Date:	Thu, 14 May 2015 16:42:31 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:	Sudeep Holla <sudeep.holla@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	"Jon Medhurst (Tixy)" <tixy@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Jassi Brar <jassisinghbrar@...il.com>,
	devicetree@...r.kernel.org
Subject: [PATCH v2 1/5] Documentation: add DT binding for ARM System Control and Power Interface(SCPI) protocol

This patch adds devicetree binding for System Control and Power
Interface (SCPI) Message Protocol used between the Application Cores(AP)
and the System Control Processor(SCP). The MHU peripheral provides a
mechanism for inter-processor communication between SCP's M3 processor
and AP.

SCP offers control and management of the core/cluster power states,
various power domain DVFS including the core/cluster, certain system
clocks configuration, thermal sensors and many others.

Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
CC: Jassi Brar <jassisinghbrar@...il.com>
Cc: Liviu Dudau <Liviu.Dudau@....com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc: Jon Medhurst (Tixy) <tixy@...aro.org>
Cc: devicetree@...r.kernel.org
---
 Documentation/devicetree/bindings/arm/arm,scpi.txt | 121 +++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/arm,scpi.txt

diff --git a/Documentation/devicetree/bindings/arm/arm,scpi.txt b/Documentation/devicetree/bindings/arm/arm,scpi.txt
new file mode 100644
index 000000000000..5db235f69e54
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/arm,scpi.txt
@@ -0,0 +1,121 @@
+System Control and Power Interface (SCPI) Message Protocol
+----------------------------------------------------------
+
+Required properties:
+
+- compatible : should be "arm,scpi"
+- mboxes: List of phandle and mailbox channel specifiers
+- shmem : List of phandle pointing to the shared memory(SHM) area between the
+	  processors using these mailboxes for IPC, one for each mailbox
+
+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].
+
+Required properties:
+- compatible : shall be one of the following:
+	"arm,scpi-clocks" - for the container node with all the clocks
+		based on the SCPI protocol
+	"arm,scpi-dvfs" - all the clocks that are variable and index based.
+		These clocks don't provide the full range 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-clk" - all the clocks that are variable and provide full
+		range within the specified range. The firmware provides the
+		supported range for each clock.
+
+Required properties for all clocks(all from common clock binding):
+- #clock-cells : should be set to 1 as each of the SCPI clocks have multiple
+	outputs. The clock specifier will be the index to an entry in the list
+	of output clocks.
+- clock-output-names : shall be the corresponding names of the outputs.
+- clock-indices: The identifyng number for the clocks(clock_id) in the node as
+	expected by the firmware. It can be non linear and hence provide the
+	mapping	of identifiers into the clock-output-names array.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Example:
+
+sram: sram@...00000 {
+	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@...00000 {
+	....
+	#mbox-cells = <1>;
+};
+
+scpi_protocol: scpi@...00000 {
+	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";
+			#clock-cells = <1>;
+			clock-indices = <0>, <1>, <2>;
+			clock-output-names = "vbig", "vlittle", "vgpu";
+		};
+		scpi_clk: scpi_clocks@3 {
+			compatible = "arm,scpi-clk";
+			#clock-cells = <1>;
+			clock-indices = <3>, <4>;
+			clock-output-names = "pxlclk0", "pxlclk1";
+		};
+	};
+};
+
+cpu@0 {
+	...
+	reg = <0 0>;
+	clocks = <&scpi_dvfs 0>;
+	clock-names = "big";
+};
+
+hdlcd@...60000 {
+	...
+	reg = <0 0x7ff60000 0 0x1000>;
+	clocks = <&scpi_clk 1>;
+	clock-names = "pxlclk";
+};
+
+In the above example, the #clock-cells is set to 1 as required.
+scpi_dvfs has 3 output clocks namely: vbig, vlittle and vgpu 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 vbig as input clock.
+The index '0' in the clock specifier here points to the first entry in the
+output clocks of scpi_dvfs for which clock_id asrequired by the firmware
+is 0.
+
+Similarly the second example is hdlcd@...60000 and it has pxlclk0 as input
+clock. The index '1' in the clock specifier here points to the second entry
+in the output clocks of scpi_clocks for which clock_id as required by the
+firmware is 4.
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists