tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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 - no-unaligned-direct-access: boolean to disable the default direct
20 mapping of the flash.
21 On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause
22 problems with JFFS2 usage, as the local bus (LPB) doesn't support
23 unaligned accesses as implemented in the JFFS2 code via memcpy().
24 By defining "no-unaligned-direct-access", the flash will not be
25 exposed directly to the MTD users (e.g. JFFS2) any more.
26 - linux,mtd-name: allow to specify the mtd name for retro capability with
27 physmap-flash drivers as boot loader pass the mtd partition via the old
28 device name physmap-flash.
29 - use-advanced-sector-protection: boolean to enable support for the
30 advanced sector protection (Spansion: PPB - Persistent Protection
31 Bits) locking.
32
33For JEDEC compatible devices, the following additional properties
34are defined:
35
36 - vendor-id : Contains the flash chip's vendor id (1 byte).
37 - device-id : Contains the flash chip's device id (1 byte).
38
39The device tree may optionally contain sub-nodes describing partitions of the
40address space. See partition.txt for more detail.
41
42Example:
43
44 flash@ff000000 {
45 compatible = "amd,am29lv128ml", "cfi-flash";
46 reg = <ff000000 01000000>;
47 bank-width = <4>;
48 device-width = <1>;
49 #address-cells = <1>;
50 #size-cells = <1>;
51 fs@0 {
52 label = "fs";
53 reg = <0 f80000>;
54 };
55 firmware@f80000 {
56 label ="firmware";
57 reg = <f80000 80000>;
58 read-only;
59 };
60 };
61
62Here an example with multiple "reg" tuples:
63
64 flash@f0000000,0 {
65 #address-cells = <1>;
66 #size-cells = <1>;
67 compatible = "intel,PC48F4400P0VB", "cfi-flash";
68 reg = <0 0x00000000 0x02000000
69 0 0x02000000 0x02000000>;
70 bank-width = <2>;
71 partition@0 {
72 label = "test-part1";
73 reg = <0 0x04000000>;
74 };
75 };
76
77An example using SRAM:
78
79 sram@2,0 {
80 compatible = "samsung,k6f1616u6a", "mtd-ram";
81 reg = <2 0 0x00200000>;
82 bank-width = <2>;
83 };
84