diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt new file mode 100644 index 000000000000..3da0ebdba8d9 --- /dev/null +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt @@ -0,0 +1,133 @@ +*** Reserved memory regions *** + +Reserved memory is specified as a node under the /reserved-memory node. +The operating system shall exclude reserved memory from normal usage +one can create child nodes describing particular reserved (excluded from +normal use) memory regions. Such memory regions are usually designed for +the special usage by various device drivers. + +Parameters for each memory region can be encoded into the device tree +with the following nodes: + +/reserved-memory node +--------------------- +#address-cells, #size-cells (required) - standard definition + - Should use the same values as the root node +ranges (required) - standard definition + - Should be empty + +/reserved-memory/ child nodes +----------------------------- +Each child of the reserved-memory node specifies one or more regions of +reserved memory. Each child node may either use a 'reg' property to +specify a specific range of reserved memory, or a 'size' property with +optional constraints to request a dynamically allocated block of memory. + +Following the generic-names recommended practice, node names should +reflect the purpose of the node (ie. "framebuffer" or "dma-pool"). Unit +address (@
) should be appended to the name if the node is a +static allocation. + +Properties: +Requires either a) or b) below. +a) static allocation + reg (required) - standard definition +b) dynamic allocation + size (required) - length based on parent's #size-cells + - Size in bytes of memory to reserve. + alignment (optional) - length based on parent's #size-cells + - Address boundary for alignment of allocation. + alloc-ranges (optional) - prop-encoded-array (address, length pairs). + - Specifies regions of memory that are + acceptable to allocate from. + +If both reg and size are present, then the reg property takes precedence +and size is ignored. + +Additional properties: +compatible (optional) - standard definition + - may contain the following strings: + - shared-dma-pool: This indicates a region of memory meant to be + used as a shared pool of DMA buffers for a set of devices. It can + be used by an operating system to instanciate the necessary pool + management subsystem if necessary. + - vendor specific string in the form