Keystone Navigator DMA Controller
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This document explains the device tree bindings for the packet dma
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on keystone devices. The Keystone Navigator DMA driver sets up the dma
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channels and flows for the QMSS(Queue Manager SubSystem) who triggers
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the actual data movements across clients using destination queues. Every
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client modules like NETCP(Network Coprocessor), SRIO(Serial Rapid IO),
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CRYPTO Engines etc has its own instance of dma hardware. QMSS has also
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an internal packet DMA module which is used as an infrastructure DMA
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with zero copy.
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Navigator DMA cloud layout:
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------------------
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| Navigator DMAs |
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------------------
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|-> DMA instance #0
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|-> DMA instance #1
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.
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.
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|-> DMA instance #n
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Navigator DMA properties:
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Required properties:
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- compatible: Should be "ti,keystone-navigator-dma"
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- clocks: phandle to dma instances clocks. The clock handles can be as
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many as the dma instances. The order should be maintained as per
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the dma instances.
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- ti,navigator-cloud-address: Should contain base address for the multi-core
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navigator cloud and number of addresses depends on SOC integration
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configuration.. Navigator cloud global address needs to be programmed
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into DMA and the DMA uses it as the physical addresses to reach queue
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managers. Note that these addresses though points to queue managers,
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they are relevant only from DMA perspective. The QMSS may not choose to
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use them since it has a different address space view to reach all
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its components.
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DMA instance properties:
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Required properties:
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- reg: Should contain register location and length of the following dma
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register regions. Register regions should be specified in the following
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order.
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- Global control register region (global).
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- Tx DMA channel configuration register region (txchan).
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- Rx DMA channel configuration register region (rxchan).
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- Tx DMA channel Scheduler configuration register region (txsched).
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- Rx DMA flow configuration register region (rxflow).
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Optional properties:
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- reg-names: Names for the register regions.
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- ti,enable-all: Enable all DMA channels vs clients opening specific channels
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what they need. This property is useful for the userspace fast path
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case where the linux drivers enables the channels used by userland
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stack.
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- ti,loop-back: To loopback Tx streaming I/F to Rx streaming I/F. Used for
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infrastructure transfers.
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- ti,rx-retry-timeout: Number of dma cycles to wait before retry on buffer
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starvation.
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Example:
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knav_dmas: knav_dmas@0 {
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compatible = "ti,keystone-navigator-dma";
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clocks = <&papllclk>, <&clkxge>;
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#address-cells = <1>;
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#size-cells = <1>;
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ranges;
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ti,navigator-cloud-address = <0x23a80000 0x23a90000
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0x23aa0000 0x23ab0000>;
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dma_gbe: dma_gbe@0 {
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reg = <0x2004000 0x100>,
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<0x2004400 0x120>,
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<0x2004800 0x300>,
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<0x2004c00 0x120>,
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<0x2005000 0x400>;
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reg-names = "global", "txchan", "rxchan",
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"txsched", "rxflow";
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};
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dma_xgbe: dma_xgbe@0 {
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reg = <0x2fa1000 0x100>,
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<0x2fa1400 0x200>,
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<0x2fa1800 0x200>,
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<0x2fa1c00 0x200>,
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<0x2fa2000 0x400>;
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reg-names = "global", "txchan", "rxchan",
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"txsched", "rxflow";
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};
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};
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Navigator DMA client:
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Required properties:
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- ti,navigator-dmas: List of one or more DMA specifiers, each consisting of
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- A phandle pointing to DMA instance node
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- A DMA channel number as a phandle arg.
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- ti,navigator-dma-names: Contains dma channel name for each DMA specifier in
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the 'ti,navigator-dmas' property.
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Example:
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netcp: netcp@2090000 {
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..
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ti,navigator-dmas = <&dma_gbe 22>,
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<&dma_gbe 23>,
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<&dma_gbe 8>;
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ti,navigator-dma-names = "netrx0", "netrx1", "nettx";
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..
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};
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