mirror of https://gitee.com/openkylin/linux.git
85 lines
2.4 KiB
Plaintext
85 lines
2.4 KiB
Plaintext
This document describes m[g]flash support in linux.
|
|
|
|
Contents
|
|
1. Overview
|
|
2. Reserved area configuration
|
|
3. Example of mflash platform driver registration
|
|
|
|
1. Overview
|
|
|
|
Mflash and gflash are embedded flash drive. The only difference is mflash is
|
|
MCP(Multi Chip Package) device. These two device operate exactly same way.
|
|
So the rest mflash repersents mflash and gflash altogether.
|
|
|
|
Internally, mflash has nand flash and other hardware logics and supports
|
|
2 different operation (ATA, IO) modes. ATA mode doesn't need any new
|
|
driver and currently works well under standard IDE subsystem. Actually it's
|
|
one chip SSD. IO mode is ATA-like custom mode for the host that doesn't have
|
|
IDE interface.
|
|
|
|
Followings are brief descriptions about IO mode.
|
|
A. IO mode based on ATA protocol and uses some custom command. (read confirm,
|
|
write confirm)
|
|
B. IO mode uses SRAM bus interface.
|
|
C. IO mode supports 4kB boot area, so host can boot from mflash.
|
|
|
|
2. Reserved area configuration
|
|
If host boot from mflash, usually needs raw area for boot loader image. All of
|
|
the mflash's block device operation will be taken this value as start offset.
|
|
Note that boot loader's size of reserved area and kernel configuration value
|
|
must be same.
|
|
|
|
3. Example of mflash platform driver registration
|
|
Working mflash is very straight forward. Adding platform device stuff to board
|
|
configuration file is all. Here is some pseudo example.
|
|
|
|
static struct mg_drv_data mflash_drv_data = {
|
|
/* If you want to polling driver set to 1 */
|
|
.use_polling = 0,
|
|
/* device attribution */
|
|
.dev_attr = MG_BOOT_DEV
|
|
};
|
|
|
|
static struct resource mg_mflash_rsc[] = {
|
|
/* Base address of mflash */
|
|
[0] = {
|
|
.start = 0x08000000,
|
|
.end = 0x08000000 + SZ_64K - 1,
|
|
.flags = IORESOURCE_MEM
|
|
},
|
|
/* mflash interrupt pin */
|
|
[1] = {
|
|
.start = IRQ_GPIO(84),
|
|
.end = IRQ_GPIO(84),
|
|
.flags = IORESOURCE_IRQ
|
|
},
|
|
/* mflash reset pin */
|
|
[2] = {
|
|
.start = 43,
|
|
.end = 43,
|
|
.name = MG_RST_PIN,
|
|
.flags = IORESOURCE_IO
|
|
},
|
|
/* mflash reset-out pin
|
|
* If you use mflash as storage device (i.e. other than MG_BOOT_DEV),
|
|
* should assign this */
|
|
[3] = {
|
|
.start = 51,
|
|
.end = 51,
|
|
.name = MG_RSTOUT_PIN,
|
|
.flags = IORESOURCE_IO
|
|
}
|
|
};
|
|
|
|
static struct platform_device mflash_dev = {
|
|
.name = MG_DEV_NAME,
|
|
.id = -1,
|
|
.dev = {
|
|
.platform_data = &mflash_drv_data,
|
|
},
|
|
.num_resources = ARRAY_SIZE(mg_mflash_rsc),
|
|
.resource = mg_mflash_rsc
|
|
};
|
|
|
|
platform_device_register(&mflash_dev);
|