How to implement redundant U-Boot partitions

I managed to make it work! In case anyone is interested, here is a patch:

diff --git a/U-Boot-2013.01.01-amsdk-06.00.00/common/spl/spl_nand.c b/U-Boot-2013.01.01-amsdk-06.00.00/common/spl/spl_nand.c
index 61de5a4..75f1fda 100644
--- a/U-Boot-2013.01.01-amsdk-06.00.00/common/spl/spl_nand.c
+++ b/U-Boot-2013.01.01-amsdk-06.00.00/common/spl/spl_nand.c
@@ -26,11 +26,17 @@
 #include <asm/io.h>
 #include <nand.h>
 
+#ifndef CONFIG_SYS_U_BOOT_PARTITIONS
+   #define CONFIG_SYS_U_BOOT_PARTITIONS   1
+#endif
+
 void spl_nand_load_image(void)
 {
-  struct image_header *header;
+   struct image_header *header;
   int *src __attribute__((unused));
   int *dst __attribute__((unused));
+   int result;
+   int i = 0;
 
   debug("spl: nand - using hw ecc\n");
   nand_init();
@@ -90,11 +96,30 @@ void spl_nand_load_image(void)
      (void *)spl_image.load_addr);
 #endif
 #endif
-  /* Load u-boot */
-  nand_spl_load_image(CONFIG_SYS_NAND_U_BOOT_OFFS,
-     CONFIG_SYS_NAND_PAGE_SIZE, (void *)header);
-  spl_parse_image_header(header);
-  nand_spl_load_image(CONFIG_SYS_NAND_U_BOOT_OFFS,
-     spl_image.size, (void *)spl_image.load_addr);
-  nand_deselect();
+
+   /* Load u-boot */
+   for (i = 0; i < CONFIG_SYS_U_BOOT_PARTITIONS; i++)
+   {
+      int current_offset = i * CONFIG_SYS_NAND_U_BOOT_PARTITION_SIZE;
+
+      printf("Trying U-Boot image no. %d...\n", i + 1);
+
+      result = nand_spl_load_image(CONFIG_SYS_NAND_U_BOOT_OFFS + current_offset,
+                                      CONFIG_SYS_NAND_PAGE_SIZE, (void *)header);
+      if (result < 0)
+         continue;
+
+      spl_parse_image_header(header);
+
+      result = nand_spl_load_image(CONFIG_SYS_NAND_U_BOOT_OFFS + current_offset,
+                                   spl_image.size, (void *)spl_image.load_addr);
+
+      if (result == 0)
+      {
+         nand_deselect();
+         return;
+      }
+   }
+
+   printf("All U-Boot images corrupted. Please re-flash your board\n");
 }
diff --git a/U-Boot-2013.01.01-amsdk-06.00.00/drivers/mtd/nand/am335x_spl_bch.c b/U-Boot-2013.01.01-amsdk-06.00.00/drivers/mtd/nand/am335x_spl_bch.c
index 9941e0e..2a3e0d1 100644
--- a/U-Boot-2013.01.01-amsdk-06.00.00/drivers/mtd/nand/am335x_spl_bch.c
+++ b/U-Boot-2013.01.01-amsdk-06.00.00/drivers/mtd/nand/am335x_spl_bch.c
@@ -129,6 +129,7 @@ static int nand_read_page(int block, int page, void *dst)
   int eccsize = CONFIG_SYS_NAND_ECCSIZE;
   int eccbytes = CONFIG_SYS_NAND_ECCBYTES;
   int eccsteps = ECCSTEPS;
+   int result;
   uint8_t *p = dst;
   uint32_t data_pos = 0;
   uint8_t *oob = &oob_data[0] + nand_ecc_pos[0];
@@ -160,12 +161,11 @@ static int nand_read_page(int block, int page, void *dst)
   p = dst;
 
   for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
-     /* No chance to do something with the possible error message
-      * from correct_data(). We just hope that all possible errors
-      * are corrected by this routine.
-      */
-     this->ecc.correct(&nand_info[0], p, &ecc_code[i], &ecc_calc[i]);
-  }
+      result = this->ecc.correct(&nand_info[0], p, &ecc_code[i], &ecc_calc[i]);
+
+      if (result < 0)
+         return -1;
+   }
 
   return 0;
 }
@@ -174,8 +174,9 @@ int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
 {
   unsigned int block, lastblock;
   unsigned int page;
+   int result;
 
-  /*
+   /*
    * offs has to be aligned to a page address!
    */
   block = offs / CONFIG_SYS_NAND_BLOCK_SIZE;
@@ -188,8 +189,12 @@ int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
          * Skip bad blocks
          */
         while (page < CONFIG_SYS_NAND_PAGE_COUNT) {
-           nand_read_page(block, page, dst);
-           dst += CONFIG_SYS_NAND_PAGE_SIZE;
+           result = nand_read_page(block, page, dst);
+
+            if (result < 0)
+               return -1;
+
+            dst += CONFIG_SYS_NAND_PAGE_SIZE;
            page++;
         }

With this, SPL will check another partition in case the first one has too many bitflip errors, but will not do this for bad blocks or if the partition is empty.

Remember, the partitions must be sequential for this to work!

Regards,

Guilherme