clk: at91: update main clk documentation

Update main clk documentation to match main clk implementation rework.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

Documentation/devicetree/bindings/clock/at91-clock.txt

@@ -15,8 +15,13 @@ Required properties:
 		All at91 specific clocks (clocks defined below) must be child
 		node of the PMC node.
 
+	"atmel,at91rm9200-clk-main-osc"
+	"atmel,at91sam9x5-clk-main-rc-osc"
+		at91 main clk sources
+
+	"atmel,at91sam9x5-clk-main"
 	"atmel,at91rm9200-clk-main":
-		at91 main oscillator
+		at91 main clock
 
 	"atmel,at91rm9200-clk-master" or
 	"atmel,at91sam9x5-clk-master":
@@ -85,24 +90,57 @@ For example:
 		/* put at91 clocks here */
 	};
 
+Required properties for main clock internal RC oscillator:
+- interrupt-parent : must reference the PMC node.
+- interrupts : shall be set to "<0>".
+- clock-frequency : define the internal RC oscillator frequency.
+
+Optional properties:
+- clock-accuracy : define the internal RC oscillator accuracy.
+
+For example:
+	main_rc_osc: main_rc_osc {
+		compatible = "atmel,at91sam9x5-clk-main-rc-osc";
+		interrupt-parent = <&pmc>;
+		interrupts = <0>;
+		clock-frequency = <12000000>;
+		clock-accuracy = <50000000>;
+	};
+
+Required properties for main clock oscillator:
+- interrupt-parent : must reference the PMC node.
+- interrupts : shall be set to "<0>".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall encode the main osc source clk sources (see atmel datasheet).
+
+Optional properties:
+- atmel,osc-bypass : boolean property. Specified if a clock signal is provided
+  on XIN.
+
+  clock signal is directly provided on XIN pin.
+
+For example:
+	main_osc: main_osc {
+		compatible = "atmel,at91rm9200-clk-main-osc";
+		interrupt-parent = <&pmc>;
+		interrupts = <0>;
+		#clock-cells = <0>;
+		clocks = <&main_xtal>;
+	};
+
 Required properties for main clock:
 - interrupt-parent : must reference the PMC node.
 - interrupts : shall be set to "<0>".
 - #clock-cells : from common clock binding; shall be set to 0.
-- clocks (optional if clock-frequency is provided) : shall be the slow clock
-	phandle. This clock is used to calculate the main clock rate if
-	"clock-frequency" is not provided.
-- clock-frequency : the main oscillator frequency.Prefer the use of
-	"clock-frequency" over automatic clock rate calculation.
+- clocks : shall encode the main clk sources (see atmel datasheet).
 
 For example:
 	main: mainck {
-		compatible = "atmel,at91rm9200-clk-main";
+		compatible = "atmel,at91sam9x5-clk-main";
 		interrupt-parent = <&pmc>;
 		interrupts = <0>;
 		#clock-cells = <0>;
-		clocks = <&ck32k>;
-		clock-frequency = <18432000>;
+		clocks = <&main_rc_osc &main_osc>;
 	};
 
 Required properties for master clock: