tools: mxsboot: Calculate ECC strength dynamically

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>
Reviewed-by: Marek Vasut <marex@denx.de>

diff --git a/tools/mxsboot.c b/tools/mxsboot.c
index 08219b34e8c1c9a865a51e84b212ba417bb363ba..185b327920189926a6ecb4ce054b525554f9dafb 100644 (file)
--- 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,