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The current DT bindings assume that the DMA will be performed by the devices through their parent DT node, and rely on that assumption for the address translation using dma-ranges. However, some SoCs have devices that will perform DMA through another bus, with separate address translation rules. We therefore need to express that relationship, through the special interconnect name "dma-mem". Acked-by: Georgi Djakov <georgi.djakov@linaro.org> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com> Signed-off-by: Rob Herring <robh@kernel.org>
65 lines
2.3 KiB
Plaintext
65 lines
2.3 KiB
Plaintext
Interconnect Provider Device Tree Bindings
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=========================================
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The purpose of this document is to define a common set of generic interconnect
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providers/consumers properties.
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= interconnect providers =
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The interconnect provider binding is intended to represent the interconnect
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controllers in the system. Each provider registers a set of interconnect
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nodes, which expose the interconnect related capabilities of the interconnect
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to consumer drivers. These capabilities can be throughput, latency, priority
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etc. The consumer drivers set constraints on interconnect path (or endpoints)
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depending on the use case. Interconnect providers can also be interconnect
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consumers, such as in the case where two network-on-chip fabrics interface
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directly.
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Required properties:
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- compatible : contains the interconnect provider compatible string
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- #interconnect-cells : number of cells in a interconnect specifier needed to
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encode the interconnect node id
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Example:
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snoc: interconnect@580000 {
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compatible = "qcom,msm8916-snoc";
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#interconnect-cells = <1>;
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reg = <0x580000 0x14000>;
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clock-names = "bus_clk", "bus_a_clk";
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clocks = <&rpmcc RPM_SMD_SNOC_CLK>,
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<&rpmcc RPM_SMD_SNOC_A_CLK>;
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};
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= interconnect consumers =
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The interconnect consumers are device nodes which dynamically express their
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bandwidth requirements along interconnect paths they are connected to. There
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can be multiple interconnect providers on a SoC and the consumer may consume
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multiple paths from different providers depending on use case and the
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components it has to interact with.
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Required properties:
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interconnects : Pairs of phandles and interconnect provider specifier to denote
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the edge source and destination ports of the interconnect path.
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Optional properties:
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interconnect-names : List of interconnect path name strings sorted in the same
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order as the interconnects property. Consumers drivers will use
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interconnect-names to match interconnect paths with interconnect
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specifier pairs.
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Reserved interconnect names:
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* dma-mem: Path from the device to the main memory of
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the system
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Example:
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sdhci@7864000 {
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...
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interconnects = <&pnoc MASTER_SDCC_1 &bimc SLAVE_EBI_CH0>;
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interconnect-names = "sdhc-mem";
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};
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