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Diffstat (limited to 'Documentation/devicetree/bindings/mtd/mtd-physmap.txt')
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diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt new file mode 100644 index 000000000..4a0a48bf4 --- /dev/null +++ b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt @@ -0,0 +1,89 @@ +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", + "mtd-ram" or "mtd-rom". + - 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. + - no-unaligned-direct-access: boolean to disable the default direct + mapping of the flash. + On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause + problems with JFFS2 usage, as the local bus (LPB) doesn't support + unaligned accesses as implemented in the JFFS2 code via memcpy(). + By defining "no-unaligned-direct-access", the flash will not be + exposed directly to the MTD users (e.g. JFFS2) any more. + - linux,mtd-name: allow to specify the mtd name for retro capability with + physmap-flash drivers as boot loader pass the mtd partition via the old + device name physmap-flash. + - use-advanced-sector-protection: boolean to enable support for the + advanced sector protection (Spansion: PPB - Persistent Protection + Bits) locking. + +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). + +For ROM compatible devices (and ROM fallback from cfi-flash), the following +additional (optional) property is defined: + + - erase-size : The chip's physical erase block size in bytes. + +The device tree may optionally contain sub-nodes describing partitions of the +address space. See partition.txt for more detail. + +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>; + }; + |