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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>
This commit is contained in:
Matthieu CASTET 2012-11-06 11:51:44 +01:00 committed by Artem Bityutskiy
parent 2fd71a294a
commit 64b37b2a63
2 changed files with 16 additions and 5 deletions
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14
drivers/mtd/nand/nand_base.c
View File

@ -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);

7
include/linux/mtd/nand.h
View File

@ -219,6 +219,13 @@ typedef enum {
#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 */