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>
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 9d8a604..7ccb3c5 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -219,6 +219,13 @@
#define NAND_OWN_BUFFERS 0x00020000
/* Chip may not exist, so silence any errors in scan */
#define NAND_SCAN_SILENT_NODEV 0x00040000
+/*
+ * Autodetect nand buswidth with readid/onfi.
+ * This suppose the driver will configure the hardware in 8 bits mode
+ * when calling nand_scan_ident, and update its configuration
+ * before calling nand_scan_tail.
+ */
+#define NAND_BUSWIDTH_AUTO 0x00080000
/* Options set by nand scan */
/* Nand scan has allocated controller struct */