Documentation/devicetree/bindings/mtd/mtd-physmap.txt

   1 CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...)
   2
   3 Flash chips (Memory Technology Devices) are often used for solid state
   4 file 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
  30 For JEDEC compatible devices, the following additional properties
  31 are defined:
  32
  33  - vendor-id : Contains the flash chip's vendor id (1 byte).
  34  - device-id : Contains the flash chip's device id (1 byte).
  35
  36 The device tree may optionally contain sub-nodes describing partitions of the
  37 address space. See partition.txt for more detail.
  38
  39 Example:
  40
  41         flash@ff000000 {
  42                 compatible = "amd,am29lv128ml", "cfi-flash";
  43                 reg = <ff000000 01000000>;
  44                 bank-width = <4>;
  45                 device-width = <1>;
  46                 #address-cells = <1>;
  47                 #size-cells = <1>;
  48                 fs@0 {
  49                         label = "fs";
  50                         reg = <0 f80000>;
  51                 };
  52                 firmware@f80000 {
  53                         label ="firmware";
  54                         reg = <f80000 80000>;
  55                         read-only;
  56                 };
  57         };
  58
  59 Here an example with multiple "reg" tuples:
  60
  61         flash@f0000000,0 {
  62                 #address-cells = <1>;
  63                 #size-cells = <1>;
  64                 compatible = "intel,PC48F4400P0VB", "cfi-flash";
  65                 reg = <0 0x00000000 0x02000000
  66                        0 0x02000000 0x02000000>;
  67                 bank-width = <2>;
  68                 partition@0 {
  69                         label = "test-part1";
  70                         reg = <0 0x04000000>;
  71                 };
  72         };
  73
  74 An example using SRAM:
  75
  76         sram@2,0 {
  77                 compatible = "samsung,k6f1616u6a", "mtd-ram";
  78                 reg = <2 0 0x00200000>;
  79                 bank-width = <2>;
  80         };
  81