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Commit 64b37b2a authored Nov 06, 2012 by Matthieu CASTET Committed by Artem Bityutskiy Dec 03, 2012

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>

parent 2fd71a29

drivers/mtd/nand/nand_base.c

+9 −5

Original line number	Original line	Diff line number	Diff line
	@@ -3250,11 +3250,15 @@ ident_done:
	break;		break;
	}		}

			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		* Check, if buswidth is correct. Hardware drivers should set
	* chip correct!		* chip correct!
	*/		*/
	if (busw != (chip->options & NAND_BUSWIDTH_16)) {
	pr_info("NAND device: Manufacturer ID:"		pr_info("NAND device: Manufacturer ID:"
	" 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,		" 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,
	*dev_id, nand_manuf_ids[maf_idx].name, mtd->name);		*dev_id, nand_manuf_ids[maf_idx].name, mtd->name);

include/linux/mtd/nand.h

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -219,6 +219,13 @@ typedef enum {
	#define NAND_OWN_BUFFERS 0x00020000		#define NAND_OWN_BUFFERS 0x00020000
	/* Chip may not exist, so silence any errors in scan */		/* Chip may not exist, so silence any errors in scan */
	#define NAND_SCAN_SILENT_NODEV 0x00040000		#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 */		/* Options set by nand scan */
	/* Nand scan has allocated controller struct */		/* Nand scan has allocated controller struct */