mtd: nand: omap: optimize chip->ecc.calculate() for H/W ECC schemes
authorpekon gupta <pekon@ti.com>
Tue, 19 Nov 2013 05:32:16 +0000 (11:02 +0530)
committerScott Wood <scottwood@freescale.com>
Tue, 4 Mar 2014 02:09:03 +0000 (20:09 -0600)
chip->ecc.calculate() is used for calculating and fetching of ECC syndrome by
processing the data passed during Read/Write accesses.

All H/W based ECC schemes use GPMC controller to calculate ECC syndrome.
But each BCHx_ECC scheme has its own implemetation of post-processing and
fetching ECC syndrome from GPMC controller.

This patch updates OMAP_ECC_BCH8_CODE_HW ECC scheme in following way:
- merges multiple chip->calculate API for different ECC schemes
  omap_calculate_ecc() + omap_calculate_ecc_bch() + omap_calculate_ecc_bch_sw()
==> omap_calculate_ecc()
- removes omap_ecc_disable() and instead uses it as inline.

Signed-off-by: Pekon Gupta <pekon@ti.com>
drivers/mtd/nand/omap_gpmc.c

index 48b2f75ed768cae80941a4ce9e88ce588c532070..ad5b0f17ccfa1d601d1c68e5065fdc52a4fbc1a7 100644 (file)
 #define SECTOR_BYTES           512
 #define ECCCLEAR               (0x1 << 8)
 #define ECCRESULTREG1          (0x1 << 0)
-
+#ifdef CONFIG_BCH
+static u8  bch8_polynomial[] = {0xef, 0x51, 0x2e, 0x09, 0xed, 0x93, 0x9a, 0xc2,
+                               0x97, 0x79, 0xe5, 0x24, 0xb5};
+#endif
 static uint8_t cs;
 static __maybe_unused struct nand_ecclayout omap_ecclayout;
 
@@ -142,42 +145,6 @@ static int __maybe_unused omap_correct_data(struct mtd_info *mtd, uint8_t *dat,
        return 0;
 }
 
-/*
- *  omap_calculate_ecc - Generate non-inverted ECC bytes.
- *
- *  Using noninverted ECC can be considered ugly since writing a blank
- *  page ie. padding will clear the ECC bytes. This is no problem as
- *  long nobody is trying to write data on the seemingly unused page.
- *  Reading an erased page will produce an ECC mismatch between
- *  generated and read ECC bytes that has to be dealt with separately.
- *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
- *  is used, the result of read will be 0x0 while the ECC offsets of the
- *  spare area will be 0xFF which will result in an ECC mismatch.
- *  @mtd:      MTD structure
- *  @dat:      unused
- *  @ecc_code: ecc_code buffer
- */
-static int __maybe_unused omap_calculate_ecc(struct mtd_info *mtd,
-               const uint8_t *dat, uint8_t *ecc_code)
-{
-       u_int32_t val;
-
-       /* Start Reading from HW ECC1_Result = 0x200 */
-       val = readl(&gpmc_cfg->ecc1_result);
-
-       ecc_code[0] = val & 0xFF;
-       ecc_code[1] = (val >> 16) & 0xFF;
-       ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
-
-       /*
-        * Stop reading anymore ECC vals and clear old results
-        * enable will be called if more reads are required
-        */
-       writel(0x000, &gpmc_cfg->ecc_config);
-
-       return 0;
-}
-
 /*
  * Generic BCH interface
  */
@@ -194,12 +161,7 @@ struct nand_bch_priv {
 #define ECC_BCH8       1
 #define ECC_BCH16      2
 
-/* GPMC ecc engine settings */
-#define BCH_WRAPMODE_1         1       /* BCH wrap mode 1 */
-#define BCH_WRAPMODE_6         6       /* BCH wrap mode 6 */
-
 /* BCH nibbles for diff bch levels */
-#define NAND_ECC_HW_BCH ((uint8_t)(NAND_ECC_HW_OOB_FIRST) + 1)
 #define ECC_BCH4_NIBBLES       13
 #define ECC_BCH8_NIBBLES       26
 #define ECC_BCH16_NIBBLES      52
@@ -211,7 +173,6 @@ struct nand_bch_priv {
  * When some users with other BCH strength will exists this have to change!
  */
 static __maybe_unused struct nand_bch_priv bch_priv = {
-       .mode = NAND_ECC_HW_BCH,
        .type = ECC_BCH8,
        .nibbles = ECC_BCH8_NIBBLES,
        .control = NULL
@@ -280,57 +241,76 @@ static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
 }
 
 /*
- * omap_ecc_disable - Disable H/W ECC calculation
- *
- * @mtd:       MTD device structure
- */
-static void __maybe_unused omap_ecc_disable(struct mtd_info *mtd)
-{
-       writel((readl(&gpmc_cfg->ecc_config) & ~0x1), &gpmc_cfg->ecc_config);
-}
-
-/*
- * BCH support using ELM module
- */
-#ifdef CONFIG_NAND_OMAP_ELM
-/*
- * omap_read_bch8_result - Read BCH result for BCH8 level
- *
- * @mtd:       MTD device structure
- * @big_endian:        When set read register 3 first
- * @ecc_code:  Read syndrome from BCH result registers
+ *  omap_calculate_ecc - Read ECC result
+ *  @mtd:      MTD structure
+ *  @dat:      unused
+ *  @ecc_code: ecc_code buffer
+ *  Using noninverted ECC can be considered ugly since writing a blank
+ *  page ie. padding will clear the ECC bytes. This is no problem as
+ *  long nobody is trying to write data on the seemingly unused page.
+ *  Reading an erased page will produce an ECC mismatch between
+ *  generated and read ECC bytes that has to be dealt with separately.
+ *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
+ *  is used, the result of read will be 0x0 while the ECC offsets of the
+ *  spare area will be 0xFF which will result in an ECC mismatch.
  */
-static void omap_read_bch8_result(struct mtd_info *mtd, uint8_t big_endian,
+static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
                                uint8_t *ecc_code)
 {
-       uint32_t *ptr;
+       struct nand_chip *chip = mtd->priv;
+       struct nand_bch_priv *bch = chip->priv;
+       uint32_t *ptr, val = 0;
        int8_t i = 0, j;
 
-       if (big_endian) {
+       switch (bch->ecc_scheme) {
+       case OMAP_ECC_HAM1_CODE_HW:
+               val = readl(&gpmc_cfg->ecc1_result);
+               ecc_code[0] = val & 0xFF;
+               ecc_code[1] = (val >> 16) & 0xFF;
+               ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
+               break;
+#ifdef CONFIG_BCH
+       case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
+#endif
+       case OMAP_ECC_BCH8_CODE_HW:
                ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
-               ecc_code[i++] = readl(ptr) & 0xFF;
+               val = readl(ptr);
+               ecc_code[i++] = (val >>  0) & 0xFF;
                ptr--;
                for (j = 0; j < 3; j++) {
-                       ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
-                       ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
-                       ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
-                       ecc_code[i++] = readl(ptr) & 0xFF;
+                       val = readl(ptr);
+                       ecc_code[i++] = (val >> 24) & 0xFF;
+                       ecc_code[i++] = (val >> 16) & 0xFF;
+                       ecc_code[i++] = (val >>  8) & 0xFF;
+                       ecc_code[i++] = (val >>  0) & 0xFF;
                        ptr--;
                }
-       } else {
-               ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[0];
-               for (j = 0; j < 3; j++) {
-                       ecc_code[i++] = readl(ptr) & 0xFF;
-                       ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
-                       ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
-                       ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
-                       ptr++;
-               }
-               ecc_code[i++] = readl(ptr) & 0xFF;
-               ecc_code[i++] = 0;      /* 14th byte is always zero */
+               break;
+       default:
+               return -EINVAL;
+       }
+       /* ECC scheme specific syndrome customizations */
+       switch (bch->ecc_scheme) {
+       case OMAP_ECC_HAM1_CODE_HW:
+               break;
+#ifdef CONFIG_BCH
+       case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
+
+               for (i = 0; i < chip->ecc.bytes; i++)
+                       *(ecc_code + i) = *(ecc_code + i) ^
+                                               bch8_polynomial[i];
+               break;
+#endif
+       case OMAP_ECC_BCH8_CODE_HW:
+               ecc_code[chip->ecc.bytes - 1] = 0x00;
+               break;
+       default:
+               return -EINVAL;
        }
+       return 0;
 }
 
+#ifdef CONFIG_NAND_OMAP_ELM
 /*
  * omap_rotate_ecc_bch - Rotate the syndrome bytes
  *
@@ -366,35 +346,6 @@ static void omap_rotate_ecc_bch(struct mtd_info *mtd, uint8_t *calc_ecc,
                syndrome[i] =  calc_ecc[j];
 }
 
-/*
- *  omap_calculate_ecc_bch - Read BCH ECC result
- *
- *  @mtd:      MTD structure
- *  @dat:      unused
- *  @ecc_code: ecc_code buffer
- */
-static int omap_calculate_ecc_bch(struct mtd_info *mtd, const uint8_t *dat,
-                               uint8_t *ecc_code)
-{
-       struct nand_chip *chip = mtd->priv;
-       struct nand_bch_priv *bch = chip->priv;
-       uint8_t big_endian = 1;
-       int8_t ret = 0;
-
-       if (bch->type == ECC_BCH8)
-               omap_read_bch8_result(mtd, big_endian, ecc_code);
-       else /* BCH4 and BCH16 currently not supported */
-               ret = -1;
-
-       /*
-        * Stop reading anymore ECC vals and clear old results
-        * enable will be called if more reads are required
-        */
-       omap_ecc_disable(mtd);
-
-       return ret;
-}
-
 /*
  * omap_fix_errors_bch - Correct bch error in the data
  *
@@ -551,57 +502,6 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
  * OMAP3 BCH8 support (with BCH library)
  */
 #ifdef CONFIG_BCH
-/*
- *  omap_calculate_ecc_bch_sw - Read BCH ECC result
- *
- *  @mtd:      MTD device structure
- *  @dat:      The pointer to data on which ecc is computed (unused here)
- *  @ecc:      The ECC output buffer
- */
-static int omap_calculate_ecc_bch_sw(struct mtd_info *mtd, const uint8_t *dat,
-                               uint8_t *ecc)
-{
-       int ret = 0;
-       size_t i;
-       unsigned long nsectors, val1, val2, val3, val4;
-
-       nsectors = ((readl(&gpmc_cfg->ecc_config) >> 4) & 0x7) + 1;
-
-       for (i = 0; i < nsectors; i++) {
-               /* Read hw-computed remainder */
-               val1 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[0]);
-               val2 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[1]);
-               val3 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[2]);
-               val4 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[3]);
-
-               /*
-                * Add constant polynomial to remainder, in order to get an ecc
-                * sequence of 0xFFs for a buffer filled with 0xFFs.
-                */
-               *ecc++ = 0xef ^ (val4 & 0xFF);
-               *ecc++ = 0x51 ^ ((val3 >> 24) & 0xFF);
-               *ecc++ = 0x2e ^ ((val3 >> 16) & 0xFF);
-               *ecc++ = 0x09 ^ ((val3 >> 8) & 0xFF);
-               *ecc++ = 0xed ^ (val3 & 0xFF);
-               *ecc++ = 0x93 ^ ((val2 >> 24) & 0xFF);
-               *ecc++ = 0x9a ^ ((val2 >> 16) & 0xFF);
-               *ecc++ = 0xc2 ^ ((val2 >> 8) & 0xFF);
-               *ecc++ = 0x97 ^ (val2 & 0xFF);
-               *ecc++ = 0x79 ^ ((val1 >> 24) & 0xFF);
-               *ecc++ = 0xe5 ^ ((val1 >> 16) & 0xFF);
-               *ecc++ = 0x24 ^ ((val1 >> 8) & 0xFF);
-               *ecc++ = 0xb5 ^ (val1 & 0xFF);
-       }
-
-       /*
-        * Stop reading anymore ECC vals and clear old results
-        * enable will be called if more reads are required
-        */
-       omap_ecc_disable(mtd);
-
-       return ret;
-}
-
 /**
  * omap_correct_data_bch_sw - Decode received data and correct errors
  * @mtd: MTD device structure
@@ -752,7 +652,7 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
                nand->ecc.bytes         = 13;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data_bch_sw;
-               nand->ecc.calculate     = omap_calculate_ecc_bch_sw;
+               nand->ecc.calculate     = omap_calculate_ecc;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;
                ecclayout->eccpos[0]    = BADBLOCK_MARKER_LENGTH;
@@ -794,7 +694,7 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
                nand->ecc.bytes         = 14;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data_bch;
-               nand->ecc.calculate     = omap_calculate_ecc_bch;
+               nand->ecc.calculate     = omap_calculate_ecc;
                nand->ecc.read_page     = omap_read_page_bch;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;