--- /dev/null
+System Control and Power Interface (SCPI) Message Protocol
+----------------------------------------------------------
+
+Firmware implementing the SCPI described in ARM document number ARM DUI 0922B
+("ARM Compute Subsystem SCP: Message Interface Protocols")[0] can be used
+by Linux to initiate various system control and power operations.
+
+Required properties:
+
+- compatible : should be "arm,scpi"
+- mboxes: List of phandle and mailbox channel specifiers
+ All the channels reserved by remote SCP firmware for use by
+ SCPI message protocol should be specified in any order
+- shmem : List of phandle pointing to the shared memory(SHM) area between the
+ processors using these mailboxes for IPC, one for each mailbox
+ SHM can be any memory reserved for the purpose of this communication
+ between the processors.
+
+See Documentation/devicetree/bindings/mailbox/mailbox.txt
+for more details about the generic mailbox controller and
+client driver bindings.
+
+Clock bindings for the clocks based on SCPI Message Protocol
+------------------------------------------------------------
+
+This binding uses the common clock binding[1].
+
+Container Node
+==============
+Required properties:
+- compatible : should be "arm,scpi-clocks"
+ All the clocks provided by SCP firmware via SCPI message
+ protocol much be listed as sub-nodes under this node.
+
+Sub-nodes
+=========
+Required properties:
+- compatible : shall include one of the following
+ "arm,scpi-dvfs-clocks" - all the clocks that are variable and index based.
+ These clocks don't provide an entire range of values between the
+ limits but only discrete points within the range. The firmware
+ provides the mapping for each such operating frequency and the
+ index associated with it. The firmware also manages the
+ voltage scaling appropriately with the clock scaling.
+ "arm,scpi-variable-clocks" - all the clocks that are variable and provide full
+ range within the specified range. The firmware provides the
+ range of values within a specified range.
+
+Other required properties for all clocks(all from common clock binding):
+- #clock-cells : Should be 1. Contains the Clock ID value used by SCPI commands.
+- clock-output-names : shall be the corresponding names of the outputs.
+- clock-indices: The identifying number for the clocks(i.e.clock_id) in the
+ node. It can be non linear and hence provide the mapping of identifiers
+ into the clock-output-names array.
+
+SRAM and Shared Memory for SCPI
+-------------------------------
+
+A small area of SRAM is reserved for SCPI communication between application
+processors and SCP.
+
+Required properties:
+- compatible : should be "arm,juno-sram-ns" for Non-secure SRAM on Juno
+
+The rest of the properties should follow the generic mmio-sram description
+found in ../../misc/sysram.txt
+
+Each sub-node represents the reserved area for SCPI.
+
+Required sub-node properties:
+- reg : The base offset and size of the reserved area with the SRAM
+- compatible : should be "arm,juno-scp-shmem" for Non-secure SRAM based
+ shared memory on Juno platforms
+
+Sensor bindings for the sensors based on SCPI Message Protocol
+--------------------------------------------------------------
+SCPI provides an API to access the various sensors on the SoC.
+
+Required properties:
+- compatible : should be "arm,scpi-sensors".
+- #thermal-sensor-cells: should be set to 1. This property follows the
+ thermal device tree bindings[2].
+
+ Valid cell values are raw identifiers (Sensor
+ ID) as used by the firmware. Refer to
+ platform documentation for your
+ implementation for the IDs to use. For Juno
+ R0 and Juno R1 refer to [3].
+
+[0] http://infocenter.arm.com/help/topic/com.arm.doc.dui0922b/index.html
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/thermal/thermal.txt
+[3] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/apas03s22.html
+
+Example:
+
+sram: sram@50000000 {
+ compatible = "arm,juno-sram-ns", "mmio-sram";
+ reg = <0x0 0x50000000 0x0 0x10000>;
+
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0x0 0x50000000 0x10000>;
+
+ cpu_scp_lpri: scp-shmem@0 {
+ compatible = "arm,juno-scp-shmem";
+ reg = <0x0 0x200>;
+ };
+
+ cpu_scp_hpri: scp-shmem@200 {
+ compatible = "arm,juno-scp-shmem";
+ reg = <0x200 0x200>;
+ };
+};
+
+mailbox: mailbox0@40000000 {
+ ....
+ #mbox-cells = <1>;
+};
+
+scpi_protocol: scpi@2e000000 {
+ compatible = "arm,scpi";
+ mboxes = <&mailbox 0 &mailbox 1>;
+ shmem = <&cpu_scp_lpri &cpu_scp_hpri>;
+
+ clocks {
+ compatible = "arm,scpi-clocks";
+
+ scpi_dvfs: scpi_clocks@0 {
+ compatible = "arm,scpi-dvfs-clocks";
+ #clock-cells = <1>;
+ clock-indices = <0>, <1>, <2>;
+ clock-output-names = "atlclk", "aplclk","gpuclk";
+ };
+ scpi_clk: scpi_clocks@3 {
+ compatible = "arm,scpi-variable-clocks";
+ #clock-cells = <1>;
+ clock-indices = <3>, <4>;
+ clock-output-names = "pxlclk0", "pxlclk1";
+ };
+ };
+
+ scpi_sensors0: sensors {
+ compatible = "arm,scpi-sensors";
+ #thermal-sensor-cells = <1>;
+ };
+};
+
+cpu@0 {
+ ...
+ reg = <0 0>;
+ clocks = <&scpi_dvfs 0>;
+};
+
+hdlcd@7ff60000 {
+ ...
+ reg = <0 0x7ff60000 0 0x1000>;
+ clocks = <&scpi_clk 4>;
+};
+
+thermal-zones {
+ soc_thermal {
+ polling-delay-passive = <100>;
+ polling-delay = <1000>;
+
+ /* sensor ID */
+ thermal-sensors = <&scpi_sensors0 3>;
+ ...
+ };
+};
+
+In the above example, the #clock-cells is set to 1 as required.
+scpi_dvfs has 3 output clocks namely: atlclk, aplclk, and gpuclk with 0,
+1 and 2 as clock-indices. scpi_clk has 2 output clocks namely: pxlclk0
+and pxlclk1 with 3 and 4 as clock-indices.
+
+The first consumer in the example is cpu@0 and it has '0' as the clock
+specifier which points to the first entry in the output clocks of
+scpi_dvfs i.e. "atlclk".
+
+Similarly the second example is hdlcd@7ff60000 and it has pxlclk1 as input
+clock. '4' in the clock specifier here points to the second entry
+in the output clocks of scpi_clocks i.e. "pxlclk1"
+
+The thermal-sensors property in the soc_thermal node uses the
+temperature sensor provided by SCP firmware to setup a thermal
+zone. The ID "3" is the sensor identifier for the temperature sensor
+as used by the firmware.
Code Review / kvmfornfv.git / blobdiff