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 isMCP(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 supports2 different operation (ATA, IO) modes. ATA mode doesn't need any newdriver and currently works well under standard IDE subsystem. Actually it'sone chip SSD. IO mode is ATA-like custom mode for the host that doesn't haveIDE 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 configurationIf host boot from mflash, usually needs raw area for boot loader image. All ofthe 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 valuemust be same. 3. Example of mflash platform driver registrationWorking mflash is very straight forward. Adding platform device stuff to boardconfiguration 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);