Re: [PATCH v2 02/10] dt-bindings: introduce RPMH RSC bindings for Qualcomm SoCs

[Rob Herring]

On Thu, Feb 15, 2018 at 10:34:59AM -0700, Lina Iyer wrote:
> Add device binding documentation for Qualcomm Technology Inc's RPMH RSC
> driver. The hardware block is used for communicating resource state
> requests for shared resources.
> 
> Cc: devicetree@xxxxxxxxxxxxxxx
> Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx>
> ---

Changes in v2?

>  .../devicetree/bindings/arm/msm/rpmh-rsc.txt       | 146 +++++++++++++++++++++
>  1 file changed, 146 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/msm/rpmh-rsc.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/msm/rpmh-rsc.txt b/Documentation/devicetree/bindings/arm/msm/rpmh-rsc.txt
> new file mode 100644
> index 000000000000..6cb36ae98bf9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/msm/rpmh-rsc.txt
> @@ -0,0 +1,146 @@
> +RPMH RSC:
> +------------
> +
> +RPMH is the mechanism for communicating with the hardened resource
> +accelerators. Requests to the resources can be written to the TCS mailbox
> +registers and using a (addr, val) pair and triggered. Messages in the TCS are
> +then sent in sequence over an internal bus.
> +
> +The hardware block (Direct Resource Voter or DRV) is a part of the h/w entity
> +(Resource State Coordinator a.k.a RSC) that can handle a multiple sleep and
> +active/wake resource requests. Multiple such DRVs can exist in a SoC and can
> +be written to from Linux. The structure of each DRV follows the same template
> +with a few variations that are captured by the properties here.
> +
> +Each DRV could have 'm' TCS instances. Each TCS could have 'n' slots. Each
> +slot has a header (u32), address (u32), data (u32), status (u32) and a
> +read-response (u32). A TCS when triggered will send all the enabled commands
> +of the 'n' commands in that slot in sequence.
> +
> +A TCS may be triggered from Linux or triggered by the F/W after all the CPUs
> +have powered off to facilitate idle power saving. TCS could be classified as -
> +
> +	SLEEP,  /* Triggered by F/W */
> +	WAKE,   /* Triggered by F/W */
> +	ACTIVE, /* Triggered by Linux */
> +	CONTROL /* Triggered by F/W */
> +
> +The order in which they are described in the DT, should match the hardware
> +configuration.
> +
> +Requests can be made for the state of a resource, when the subsystem is active
> +or idle. When all subsystems like Modem, GPU, CPU are idle, the resource state
> +will be an aggregate of the sleep votes from each of those subsystem. Drivers
> +may request a sleep value for their shared resources in addition to the active
> +mode requests.
> +
> +Control requests are instance specific requests that may or may not reach an
> +accelerator. Only one platform device in Linux can request a control channel
> +on a DRV.
> +
> +CONTROLLER:
> +----------
> +
> +PROPERTIES:
> +
> +- compatible:
> +	Usage: required
> +	Value type: <string>
> +	Definition: Should be "qcom,rpmh-rsc".
> +
> +- reg:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: The first register specifies the base address of the DRV.
> +	            The second register specifies the start address of the
> +	            TCS.
> +
> +- reg-names:
> +	Usage: required
> +	Value type: <string>
> +	Definition: Maps the register specified in the reg property. Must be
> +	            "drv" and "tcs".
> +
> +- interrupts:
> +	Usage: required
> +	Value type: <prop-encoded-interrupt>
> +	Definition: The interrupt that trips when a message complete/response
> +	           is received for this DRV from the accelerators.
> +
> +- qcom,drv-id:
> +	Usage: required
> +	Value type: <u32>
> +	Definition: the id of the DRV in the RSC block.
> +
> +- qcom,tcs-config:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: the tuple defining the configuration of TCS.
> +	            Must have 2 cells which describe each TCS type.
> +	            <type number_of_tcs>.
> +	            The order of the TCS must match the hardware
> +	            configuration.
> +	- Cell #1 (TCS Type): TCS types to be specified -
> +		SLEEP_TCS
> +		WAKE_TCS
> +		ACTIVE_TCS
> +		CONTROL_TCS
> +	- Cell #2 (Number of TCS): <u32>
> +
> +- label:
> +	Usage: optional
> +	Value type: <string>
> +	Definition: Name for the RSC. The name would be used in trace logs.
> +
> +Platform drivers that want to use the RSC to communicate with RPMH must

Platform driver is a linux term. DT is not a platform driver 
instantiation language.

> +specify their bindings as child of the corresponding RSC controllers.
> +
> +EXAMPLE 1:
> +
> +For a TCS whose RSC base address is is 0x179C0000 and is at a DRV id of 2, the
> +register offsets for DRV2 start at 0D00, the register calculations are like
> +this -
> +First tuple: 0x179C0000 + 0x10000 * 2 = 0x179E0000
> +Second tuple: 0x179E0000 + 0xD00 = 0x179E0D00
> +
> +	apps_rsc: rsc@179e000 {
> +		label = "apps_rsc";
> +		compatible = "qcom,rpmh-rsc";
> +		reg = <0x179e0000 0x10000>, <0x179e0d00 0x3000>;
> +		reg-names = "drv", "tcs";
> +		interrupts = <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>
> +		qcom,drv-id = <2>;
> +		qcom,tcs-config = <SLEEP_TCS   3>,
> +				  <WAKE_TCS    3>,
> +				  <ACTIVE_TCS  2>,
> +				  <CONTROL_TCS 1>;
> +
> +		foo-clk {
> +			compatible = "foo-clk";

What is this? Child nodes need to be documented too.

> +		};
> +	};
> +