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author | Arnd Bergmann <arnd@arndb.de> | 2015-10-14 17:07:32 +0200 |
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committer | Arnd Bergmann <arnd@arndb.de> | 2015-10-14 17:07:32 +0200 |
commit | c049adc9fd2937562b4880bdc35b8303ff56d425 (patch) | |
tree | f75d32289b1053b3e65cb0e7d330079bee2c9a9b /Documentation | |
parent | 273395f0c2973b96a35772f8aa3b65c25517a45d (diff) | |
parent | 68acc77a2d5197141ba376fd8872eccb43bfcd7d (diff) | |
download | linux-stable-c049adc9fd2937562b4880bdc35b8303ff56d425.tar.gz linux-stable-c049adc9fd2937562b4880bdc35b8303ff56d425.tar.bz2 linux-stable-c049adc9fd2937562b4880bdc35b8303ff56d425.zip |
Merge tag 'arm-scpi-for-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into next/drivers
Merge "ARM System Control and Power Interface(SCPI) support" from Sudeep Holla
It adds support for the following features provided by SCP firmware
using different subsystems in Linux:
1. SCPI mailbox protocol driver which using mailbox framework
2. Clocks provided by SCP using clock framework
3. CPU DVFS(cpufreq) using existing arm-big-little driver
4. SCPI based sensors including temperature sensors
* tag 'arm-scpi-for-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
hwmon: Support thermal zones registration for SCP temperature sensors
hwmon: Support sensors exported via ARM SCP interface
firmware: arm_scpi: Extend to support sensors
Documentation: add DT bindings for ARM SCPI sensors
cpufreq: arm_big_little: add SCPI interface driver
clk: scpi: add support for cpufreq virtual device
clk: add support for clocks provided by SCP(System Control Processor)
firmware: add support for ARM System Control and Power Interface(SCPI) protocol
Documentation: add DT binding for ARM System Control and Power Interface(SCPI) protocol
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/devicetree/bindings/arm/arm,scpi.txt | 188 | ||||
-rw-r--r-- | Documentation/hwmon/scpi-hwmon | 33 |
2 files changed, 221 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/arm,scpi.txt b/Documentation/devicetree/bindings/arm/arm,scpi.txt new file mode 100644 index 000000000000..86302de67c2c --- /dev/null +++ b/Documentation/devicetree/bindings/arm/arm,scpi.txt @@ -0,0 +1,188 @@ +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. diff --git a/Documentation/hwmon/scpi-hwmon b/Documentation/hwmon/scpi-hwmon new file mode 100644 index 000000000000..4cfcdf2d5eab --- /dev/null +++ b/Documentation/hwmon/scpi-hwmon @@ -0,0 +1,33 @@ +Kernel driver scpi-hwmon +======================== + +Supported chips: + * Chips based on ARM System Control Processor Interface + Addresses scanned: - + Datasheet: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0922b/index.html + +Author: Punit Agrawal <punit.agrawal@arm.com> + +Description +----------- + +This driver supports hardware monitoring for SoC's based on the ARM +System Control Processor (SCP) implementing the System Control +Processor Interface (SCPI). The following sensor types are supported +by the SCP - + + * temperature + * voltage + * current + * power + +The SCP interface provides an API to query the available sensors and +their values which are then exported to userspace by this driver. + +Usage Notes +----------- + +The driver relies on device tree node to indicate the presence of SCPI +support in the kernel. See +Documentation/devicetree/bindings/arm/arm,scpi.txt for details of the +devicetree node.
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