projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| fc28c39f | 1 | CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...) |
| efcc2da3 SR |
2 | |
| 3 | Flash chips (Memory Technology Devices) are often used for solid state | |
| 4 | file systems on embedded devices. | |
| 5 | ||
| fc28c39f WS |
6 | - compatible : should contain the specific model of mtd chip(s) |
| 7 | used, if known, followed by either "cfi-flash", "jedec-flash" | |
| 8 | or "mtd-ram". | |
| 9 | - reg : Address range(s) of the mtd chip(s) | |
| c5a88dd9 | 10 | It's possible to (optionally) define multiple "reg" tuples so that |
| fc28c39f WS |
11 | non-identical chips can be described in one node. |
| 12 | - bank-width : Width (in bytes) of the bank. Equal to the | |
| efcc2da3 | 13 | device width times the number of interleaved chips. |
| fc28c39f | 14 | - device-width : (optional) Width of a single mtd chip. If |
| efcc2da3 | 15 | omitted, assumed to be equal to 'bank-width'. |
| fc28c39f | 16 | - #address-cells, #size-cells : Must be present if the device has |
| efcc2da3 SR |
17 | sub-nodes representing partitions (see below). In this case |
| 18 | both #address-cells and #size-cells must be equal to 1. | |
| 19 | ||
| 20 | For JEDEC compatible devices, the following additional properties | |
| 21 | are defined: | |
| 22 | ||
| 23 | - vendor-id : Contains the flash chip's vendor id (1 byte). | |
| 24 | - device-id : Contains the flash chip's device id (1 byte). | |
| 25 | ||
| fc28c39f | 26 | In addition to the information on the mtd bank itself, the |
| efcc2da3 | 27 | device tree may optionally contain additional information |
| fc28c39f | 28 | describing partitions of the address space. This can be |
| efcc2da3 | 29 | used on platforms which have strong conventions about which |
| fc28c39f | 30 | portions of a flash are used for what purposes, but which don't |
| efcc2da3 SR |
31 | use an on-flash partition table such as RedBoot. |
| 32 | ||
| fc28c39f | 33 | Each partition is represented as a sub-node of the mtd device. |
| efcc2da3 | 34 | Each node's name represents the name of the corresponding |
| fc28c39f | 35 | partition of the mtd device. |
| efcc2da3 SR |
36 | |
| 37 | Flash partitions | |
| fc28c39f WS |
38 | - reg : The partition's offset and size within the mtd bank. |
| 39 | - label : (optional) The label / name for this partition. | |
| efcc2da3 SR |
40 | If omitted, the label is taken from the node name (excluding |
| 41 | the unit address). | |
| 42 | - read-only : (optional) This parameter, if present, is a hint to | |
| fc28c39f | 43 | Linux that this partition should only be mounted |
| efcc2da3 SR |
44 | read-only. This is usually used for flash partitions |
| 45 | containing early-boot firmware images or data which should not | |
| 46 | be clobbered. | |
| 47 | ||
| 48 | Example: | |
| 49 | ||
| 50 | flash@ff000000 { | |
| 51 | compatible = "amd,am29lv128ml", "cfi-flash"; | |
| 52 | reg = <ff000000 01000000>; | |
| 53 | bank-width = <4>; | |
| 54 | device-width = <1>; | |
| 55 | #address-cells = <1>; | |
| 56 | #size-cells = <1>; | |
| 57 | fs@0 { | |
| 58 | label = "fs"; | |
| 59 | reg = <0 f80000>; | |
| 60 | }; | |
| 61 | firmware@f80000 { | |
| 62 | label ="firmware"; | |
| 63 | reg = <f80000 80000>; | |
| 64 | read-only; | |
| 65 | }; | |
| 66 | }; | |
| c5a88dd9 SR |
67 | |
| 68 | Here an example with multiple "reg" tuples: | |
| 69 | ||
| 70 | flash@f0000000,0 { | |
| 71 | #address-cells = <1>; | |
| 72 | #size-cells = <1>; | |
| 73 | compatible = "intel,PC48F4400P0VB", "cfi-flash"; | |
| 74 | reg = <0 0x00000000 0x02000000 | |
| 75 | 0 0x02000000 0x02000000>; | |
| 76 | bank-width = <2>; | |
| 77 | partition@0 { | |
| 78 | label = "test-part1"; | |
| 79 | reg = <0 0x04000000>; | |
| 80 | }; | |
| 81 | }; | |
| fc28c39f WS |
82 | |
| 83 | An example using SRAM: | |
| 84 | ||
| 85 | sram@2,0 { | |
| 86 | compatible = "samsung,k6f1616u6a", "mtd-ram"; | |
| 87 | reg = <2 0 0x00200000>; | |
| 88 | bank-width = <2>; | |
| 89 | }; | |
| 90 |