68 lines
2.0 KiB
Plaintext
68 lines
2.0 KiB
Plaintext
* Memory binding
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The memory binding for U-Boot is as in the ePAPR with the following additions:
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Optional subnodes can be used defining the memory layout for different board
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ID masks. To match a set of board ids, a board-id node may define match-mask
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and match-value ints to define a mask to apply to the board id, and the value
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that the result should have for the match to be considered valid. The mask
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defaults to -1, meaning that the value must fully match the board id.
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If subnodes are present, then the /memory node must define these properties:
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- #address-cells: should be 1.
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- #size-cells: should be 0.
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Each subnode must define
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reg - board ID or mask for this subnode
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memory-banks - list of memory banks in the same format as normal
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Each subnode may optionally define:
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match-mask - A mask to apply to the board id. This must be accompanied by
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match-value.
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match-value - The required resulting value of the board id mask for the given
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node to be considered a match.
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auto-size - Indicates that the value given for a bank is the maximum size,
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each bank is probed to determine its actual size, which may be
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smaller
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The board id determination is up to the vendor and is not defined by this
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binding.
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Example:
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memory {
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#address-cells = <1>;
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#size-cells = <1>;
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reg = <0x20000000 0x20000000
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0x40000000 0x20000000
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0x60000000 0x20000000
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0x80000000 0x20000000>;
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auto-size;
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board-id@0 {
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match-value = <17>;
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reg = <0x20000000 0x20000000
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0x40000000 0x20000000>;
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};
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board-id@1 {
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match-mask = <2>;
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match-value = <2>;
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reg = <0x20000000 0x20000000
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0x40000000 0x20000000
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0x60000000 0x20000000
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0x80000000 0x20000000
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0xa0000000 0x20000000
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0xc0000000 0x20000000
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0xe0000000 0x20000000>;
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};
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};
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This shows a system with the following properties:
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* Default of 2GB of memory, auto-sized, so could be smaller
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* 3.5GB of memory (with no auto-size) if (board id & 2) is 2
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* 1GB of memory (with no auto-size) if board id is 17.
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