Dump SCMI DT bindings documentation from Linux kernel source tree v5.8-rc1.
Signed-off-by: Etienne Carriere etienne.carriere@linaro.org Reviewed-by: Simon Glass sjg@chromium.org ---
No change in v4.
No change in v3.
Changes in v2: - No change but added R-b tag. - Yet a question: do we need to add this binding doc in U-Boot since already existing in Linux DT bindings docs? Related to review comment https://www.mail-archive.com/u-boot@lists.denx.de/msg377725.html --- doc/device-tree-bindings/arm/arm,scmi.txt | 197 ++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 doc/device-tree-bindings/arm/arm,scmi.txt
diff --git a/doc/device-tree-bindings/arm/arm,scmi.txt b/doc/device-tree-bindings/arm/arm,scmi.txt new file mode 100644 index 0000000000..1f293ea24c --- /dev/null +++ b/doc/device-tree-bindings/arm/arm,scmi.txt @@ -0,0 +1,197 @@ +System Control and Management Interface (SCMI) Message Protocol +---------------------------------------------------------- + +The SCMI is intended to allow agents such as OSPM to manage various functions +that are provided by the hardware platform it is running on, including power +and performance functions. + +This binding is intended to define the interface the firmware implementing +the SCMI as described in ARM document number ARM DEN 0056A ("ARM System Control +and Management Interface Platform Design Document")[0] provide for OSPM in +the device tree. + +Required properties: + +The scmi node with the following properties shall be under the /firmware/ node. + +- compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports +- mboxes: List of phandle and mailbox channel specifiers. It should contain + exactly one or two mailboxes, one for transmitting messages("tx") + and another optional for receiving the notifications("rx") if + supported. +- shmem : List of phandle pointing to the shared memory(SHM) area as per + generic mailbox client binding. +- #address-cells : should be '1' if the device has sub-nodes, maps to + protocol identifier for a given sub-node. +- #size-cells : should be '0' as 'reg' property doesn't have any size + associated with it. +- arm,smc-id : SMC id required when using smc or hvc transports + +Optional properties: + +- mbox-names: shall be "tx" or "rx" depending on mboxes entries. + +See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details +about the generic mailbox controller and client driver bindings. + +The mailbox is the only permitted method of calling the SCMI firmware. +Mailbox doorbell is used as a mechanism to alert the presence of a +messages and/or notification. + +Each protocol supported shall have a sub-node with corresponding compatible +as described in the following sections. If the platform supports dedicated +communication channel for a particular protocol, the 3 properties namely: +mboxes, mbox-names and shmem shall be present in the sub-node corresponding +to that protocol. + +Clock/Performance bindings for the clocks/OPPs based on SCMI Message Protocol +------------------------------------------------------------ + +This binding uses the common clock binding[1]. + +Required properties: +- #clock-cells : Should be 1. Contains the Clock ID value used by SCMI commands. + +Power domain bindings for the power domains based on SCMI Message Protocol +------------------------------------------------------------ + +This binding for the SCMI power domain providers uses the generic power +domain binding[2]. + +Required properties: + - #power-domain-cells : Should be 1. Contains the device or the power + domain ID value used by SCMI commands. + +Sensor bindings for the sensors based on SCMI Message Protocol +-------------------------------------------------------------- +SCMI provides an API to access the various sensors on the SoC. + +Required properties: +- #thermal-sensor-cells: should be set to 1. This property follows the + thermal device tree bindings[3]. + + Valid cell values are raw identifiers (Sensor ID) + as used by the firmware. Refer to platform details + for your implementation for the IDs to use. + +Reset signal bindings for the reset domains based on SCMI Message Protocol +------------------------------------------------------------ + +This binding for the SCMI reset domain providers uses the generic reset +signal binding[5]. + +Required properties: + - #reset-cells : Should be 1. Contains the reset domain ID value used + by SCMI commands. + +SRAM and Shared Memory for SCMI +------------------------------- + +A small area of SRAM is reserved for SCMI communication between application +processors and SCP. + +The properties should follow the generic mmio-sram description found in [4] + +Each sub-node represents the reserved area for SCMI. + +Required sub-node properties: +- reg : The base offset and size of the reserved area with the SRAM +- compatible : should be "arm,scmi-shmem" for Non-secure SRAM based + shared memory + +[0] http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/index.html +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt +[2] Documentation/devicetree/bindings/power/power-domain.yaml +[3] Documentation/devicetree/bindings/thermal/thermal.txt +[4] Documentation/devicetree/bindings/sram/sram.yaml +[5] Documentation/devicetree/bindings/reset/reset.txt + +Example: + +sram@50000000 { + compatible = "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,scmi-shmem"; + reg = <0x0 0x200>; + }; + + cpu_scp_hpri: scp-shmem@200 { + compatible = "arm,scmi-shmem"; + reg = <0x200 0x200>; + }; +}; + +mailbox@40000000 { + .... + #mbox-cells = <1>; + reg = <0x0 0x40000000 0x0 0x10000>; +}; + +firmware { + + ... + + scmi { + compatible = "arm,scmi"; + mboxes = <&mailbox 0 &mailbox 1>; + mbox-names = "tx", "rx"; + shmem = <&cpu_scp_lpri &cpu_scp_hpri>; + #address-cells = <1>; + #size-cells = <0>; + + scmi_devpd: protocol@11 { + reg = <0x11>; + #power-domain-cells = <1>; + }; + + scmi_dvfs: protocol@13 { + reg = <0x13>; + #clock-cells = <1>; + }; + + scmi_clk: protocol@14 { + reg = <0x14>; + #clock-cells = <1>; + }; + + scmi_sensors0: protocol@15 { + reg = <0x15>; + #thermal-sensor-cells = <1>; + }; + + scmi_reset: protocol@16 { + reg = <0x16>; + #reset-cells = <1>; + }; + }; +}; + +cpu@0 { + ... + reg = <0 0>; + clocks = <&scmi_dvfs 0>; +}; + +hdlcd@7ff60000 { + ... + reg = <0 0x7ff60000 0 0x1000>; + clocks = <&scmi_clk 4>; + power-domains = <&scmi_devpd 1>; + resets = <&scmi_reset 10>; +}; + +thermal-zones { + soc_thermal { + polling-delay-passive = <100>; + polling-delay = <1000>; + /* sensor ID */ + thermal-sensors = <&scmi_sensors0 3>; + ... + }; +};