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64 lines
2.2 KiB
Plaintext
64 lines
2.2 KiB
Plaintext
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CFI or JEDEC memory-mapped NOR flash
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Flash chips (Memory Technology Devices) are often used for solid state
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file systems on embedded devices.
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- compatible : should contain the specific model of flash chip(s)
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used, if known, followed by either "cfi-flash" or "jedec-flash"
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- reg : Address range of the flash chip
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- bank-width : Width (in bytes) of the flash bank. Equal to the
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device width times the number of interleaved chips.
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- device-width : (optional) Width of a single flash chip. If
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omitted, assumed to be equal to 'bank-width'.
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- #address-cells, #size-cells : Must be present if the flash has
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sub-nodes representing partitions (see below). In this case
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both #address-cells and #size-cells must be equal to 1.
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For JEDEC compatible devices, the following additional properties
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are defined:
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- vendor-id : Contains the flash chip's vendor id (1 byte).
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- device-id : Contains the flash chip's device id (1 byte).
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In addition to the information on the flash bank itself, the
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device tree may optionally contain additional information
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describing partitions of the flash address space. This can be
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used on platforms which have strong conventions about which
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portions of the flash are used for what purposes, but which don't
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use an on-flash partition table such as RedBoot.
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Each partition is represented as a sub-node of the flash device.
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Each node's name represents the name of the corresponding
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partition of the flash device.
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Flash partitions
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- reg : The partition's offset and size within the flash bank.
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- label : (optional) The label / name for this flash partition.
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If omitted, the label is taken from the node name (excluding
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the unit address).
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- read-only : (optional) This parameter, if present, is a hint to
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Linux that this flash partition should only be mounted
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read-only. This is usually used for flash partitions
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containing early-boot firmware images or data which should not
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be clobbered.
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Example:
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flash@ff000000 {
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compatible = "amd,am29lv128ml", "cfi-flash";
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reg = <ff000000 01000000>;
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bank-width = <4>;
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device-width = <1>;
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#address-cells = <1>;
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#size-cells = <1>;
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fs@0 {
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label = "fs";
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reg = <0 f80000>;
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};
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firmware@f80000 {
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label ="firmware";
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reg = <f80000 80000>;
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read-only;
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};
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};
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