With increase in NAND flash densities occurence of bit-flips has increased.
Thus stronger ECC schemes are required for detecting and correcting multiple
simultaneous bit-flips in same NAND page. But stronger ECC schemes have large
ECC syndrome which require more space in OOB/Spare.
This patch add support for BCH16_ECC:
(a) BCH16_ECC can correct 16 bit-flips per 512Bytes of data.
(b) BCH16_ECC generates 26-bytes of ECC syndrome / 512B.
Due to (b) this scheme can only be used with NAND devices which have enough
OOB to satisfy following equation:
OOBsize per page >= 26 * (page-size / 512)
Signed-off-by: Pekon Gupta <pe...@ti.com>
---
arch/arm/cpu/armv7/am33xx/elm.c | 91 +++++++++++++++++++++++-----------
arch/arm/include/asm/arch-am33xx/elm.h | 16 +++---
2 files changed, 68 insertions(+), 39 deletions(-)
diff --git a/arch/arm/cpu/armv7/am33xx/elm.c b/arch/arm/cpu/armv7/am33xx/elm.c
index 8f1d6af..47ccbbd 100644
--- a/arch/arm/cpu/armv7/am33xx/elm.c
+++ b/arch/arm/cpu/armv7/am33xx/elm.c
@@ -27,29 +27,27 @@ struct elm *elm_cfg;
/**
* elm_load_syndromes - Load BCH syndromes based on nibble selection
* @syndrome: BCH syndrome
- * @nibbles:
* @poly: Syndrome Polynomial set to use
*
* Load BCH syndromes based on nibble selection
*/
-static void elm_load_syndromes(u8 *syndrome, u32 nibbles, u8 poly)
+static int elm_load_syndromes(u8 *syndrome, u32 bch_type, u8 poly)
{
u32 *ptr;
u32 val;
- /* reg 0 */
- ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
- val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
- (syndrome[3] << 24);
- writel(val, ptr);
- /* reg 1 */
- ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
- val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
- (syndrome[7] << 24);
- writel(val, ptr);
-
- /* BCH 8-bit with 26 nibbles (4*8=32) */
- if (nibbles > 13) {
+ switch (bch_type) {
+ case ECC_BCH16:
+ /* reg 0 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
+ val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
+ (syndrome[3] << 24);
+ writel(val, ptr);
+ /* reg 1 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
+ val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
+ (syndrome[7] << 24);
+ writel(val, ptr);
/* reg 2 */
ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[2];
val = syndrome[8] | (syndrome[9] << 8) | (syndrome[10] << 16) |
@@ -60,34 +58,65 @@ static void elm_load_syndromes(u8 *syndrome, u32 nibbles,
u8 poly)
val = syndrome[12] | (syndrome[13] << 8) |
(syndrome[14] << 16) | (syndrome[15] << 24);
writel(val, ptr);
- }
-
- /* BCH 16-bit with 52 nibbles (7*8=56) */
- if (nibbles > 26) {
/* reg 4 */
ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[4];
val = syndrome[16] | (syndrome[17] << 8) |
(syndrome[18] << 16) | (syndrome[19] << 24);
writel(val, ptr);
-
/* reg 5 */
ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[5];
val = syndrome[20] | (syndrome[21] << 8) |
(syndrome[22] << 16) | (syndrome[23] << 24);
writel(val, ptr);
-
/* reg 6 */
ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6];
- val = syndrome[24] | (syndrome[25] << 8) |
- (syndrome[26] << 16) | (syndrome[27] << 24);
+ val = syndrome[24] | (syndrome[25] << 8);
+ writel(val, ptr);
+ break;
+ case ECC_BCH8:
+ /* reg 0 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
+ val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
+ (syndrome[3] << 24);
+ writel(val, ptr);
+ /* reg 1 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
+ val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
+ (syndrome[7] << 24);
+ writel(val, ptr);
+ /* reg 2 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[2];
+ val = syndrome[8] | (syndrome[9] << 8) | (syndrome[10] << 16) |
+ (syndrome[11] << 24);
+ writel(val, ptr);
+ /* reg 3 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[3];
+ val = syndrome[12];
+ writel(val, ptr);
+ break;
+ case ECC_BCH4:
+ /* reg 0 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
+ val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
+ (syndrome[3] << 24);
+ writel(val, ptr);
+ /* reg 1 */
+ ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
+ val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
+ (syndrome[7] << 24);
writel(val, ptr);
+ break;
+ default:
+ return -1;
}
+
+ return 0;
}
/**
- * elm_check_errors - Check for BCH errors and return error locations
+ * elm_check_error - Check for BCH errors and return error locations
* @syndrome: BCH syndrome
- * @nibbles:
+ * @bch_type: BCH4/BCH8/BCH16
* @error_count: Returns number of errrors in the syndrome
* @error_locations: Returns error locations (in decimal) in this array
*
@@ -95,15 +124,17 @@ static void elm_load_syndromes(u8 *syndrome, u32 nibbles,
u8 poly)
* and locations in the array passed. Returns -1 if error is not correctable,
* else returns 0
*/
-int elm_check_error(u8 *syndrome, u32 nibbles, u32 *error_count,
+int elm_check_error(u8 *syndrome, u32 bch_type, u32 *error_count,
u32 *error_locations)
{
u8 poly = ELM_DEFAULT_POLY;
s8 i;
u32 location_status;
- elm_load_syndromes(syndrome, nibbles, poly);
-
+ if (elm_load_syndromes(syndrome, bch_type, poly)) {
+ printf("ELM: *Error: invalid driver configuration\n");
+ return -1;
+ }
/* start processing */
writel((readl(&elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6])
| ELM_SYNDROME_FRAGMENT_6_SYNDROME_VALID),
@@ -143,14 +174,14 @@ int elm_check_error(u8 *syndrome, u32 nibbles, u32
*error_count,
* Currently we are using only syndrome 0 and syndromes 1 to 6 are not used.
* Also, the mode is set only for syndrome 0
*/
-int elm_config(enum bch_level level)
+int elm_config(u32 bch_type)
{
u32 val;
u8 poly = ELM_DEFAULT_POLY;
u32 buffer_size = 0x7FF;
/* config size and level */
- val = (u32)(level) & ELM_LOCATION_CONFIG_ECC_BCH_LEVEL_MASK;
+ val = bch_type & ELM_LOCATION_CONFIG_ECC_BCH_LEVEL_MASK;
val |= ((buffer_size << ELM_LOCATION_CONFIG_ECC_SIZE_POS) &
ELM_LOCATION_CONFIG_ECC_SIZE_MASK);
writel(val, &elm_cfg->location_config);
diff --git a/arch/arm/include/asm/arch-am33xx/elm.h
b/arch/arm/include/asm/arch-am33xx/elm.h
index 45454ea..857dc27 100644
--- a/arch/arm/include/asm/arch-am33xx/elm.h
+++ b/arch/arm/include/asm/arch-am33xx/elm.h
@@ -24,14 +24,12 @@
#define ELM_LOCATION_STATUS_ECC_CORRECTABLE_MASK (0x100)
#define ELM_LOCATION_STATUS_ECC_NB_ERRORS_MASK (0x1F)
-#ifndef __ASSEMBLY__
-
-enum bch_level {
- BCH_4_BIT = 0,
- BCH_8_BIT,
- BCH_16_BIT
-};
+/* bch types */
+#define ECC_BCH4 0
+#define ECC_BCH8 1
+#define ECC_BCH16 2
+#ifndef __ASSEMBLY__
/* BCH syndrome registers */
struct syndrome {
@@ -68,9 +66,9 @@ struct elm {
struct location error_location[8]; /* 0x800 */
};
-int elm_check_error(u8 *syndrome, u32 nibbles, u32 *error_count,
+int elm_check_error(u8 *syndrome, u32 bch_type, u32 *error_count,
u32 *error_locations);
-int elm_config(enum bch_level level);
+int elm_config(u32 bch_type);
void elm_reset(void);
void elm_init(void);
#endif /* __ASSEMBLY__ */
--
1.8.1
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