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-Qualcomm Technologies HIDMA Management interface
-
-Qualcomm Technologies HIDMA is a high speed DMA device. It only supports
-memcpy and memset capabilities. It has been designed for virtualized
-environments.
-
-Each HIDMA HW instance consists of multiple DMA channels. These channels
-share the same bandwidth. The bandwidth utilization can be partitioned
-among channels based on the priority and weight assignments.
-
-There are only two priority levels and 15 weigh assignments possible.
-
-Other parameters here determine how much of the system bus this HIDMA
-instance can use like maximum read/write request and number of bytes to
-read/write in a single burst.
-
-Main node required properties:
-- compatible: "qcom,hidma-mgmt-1.0";
-- reg: Address range for DMA device
-- dma-channels: Number of channels supported by this DMA controller.
-- max-write-burst-bytes: Maximum write burst in bytes that HIDMA can
- occupy the bus for in a single transaction. A memcpy requested is
- fragmented to multiples of this amount. This parameter is used while
- writing into destination memory. Setting this value incorrectly can
- starve other peripherals in the system.
-- max-read-burst-bytes: Maximum read burst in bytes that HIDMA can
- occupy the bus for in a single transaction. A memcpy request is
- fragmented to multiples of this amount. This parameter is used while
- reading the source memory. Setting this value incorrectly can starve
- other peripherals in the system.
-- max-write-transactions: This value is how many times a write burst is
- applied back to back while writing to the destination before yielding
- the bus.
-- max-read-transactions: This value is how many times a read burst is
- applied back to back while reading the source before yielding the bus.
-- channel-reset-timeout-cycles: Channel reset timeout in cycles for this SOC.
- Once a reset is applied to the HW, HW starts a timer for reset operation
- to confirm. If reset is not completed within this time, HW reports reset
- failure.
-
-Sub-nodes:
-
-HIDMA has one or more DMA channels that are used to move data from one
-memory location to another.
-
-When the OS is not in control of the management interface (i.e. it's a guest),
-the channel nodes appear on their own, not under a management node.
-
-Required properties:
-- compatible: must contain "qcom,hidma-1.0" for initial HW or
- "qcom,hidma-1.1"/"qcom,hidma-1.2" for MSI capable HW.
-- reg: Addresses for the transfer and event channel
-- interrupts: Should contain the event interrupt
-- desc-count: Number of asynchronous requests this channel can handle
-- iommus: required a iommu node
-
-Optional properties for MSI:
-- msi-parent : See the generic MSI binding described in
- devicetree/bindings/interrupt-controller/msi.txt for a description of the
- msi-parent property.
-
-Example:
-
-Hypervisor OS configuration:
-
- hidma-mgmt@f9984000 = {
- compatible = "qcom,hidma-mgmt-1.0";
- reg = <0xf9984000 0x15000>;
- dma-channels = <6>;
- max-write-burst-bytes = <1024>;
- max-read-burst-bytes = <1024>;
- max-write-transactions = <31>;
- max-read-transactions = <31>;
- channel-reset-timeout-cycles = <0x500>;
-
- hidma_24: dma-controller@5c050000 {
- compatible = "qcom,hidma-1.0";
- reg = <0 0x5c050000 0x0 0x1000>,
- <0 0x5c0b0000 0x0 0x1000>;
- interrupts = <0 389 0>;
- desc-count = <10>;
- iommus = <&system_mmu>;
- };
- };
-
-Guest OS configuration:
-
- hidma_24: dma-controller@5c050000 {
- compatible = "qcom,hidma-1.0";
- reg = <0 0x5c050000 0x0 0x1000>,
- <0 0x5c0b0000 0x0 0x1000>;
- interrupts = <0 389 0>;
- desc-count = <10>;
- iommus = <&system_mmu>;
- };