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author | Arnd Bergmann <arnd@arndb.de> | 2018-03-07 16:45:07 +0100 |
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committer | Arnd Bergmann <arnd@arndb.de> | 2018-03-07 16:45:07 +0100 |
commit | f46f11dc1e86270935041fbc3920ba71a050a5fd (patch) | |
tree | e049f00eb27f573e2f3d90d379554c869f6469c3 /Documentation | |
parent | 819d38e95f8ac3fb2e26e42e5c3f19d95a07c847 (diff) | |
parent | 02f208c5c60549039445402505dea284e15f0f4f (diff) | |
download | linux-f46f11dc1e86270935041fbc3920ba71a050a5fd.tar.gz linux-f46f11dc1e86270935041fbc3920ba71a050a5fd.tar.bz2 linux-f46f11dc1e86270935041fbc3920ba71a050a5fd.zip |
Merge tag 'scmi-updates-4.17' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into next/drivers
Pull "ARM SCMI support for v4.17" from Sudeep Holla:
ARM System Control and Management Interface(SCMI)[1] is more flexible and
easily extensible than any of the existing interfaces.
Few existing as well as future ARM platforms provide micro-controllers
to abstract various power and other system management tasks which have
similar interfaces, both in terms of the functions that are provided by
them, and in terms of how requests are communicated to them.
There are quite a few protocols like ARM SCPI, TI SCI, QCOM RPM, Nvidia Tegra
BPMP, and so on already. This specification is to standardize and avoid any
further fragmentation in the design of such interface by various vendors.
The current SCMI driver implementation is very basic and initial support.
It lacks support for notifications, asynchronous/delayed response, perf/power
statistics region and sensor register region.
Mailbox is the only form of transport supported currently in the driver.
SCMI supports interrupt based mailbox communication, where, on completion
of the processing of a message, the caller receives an interrupt as well as
polling for completion.
SCMI is designed to minimize the dependency on the mailbox/transport
hardware. So in terms of SCMI, each channel in the mailbox includes
memory area, doorbell and completion interrupt.
However the doorbell and completion interrupt is highly mailbox dependent
which was bit of controversial as part of SCMI/mailbox discussions.
Arnd and me discussed about the few aspects of SCMI and the mailbox framework:
1. Use of mailbox framework for doorbell type mailbox controller:
- Such hardware may not require any data to be sent to signal the remote
about the presence of a message. The channel will have in-built
information on how to trigger the signal to the remote.
There are few mailbox controller drivers which are purely doorbell based.
e.g.QCOM IPC, STM, Tegra, ACPI PCC,..etc
2. Supporting other mailbox controller:
- SCMI just needs a mechanism to signal the remote firmware. Such
controller may need fixed message to be sent to trigger a doorbell.
In such case we may need to get that data from DT and pass the same
to the controller. It's not covered in the current DT binding, but
can be extended as optional property in future.
However handling notifications may be interesting on such mailbox, but
again there is no way to interpret what the data field(remote message)
means, it could be a bit mask or a number or don't-care.
Arnd mentioned that he doesn't like the way the mailbox binding deals
with doorbell-type hardware, but we do have quite a few precedent drivers
already and changing the binding to add a data field would not make it any
better, but could cause other problems. So he is happy with the status quo
of SCMI implementation.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0056a/index.html
* tag 'scmi-updates-4.17' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
cpufreq: scmi: add support for fast frequency switching
cpufreq: add support for CPU DVFS based on SCMI message protocol
hwmon: add support for sensors exported via ARM SCMI
hwmon: (core) Add hwmon_max to hwmon_sensor_types enumeration
clk: add support for clocks provided by SCMI
firmware: arm_scmi: add device power domain support using genpd
firmware: arm_scmi: add per-protocol channels support using idr objects
firmware: arm_scmi: refactor in preparation to support per-protocol channels
firmware: arm_scmi: add option for polling based performance domain operations
firmware: arm_scmi: add support for polling based SCMI transfers
firmware: arm_scmi: probe and initialise all the supported protocols
firmware: arm_scmi: add initial support for sensor protocol
firmware: arm_scmi: add initial support for power protocol
firmware: arm_scmi: add initial support for clock protocol
firmware: arm_scmi: add initial support for performance protocol
firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices
firmware: arm_scmi: add common infrastructure and support for base protocol
firmware: arm_scmi: add basic driver infrastructure for SCMI
dt-bindings: arm: add support for ARM System Control and Management Interface(SCMI) protocol
dt-bindings: mailbox: add support for mailbox client shared memory
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/devicetree/bindings/arm/arm,scmi.txt | 179 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/mailbox/mailbox.txt | 28 |
2 files changed, 207 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt new file mode 100644 index 000000000000..5f3719ab7075 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt @@ -0,0 +1,179 @@ +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 DUI 0922B ("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" +- 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. + +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. + +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.txt +[3] Documentation/devicetree/bindings/thermal/thermal.txt +[4] Documentation/devicetree/bindings/sram/sram.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>; + }; + }; +}; + +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>; +}; + +thermal-zones { + soc_thermal { + polling-delay-passive = <100>; + polling-delay = <1000>; + /* sensor ID */ + thermal-sensors = <&scmi_sensors0 3>; + ... + }; +}; diff --git a/Documentation/devicetree/bindings/mailbox/mailbox.txt b/Documentation/devicetree/bindings/mailbox/mailbox.txt index be05b9746c69..af8ecee2ac68 100644 --- a/Documentation/devicetree/bindings/mailbox/mailbox.txt +++ b/Documentation/devicetree/bindings/mailbox/mailbox.txt @@ -23,6 +23,11 @@ Required property: Optional property: - mbox-names: List of identifier strings for each mailbox channel. +- shmem : List of phandle pointing to the shared memory(SHM) area between the + users of these mailboxes for IPC, one for each mailbox. This shared + memory can be part of any memory reserved for the purpose of this + communication between the mailbox client and the remote. + Example: pwr_cntrl: power { @@ -30,3 +35,26 @@ Example: mbox-names = "pwr-ctrl", "rpc"; mboxes = <&mailbox 0 &mailbox 1>; }; + +Example with shared memory(shmem): + + sram: sram@50000000 { + compatible = "mmio-sram"; + reg = <0x50000000 0x10000>; + + #address-cells = <1>; + #size-cells = <1>; + ranges = <0 0x50000000 0x10000>; + + cl_shmem: shmem@0 { + compatible = "client-shmem"; + reg = <0x0 0x200>; + }; + }; + + client@2e000000 { + ... + mboxes = <&mailbox 0>; + shmem = <&cl_shmem>; + .. + }; |