git://bbs.cooldavid.org / net-next-2.6.git / blame
| Commit | Line | Data |
|---|---|---|
| 3fbed4c6 K |
1 | This document describes m[g]flash support in linux. |
| 2 | ||
| 3 | Contents | |
| 4 | 1. Overview | |
| 5 | 2. Reserved area configuration | |
| 6 | 3. Example of mflash platform driver registration | |
| 7 | ||
| 8 | 1. Overview | |
| 9 | ||
| 10 | Mflash and gflash are embedded flash drive. The only difference is mflash is | |
| 11 | MCP(Multi Chip Package) device. These two device operate exactly same way. | |
| 12 | So the rest mflash repersents mflash and gflash altogether. | |
| 13 | ||
| 14 | Internally, mflash has nand flash and other hardware logics and supports | |
| 15 | 2 different operation (ATA, IO) modes. ATA mode doesn't need any new | |
| 16 | driver and currently works well under standard IDE subsystem. Actually it's | |
| 17 | one chip SSD. IO mode is ATA-like custom mode for the host that doesn't have | |
| 18 | IDE interface. | |
| 19 | ||
| 20 | Followings are brief descriptions about IO mode. | |
| 21 | A. IO mode based on ATA protocol and uses some custom command. (read confirm, | |
| 22 | write confirm) | |
| 23 | B. IO mode uses SRAM bus interface. | |
| 24 | C. IO mode supports 4kB boot area, so host can boot from mflash. | |
| 25 | ||
| 26 | 2. Reserved area configuration | |
| 27 | If host boot from mflash, usually needs raw area for boot loader image. All of | |
| 28 | the mflash's block device operation will be taken this value as start offset. | |
| 29 | Note that boot loader's size of reserved area and kernel configuration value | |
| 30 | must be same. | |
| 31 | ||
| 32 | 3. Example of mflash platform driver registration | |
| 33 | Working mflash is very straight forward. Adding platform device stuff to board | |
| 34 | configuration file is all. Here is some pseudo example. | |
| 35 | ||
| 36 | static struct mg_drv_data mflash_drv_data = { | |
| 37 | /* If you want to polling driver set to 1 */ | |
| 38 | .use_polling = 0, | |
| 39 | /* device attribution */ | |
| 40 | .dev_attr = MG_BOOT_DEV | |
| 41 | }; | |
| 42 | ||
| 43 | static struct resource mg_mflash_rsc[] = { | |
| 44 | /* Base address of mflash */ | |
| 45 | [0] = { | |
| 46 | .start = 0x08000000, | |
| 47 | .end = 0x08000000 + SZ_64K - 1, | |
| 48 | .flags = IORESOURCE_MEM | |
| 49 | }, | |
| 50 | /* mflash interrupt pin */ | |
| 51 | [1] = { | |
| 52 | .start = IRQ_GPIO(84), | |
| 53 | .end = IRQ_GPIO(84), | |
| 54 | .flags = IORESOURCE_IRQ | |
| 55 | }, | |
| 56 | /* mflash reset pin */ | |
| 57 | [2] = { | |
| 58 | .start = 43, | |
| 59 | .end = 43, | |
| 60 | .name = MG_RST_PIN, | |
| 61 | .flags = IORESOURCE_IO | |
| 62 | }, | |
| 63 | /* mflash reset-out pin | |
| 64 | * If you use mflash as storage device (i.e. other than MG_BOOT_DEV), | |
| 65 | * should assign this */ | |
| 66 | [3] = { | |
| 67 | .start = 51, | |
| 68 | .end = 51, | |
| 69 | .name = MG_RSTOUT_PIN, | |
| 70 | .flags = IORESOURCE_IO | |
| 71 | } | |
| 72 | }; | |
| 73 | ||
| 74 | static struct platform_device mflash_dev = { | |
| 75 | .name = MG_DEV_NAME, | |
| 76 | .id = -1, | |
| 77 | .dev = { | |
| 78 | .platform_data = &mflash_drv_data, | |
| 79 | }, | |
| 80 | .num_resources = ARRAY_SIZE(mg_mflash_rsc), | |
| 81 | .resource = mg_mflash_rsc | |
| 82 | }; | |
| 83 | ||
| 84 | platform_device_register(&mflash_dev); |