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authorLinus Torvalds <torvalds@linux-foundation.org>2013-10-15 17:14:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-10-15 17:14:13 -0700
commit34ec4de42be5006abdd8d0c08b306ffaa64d0d5d (patch)
treec5fe826846f5bf532e56e1e39ee789047a700d59 /Documentation
parentba0a062ef55a6f8e8361a63ee48e654879ba00bf (diff)
parent1931ee143b0ab72924944bc06e363d837ba05063 (diff)
downloadlinux-linaro-stable-34ec4de42be5006abdd8d0c08b306ffaa64d0d5d.tar.gz
Merge tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux
Pull device tree fixes and reverts from Grant Likely: "One bug fix and three reverts. The reverts back out the slightly controversial feeding the entire device tree into the random pool and the reserved-memory binding which isn't fully baked yet. Expect the reserved-memory patches at least to resurface for v3.13. The bug fixes removes a scary but harmless warning on SPARC that was introduced in the v3.12 merge window. v3.13 will contain a proper fix that makes the new code work on SPARC. On the plus side, the diffstat looks *awesome*. I love removing lines of code" * tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux: Revert "drivers: of: add initialization code for dma reserved memory" Revert "ARM: init: add support for reserved memory defined by device tree" Revert "of: Feed entire flattened device tree into the random pool" of: fix unnecessary warning on missing /cpus node
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/memory.txt168
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diff --git a/Documentation/devicetree/bindings/memory.txt b/Documentation/devicetree/bindings/memory.txt
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-*** Memory binding ***
-
-The /memory node provides basic information about the address and size
-of the physical memory. This node is usually filled or updated by the
-bootloader, depending on the actual memory configuration of the given
-hardware.
-
-The memory layout is described by the following node:
-
-/ {
- #address-cells = <(n)>;
- #size-cells = <(m)>;
- memory {
- device_type = "memory";
- reg = <(baseaddr1) (size1)
- (baseaddr2) (size2)
- ...
- (baseaddrN) (sizeN)>;
- };
- ...
-};
-
-A memory node follows the typical device tree rules for "reg" property:
-n: number of cells used to store base address value
-m: number of cells used to store size value
-baseaddrX: defines a base address of the defined memory bank
-sizeX: the size of the defined memory bank
-
-
-More than one memory bank can be defined.
-
-
-*** Reserved memory regions ***
-
-In /memory/reserved-memory node 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. A good example are contiguous memory allocations or
-memory sharing with other operating system on the same hardware board.
-Those special memory regions might depend on the board configuration and
-devices used on the target system.
-
-Parameters for each memory region can be encoded into the device tree
-with the following convention:
-
-[(label):] (name) {
- compatible = "linux,contiguous-memory-region", "reserved-memory-region";
- reg = <(address) (size)>;
- (linux,default-contiguous-region);
-};
-
-compatible: one or more of:
- - "linux,contiguous-memory-region" - enables binding of this
- region to Contiguous Memory Allocator (special region for
- contiguous memory allocations, shared with movable system
- memory, Linux kernel-specific).
- - "reserved-memory-region" - compatibility is defined, given
- region is assigned for exclusive usage for by the respective
- devices.
-
-reg: standard property defining the base address and size of
- the memory region
-
-linux,default-contiguous-region: property indicating that the region
- is the default region for all contiguous memory
- allocations, Linux specific (optional)
-
-It is optional to specify the base address, so if one wants to use
-autoconfiguration of the base address, '0' can be specified as a base
-address in the 'reg' property.
-
-The /memory/reserved-memory node must contain the same #address-cells
-and #size-cells value as the root node.
-
-
-*** Device node's properties ***
-
-Once regions in the /memory/reserved-memory node have been defined, they
-may be referenced by other device nodes. Bindings that wish to reference
-memory regions should explicitly document their use of the following
-property:
-
-memory-region = <&phandle_to_defined_region>;
-
-This property indicates that the device driver should use the memory
-region pointed by the given phandle.
-
-
-*** Example ***
-
-This example defines a memory consisting of 4 memory banks. 3 contiguous
-regions are defined for Linux kernel, one default of all device drivers
-(named contig_mem, placed at 0x72000000, 64MiB), one dedicated to the
-framebuffer device (labelled display_mem, placed at 0x78000000, 8MiB)
-and one for multimedia processing (labelled multimedia_mem, placed at
-0x77000000, 64MiB). 'display_mem' region is then assigned to fb@12300000
-device for DMA memory allocations (Linux kernel drivers will use CMA is
-available or dma-exclusive usage otherwise). 'multimedia_mem' is
-assigned to scaler@12500000 and codec@12600000 devices for contiguous
-memory allocations when CMA driver is enabled.
-
-The reason for creating a separate region for framebuffer device is to
-match the framebuffer base address to the one configured by bootloader,
-so once Linux kernel drivers starts no glitches on the displayed boot
-logo appears. Scaller and codec drivers should share the memory
-allocations.
-
-/ {
- #address-cells = <1>;
- #size-cells = <1>;
-
- /* ... */
-
- memory {
- reg = <0x40000000 0x10000000
- 0x50000000 0x10000000
- 0x60000000 0x10000000
- 0x70000000 0x10000000>;
-
- reserved-memory {
- #address-cells = <1>;
- #size-cells = <1>;
-
- /*
- * global autoconfigured region for contiguous allocations
- * (used only with Contiguous Memory Allocator)
- */
- contig_region@0 {
- compatible = "linux,contiguous-memory-region";
- reg = <0x0 0x4000000>;
- linux,default-contiguous-region;
- };
-
- /*
- * special region for framebuffer
- */
- display_region: region@78000000 {
- compatible = "linux,contiguous-memory-region", "reserved-memory-region";
- reg = <0x78000000 0x800000>;
- };
-
- /*
- * special region for multimedia processing devices
- */
- multimedia_region: region@77000000 {
- compatible = "linux,contiguous-memory-region";
- reg = <0x77000000 0x4000000>;
- };
- };
- };
-
- /* ... */
-
- fb0: fb@12300000 {
- status = "okay";
- memory-region = <&display_region>;
- };
-
- scaler: scaler@12500000 {
- status = "okay";
- memory-region = <&multimedia_region>;
- };
-
- codec: codec@12600000 {
- status = "okay";
- memory-region = <&multimedia_region>;
- };
-};