Re: the structs of MTD

[Thomas Gleixner <gleixner@autronix.de>]

On Monday, 29. April 2002 04:35,  wrote:
> Hi, I'm new to linux-mtd.
> I have a SAMSUNG  k9F5608U0M flash, 32M NAND Flash Memory.
> But the difficulty is I know little about the structs of MTD , such as
> struct mtd_chip_driver.
> So I don't know how to drive it . can you  explain these interrelated
> struct ?
> By the way, please explain detailedly how to drive the forenamed NAND Flash
> Memory ?
This chip is supported by the generic NAND driver already. You need just a 
driver for your specific hardware, where you supply baseaddress and access to 
CE, ALE and CLE pins. Have a look at drivers/mtd/nand/nand.c (generic nand 
driver) and drivers/mtd/nand/autcpu12.c (example for a hardware driver). Use 
latest CVS code. It contains all enhancements for NAND support.

The important pieces of the hardware driver are

void autcpu12_hwcontrol(iCONFIG_JFFS2_FS=y
CONFIG_JFFS2_FS_DEBUG=0
CONFIG_JFFS2_FS_NAND=y
nt cmd)
This is the function, which supplies the manipulation of CE, CLE and ALE pins.

int __init autcpu12_init (void)
This is the main init function of the hardware driver
The main points of this function are
	/* map physical adress */
	autcpu12_fio_base=(unsigned long)ioremap(autcpu12_fio_pbase,SZ_1K);
Remaps the physical base address to a virtual address for driver usage

	/* Set address of NAND IO lines */
	this->IO_ADDR_R = autcpu12_fio_base;
	this->IO_ADDR_W = autcpu12_fio_base;
Set the address for read / write access to the chips data bus. In most cases 
the base address.

	this->hwcontrol = autcpu12_hwcontrol;
Set the function for access to controllines (CE, CLE, ALE)

	this->dev_ready = autcpu12_device_ready;
Give the function to read the ready/busy pin of the chip. If you do not have 
access to this pin set it to NULL.
	/* 20 us command delay time */
	this->chip_delay = 20;
Give a appropriate command delay time according to the chips datasheet.

Supply partitioning information, if you want to use more than one partition 
on the chip.

Following CONFIG's should be set
CONFIG_MTD=y
CONFIG_MTD_PARTITIONS=y	<--- if you want to use partitions
CONFIG_MTD_CHAR=y
CONFIG_MTD_BLOCK=y
CONFIG_MTD_NAND=y
CONFIG_MTD_NAND_ECC=y
CONFIG_MTD_NAND_ECC_JFFS2=y <-- If you want to use JFFS2, which is recommended
CONFIG_MTD_NAND_AUTCPU12=y <-- Replace this by your hardware driver

For JFFS2 usage set
CONFIG_JFFS2_FS=y
CONFIG_JFFS2_FS_DEBUG=0
CONFIG_JFFS2_FS_NAND=y

Enjoy.
-- 
Thomas
___________________________________
autronix automation GmbH
http://www.autronix.de gleixner@autronix.de