UM0851 datasheet(147/245 Pages) STMICROELECTRONICS

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UM0851

Non-volatile memory device drivers

Doc ID 16604 Rev 2

147/245

The offset of any partition is in multiples of the sector size of NOR Flash. While modifying

the static partition table you should take care of this to avoid getting warning messages

when creating partitions.

Dynamic parititions are defined in the command-line arguments by using this command:

setenv bootargs console=ttyS0 root=/dev/mtdblock3 rootfstype=jffs2

mtdparts=SMI-NOR0: 4k(XLoader),200k(uBoot),2M(Linux),5M(Ramdisk)

The command-line argument creates 4 partitions (XLoader, Uboot, Linux and Ramdisk) in

the NOR Flash. Sizes are also given in the partitions.

How to support a new NOR Flash

In case of a new NOR Flash chip, the following needs to be checked in the device driver:

NOR chip should be listed in "arch/arm/plat-spear/include/plat/flash_chars.h".

NOR chip base address should be defined in platform device of "arch/arm/mach-

spear600/spear600.c or arch/arm/mach- spear300/spear300.c".

static struct resource nand_resources[] = {

…

[x] = {

.start = (SPEAR_START_SFLASH_MEM),

.end

= (SPEAR_START_SFLASH_MEM + SPEAR_SIZE_SFLASH_MEM - 1),

.flags = IORESOURCE_MEM,

…

};

NOR chip should be supported by SMI (families supported by SMI are listed in SPEAr-

user manuals).

5.3.4

NOR Flash file system image creation

JFFS2 image creation

To create the JFFS2 file system image for NOR Flash, use the command:

# mkfs.jffs2 -n -p -l -s 0x200 -e 0x10000 -r <dir name > -o <image name >

-n: don't add a cleanmarker to every eraseblock

-p: add pad bytes to the end of the final erase block

-l: create a little-endian filesystem

-s: page size

-e: erase block size

5.3.5

Serial NOR device usage

The user space application can access the NOR Flash device content using the mtdblock

nodes (/dev/mtdblockN) and the mtdchar nodes (/dev/mtdN), either in raw mode, for

example using the 'dd' command, or in logical mode, by mounting a file system (usually

JFFS2) and accessing its files through open/read/write system calls.

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