Merge branch 'omap-pool'

[linux-2.6-omap-h63xx.git] / Documentation / blockdev / mflash.txt

diff --git a/Documentation/blockdev/mflash.txt b/Documentation/blockdev/mflash.txt
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+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);