summaryrefslogtreecommitdiff
path: root/Documentation/devicetree/bindings/mtd/mtd-physmap.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/devicetree/bindings/mtd/mtd-physmap.txt')
-rw-r--r--Documentation/devicetree/bindings/mtd/mtd-physmap.txt90
1 files changed, 90 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt
new file mode 100644
index 000000000000..80152cb567d9
--- /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 = <ff000000 01000000>;
+ bank-width = <4>;
+ device-width = <1>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ fs@0 {
+ label = "fs";
+ reg = <0 f80000>;
+ };
+ firmware@f80000 {
+ label ="firmware";
+ reg = <f80000 80000>;
+ 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>;
+ };
+