clk: emev2: Add support for emev2 SMU clocks with DT

Device tree clock binding document for EMMA Mobile EV2 SMU,
And Common clock framework based implementation of it.
Following nodes are defined to describe clock tree.
- renesas,emev2-smu
- renesas,emev2-smu-clkdiv
- renesas,emev2-smu-gclk

These bindings are designed manually based on
 19UH0037EJ1000_SMU : System Management Unit User's Manual

So far, reparent is not implemented, and is fixed to index #0.
Clock tree description is not included, and should be provided
by device-tree.

Signed-off-by: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

1 files changed, 98 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/emev2-clock.txt b/Documentation/devicetree/bindings/clock/emev2-clock.txt
new file mode 100644
index 000000000000..60bbb1a8c69a
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/emev2-clock.txt
@@ -0,0 +1,98 @@
+Device tree Clock bindings for Renesas EMMA Mobile EV2
+
+This binding uses the common clock binding.
+
+* SMU
+System Management Unit described in user's manual R19UH0037EJ1000_SMU.
+This is not a clock provider, but clocks under SMU depend on it.
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu"
+- reg: Address and Size of SMU registers
+
+* SMU_CLKDIV
+Function block with an input mux and a divider, which corresponds to
+"Serial clock generator" in fig."Clock System Overview" of the manual,
+and "xxx frequency division setting register" (XXXCLKDIV) registers.
+This makes internal (neither input nor output) clock that is provided
+to input of xxxGCLK block.
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu-clkdiv"
+- reg: Byte offset from SMU base and Bit position in the register
+- clocks: Parent clocks. Input clocks as described in clock-bindings.txt
+- #clock-cells: Should be <0>
+
+* SMU_GCLK
+Clock gating node shown as "Clock stop processing block" in the
+fig."Clock System Overview" of the manual.
+Registers are "xxx clock gate control register" (XXXGCLKCTRL).
+
+Required properties:
+- compatible: Should be "renesas,emev2-smu-gclk"
+- reg: Byte offset from SMU base and Bit position in the register
+- clocks: Input clock as described in clock-bindings.txt
+- #clock-cells: Should be <0>
+
+Example of provider:
+
+usia_u0_sclkdiv: usia_u0_sclkdiv {
+	compatible = "renesas,emev2-smu-clkdiv";
+	reg = <0x610 0>;
+	clocks = <&pll3_fo>, <&pll4_fo>, <&pll1_fo>, <&osc1_fo>;
+	#clock-cells = <0>;
+};
+
+usia_u0_sclk: usia_u0_sclk {
+	compatible = "renesas,emev2-smu-gclk";
+	reg = <0x4a0 1>;
+	clocks = <&usia_u0_sclkdiv>;
+	#clock-cells = <0>;
+};
+
+Example of consumer:
+
+uart@e1020000 {
+	compatible = "renesas,em-uart";
+	reg = <0xe1020000 0x38>;
+	interrupts = <0 8 0>;
+	clocks = <&usia_u0_sclk>;
+	clock-names = "sclk";
+};
+
+Example of clock-tree description:
+
+ This describes a clock path in the clock tree
+  c32ki -> pll3_fo -> usia_u0_sclkdiv -> usia_u0_sclk
+
+smu@e0110000 {
+	compatible = "renesas,emev2-smu";
+	reg = <0xe0110000 0x10000>;
+	#address-cells = <2>;
+	#size-cells = <0>;
+
+	c32ki: c32ki {
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+		#clock-cells = <0>;
+	};
+	pll3_fo: pll3_fo {
+		compatible = "fixed-factor-clock";
+		clocks = <&c32ki>;
+		clock-div = <1>;
+		clock-mult = <7000>;
+		#clock-cells = <0>;
+	};
+	usia_u0_sclkdiv: usia_u0_sclkdiv {
+		compatible = "renesas,emev2-smu-clkdiv";
+		reg = <0x610 0>;
+		clocks = <&pll3_fo>;
+		#clock-cells = <0>;
+	};
+	usia_u0_sclk: usia_u0_sclk {
+		compatible = "renesas,emev2-smu-gclk";
+		reg = <0x4a0 1>;
+		clocks = <&usia_u0_sclkdiv>;
+		#clock-cells = <0>;
+	};
+};