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