On Fri, 28 Feb 2014 14:42:46 +0100, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > From: Grant Likely <grant.likely@xxxxxxxxxx> > > Reserved memory nodes allow for the reservation of static (fixed > address) regions, or dynamically allocated regions for a specific > purpose. > > Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxx> > [joshc: Based on binding document proposed (in non-patch form) here: > http://lkml.kernel.org/g/20131030134702.19B57C402A0@xxxxxxxxxxxxxxxxxxx > adapted to support #memory-region-cells] > Signed-off-by: Josh Cartwright <joshc@xxxxxxxxxxxxxx> > [mszyprow: removed #memory-region-cells property] > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Merged, thanks. g. > --- > .../bindings/reserved-memory/reserved-memory.txt | 136 ++++++++++++++++++++ > 1 file changed, 136 insertions(+) > create mode 100644 Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > > 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..8b0d747a38e7 > --- /dev/null > +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > @@ -0,0 +1,136 @@ > +*** 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 (@<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 <vendor>,[<device>-]<usage> > +no-map (optional) - empty property > + - Indicates the operating system must not create a virtual mapping > + of the region as part of its standard mapping of system memory, > + nor permit speculative access to it under any circumstances other > + than under the control of the device driver using the region. > +reusable (optional) - empty property > + - The operating system can use the memory in this region with the > + limitation that the device driver(s) owning the region need to be > + able to reclaim it back. Typically that means that the operating > + system can use that region to store volatile or cached data that > + can be otherwise regenerated or migrated elsewhere. > + > +Linux implementation note: > +- If a "linux,cma-default" property is present, then Linux will use the > + region for the default pool of the contiguous memory allocator. > + > +Device node references to reserved memory > +----------------------------------------- > +Regions in the /reserved-memory node may be referenced by other device > +nodes by adding a memory-region property to the device node. > + > +memory-region (optional) - phandle, specifier pairs to children of /reserved-memory > + > +Example > +------- > +This example defines 3 contiguous regions are defined for Linux kernel: > +one default of all device drivers (named linux,cma@72000000 and 64MiB in size), > +one dedicated to the framebuffer device (named framebuffer@78000000, 8MiB), and > +one for multimedia processing (named multimedia-memory@77000000, 64MiB). > + > +/ { > + #address-cells = <1>; > + #size-cells = <1>; > + > + memory { > + reg = <0x40000000 0x40000000>; > + }; > + > + reserved-memory { > + #address-cells = <1>; > + #size-cells = <1>; > + ranges; > + > + /* global autoconfigured region for contiguous allocations */ > + linux,cma { > + compatible = "shared-dma-pool"; > + reusable; > + #memory-region-cells = <0>; > + size = <0x4000000>; > + alignment = <0x2000>; > + linux,cma-default; > + }; > + > + display_reserved: framebuffer@78000000 { > + #memory-region-cells = <0>; > + reg = <0x78000000 0x800000>; > + }; > + > + multimedia_reserved: multimedia@77000000 { > + compatible = "acme,multimedia-memory"; > + #memory-region-cells = <1>; > + reg = <0x77000000 0x4000000>; > + }; > + }; > + > + /* ... */ > + > + fb0: video@12300000 { > + memory-region = <&display_reserved>; > + /* ... */ > + }; > + > + scaler: scaler@12500000 { > + memory-region = <&multimedia_reserved 0xdeadbeef>; > + /* ... */ > + }; > + > + codec: codec@12600000 { > + memory-region = <&multimedia_reserved 0xfeebdaed>; > + /* ... */ > + }; > +}; > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
