mtd: nand: add NAND_BUSWIDTH_AUTO to autodetect bus width

The driver call nand_scan_ident in 8 bit mode, then
readid or onfi detection are done (and detect bus width).
The driver should update its bus width before calling nand_scan_tail.

This work because readid and onfi are read work 8 byte mode.

Note that nand_scan_ident send command (NAND_CMD_RESET, NAND_CMD_READID, NAND_CMD_PARAM), address and read data
The ONFI specificication is not very clear for x16 device if high byte of address should be driven to 0,
but according to [1] it should be ok to not drive it during autodetection.

[1]
3.3.2. Target Initialization

[...]
The Read ID and Read Parameter Page commands only use the lower 8-bits of the data bus.
The host shall not issue commands that use a word data width on x16 devices until the host
determines the device supports a 16-bit data bus width in the parameter page.

Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 6f58e1633e2f..5851c51ac2df 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3250,11 +3250,15 @@ ident_done:
                         break;
         }
 
-        /*
-         * Check, if buswidth is correct. Hardware drivers should set
-         * chip correct!
-         */
-        if (busw != (chip->options & NAND_BUSWIDTH_16)) {
+        if (chip->options & NAND_BUSWIDTH_AUTO) {
+                WARN_ON(chip->options & NAND_BUSWIDTH_16);
+                chip->options |= busw;
+                nand_set_defaults(chip, busw);
+        } else if (busw != (chip->options & NAND_BUSWIDTH_16)) {
+                /*
+                 * Check, if buswidth is correct. Hardware drivers should set
+                 * chip correct!
+                 */
                 pr_info("NAND device: Manufacturer ID:"
                         " 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,
                         *dev_id, nand_manuf_ids[maf_idx].name, mtd->name);