Add documentation for the Qualcomm Technologies HIDMA driver. Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx> --- .../devicetree/bindings/dma/qcom_hidma_mgmt.txt | 79 ++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt diff --git a/Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt b/Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt new file mode 100644 index 0000000..0e6ed1f --- /dev/null +++ b/Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt @@ -0,0 +1,79 @@ +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 parititioned +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 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. A memcpy requested is + fragmented to multiples of this amount. +- max-read-burst-bytes: Maximum read burst in bytes. A memcpy request is + fragmented to multiples of this amount. +- max-write-transactions: Maximum write transactions to perform in a burst +- max-read-transactions: Maximum read transactions to perform in a burst +- channel-reset-timeout-cycles: Channel reset timeout in cycles for this SOC. + +Sub-nodes: + +HIDMA has one or more DMA channels that are used to move data from one +memory location to another. + +Each DMA channel is described as a sub-node under the management object. +When a transfer channel is given to the guest operating system, only the channel +object is created. The drivers have support for both flat and hierarchical +configuration. + +Required properties: +- compatible: must contain "qcom,hidma-1.0" +- reg: Addresses for the transfer and event channel +- interrupts: Should contain the event interrupt +- desc-count: Number of asynchronous requests this channel can handle +- channel-index: The HW event channel completions will be delivered. + +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@0x5c050000 { + compatible = "qcom,hidma-1.0"; + reg = <0 0x5c050000 0x0 0x1000>, + <0 0x5c0b0000 0x0 0x1000>; + interrupts = <0 389 0>; + desc-count = <10>; + channel-index = <4>; + }; + }; + +Guest OS configuration: + + hidma_24: dma-controller@0x5c050000 { + compatible = "qcom,hidma-1.0"; + reg = <0 0x5c050000 0x0 0x1000>, + <0 0x5c0b0000 0x0 0x1000>; + interrupts = <0 389 0>; + desc-count = <10>; + channel-index = <4>; + }; -- Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html