cmd_nand: add nand write.trimffs command

Add another nand write. variant, trimffs. This command will request of
nand_write_skip_bad() that all trailing all-0xff pages will be
dropped from eraseblocks when they are written to flash as-per the
reccommended behaviour of the UBI FAQ [1].

The function that implements this timming is the drop_ffs() function
by Artem Bityutskiy, ported from the mtd-utils tree.

[1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
CC: Artem Bityutskiy <dedekind1@gmail.com>
CC: Detlev Zundel <dzu@denx.de>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

diff --git a/common/cmd_nand.c b/common/cmd_nand.c
index 27a8879..b767cd2 100644 (file)
--- a/common/cmd_nand.c
+++ b/common/cmd_nand.c
@@ -575,6 +575,16 @@ int do_nand(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
                        else
                                ret = nand_write_skip_bad(nand, off, &rwsize,
                                                          (u_char *)addr, 0);
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+               } else if (!strcmp(s, ".trimffs")) {
+                       if (read) {
+                               printf("Unknown nand command suffix '%s'\n", s);
+                               return 1;
+                       }
+                       ret = nand_write_skip_bad(nand, off, &rwsize,
+                                               (u_char *)addr,
+                                               WITH_DROP_FFS);
+#endif
 #ifdef CONFIG_CMD_NAND_YAFFS
                } else if (!strcmp(s, ".yaffs")) {
                        if (read) {
@@ -689,6 +699,12 @@ U_BOOT_CMD(
        "nand write - addr off|partition size\n"
        "    read/write 'size' bytes starting at offset 'off'\n"
        "    to/from memory address 'addr', skipping bad blocks.\n"
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+       "nand write.trimffs - addr off|partition size\n"
+       "    write 'size' bytes starting at offset 'off' from memory address\n"
+       "    'addr', skipping bad blocks and dropping any pages at the end\n"
+       "    of eraseblocks that contain only 0xFF\n"
+#endif
 #ifdef CONFIG_CMD_NAND_YAFFS
        "nand write.yaffs - addr off|partition size\n"
        "    write 'size' bytes starting at offset 'off' with yaffs format\n"

diff --git a/doc/README.nand b/doc/README.nand
index 8eedb6c..751b693 100644 (file)
--- a/doc/README.nand
+++ b/doc/README.nand
@@ -78,6 +78,16 @@ Commands:
       should work well, but loading an image copied from another flash is
       going to be trouble if there are any bad blocks.
 
+   nand write.trimffs addr ofs|partition size
+      Enabled by the CONFIG_CMD_NAND_TRIMFFS macro. This command will write to
+      the NAND flash in a manner identical to the 'nand write' command
+      described above -- with the additional check that all pages at the end
+      of eraseblocks which contain only 0xff data will not be written to the
+      NAND flash. This behaviour is required when flashing UBI images
+      containing UBIFS volumes as per the UBI FAQ[1].
+
+      [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo
+
    nand write.oob addr ofs|partition size
       Write `size' bytes from `addr' to the out-of-band data area
       corresponding to `ofs' in NAND flash. This is limited to the 16 bytes