From d524dac9279b6a41ffdf7ff7958c577f2e387db6 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Wed, 26 Jan 2011 10:10:40 -0700 Subject: dt: Move device tree documentation out of powerpc directory The device tree is used by more than just PowerPC. Make the documentation directory available to all. v2: reorganized files while moving to create arch and driver specific directories. Signed-off-by: Grant Likely Acked-by: Josh Boyer --- .../devicetree/bindings/mtd/mtd-physmap.txt | 90 ++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 Documentation/devicetree/bindings/mtd/mtd-physmap.txt (limited to 'Documentation/devicetree/bindings/mtd/mtd-physmap.txt') diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt new file mode 100644 index 0000000..80152cb --- /dev/null +++ b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt @@ -0,0 +1,90 @@ +CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...) + +Flash chips (Memory Technology Devices) are often used for solid state +file systems on embedded devices. + + - compatible : should contain the specific model of mtd chip(s) + used, if known, followed by either "cfi-flash", "jedec-flash" + or "mtd-ram". + - reg : Address range(s) of the mtd chip(s) + It's possible to (optionally) define multiple "reg" tuples so that + non-identical chips can be described in one node. + - bank-width : Width (in bytes) of the bank. Equal to the + device width times the number of interleaved chips. + - device-width : (optional) Width of a single mtd chip. If + omitted, assumed to be equal to 'bank-width'. + - #address-cells, #size-cells : Must be present if the device has + sub-nodes representing partitions (see below). In this case + both #address-cells and #size-cells must be equal to 1. + +For JEDEC compatible devices, the following additional properties +are defined: + + - vendor-id : Contains the flash chip's vendor id (1 byte). + - device-id : Contains the flash chip's device id (1 byte). + +In addition to the information on the mtd bank itself, the +device tree may optionally contain additional information +describing partitions of the address space. This can be +used on platforms which have strong conventions about which +portions of a flash are used for what purposes, but which don't +use an on-flash partition table such as RedBoot. + +Each partition is represented as a sub-node of the mtd device. +Each node's name represents the name of the corresponding +partition of the mtd device. + +Flash partitions + - reg : The partition's offset and size within the mtd bank. + - label : (optional) The label / name for this partition. + If omitted, the label is taken from the node name (excluding + the unit address). + - read-only : (optional) This parameter, if present, is a hint to + Linux that this partition should only be mounted + read-only. This is usually used for flash partitions + containing early-boot firmware images or data which should not + be clobbered. + +Example: + + flash@ff000000 { + compatible = "amd,am29lv128ml", "cfi-flash"; + reg = ; + bank-width = <4>; + device-width = <1>; + #address-cells = <1>; + #size-cells = <1>; + fs@0 { + label = "fs"; + reg = <0 f80000>; + }; + firmware@f80000 { + label ="firmware"; + reg = ; + read-only; + }; + }; + +Here an example with multiple "reg" tuples: + + flash@f0000000,0 { + #address-cells = <1>; + #size-cells = <1>; + compatible = "intel,PC48F4400P0VB", "cfi-flash"; + reg = <0 0x00000000 0x02000000 + 0 0x02000000 0x02000000>; + bank-width = <2>; + partition@0 { + label = "test-part1"; + reg = <0 0x04000000>; + }; + }; + +An example using SRAM: + + sram@2,0 { + compatible = "samsung,k6f1616u6a", "mtd-ram"; + reg = <2 0 0x00200000>; + bank-width = <2>; + }; + -- cgit v1.1