Binding explaining devicetree usage for enabling Root DMA capability
Signed-off-by: Ravi Shankar Jonnalagadda <[email protected]>
Signed-off-by: RaviKiran Gummaluri <[email protected]>
---
.../devicetree/bindings/dma/xilinx/ps-pcie-dma.txt | 67 ++++++++++++++++++++++
1 file changed, 67 insertions(+)
create mode 100644 Documentation/devicetree/bindings/dma/xilinx/ps-pcie-dma.txt
diff --git a/Documentation/devicetree/bindings/dma/xilinx/ps-pcie-dma.txt
b/Documentation/devicetree/bindings/dma/xilinx/ps-pcie-dma.txt
new file mode 100644
index 0000000..1522a49
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/xilinx/ps-pcie-dma.txt
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+* Xilinx PS PCIe Root DMA
+
+Required properties:
+- compatible: Should be "xlnx,ps_pcie_dma-1.00.a"
+- reg: Register offset for Root DMA channels
+- reg-names: Name for the register. Should be "xlnx,ps_pcie_regbase"
+- interrupts: Interrupt pin for Root DMA
+- interrupt-names: Name for the interrupt. Should be
"xlnx,ps_pcie_rootdma_intr"
+- interrupt-parent: Should be gic in case of zynqmp
+- xlnx,rootdma: Indicates this platform device is root dma.
+ This is required as the same platform driver will be invoked by pcie
end points too
+- xlnx,dma_vendorid: 16 bit PCIe device vendor id.
+ This can be later used by dma client for matching while using
dma_request_channel
+- xlnx,dma_deviceid: 16 bit PCIe device id
+ This can be later used by dma client for matching while using
dma_request_channel
+- xlnx,numchannels: Indicates number of channels to be enabled for the device.
+ Valid values are from 1 to 4 for zynqmp
+- xlnx,ps_pcie_channel : One for each channel to be enabled.
+ This array contains channel specific properties.
+ Index 0: Direction of channel
+ Direction of channel can be either PCIe Memory to AXI memory
i.e., Host to Card or
+ AXI Memory to PCIe memory i.e., Card to Host
+ PCIe to AXI Channel Direction is represented as 0x1
+ AXI to PCIe Channel Direction is represented as 0x0
+ Index 1: Number of Buffer Descriptors
+ This number describes number of buffer descriptors to be
allocated for a channel
+ Index 2: Number of Queues
+ Each Channel has four DMA Buffer Descriptor Queues.
+ By default All four Queues will be managed by Root DMA driver.
+ User may choose to have only two queues either Source and it's
Status Queue or
+ Destination and it's Status Queue to be handled by
Driver.
+ The other two queues need to be handled by user logic which
will not be part of this driver.
+ All Queues on Host is represented by 0x4
+ Two Queues on Host is represented by 0x2
+ Index 3: Coaelse Count
+ This number indicates the number of transfers after which
interrupt needs to
+ be raised for the particular channel. The allowed range is from
0 to 255
+ Index 4: Coaelse Count Timer frequency
+ This property is used to control the frequency of poll timer.
Poll timer is
+ created for a channel whenever coalesce count value (>= 1) is
programmed for the particular
+ channel. This timer is helpful in draining out completed
transactions even though interrupt is
+ not generated.
+
+Client Usage:
+ DMA clients can request for these channels using dma_request_channel API
+
+
+Xilinx PS PCIe Root DMA node Example
+++++++++++++++++++++++++++++++++++++
+
+ pci_rootdma: rootdma@fd0f0000 {
+ compatible = "xlnx,ps_pcie_dma-1.00.a";
+ reg = <0x0 0xfd0f0000 0x0 0x1000>;
+ reg-names = "xlnx,ps_pcie_regbase";
+ interrupts = <0 117 4>;
+ interrupt-names = "xlnx,ps_pcie_rootdma_intr";
+ interrupt-parent = <&gic>;
+ xlnx,rootdma;
+ xlnx,dma_vendorid = /bits/ 16 <0x10EE>;
+ xlnx,dma_deviceid = /bits/ 16 <0xD021>;
+ xlnx,numchannels = <0x4>;
+ #size-cells = <0x5>;
+ xlnx,ps_pcie_channel0 = <0x1 0x7CF 0x4 0x0 0x3E8>;
+ xlnx,ps_pcie_channel1 = <0x0 0x7CF 0x4 0x0 0x3E8>;
+ xlnx,ps_pcie_channel2 = <0x1 0x7CF 0x4 0x0 0x3E8>;
+ xlnx,ps_pcie_channel3 = <0x0 0x7CF 0x4 0x0 0x3E8>;
+ };
--
2.7.4
