Calculating the ECC strength dynamically to be aligned with the mxs NAND
driver and the Linux Kernel.
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
---
Changes for v3:
- Coding Style cleanup
Changes for v2:
- New patch
---
tools/mxsboot.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)
diff --git a/tools/mxsboot.c b/tools/mxsboot.c
index aaa872b..53de452 100644
--- a/tools/mxsboot.c
+++ b/tools/mxsboot.c
@@ -14,6 +14,10 @@
#include "compiler.h"
+/* Taken from <linux/kernel.h> */
+#define __round_mask(x, y) ((__typeof__(x))((y)-1))
+#define round_down(x, y) ((x) & ~__round_mask(x, y))
+
/*
* Default BCB layout.
*
@@ -126,6 +130,11 @@ struct mx28_sd_config_block {
struct mx28_sd_drive_info drv_info[1];
};
+static inline uint32_t mx28_nand_ecc_chunk_cnt(uint32_t page_data_size)
+{
+ return page_data_size / MXS_NAND_CHUNK_DATA_CHUNK_SIZE;
+}
+
static inline uint32_t mx28_nand_ecc_size_in_bits(uint32_t ecc_strength)
{
return ecc_strength * MXS_NAND_BITS_PER_ECC_LEVEL;
@@ -134,21 +143,21 @@ static inline uint32_t
mx28_nand_ecc_size_in_bits(uint32_t ecc_strength)
static inline uint32_t mx28_nand_get_ecc_strength(uint32_t page_data_size,
uint32_t page_oob_size)
{
- if (page_data_size == 2048)
- return 8;
-
- if (page_data_size == 4096) {
- if (page_oob_size == 128)
- return 8;
+ int ecc_strength;
- if (page_oob_size == 218)
- return 16;
-
- if (page_oob_size == 224)
- return 16;
- }
+ /*
+ * Determine the ECC layout with the formula:
+ * ECC bits per chunk = (total page spare data bits) /
+ * (bits per ECC level) / (chunks per page)
+ * where:
+ * total page spare data bits =
+ * (page oob size - meta data size) * (bits per byte)
+ */
+ ecc_strength = ((page_oob_size - MXS_NAND_METADATA_SIZE) * 8)
+ / (MXS_NAND_BITS_PER_ECC_LEVEL *
+ mx28_nand_ecc_chunk_cnt(page_data_size));
- return 0;
+ return round_down(ecc_strength, 2);
}
static inline uint32_t mx28_nand_get_mark_offset(uint32_t page_data_size,
--
2.3.5
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