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Tue, 18 Feb 2014 22:42:34 +0900 (KST) From: Marek Szyprowski To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org Subject: [PATCH v3 6/6] of: document bindings for reserved-memory nodes Date: Tue, 18 Feb 2014 14:38:01 +0100 Message-id: <1392730681-14695-7-git-send-email-m.szyprowski@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1392730681-14695-1-git-send-email-m.szyprowski@samsung.com> References: <1392730681-14695-1-git-send-email-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrAIsWRmVeSWpSXmKPExsVy+t9jAV2vZOZgg0en5Sz+TjrGbvGhqZXZ Yv6Rc6wW/W8Wsloc+LOD0eJNbweLxc517xgtzja9YbfY3jmD3eLLlYdMFpseX2O1WNi2hMXi 8q45bBZrj9xlt9jw8iCTxdLrF5ksFhxvYbX4M13O4tT1z2wWE6avZbFo3XuE3eLv9k0sFq8O trFYrJ/xmsVi1a4/jA6SHmvmrWH0+P1rEqPH68kTGD0u9/UyeeycdZfdo+dNC6vHplWdbB53 ru1h89i8pN7j9r/HzB5XTjSxeqz784rJo/+vgUffllWMHp83yXlsnBsaIBDFZZOSmpNZllqk b5fAlXFgfzNTwQnDiovvGlkaGA+rdzFyckgImEi8/9zFBGGLSVy4t56ti5GLQ0hgEaPEvr8z mCCcViaJSdsvgFWxCRhKdL3tYgOxRQQWMkp8nscCUsQsMJ1NYvHW92AJYQF3iftvl4PZLAKq Er3rDoA18wp4SOz5soq1i5EDaJ2CxJxJNiAmp4CnxJfrOiAVQkAVW+8/Zp7AyLuAkWEVo2hq QXJBcVJ6rqFecWJucWleul5yfu4mRnC8PZPawbiyweIQowAHoxIP7wdlpmAh1sSy4srcQ4wS HMxKIryaUczBQrwpiZVVqUX58UWlOanFhxilOViUxHkPtFoHCgmkJ5akZqemFqQWwWSZODil GhiPXtB51JhXw/XjZeOTpx48vJ+qPYV6QneejL16faFQmqVo7selWXuvuRhyyD0tLm1fmGoh XBAbtEiuIzA6coH/YdX8h1trrfgdw47sPnOU93gHt7Ch4kNePz/ea3JRbWeZlkew//JRE2j7 8FXUvySwv1Tci6/IadPKFz+2uv6trVfKfp7cpMRSnJFoqMVcVJwIAPEMtuizAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140218_084257_235645_38C7678C X-CRM114-Status: GOOD ( 18.91 ) X-Spam-Score: -4.6 (----) Cc: Mark Rutland , Laura Abbott , Pawel Moll , Arnd Bergmann , Stephen Warren , Josh Cartwright , Benjamin Herrenschmidt , Tomasz Figa , Tomasz Figa , Michal Nazarewicz , Olof Johansson , Kyungmin Park , Rob Herring , Kumar Gala , Grant Likely , Ian Campbell , Nishanth Peethambaran , Sascha Hauer , Marc , Marek Szyprowski X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,KHOP_BIG_TO_CC, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Grant Likely 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 [joshc: Based on binding document proposed (in non-patch form) here: http://lkml.kernel.org/g/20131030134702.19B57C402A0@trevor.secretlab.ca adapted to support #memory-region-cells] Signed-off-by: Josh Cartwright Signed-off-by: Marek Szyprowski --- .../bindings/reserved-memory/reserved-memory.txt | 138 ++++++++++++++++++++ 1 file changed, 138 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..a606ce90c9c4 --- /dev/null +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt @@ -0,0 +1,138 @@ +*** 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 +#memory-region-cells (required) - dictates number of cells used in the child + nodes memory-region specifier +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 ,[-] +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>; + /* ... */ + }; +};