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1CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...)
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 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)
10 It's possible to (optionally) define multiple "reg" tuples so that
11 non-identical chips can be described in one node.
12 - bank-width : Width (in bytes) of the bank. Equal to the
13 device width times the number of interleaved chips.
14 - device-width : (optional) Width of a single mtd chip. If
15 omitted, assumed to be equal to 'bank-width'.
16 - #address-cells, #size-cells : Must be present if the device has
17 sub-nodes representing partitions (see below). In this case
18 both #address-cells and #size-cells must be equal to 1.
19
20For JEDEC compatible devices, the following additional properties
21are 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
26In addition to the information on the mtd bank itself, the
27device tree may optionally contain additional information
28describing partitions of the address space. This can be
29used on platforms which have strong conventions about which
30portions of a flash are used for what purposes, but which don't
31use an on-flash partition table such as RedBoot.
32
33Each partition is represented as a sub-node of the mtd device.
34Each node's name represents the name of the corresponding
35partition of the mtd device.
36
37Flash partitions
38 - reg : The partition's offset and size within the mtd bank.
39 - label : (optional) The label / name for this partition.
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
43 Linux that this partition should only be mounted
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
48Example:
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 };
67
68Here 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 };
82
83An 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