aboutsummaryrefslogtreecommitdiff
path: root/Documentation/blockdev/mflash.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/blockdev/mflash.txt')
-rw-r--r--Documentation/blockdev/mflash.txt84
1 files changed, 84 insertions, 0 deletions
diff --git a/Documentation/blockdev/mflash.txt b/Documentation/blockdev/mflash.txt
new file mode 100644
index 00000000..1f610ecf
--- /dev/null
+++ b/Documentation/blockdev/mflash.txt
@@ -0,0 +1,84 @@
+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);