UM0851 datasheet(138/245 Pages) STMICROELECTRONICS

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Non-volatile memory device drivers

UM0851

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Doc ID 16604 Rev 2

5.1.7

Configuration options

5.1.8

References

●

http://www.linux-mtd.infradead.org/tech/mtdnand/index.html

●

MTD source code under directory drivers/mtd/nand for Linux 2.6.27

●

SPEAr NAND Flash device driver (drivers/mtd/nand/spr_nand_st.c)

●

http://www.linux-mtd.infradead.org/index.html

Note:

By default the FSMC's wait feature is enabled. When the 'wait feature' is enabled the FSMC

Controller does not acknowledge any AHB read/write transaction until the NAND ready/busy

signal indicates that the device is ready.So if a particular software program is accessing (in

either read or write) the NAND device, the system becomes completely unresponsive to

external interrupt events (both IRQ and FIQ) for a few tens of microseconds, the ARM core

is in a 'frozen' state, waiting for the completion of a r/w 'LDR' instruction. For specific

applications that require hard real time interrupt latency this behavior must be avoided. In

such cases it is desirable to disable the 'wait' feature of the FSMC controller and connect the

NAND ready/busy signal directly to a SPEAr GPIO pin, which needs to be monitored by

implementing the Device Ready function in the NAND device driver.

The function has no arguments and should return 0, if the NAND device is busy (R/B pin is

low) and 1, if the NAND device is ready (R/B pin is high). If the hardware interface does not

Table 39.

NAND Flash driver configuration options

Configuration option

Comment

CONFIG_MTD_NAND_SPEAR

This option is used to enable the NAND Driver

support for SPEAr platform.

CONFIG_MTD

This option provides the generic support for MTD

drivers.

CONFIG_MTD_PARTITIONS

This option enables multiple 'partitions', each of

which appears to the user as a separate MTD

device.

CONFIG_MTD_CHAR

This option provides a character device for each

MTD device.

CONFIG_MTD_BLOCK

This option provides a block device for each MTD

device.

CONFIG_MTD_NAND

This option enables support for accessing all type

of NAND Flash devices.

CONFIG_JFFS2_FS

This option includes the JFFS2 file system.

CONFIG_JFFS2_CMODE_NONE

This option disables the compression for JFFS2.

CONFIG_YAFFS_FS

This option includes the YAFFS file system.

CONFIG_SPEAR_DMAC_PL080

This option ensures that all data transfer to NAND

Flash will use DMA.

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