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,util-fact:		Parameter that represents the DDR utilization factor. 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. It is represented as actual
			vrail-comp * 100.
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.
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.


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.


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,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>;
        };

        mm_int_bimc: mm-int-bimc {
                cell-id = <10003>;
                label = "mm-int-bimc";
                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>;

