[MTD] [NOR] Add support for flash chips with ID in bank other than 0

According to JEDEC "Standard Manufacturer's Identification Code"
(http://www.jedec.org/download/search/jep106W.pdf)
several first banks of NOR flash can contain 0x7f instead of actual ID.
This patch adds support for reading manufacturer ID from banks other than 0.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/mtd/chips/jedec_probe.c b/drivers/mtd/chips/jedec_probe.c
index b717f1a5d6b2..279fe60b7855 100644
--- a/drivers/mtd/chips/jedec_probe.c
+++ b/drivers/mtd/chips/jedec_probe.c
@@ -37,6 +37,7 @@
 #define MANUFACTURER_ST         0x0020
 #define MANUFACTURER_TOSHIBA    0x0098
 #define MANUFACTURER_WINBOND    0x00da
+#define CONTINUATION_CODE       0x007f
 
 
 /* AMD */
@@ -1760,9 +1761,21 @@ static inline u32 jedec_read_mfr(struct map_info *map, uint32_t base,
 {
         map_word result;
         unsigned long mask;
-        u32 ofs = cfi_build_cmd_addr(0, cfi_interleave(cfi), cfi->device_type);
-        mask = (1 << (cfi->device_type * 8)) -1;
-        result = map_read(map, base + ofs);
+        int bank = 0;
+
+        /* According to JEDEC "Standard Manufacturer's Identification Code"
+         * (http://www.jedec.org/download/search/jep106W.pdf)
+         * several first banks can contain 0x7f instead of actual ID
+         */
+        do {
+                uint32_t ofs = cfi_build_cmd_addr(0 + (bank << 8),
+                                                  cfi_interleave(cfi),
+                                                  cfi->device_type);
+                mask = (1 << (cfi->device_type * 8)) - 1;
+                result = map_read(map, base + ofs);
+                bank++;
+        } while ((result.x[0] & mask) == CONTINUATION_CODE);
+
         return result.x[0] & mask;
 }