UM0851 datasheet(146/245 Pages) STMICROELECTRONICS

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Non-volatile memory device drivers

UM0851

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Doc ID 16604 Rev 2

5.3.3

Serial NOR device driver overview

MTD overview

The MTD is common to both NAND and NOR Flash, an overview is given in MTD overview.

NOR device driver interface to MTD

The NOR device driver allocates and fills the structure struct mtd_info, so that the MTD layer

obtains information about the hardware. The code snippet shows some of the important

data sent to MTD.

struct mtd_info mtd;

mtd.name

= "SMI-NOR";

/*Name for the NOR device*/

mtd.type

= MTD_NORFLASH;

/*Type of MTD device*/

mtd.writesize

= 1;

mtd.flags

= MTD_CAP_NORFLASH;

mtd.size

= sflash_ids [nor_chip].size_in_bytes;

mtd.erasesize

= sflash_ids [nor_chip].sectorsize;

mtd.erase

= spear_snor_erase;

mtd.read

= spear_snor_read;

mtd.write

= spear_snor_write;

Read, Write and Erase operations on serial NOR Flash are simple and are controlled using

the SMI. The SMI clock is enabled just before starting any of these operations and disabled

just after completion.

The NOR Flash device driver populates the struct mtd_info to MTD layer by calling these

routines.

…

err = add_mtd_partitions( &mtd, mtd_partition_table,

total_num_of_mtd_partitions );

} else {

err = add_mtd_device( &mtd );

}

Standard serial NOR partitioning

Partitioning can be done by two ways: static or dynamic.To divide the device into static

partitions, define a partitioning scheme in the NOR driver like a table

(drivers/mtd/devices/spr_nor_st.h).

#define NUM_PARTITIONS 4

static struct mtd_partition stwsf_par_info_primary[] =

{

offset: 0x00000000,

size: 0x00010000,

{

offset: 0x00010000,

size: 0x00040000,

{

offset: 0x0050000,

size: 0x002c0000,

{

offset: 0x00310000,

size :0x004F0000,

}

};

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