dt-bindings: introduce RPMH RSC bindings for Qualcomm SoCs

Add device binding documentation for Qualcomm Technology Inc's RPMH RSC
driver. The driver is used for communicating resource state requests for
shared resources.

Cc: devicetree@vger.kernel.org
Signed-off-by: NLina Iyer <ilina@codeaurora.org>
Reviewed-by: NRob Herring <robh@kernel.org>
[rplsssn@codeaurora.org: minor order correction for TCS type]
Signed-off-by: NRaju P.L.S.S.S.N <rplsssn@codeaurora.org>
Signed-off-by: NAndy Gross <andy.gross@linaro.org>

Documentation/devicetree/bindings/soc/qcom/rpmh-rsc.txt

+RPMH RSC:
+------------
+
+Resource Power Manager Hardened (RPMH) is the mechanism for communicating with
+the hardened resource accelerators on Qualcomm SoCs. Requests to the resources
+can be written to the Trigger Command Set (TCS)  registers and using a (addr,
+val) pair and triggered. Messages in the TCS are then sent in sequence over an
+internal bus.
+
+The hardware block (Direct Resource Voter or DRV) is a part of the h/w entity
+(Resource State Coordinator a.k.a RSC) that can handle multiple sleep and
+active/wake resource requests. Multiple such DRVs can exist in a SoC and can
+be written to from Linux. The structure of each DRV follows the same template
+with a few variations that are captured by the properties here.
+
+A TCS may be triggered from Linux or triggered by the F/W after all the CPUs
+have powered off to facilitate idle power saving. TCS could be classified as -
+
+	ACTIVE  /* Triggered by Linux */
+	SLEEP   /* Triggered by F/W */
+	WAKE    /* Triggered by F/W */
+	CONTROL /* Triggered by F/W */
+
+The order in which they are described in the DT, should match the hardware
+configuration.
+
+Requests can be made for the state of a resource, when the subsystem is active
+or idle. When all subsystems like Modem, GPU, CPU are idle, the resource state
+will be an aggregate of the sleep votes from each of those subsystems. Clients
+may request a sleep value for their shared resources in addition to the active
+mode requests.
+
+Properties:
+
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: Should be "qcom,rpmh-rsc".
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: The first register specifies the base address of the
+		    DRV(s). The number of DRVs in the dependent on the RSC.
+	            The tcs-offset specifies the start address of the
+	            TCS in the DRVs.
+
+- reg-names:
+	Usage: required
+	Value type: <string>
+	Definition: Maps the register specified in the reg property. Must be
+	            "drv-0", "drv-1", "drv-2" etc and "tcs-offset". The
+
+- interrupts:
+	Usage: required
+	Value type: <prop-encoded-interrupt>
+	Definition: The interrupt that trips when a message complete/response
+	           is received for this DRV from the accelerators.
+
+- qcom,drv-id:
+	Usage: required
+	Value type: <u32>
+	Definition: The id of the DRV in the RSC block that will be used by
+		    this controller.
+
+- qcom,tcs-config:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: The tuple defining the configuration of TCS.
+	            Must have 2 cells which describe each TCS type.
+	            <type number_of_tcs>.
+	            The order of the TCS must match the hardware
+	            configuration.
+	- Cell #1 (TCS Type): TCS types to be specified -
+	            ACTIVE_TCS
+	            SLEEP_TCS
+	            WAKE_TCS
+	            CONTROL_TCS
+	- Cell #2 (Number of TCS): <u32>
+
+- label:
+	Usage: optional
+	Value type: <string>
+	Definition: Name for the RSC. The name would be used in trace logs.
+
+Drivers that want to use the RSC to communicate with RPMH must specify their
+bindings as child nodes of the RSC controllers they wish to communicate with.
+
+Example 1:
+
+For a TCS whose RSC base address is is 0x179C0000 and is at a DRV id of 2, the
+register offsets for DRV2 start at 0D00, the register calculations are like
+this -
+DRV0: 0x179C0000
+DRV2: 0x179C0000 + 0x10000 = 0x179D0000
+DRV2: 0x179C0000 + 0x10000 * 2 = 0x179E0000
+TCS-OFFSET: 0xD00
+
+	apps_rsc: rsc@179c0000 {
+		label = "apps_rsc";
+		compatible = "qcom,rpmh-rsc";
+		reg = <0x179c0000 0x10000>,
+		      <0x179d0000 0x10000>,
+		      <0x179e0000 0x10000>;
+		reg-names = "drv-0", "drv-1", "drv-2";
+		interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>;
+		qcom,tcs-offset = <0xd00>;
+		qcom,drv-id = <2>;
+		qcom,tcs-config = <ACTIVE_TCS  2>,
+				  <SLEEP_TCS   3>,
+				  <WAKE_TCS    3>,
+				  <CONTROL_TCS 1>;
+	};
+
+Example 2:
+
+For a TCS whose RSC base address is 0xAF20000 and is at DRV id of 0, the
+register offsets for DRV0 start at 01C00, the register calculations are like
+this -
+DRV0: 0xAF20000
+TCS-OFFSET: 0x1C00
+
+	disp_rsc: rsc@af20000 {
+		label = "disp_rsc";
+		compatible = "qcom,rpmh-rsc";
+		reg = <0xaf20000 0x10000>;
+		reg-names = "drv-0";
+		interrupts = <GIC_SPI 129 IRQ_TYPE_LEVEL_HIGH>;
+		qcom,tcs-offset = <0x1c00>;
+		qcom,drv-id = <0>;
+		qcom,tcs-config = <ACTIVE_TCS  0>,
+				  <SLEEP_TCS   1>,
+				  <WAKE_TCS    1>,
+				  <CONTROL_TCS 0>;
+	};