                       __func__, page, status);
+               mtd->ecc_stats.corrected++;
+               return 1;
+       }
+
+       return 0;
+}
+
 /**
  * pl35x_nand_read_page_raw - [Intern] read raw page data without ecc
  * @mtd:               Pointer to the mtd info structure
@@ -1088,7 +1161,7 @@ static void pl35x_nand_ecc_init(struct mtd_info *mtd, struct nand_ecc_ctrl *ecc,
                 */
                ecc->bytes = 0;
                mtd_set_ooblayout(mtd, &fsmc_ecc_ooblayout_ondie64_ops);
-               ecc->read_page = pl35x_nand_read_page_raw;
+               ecc->read_page = pl35x_nand_read_page_ondie;
                ecc->write_page = pl35x_nand_write_page_raw;
                ecc->size = mtd->writesize;
                /*