CLK: Add binding document for Pistachio clock controllers

Add a device-tree binding document describing the four clock
controllers present on the IMG Pistachio SoC.

Signed-off-by: Damien Horsley <Damien.Horsley@imgtec.com>
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: James Hartley <james.hartley@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Damien Horsley <Damien.Horsley@imgtec.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Patchwork: https://patchwork.linux-mips.org/patch/9319/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/pistachio-clock.txt b/Documentation/devicetree/bindings/clock/pistachio-clock.txt
new file mode 100644
index 000000000000..868db499eed2
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/pistachio-clock.txt
@@ -0,0 +1,123 @@
+Imagination Technologies Pistachio SoC clock controllers
+========================================================
+
+Pistachio has four clock controllers (core clock, peripheral clock, peripheral
+general control, and top general control) which are instantiated individually
+from the device-tree.
+
+External clocks:
+----------------
+
+There are three external inputs to the clock controllers which should be
+defined with the following clock-output-names:
+- "xtal": External 52Mhz oscillator (required)
+- "audio_clk_in": Alternate audio reference clock (optional)
+- "enet_clk_in": Alternate ethernet PHY clock (optional)
+
+Core clock controller:
+----------------------
+
+The core clock controller generates clocks for the CPU, RPU (WiFi + BT
+co-processor), audio, and several peripherals.
+
+Required properties:
+- compatible: Must be "img,pistachio-clk".
+- reg: Must contain the base address and length of the core clock controller.
+- #clock-cells: Must be 1.  The single cell is the clock identifier.
+  See dt-bindings/clock/pistachio-clk.h for the list of valid identifiers.
+- clocks: Must contain an entry for each clock in clock-names.
+- clock-names: Must include "xtal" (see "External clocks") and
+  "audio_clk_in_gate", "enet_clk_in_gate" which are generated by the
+  top-level general control.
+
+Example:
+	clk_core: clock-controller@18144000 {
+		compatible = "img,pistachio-clk";
+		reg = <0x18144000 0x800>;
+		clocks = <&xtal>, <&cr_top EXT_CLK_AUDIO_IN>,
+			 <&cr_top EXT_CLK_ENET_IN>;
+		clock-names = "xtal", "audio_clk_in_gate", "enet_clk_in_gate";
+
+		#clock-cells = <1>;
+	};
+
+Peripheral clock controller:
+----------------------------
+
+The peripheral clock controller generates clocks for the DDR, ROM, and other
+peripherals.  The peripheral system clock ("periph_sys") generated by the core
+clock controller is the input clock to the peripheral clock controller.
+
+Required properties:
+- compatible: Must be "img,pistachio-periph-clk".
+- reg: Must contain the base address and length of the peripheral clock
+  controller.
+- #clock-cells: Must be 1.  The single cell is the clock identifier.
+  See dt-bindings/clock/pistachio-clk.h for the list of valid identifiers.
+- clocks: Must contain an entry for each clock in clock-names.
+- clock-names: Must include "periph_sys", the peripheral system clock generated
+  by the core clock controller.
+
+Example:
+	clk_periph: clock-controller@18144800 {
+		compatible = "img,pistachio-clk-periph";
+		reg = <0x18144800 0x800>;
+		clocks = <&clk_core CLK_PERIPH_SYS>;
+		clock-names = "periph_sys";
+
+		#clock-cells = <1>;
+	};
+
+Peripheral general control:
+---------------------------
+
+The peripheral general control block generates system interface clocks and
+resets for various peripherals.  It also contains miscellaneous peripheral
+control registers.  The system clock ("sys") generated by the peripheral clock
+controller is the input clock to the system clock controller.
+
+Required properties:
+- compatible: Must include "img,pistachio-periph-cr" and "syscon".
+- reg: Must contain the base address and length of the peripheral general
+  control registers.
+- #clock-cells: Must be 1.  The single cell is the clock identifier.
+  See dt-bindings/clock/pistachio-clk.h for the list of valid identifiers.
+- clocks: Must contain an entry for each clock in clock-names.
+- clock-names: Must include "sys", the system clock generated by the peripheral
+  clock controller.
+
+Example:
+	cr_periph: syscon@18144800 {
+		compatible = "img,pistachio-cr-periph", "syscon";
+		reg = <0x18148000 0x1000>;
+		clocks = <&clock_periph PERIPH_CLK_PERIPH_SYS>;
+		clock-names = "sys";
+
+		#clock-cells = <1>;
+	};
+
+Top-level general control:
+--------------------------
+
+The top-level general control block contains miscellaneous control registers and
+gates for the external clocks "audio_clk_in" and "enet_clk_in".
+
+Required properties:
+- compatible: Must include "img,pistachio-cr-top" and "syscon".
+- reg: Must contain the base address and length of the top-level
+  control registers.
+- clocks: Must contain an entry for each clock in clock-names.
+- clock-names: Two optional clocks, "audio_clk_in" and "enet_clk_in" (see
+  "External clocks").
+- #clock-cells: Must be 1.  The single cell is the clock identifier.
+  See dt-bindings/clock/pistachio-clk.h for the list of valid identifiers.
+
+Example:
+	cr_top: syscon@18144800 {
+		compatible = "img,pistachio-cr-top", "syscon";
+		reg = <0x18149000 0x200>;
+		clocks = <&audio_refclk>, <&ext_enet_in>;
+		clock-names = "audio_clk_in", "enet_clk_in";
+
+		#clock-cells = <1>;
+	};