[PATCH v3 3/4] dt-bindings: add documentation of rk3399 clock controller

[jianqun.xu]

From: Xing Zheng <zhengxing at rock-chips.com>

Add the devicetree binding for the cru on the rk3399 which quite
similar structured as previous clock controllers.

Signed-off-by: Xing Zheng <zhengxing at rock-chips.com>
Signed-off-by: Jianqun Xu <jay.xu at rock-chips.com>
---
changes in v3:
- none

changes in v2:
- none

 .../bindings/clock/rockchip,rk3399-cru.txt         | 82 ++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.txt

diff --git a/Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.txt b/Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.txt
new file mode 100644
index 0000000..07bcc6e
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.txt
@@ -0,0 +1,82 @@
+* Rockchip RK3399 Clock and Reset Unit
+
+The RK3399 clock controller generates and supplies clock to various
+controllers within the SoC and also implements a reset controller for SoC
+peripherals.
+
+Required Properties:
+
+- compatible: PMU for CRU should be "rockchip,rk3399-pmucru"
+- compatible: CRU should be "rockchip,rk3399-cru"
+- reg: physical base address of the controller and length of memory mapped
+  region.
+- #clock-cells: should be 1.
+- #reset-cells: should be 1.
+
+Optional Properties:
+
+- rockchip,grf: phandle to the syscon managing the "general register files"
+  If missing, pll rates are not changeable, due to the missing pll lock status.
+
+Each clock is assigned an identifier and client nodes can use this identifier
+to specify the clock which they consume. All available clocks are defined as
+preprocessor macros in the dt-bindings/clock/rk3399-cru.h headers and can be
+used in device tree sources. Similar macros exist for the reset sources in
+these files.
+
+External clocks:
+
+There are several clocks that are generated outside the SoC. It is expected
+that they are defined using standard clock bindings with following
+clock-output-names:
+ - "xin24m" - crystal input - required,
+ - "xin32k" - rtc clock - optional,
+ - "ext_i2s" - external I2S clock - optional,
+ - "ext_gmac" - external GMAC clock - optional
+ - "ext_hsadc" - external HSADC clock - optional,
+ - "ext_isp" - external ISP clock - optional,
+ - "ext_jtag" - external JTAG clock - optional
+ - "ext_vip" - external VIP clock - optional,
+ - "usbotg_out" - output clock of the pll in the otg phy
+
+Example: General Register Files
+
+	pmugrf: syscon at ff320000 {
+		compatible = "rockchip,rk3399-pmugrf", "syscon";
+		reg = <0x0 0xff320000 0x0 0x1000>;
+	};
+
+	grf: syscon at ff770000 {
+		compatible = "rockchip,rk3399-grf", "syscon";
+		reg = <0x0 0xff770000 0x0 0x10000>;
+	};
+
+Example: Clock controller node:
+
+	pmucru: pmu-clock-controller at ff750000 {
+		compatible = "rockchip,rk3399-pmucru";
+		reg = <0x0 0xff750000 0x0 0x1000>;
+		#clock-cells = <1>;
+		#reset-cells = <1>;
+	};
+
+	cru: clock-controller at ff760000 {
+		compatible = "rockchip,rk3399-cru";
+		reg = <0x0 0xff760000 0x0 0x1000>;
+		rockchip,grf = <&grf>;
+		#clock-cells = <1>;
+		#reset-cells = <1>;
+	};
+
+Example: UART controller node that consumes the clock generated by the clock
+  controller:
+
+	uart0: serial at ff1a0000 {
+		compatible = "rockchip,rk3399-uart", "snps,dw-apb-uart";
+		reg = <0x0 0xff180000 0x0 0x100>;
+		clocks = <&cru SCLK_UART0>, <&cru PCLK_UART0>;
+		clock-names = "baudclk", "apb_pclk";
+		interrupts = <GIC_SPI 99 IRQ_TYPE_LEVEL_HIGH>;
+		reg-shift = <2>;
+		reg-io-width = <4>;
+	};
-- 
1.9.1