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