232 lines
10 KiB
Plaintext
232 lines
10 KiB
Plaintext
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MSM Bus Devices for adhoc bus topologies
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Buses are the interconnects between various devices. The devices are
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connected in different topologies. The bus scaling driver accepts
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bandwidth requests from clients and ensures that the bandwidth requests
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can be met between the source and destination for that client.
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In order to accept and honor bandwidth requests the bus scaling driver
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needs to know about the bus topology.
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This device tree binding represents the bus devices in the SOC, their
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connections to other bus devices and the resources associated with each
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node. The bus scaling driver uses this device tree to setup the bus
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topology in order to apply client bandwidth requests.
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The mandatory properties for bus driver are:
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compatible: "qcom,msm-bus-device"
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The register space associated with the bus devices are represented with
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the following optional properties:
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reg: Register space for a bus device.
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reg-name: Name of the register space for the bus device.
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The child nodes represent the devices on the bus.
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The following properties are mandatory for a child node
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cell-id: The unique device id of the child node.
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For a master the ID is between 0 - 512
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For a slave the ID is between 512 - 1024
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For internal nodes the range is > 10000
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The range of ids for the different types of child
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devices are chosen for convenience, the only
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requirement is that the id's be unique among the
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child devices.
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label: Unique name of the device.
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The following are optional properties for child nodes:
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qcom,fab-dev: Optional boolean parameter that states if the device
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is a fabric device or not.
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Typically these optional properties are used for
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devices that represent fabric devices.
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qcom,bypass-qos-prg: Optional debug parameter to avoid programming the QoS
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HW registers for a given fabric device.
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Typically these optional properties are used for
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devices that represent fabric devices.
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qcom,base-name: Parameter that specifies the physical base address for
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accessing registers associated with the child device.
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Typically these optional properties are used for
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devices that represent fabric devices.
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qcom,base-offset: Parameter that gives the offset from the base address to access
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the QoS registers.
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Typically these optional properties are used for
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devices that represent fabric devices.
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qcom,qos-off: Parameter that represents the delta between QoS register address
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space for different devices.
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Typically these optional properties are used for
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devices that represent fabric devices.
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qcom,agg-scheme: Parameter that represents the aggregation scheme to be used for the
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node. This parameter defaults to LEGACY scheme. The valid options
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are LEGACY/SCHEME_1.
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qcom,util-fact: Parameter that represents the DDR utilization factor to be used in
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LEGACY scheme. It is represented as actual util-factor * 100.
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qcom,vrail-comp: Parameter that represents the voltage rail compensation to push
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the bus to the next level if needed in LEGACY and SCHEME 1 aggregation
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schemes. It is represented as actual vrail-comp * 100.
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qcom,util-levels: Array of tuples that represent a bandwidth threshold and util factor
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to be used uptil the given threshold.
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qcom,bus-type: Parameter that represents the bus type such as BIMC or NOC.
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Typically these optional properties are used for
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devices that represent fabric devices.
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bus-gdsc-supply: Optional fabric device parameter that is a reference to the dual
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context GDSC supply that is needed before clock operations.
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bus-a-gdsc-supply: Optional fabric device parameter that is a reference to an active
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only context GDSC supply that is needed before clock operations.
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bus-qos-gdsc-supply: Optional node or fabric device parameter that is a reference to a GDSC
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supply that is needed before use of the clock needed to program
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QoS registers.
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node-gdsc-supply: Optional node device parameter that is a reference to a GDSC supply
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that is needed before node-clock operations.
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qcom,enable-only-clk: Optional property that is represents if the clock doesn't support
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the clk_set_rate API and should only be enabled/disabled.
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qcom,setrate-only-clk: Optional property that is indicates that bus driver should only
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set a rate on a clock handle and not call the enable/disable
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clock API.
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clock-names: Optional property that represents the clock name associated
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with the device "bus_clk", "bus_a_clk";
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clocks: Property pair that represents the clock controller and the clock
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id. This in combimination with the clock-name is used to obtain
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the handle for the clock associated with this device.
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qcom,virt-dev: Parameter used for devices that represent virtual devices. Virtual
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devices aren't real devices on the SOC but are used to aggregate
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resources in some special cases.
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qcom,qport: The offset index into the masters QoS register space.
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qcom,num-ports: The number of ports that the device has.
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qcom,ap-owned: Property that states if the device is "owned" by the Apps processor.
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If true then the AP will program the QoS registers for the device
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else it is done by RPM.
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qcom,connections: An array of phandles that represent the devices this device is connected to.;
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qcom,bus-dev: Phandle that represents the fabric device that this child node belongs to.
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qcom,qos-mode: QoS mode to be programmed for this device, only applicable for AP owned resource.
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qcom,prio-rd: Read priority for a BIMC bus master (Can be 0/1/2)
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qcom,prio-wr: Write priority for a BIMC bus master (Can be 0/1/2)
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qcom,prio0: Priority low signal for a NoC bus master
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(Can be 0/1/2).
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qcom,reg-prio1: Regulator mode Priority high signal for a NoC bus master if the master port is in
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regulator QoS mode
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qcom,reg-prio0: Regulator Priority low signal for a NoC bus master if the master port is in
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regulator Qos mode.
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(Can be 0/1/2).
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qcom,prio1: Priority high signal for a NoC bus master
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qcom,bw_buffer: Optional parameter in KBytes used to specify a buffer value that should be added to
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the voted bandwidth value to figure out the limiting bandwidth for a master port.
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qcom,buswidth: The buswidth at the device, default is 8 bytes.
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qcom,mas-rpm-id: For non-AP owned device this is the RPM id for devices that are bus masters.
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This is the id that is used when sending a message to RPM for this device.
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qcom,slv-rpm-id: For non-AP owned device this is the RPM id for devices that are bus slaves.
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This is the id that is used when sending a message to RPM for this device.
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qcom,blacklist: An array of phandles that represent devices that this device
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cannot connect to either directly or via any number of
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intermediate nodes.
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qcom,agg-ports: The number of aggregation ports on the bus.
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The following properties are optional as collecting data via coresight might
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and are present on child nodes that represent NOC devices. The documentation
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for coresight properties can be found in:
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Documentation/devicetree/bindings/coresight/coresight.txt
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coreisght-id Unique integer identifier for the bus.
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coresight-name Unique descriptive name of the bus.
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coresight-nr-inports Number of input ports on the bus.
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coresight-outports List of output port numbers on the bus.
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coresight-child-list List of phandles pointing to the children of this
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component.
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coresight-child-ports List of input port numbers of the children.
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The following sub-nodes are optional paramters:
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qcom,node-qos-clks: Optional node listing all the clocks and regulators required for programming of
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QoS registers. Usually these are associated with fabric nodes.
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clock-names: An array of clock names for QoS programming,
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clocks: An array of clock phandles corresponding to the clock names listed above.
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clock-name-gdsc:
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An optional property listing the regulator associated with a given clock name.
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Example:
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&ad_hoc_bus {
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compatible = "msm-bus-device";
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reg = <0x580000 0x62000>;
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reg-names = "snoc-base";
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fab_snoc: fab-snoc {
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cell-id = <1024>;
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label = "fab-snoc";
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qcom,fab-dev;
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qcom,bypass-qos-prg;
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qcom,agg-scheme = <SCHEME_1>;
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qcom,util-levels = <450000 133>,
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<750000 154>;
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qcom,base-name = "snoc-base";
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qcom,base-offset = <0x7000>;
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qcom,qos-off = <0x1000>;
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qcom,bus-type = <1>;
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clock-names = "bus_clk", "bus_a_clk";
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clocks = <&clock_rpm clk_snoc_msmbus_clk>,
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<&clock_rpm clk_snoc_msmbus_a_clk>;
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qcom,node-qos-clks {
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clock-names = "q0-clk", "q1-clk";
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clocks = <&clock_gcc clk_q0_clk>,
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<&clock_gcc clk_q1_clk>;
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q0-clk-supply = <&gdsc_q0_clk>;
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};
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};
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mm_int_bimc: mm-int-bimc {
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cell-id = <10003>;
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label = "mm-int-bimc";
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qcom,util-fact = <154>;
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qcom,vrail-comp = <100>;
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qcom,ap-owned;
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qcom,connections = <&snoc_bimc_1_mas>;
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qcom,bus-dev = <&fab_snoc>;
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qcom,buswidth = <16>;
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};
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snoc_int_0: snoc-int-0 {
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cell-id = <10004>;
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label = "snoc-int-0";
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qcom,connections = <&slv_qdss_stm &slv_imem &snoc_pnoc_mas>;
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qcom,bus-dev = <&fab_snoc>;
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qcom,mas-rpm-id = <99>;
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qcom,slv-rpm-id = <130>;
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qcom,buswidth = <8>;
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};
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};
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The bus scaling driver also provides the ability to configure
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bus performance parameters across the entire chip-set.
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Various clients use MSM scaling APIs to request bandwidth
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between multiple master-slave pairs. The bus driver then finds
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the optimal path between the master and the slave, and aggregates
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the bandwidth and clock requests for all master-slave pairs on
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that path, and programs hardware accordingly.
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The device-tree data required for bus-scaling can be embedded within
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the clients' device nodes. The clients can register with the bus driver
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using the following properties:
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- qcom,msm-bus,name: String representing the client-name
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- qcom,msm-bus,num-cases: Total number of usecases
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- qcom,msm-bus,active-only: Boolean context flag for requests in active or
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dual (active & sleep) contex
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- qcom,msm-bus,num-paths: Total number of master-slave pairs
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- qcom,msm-bus,vectors-KBps: Arrays of unsigned integers representing:
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master-id, slave-id, arbitrated bandwidth
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in KBps, instantaneous bandwidth in KBps
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Example:
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qcom,msm-bus,name = "client-name";
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qcom,msm-bus,num-cases = <3>;
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qcom,msm-bus,active-only;
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qcom,msm-bus,num-paths = <2>;
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qcom,msm-bus,vectors =
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<22 512 0 0>, <26 512 0 0>,
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<22 512 320000 3200000>, <26 512 3200000 3200000>,
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<22 512 160000 1600000>, <26 512 1600000 1600000>;
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