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