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239 lines
7.0 KiB
239 lines
7.0 KiB
System Control and Management Interface (SCMI) Message Protocol |
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---------------------------------------------------------- |
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The SCMI is intended to allow agents such as OSPM to manage various functions |
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that are provided by the hardware platform it is running on, including power |
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and performance functions. |
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This binding is intended to define the interface the firmware implementing |
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the SCMI as described in ARM document number ARM DEN 0056A ("ARM System Control |
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and Management Interface Platform Design Document")[0] provide for OSPM in |
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the device tree. |
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Required properties: |
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The scmi node with the following properties shall be under the /firmware/ node. |
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- compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports |
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- mboxes: List of phandle and mailbox channel specifiers. It should contain |
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exactly one or two mailboxes, one for transmitting messages("tx") |
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and another optional for receiving the notifications("rx") if |
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supported. |
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- shmem : List of phandle pointing to the shared memory(SHM) area as per |
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generic mailbox client binding. |
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- #address-cells : should be '1' if the device has sub-nodes, maps to |
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protocol identifier for a given sub-node. |
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- #size-cells : should be '0' as 'reg' property doesn't have any size |
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associated with it. |
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- arm,smc-id : SMC id required when using smc or hvc transports |
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Optional properties: |
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- mbox-names: shall be "tx" or "rx" depending on mboxes entries. |
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- interrupts : when using smc or hvc transports, this optional |
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property indicates that msg completion by the platform is indicated |
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by an interrupt rather than by the return of the smc call. This |
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should not be used except when the platform requires such behavior. |
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- interrupt-names : if "interrupts" is present, interrupt-names must also |
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be present and have the value "a2p". |
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See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details |
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about the generic mailbox controller and client driver bindings. |
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The mailbox is the only permitted method of calling the SCMI firmware. |
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Mailbox doorbell is used as a mechanism to alert the presence of a |
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messages and/or notification. |
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Each protocol supported shall have a sub-node with corresponding compatible |
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as described in the following sections. If the platform supports dedicated |
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communication channel for a particular protocol, the 3 properties namely: |
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mboxes, mbox-names and shmem shall be present in the sub-node corresponding |
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to that protocol. |
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Clock/Performance bindings for the clocks/OPPs based on SCMI Message Protocol |
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------------------------------------------------------------ |
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This binding uses the common clock binding[1]. |
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Required properties: |
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- #clock-cells : Should be 1. Contains the Clock ID value used by SCMI commands. |
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Power domain bindings for the power domains based on SCMI Message Protocol |
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------------------------------------------------------------ |
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This binding for the SCMI power domain providers uses the generic power |
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domain binding[2]. |
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Required properties: |
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- #power-domain-cells : Should be 1. Contains the device or the power |
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domain ID value used by SCMI commands. |
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Regulator bindings for the SCMI Regulator based on SCMI Message Protocol |
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------------------------------------------------------------ |
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An SCMI Regulator is permanently bound to a well defined SCMI Voltage Domain, |
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and should be always positioned as a root regulator. |
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It does not support any current operation. |
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SCMI Regulators are grouped under a 'regulators' node which in turn is a child |
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of the SCMI Voltage protocol node inside the desired SCMI instance node. |
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This binding uses the common regulator binding[6]. |
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Required properties: |
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- reg : shall identify an existent SCMI Voltage Domain. |
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Sensor bindings for the sensors based on SCMI Message Protocol |
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-------------------------------------------------------------- |
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SCMI provides an API to access the various sensors on the SoC. |
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Required properties: |
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- #thermal-sensor-cells: should be set to 1. This property follows the |
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thermal device tree bindings[3]. |
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Valid cell values are raw identifiers (Sensor ID) |
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as used by the firmware. Refer to platform details |
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for your implementation for the IDs to use. |
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Reset signal bindings for the reset domains based on SCMI Message Protocol |
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------------------------------------------------------------ |
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This binding for the SCMI reset domain providers uses the generic reset |
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signal binding[5]. |
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Required properties: |
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- #reset-cells : Should be 1. Contains the reset domain ID value used |
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by SCMI commands. |
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SRAM and Shared Memory for SCMI |
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------------------------------- |
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A small area of SRAM is reserved for SCMI communication between application |
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processors and SCP. |
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The properties should follow the generic mmio-sram description found in [4] |
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Each sub-node represents the reserved area for SCMI. |
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Required sub-node properties: |
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- reg : The base offset and size of the reserved area with the SRAM |
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- compatible : should be "arm,scmi-shmem" for Non-secure SRAM based |
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shared memory |
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[0] http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/index.html |
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[1] Documentation/devicetree/bindings/clock/clock-bindings.txt |
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[2] Documentation/devicetree/bindings/power/power-domain.yaml |
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[3] Documentation/devicetree/bindings/thermal/thermal*.yaml |
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[4] Documentation/devicetree/bindings/sram/sram.yaml |
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[5] Documentation/devicetree/bindings/reset/reset.txt |
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[6] Documentation/devicetree/bindings/regulator/regulator.yaml |
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Example: |
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sram@50000000 { |
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compatible = "mmio-sram"; |
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reg = <0x0 0x50000000 0x0 0x10000>; |
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#address-cells = <1>; |
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#size-cells = <1>; |
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ranges = <0 0x0 0x50000000 0x10000>; |
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cpu_scp_lpri: scp-shmem@0 { |
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compatible = "arm,scmi-shmem"; |
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reg = <0x0 0x200>; |
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}; |
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cpu_scp_hpri: scp-shmem@200 { |
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compatible = "arm,scmi-shmem"; |
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reg = <0x200 0x200>; |
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}; |
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}; |
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mailbox@40000000 { |
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.... |
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#mbox-cells = <1>; |
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reg = <0x0 0x40000000 0x0 0x10000>; |
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}; |
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firmware { |
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... |
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scmi { |
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compatible = "arm,scmi"; |
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mboxes = <&mailbox 0 &mailbox 1>; |
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mbox-names = "tx", "rx"; |
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shmem = <&cpu_scp_lpri &cpu_scp_hpri>; |
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#address-cells = <1>; |
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#size-cells = <0>; |
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scmi_devpd: protocol@11 { |
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reg = <0x11>; |
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#power-domain-cells = <1>; |
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}; |
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scmi_dvfs: protocol@13 { |
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reg = <0x13>; |
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#clock-cells = <1>; |
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}; |
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scmi_clk: protocol@14 { |
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reg = <0x14>; |
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#clock-cells = <1>; |
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}; |
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scmi_sensors0: protocol@15 { |
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reg = <0x15>; |
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#thermal-sensor-cells = <1>; |
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}; |
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scmi_reset: protocol@16 { |
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reg = <0x16>; |
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#reset-cells = <1>; |
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}; |
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scmi_voltage: protocol@17 { |
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reg = <0x17>; |
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regulators { |
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regulator_devX: regulator@0 { |
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reg = <0x0>; |
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regulator-max-microvolt = <3300000>; |
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}; |
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regulator_devY: regulator@9 { |
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reg = <0x9>; |
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regulator-min-microvolt = <500000>; |
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regulator-max-microvolt = <4200000>; |
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}; |
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... |
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}; |
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}; |
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}; |
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}; |
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cpu@0 { |
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... |
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reg = <0 0>; |
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clocks = <&scmi_dvfs 0>; |
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}; |
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hdlcd@7ff60000 { |
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... |
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reg = <0 0x7ff60000 0 0x1000>; |
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clocks = <&scmi_clk 4>; |
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power-domains = <&scmi_devpd 1>; |
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resets = <&scmi_reset 10>; |
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}; |
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thermal-zones { |
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soc_thermal { |
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polling-delay-passive = <100>; |
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polling-delay = <1000>; |
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/* sensor ID */ |
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thermal-sensors = <&scmi_sensors0 3>; |
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... |
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}; |
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};
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