dt-bindings: clk: Hi6220: Document stub clock driver

Document the new compatible for stub clock driver which is used for CPU
and DDR's dynamic frequency scaling.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 18 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/clock/hi6220-clock.txt b/Documentation/devicetree/bindings/clock/hi6220-clock.txt
index 259e30af9597..e4d5feaebc29 100644
--- a/Documentation/devicetree/bindings/clock/hi6220-clock.txt
+++ b/Documentation/devicetree/bindings/clock/hi6220-clock.txt
@@ -15,19 +15,36 @@ Required Properties:
         - "hisilicon,hi6220-sysctrl"
         - "hisilicon,hi6220-mediactrl"
         - "hisilicon,hi6220-pmctrl"
+        - "hisilicon,hi6220-stub-clk"
 
 - reg: physical base address of the controller and length of memory mapped
   region.
 
 - #clock-cells: should be 1.
 
-For example:
+Optional Properties:
+
+- hisilicon,hi6220-clk-sram: phandle to the syscon managing the SoC internal sram;
+  the driver need use the sram to pass parameters for frequency change.
+
+- mboxes: use the label reference for the mailbox as the first parameter, the
+  second parameter is the channel number.
+
+Example 1:
         sys_ctrl: sys_ctrl@f7030000 {
                 compatible = "hisilicon,hi6220-sysctrl", "syscon";
                 reg = <0x0 0xf7030000 0x0 0x2000>;
                 #clock-cells = <1>;
         };
 
+Example 2:
+        stub_clock: stub_clock {
+                compatible = "hisilicon,hi6220-stub-clk";
+                hisilicon,hi6220-clk-sram = <&sram>;
+                #clock-cells = <1>;
+                mboxes = <&mailbox 1>;
+        };
+
 Each clock is assigned an identifier and client nodes use this identifier
 to specify the clock which they consume.