target/linux/mvebu/patches-3.10/0153-mtd-nand-pxa3xx-Add-ECC-BCH-correctable-errors-detec.patch

   1 From 26d82e0081aa6f0c7db5e4bb5b154b7c528cb8d6 Mon Sep 17 00:00:00 2001
   2 From: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
   3 Date: Thu, 14 Nov 2013 18:25:39 -0300
   4 Subject: [PATCH 153/203] mtd: nand: pxa3xx: Add ECC BCH correctable errors
   5  detection
   6
   7 This commit extends the ECC correctable error detection to include
   8 ECC BCH errors. The number of BCH correctable errors can be any up to 16,
   9 and the actual value is exposed in the NDSR register.
  10
  11 Therefore, we change some symbol names to refer to correctable or
  12 uncorrectable (instead of single-bit or double-bit as it was in the
  13 Hamming case) and while at it, cleanup the detection code slightly.
  14
  15 Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
  16 Tested-by: Daniel Mack <zonque@gmail.com>
  17 Signed-off-by: Brian Norris <computersforpeace@gmail.com>
  18 ---
  19  drivers/mtd/nand/pxa3xx_nand.c | 57 ++++++++++++++++++++++++++----------------
  20  1 file changed, 35 insertions(+), 22 deletions(-)
  21
  22 --- a/drivers/mtd/nand/pxa3xx_nand.c
  23 +++ b/drivers/mtd/nand/pxa3xx_nand.c
  24 @@ -85,6 +85,9 @@
  25  #define NDCR_INT_MASK           (0xFFF)
  26
  27  #define NDSR_MASK              (0xfff)
  28 +#define NDSR_ERR_CNT_OFF       (16)
  29 +#define NDSR_ERR_CNT_MASK       (0x1f)
  30 +#define NDSR_ERR_CNT(sr)       ((sr >> NDSR_ERR_CNT_OFF) & NDSR_ERR_CNT_MASK)
  31  #define NDSR_RDY                (0x1 << 12)
  32  #define NDSR_FLASH_RDY          (0x1 << 11)
  33  #define NDSR_CS0_PAGED         (0x1 << 10)
  34 @@ -93,8 +96,8 @@
  35  #define NDSR_CS1_CMDD          (0x1 << 7)
  36  #define NDSR_CS0_BBD           (0x1 << 6)
  37  #define NDSR_CS1_BBD           (0x1 << 5)
  38 -#define NDSR_DBERR             (0x1 << 4)
  39 -#define NDSR_SBERR             (0x1 << 3)
  40 +#define NDSR_UNCORERR          (0x1 << 4)
  41 +#define NDSR_CORERR            (0x1 << 3)
  42  #define NDSR_WRDREQ            (0x1 << 2)
  43  #define NDSR_RDDREQ            (0x1 << 1)
  44  #define NDSR_WRCMDREQ          (0x1)
  45 @@ -135,9 +138,9 @@ enum {
  46         ERR_NONE        = 0,
  47         ERR_DMABUSERR   = -1,
  48         ERR_SENDCMD     = -2,
  49 -       ERR_DBERR       = -3,
  50 +       ERR_UNCORERR    = -3,
  51         ERR_BBERR       = -4,
  52 -       ERR_SBERR       = -5,
  53 +       ERR_CORERR      = -5,
  54  };
  55
  56  enum {
  57 @@ -221,6 +224,8 @@ struct pxa3xx_nand_info {
  58         unsigned int            oob_size;
  59         unsigned int            spare_size;
  60         unsigned int            ecc_size;
  61 +       unsigned int            ecc_err_cnt;
  62 +       unsigned int            max_bitflips;
  63         int                     retcode;
  64
  65         /* cached register value */
  66 @@ -571,10 +576,25 @@ static irqreturn_t pxa3xx_nand_irq(int i
  67
  68         status = nand_readl(info, NDSR);
  69
  70 -       if (status & NDSR_DBERR)
  71 -               info->retcode = ERR_DBERR;
  72 -       if (status & NDSR_SBERR)
  73 -               info->retcode = ERR_SBERR;
  74 +       if (status & NDSR_UNCORERR)
  75 +               info->retcode = ERR_UNCORERR;
  76 +       if (status & NDSR_CORERR) {
  77 +               info->retcode = ERR_CORERR;
  78 +               if (info->variant == PXA3XX_NAND_VARIANT_ARMADA370 &&
  79 +                   info->ecc_bch)
  80 +                       info->ecc_err_cnt = NDSR_ERR_CNT(status);
  81 +               else
  82 +                       info->ecc_err_cnt = 1;
  83 +
  84 +               /*
  85 +                * Each chunk composing a page is corrected independently,
  86 +                * and we need to store maximum number of corrected bitflips
  87 +                * to return it to the MTD layer in ecc.read_page().
  88 +                */
  89 +               info->max_bitflips = max_t(unsigned int,
  90 +                                          info->max_bitflips,
  91 +                                          info->ecc_err_cnt);
  92 +       }
  93         if (status & (NDSR_RDDREQ | NDSR_WRDREQ)) {
  94                 /* whether use dma to transfer data */
  95                 if (info->use_dma) {
  96 @@ -672,6 +692,7 @@ static void prepare_start_command(struct
  97         info->use_ecc           = 0;
  98         info->use_spare         = 1;
  99         info->retcode           = ERR_NONE;
 100 +       info->ecc_err_cnt       = 0;
 101         info->ndcb3             = 0;
 102
 103         switch (command) {
 104 @@ -1053,26 +1074,18 @@ static int pxa3xx_nand_read_page_hwecc(s
 105  {
 106         struct pxa3xx_nand_host *host = mtd->priv;
 107         struct pxa3xx_nand_info *info = host->info_data;
 108 -       int max_bitflips = 0;
 109
 110         chip->read_buf(mtd, buf, mtd->writesize);
 111         chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
 112
 113 -       if (info->retcode == ERR_SBERR) {
 114 -               switch (info->use_ecc) {
 115 -               case 1:
 116 -                       max_bitflips = 1;
 117 -                       mtd->ecc_stats.corrected++;
 118 -                       break;
 119 -               case 0:
 120 -               default:
 121 -                       break;
 122 -               }
 123 -       } else if (info->retcode == ERR_DBERR) {
 124 +       if (info->retcode == ERR_CORERR && info->use_ecc) {
 125 +               mtd->ecc_stats.corrected += info->ecc_err_cnt;
 126 +
 127 +       } else if (info->retcode == ERR_UNCORERR) {
 128                 /*
 129                  * for blank page (all 0xff), HW will calculate its ECC as
 130                  * 0, which is different from the ECC information within
 131 -                * OOB, ignore such double bit errors
 132 +                * OOB, ignore such uncorrectable errors
 133                  */
 134                 if (is_buf_blank(buf, mtd->writesize))
 135                         info->retcode = ERR_NONE;
 136 @@ -1080,7 +1093,7 @@ static int pxa3xx_nand_read_page_hwecc(s
 137                         mtd->ecc_stats.failed++;
 138         }
 139
 140 -       return max_bitflips;
 141 +       return info->max_bitflips;
 142  }
 143
 144  static uint8_t pxa3xx_nand_read_byte(struct mtd_info *mtd)