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   "mtd-ram" or "mtd-rom".
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 - addr-gpios : (optional) List of GPIO descriptors that will be used to
33   address the MSBs address lines. The order goes from LSB to MSB.
34
35For JEDEC compatible devices, the following additional properties
36are defined:
37
38 - vendor-id : Contains the flash chip's vendor id (1 byte).
39 - device-id : Contains the flash chip's device id (1 byte).
40
41For ROM compatible devices (and ROM fallback from cfi-flash), the following
42additional (optional) property is defined:
43
44 - erase-size : The chip's physical erase block size in bytes.
45
46 The device tree may optionally contain endianness property.
47 little-endian or big-endian : It Represents the endianness that should be used
48                               by the controller to  properly read/write data
49			       from/to the flash. If this property is missing,
50			       the endianness is chosen by the system
51			       (potentially based on extra configuration options).
52
53The device tree may optionally contain sub-nodes describing partitions of the
54address space. See partition.txt for more detail.
55
56Example:
57
58	flash@ff000000 {
59		compatible = "amd,am29lv128ml", "cfi-flash";
60		reg = <ff000000 01000000>;
61		bank-width = <4>;
62		device-width = <1>;
63		#address-cells = <1>;
64		#size-cells = <1>;
65		fs@0 {
66			label = "fs";
67			reg = <0 f80000>;
68		};
69		firmware@f80000 {
70			label ="firmware";
71			reg = <f80000 80000>;
72			read-only;
73		};
74	};
75
76Here an example with multiple "reg" tuples:
77
78	flash@f0000000,0 {
79		#address-cells = <1>;
80		#size-cells = <1>;
81		compatible = "intel,PC48F4400P0VB", "cfi-flash";
82		reg = <0 0x00000000 0x02000000
83		       0 0x02000000 0x02000000>;
84		bank-width = <2>;
85		partition@0 {
86			label = "test-part1";
87			reg = <0 0x04000000>;
88		};
89	};
90
91An example using SRAM:
92
93	sram@2,0 {
94		compatible = "samsung,k6f1616u6a", "mtd-ram";
95		reg = <2 0 0x00200000>;
96		bank-width = <2>;
97	};
98
99An example using gpio-addrs
100
101	flash@20000000 {
102		#address-cells = <1>;
103		#size-cells = <1>;
104		compatible = "cfi-flash", "jedec-flash";
105		reg = <0x20000000 0x02000000>;
106		ranges = <0 0x00000000 0x02000000
107		          1 0x02000000 0x02000000>;
108		bank-width = <2>;
109		addr-gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
110		partition@0 {
111			label = "test-part1";
112			reg = <0 0x04000000>;
113		};
114	};
115