On Jul 31, 2013, at 7:51 AM, Marek Szyprowski wrote:
Add device tree support for contiguous and reserved memory regions defined in device tree. Initialization is done in 2 steps. First, the memory is reserved, what happens very early when only flattened device tree is available. Then on device initialization the corresponding cma and reserved regions are assigned to each device structure.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Acked-by: Kyungmin Park kyungmin.park@samsung.com
Documentation/devicetree/bindings/memory.txt | 152 ++++++++++++++++++++++ drivers/of/Kconfig | 6 + drivers/of/Makefile | 1 + drivers/of/of_reserved_mem.c | 175 ++++++++++++++++++++++++++ include/asm-generic/dma-coherent.h | 6 + 5 files changed, 340 insertions(+) create mode 100644 Documentation/devicetree/bindings/memory.txt create mode 100644 drivers/of/of_reserved_mem.c
diff --git a/Documentation/devicetree/bindings/memory.txt b/Documentation/devicetree/bindings/memory.txt new file mode 100644 index 0000000..4aece19 --- /dev/null +++ b/Documentation/devicetree/bindings/memory.txt @@ -0,0 +1,152 @@ +*** 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 folllowing node:
+memory {
- reg = <(baseaddr1) (size1)
(baseaddr2) (size2)...(baseaddrN) (sizeN)>;+};
+baseaddrX: the 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 additional 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 +wit the following convention:
+[(label):] (name)@(address) {
- compatible = "contiguous-memory-region", "reserved-memory-region";
- reg = <(address) (size)>;
- (linux,contiguous-region);
- (linux,default-contiguous-region);
+};
+label: label given to the defined region (optional) +name: an name given to the defined region +address: the base address of the defined region +size: the size of the memory region
Should we try and convey some type of cacheability attributes, I know this is difficult to do in a generic way, but would seem useful and necessary.
+compatible: "contiguous-memory-region" - enables binding of this
region to Contiguous Memory Allocator (special region forcontiguous memory allocations, shared with movable systemmemory, Linux kernel-specific), alternatively if"reserved-memory-region" - compatibility is defined, givenregion is assigned for exclusive usage for DMA transfers+linux,default-contiguous-region: property indicating that the region
is the default region for all contiguous memoryallocations, Linux specific (optional)+Each defined region must use unique name. It is optional to specify the +base address, so if one wants to use autoconfiguration of the base +address, he must specify the '0' as base address in the 'reg' property +and assign ann uniqe name to such regions.
+*** Device node's properties ***
+Once the regions in the /memory/reserved-memory node are defined, they +can be assigned to device nodes to enable drivers for their special use. +The following properties are defined:
+dma-memory-region = <&phandle_to_defined_region>;
Should we go with just 'memory-region' to be more generic? An example might be a region of memory used for multiprocessor communication that isn't cache-able.
+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 scaller@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.
+/ {
- /* ... */
- memory {
reg = <0x40000000 0x100000000x50000000 0x100000000x60000000 0x100000000x70000000 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 = "contiguous-memory-region";reg = <0x0 0x4000000>;linux,default-contiguous-region;};/** special region for framebuffer*/display_mem: region@78000000 {compatible = "contiguous-memory-region", "reserved-memory-region";reg = <0x78000000 0x800000>;};/** special region for multimedia processing devices*/multimedia_mem: region@77000000 {compatible = "contiguous-memory-region";reg = <0x77000000 0x4000000>;};};- };
- /* ... */
- fb0: fb@12300000 {
status = "okay";dma-memory-region = <&display_mem>;- };
- scaller: scaller@12500000 {
status = "okay";dma-memory-region = <&multimedia_mem>;- };
- codec: codec@12600000 {
status = "okay";dma-memory-region = <&multimedia_mem>;- };
+};
- k
-- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation