dt-bindings: firmware: arm,scpi: Convert to json schema

Convert the old text format binding for System Control and Power Interface
(SCPI) Message Protocol into the new and shiny YAML format.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20210604205710.1944363-3-sudeep.holla@arm.com
[robh: Move fixed strings to 'properties', drop some literal block notations]
Signed-off-by: Rob Herring <robh@kernel.org>
This commit is contained in:
Sudeep Holla 2021-06-04 21:57:06 +01:00 committed by Rob Herring
parent e837220a27
commit 1496be7194
3 changed files with 226 additions and 205 deletions

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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" : For implementations complying to SCPI v1.0 or above
* "arm,scpi-pre-1.0" : For implementations complying to all
unversioned releases prior to SCPI v1.0
- 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.
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 details
for your implementation for the IDs to use.
Power domain bindings for the power domains based on SCPI Message Protocol
------------------------------------------------------------
This binding uses the generic power domain binding[4].
PM domain providers
===================
Required properties:
- #power-domain-cells : Should be 1. Contains the device or the power
domain ID value used by SCPI commands.
- num-domains: Total number of power domains provided by SCPI. This is
needed as the SCPI message protocol lacks a mechanism to
query this information at runtime.
PM domain consumers
===================
Required properties:
- power-domains : A phandle and PM domain specifier as defined by bindings of
the power controller specified by phandle.
[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*.yaml
[3] Documentation/devicetree/bindings/sram/sram.yaml
[4] Documentation/devicetree/bindings/power/power-domain.yaml
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>;
};
scpi_devpd: scpi-power-domains {
compatible = "arm,scpi-power-domains";
num-domains = <2>;
#power-domain-cells = <1>;
};
};
cpu@0 {
...
reg = <0 0>;
clocks = <&scpi_dvfs 0>;
};
hdlcd@7ff60000 {
...
reg = <0 0x7ff60000 0 0x1000>;
clocks = <&scpi_clk 4>;
power-domains = <&scpi_devpd 1>;
};
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.
The num-domains property in scpi-power-domains domain specifies that
SCPI provides 2 power domains. The hdlcd node uses the power domain with
domain ID 1.

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# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
# Copyright 2021 ARM Ltd.
%YAML 1.2
---
$id: http://devicetree.org/schemas/firmware/arm,scpi.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: System Control and Power Interface (SCPI) Message Protocol bindings
maintainers:
- Sudeep Holla <sudeep.holla@arm.com>
description: |
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.
This binding is intended to define the interface the firmware implementing
the SCPI provide for OSPM in the device tree.
[0] http://infocenter.arm.com/help/topic/com.arm.doc.dui0922b/index.html
properties:
$nodename:
const: scpi
compatible:
description:
SCPI compliant firmware complying to SCPI v1.0 and above OR
SCPI compliant firmware complying to all unversioned releases
prior to SCPI v1.0
oneOf:
- const: arm,scpi # SCPI v1.0 and above
- const: arm,scpi-pre-1.0 # Unversioned SCPI before v1.0
mboxes:
description:
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.
minItems: 1
shmem:
description:
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.
minItems: 1
power-controller:
type: object
description:
This sub-node represents SCPI power domain controller.
properties:
compatible:
const: arm,scpi-power-domains
'#power-domain-cells':
const: 1
num-domains:
$ref: /schemas/types.yaml#/definitions/uint32
description:
Total number of power domains provided by SCPI. This is needed as
the SCPI message protocol lacks a mechanism to query this
information at runtime.
required:
- compatible
- '#power-domain-cells'
- num-domains
additionalProperties: false
sensors:
type: object
description: |
This sub-node represents SCPI sensors controller.
properties:
compatible:
const: arm,scpi-sensors
'#thermal-sensor-cells':
const: 1
required:
- compatible
- '#thermal-sensor-cells'
additionalProperties: false
clocks:
type: object
description:
This is the container node. Each sub-node represents one of the types
of clock controller - indexed or full range.
properties:
compatible:
const: arm,scpi-clocks
patternProperties:
"^clocks-[0-9a-f]+$":
type: object
description: |
This sub-node represents one of the types of clock controller
- indexed or full range.
"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.
properties:
compatible:
oneOf:
- const: arm,scpi-dvfs-clocks
- const: arm,scpi-variable-clocks
'#clock-cells':
const: 1
clock-output-names: true
clock-indices:
$ref: /schemas/types.yaml#/definitions/uint32-array
description:
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.
required:
- compatible
- '#clock-cells'
- clock-output-names
- clock-indices
additionalProperties: false
required:
- compatible
additionalProperties: false
additionalProperties: false
required:
- compatible
- mboxes
- shmem
examples:
- |
firmware {
scpi {
compatible = "arm,scpi";
mboxes = <&mhuA 1>;
shmem = <&cpu_scp_hpri>; /* HP-NonSecure */
scpi_devpd: power-controller {
compatible = "arm,scpi-power-domains";
num-domains = <2>;
#power-domain-cells = <1>;
};
clocks {
compatible = "arm,scpi-clocks";
scpi_dvfs: clocks-0 {
compatible = "arm,scpi-dvfs-clocks";
#clock-cells = <1>;
clock-indices = <0>, <1>, <2>;
clock-output-names = "atlclk", "aplclk","gpuclk";
};
scpi_clk: clocks-1 {
compatible = "arm,scpi-variable-clocks";
#clock-cells = <1>;
clock-indices = <3>, <4>;
clock-output-names = "pxlclk0", "pxlclk1";
};
};
scpi_sensors: sensors {
compatible = "arm,scpi-sensors";
#thermal-sensor-cells = <1>;
};
};
};
soc {
#address-cells = <2>;
#size-cells = <2>;
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-sram-section@0 {
compatible = "arm,scp-shmem";
reg = <0x0 0x200>;
};
cpu_scp_hpri: scp-sram-section@200 {
compatible = "arm,scp-shmem";
reg = <0x200 0x200>;
};
};
};
...

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@ -17696,7 +17696,7 @@ M: Sudeep Holla <sudeep.holla@arm.com>
R: Cristian Marussi <cristian.marussi@arm.com>
L: linux-arm-kernel@lists.infradead.org
S: Maintained
F: Documentation/devicetree/bindings/arm/arm,sc[mp]i.txt
F: Documentation/devicetree/bindings/firmware/arm,sc[mp]i.yaml
F: drivers/clk/clk-sc[mp]i.c
F: drivers/cpufreq/sc[mp]i-cpufreq.c
F: drivers/firmware/arm_scmi/