dt: binding: add at91 clks dt bindings documentation

This patch adds new at91 clks dt bindings documentation.

Signed-off-by: Boris BREZILLON <[e-mail]>
Acked-by: Mike Turquette <[e-mail]>
Signed-off-by: Nicolas Ferre <[e-mail]>

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

···
+Device Tree Clock bindings for arch-at91
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be one of the following:
+	"atmel,at91rm9200-pmc" or
+	"atmel,at91sam9g45-pmc" or
+	"atmel,at91sam9n12-pmc" or
+	"atmel,at91sam9x5-pmc" or
+	"atmel,sama5d3-pmc":
+		at91 PMC (Power Management Controller)
+		All at91 specific clocks (clocks defined below) must be child
+		node of the PMC node.
+
+	"atmel,at91rm9200-clk-main":
+		at91 main oscillator
+
+	"atmel,at91rm9200-clk-master" or
+	"atmel,at91sam9x5-clk-master":
+		at91 master clock
+
+	"atmel,at91sam9x5-clk-peripheral" or
+	"atmel,at91rm9200-clk-peripheral":
+		at91 peripheral clocks
+
+	"atmel,at91rm9200-clk-pll" or
+	"atmel,at91sam9g45-clk-pll" or
+	"atmel,at91sam9g20-clk-pllb" or
+	"atmel,sama5d3-clk-pll":
+		at91 pll clocks
+
+	"atmel,at91sam9x5-clk-plldiv":
+		at91 plla divisor
+
+	"atmel,at91rm9200-clk-programmable" or
+	"atmel,at91sam9g45-clk-programmable" or
+	"atmel,at91sam9x5-clk-programmable":
+		at91 programmable clocks
+
+	"atmel,at91sam9x5-clk-smd":
+		at91 SMD (Soft Modem) clock
+
+	"atmel,at91rm9200-clk-system":
+		at91 system clocks
+
+	"atmel,at91rm9200-clk-usb" or
+	"atmel,at91sam9x5-clk-usb" or
+	"atmel,at91sam9n12-clk-usb":
+		at91 usb clock
+
+	"atmel,at91sam9x5-clk-utmi":
+		at91 utmi clock
+
+Required properties for PMC node:
+- reg : defines the IO memory reserved for the PMC.
+- #size-cells : shall be 0 (reg is used to encode clk id).
+- #address-cells : shall be 1 (reg is used to encode clk id).
+- interrupts : shall be set to PMC interrupt line.
+- interrupt-controller : tell that the PMC is an interrupt controller.
+- #interrupt-cells : must be set to 1. The first cell encodes the interrupt id,
+	and reflect the bit position in the PMC_ER/DR/SR registers.
+	You can use the dt macros defined in dt-bindings/clk/at91.h.
+	0 (AT91_PMC_MOSCS) -> main oscillator ready
+	1 (AT91_PMC_LOCKA) -> PLL A ready
+	2 (AT91_PMC_LOCKB) -> PLL B ready
+	3 (AT91_PMC_MCKRDY) -> master clock ready
+	6 (AT91_PMC_LOCKU) -> UTMI PLL clock ready
+	8 .. 15 (AT91_PMC_PCKRDY(id)) -> programmable clock ready
+	16 (AT91_PMC_MOSCSELS) -> main oscillator selected
+	17 (AT91_PMC_MOSCRCS) -> RC main oscillator stabilized
+	18 (AT91_PMC_CFDEV) -> clock failure detected
+
+For example:
+	pmc: pmc@fffffc00 {
+		compatible = "atmel,sama5d3-pmc";
+		interrupts = <1 4 7>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
+		#size-cells = <0>;
+		#address-cells = <1>;
+
+		/* put at91 clocks here */
+	};
+
+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.
+
+For example:
+	main: mainck {
+		compatible = "atmel,at91rm9200-clk-main";
+		interrupt-parent = <&pmc>;
+		interrupts = <0>;
+		#clock-cells = <0>;
+		clocks = <&ck32k>;
+		clock-frequency = <18432000>;
+	};
+
+Required properties for master clock:
+- interrupt-parent : must reference the PMC node.
+- interrupts : shall be set to "<3>".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the master clock sources (see atmel datasheet) phandles.
+	e.g. "<&ck32k>, <&main>, <&plla>, <&pllb>".
+- atmel,clk-output-range : minimum and maximum clock frequency (two u32
+			   fields).
+	   e.g. output = <0 133000000>; <=> 0 to 133MHz.
+- atmel,clk-divisors : master clock divisors table (four u32 fields).
+		0 <=> reserved value.
+		e.g. divisors = <1 2 4 6>;
+- atmel,master-clk-have-div3-pres : some SoC use the reserved value 7 in the
+				    PRES field as CLOCK_DIV3 (e.g sam9x5).
+
+For example:
+	mck: mck {
+		compatible = "atmel,at91rm9200-clk-master";
+		interrupt-parent = <&pmc>;
+		interrupts = <3>;
+		#clock-cells = <0>;
+		atmel,clk-output-range = <0 133000000>;
+		atmel,clk-divisors = <1 2 4 0>;
+	};
+
+Required properties for peripheral clocks:
+- #size-cells : shall be 0 (reg is used to encode clk id).
+- #address-cells : shall be 1 (reg is used to encode clk id).
+- clocks : shall be the master clock phandle.
+	e.g. clocks = <&mck>;
+- name: device tree node describing a specific system clock.
+	* #clock-cells : from common clock binding; shall be set to 0.
+	* reg: peripheral id. See Atmel's datasheets to get a full
+	  list of peripheral ids.
+	* atmel,clk-output-range : minimum and maximum clock frequency
+	  (two u32 fields). Only valid on at91sam9x5-clk-peripheral
+	  compatible IPs.
+
+For example:
+	periph: periphck {
+		compatible = "atmel,at91sam9x5-clk-peripheral";
+		#size-cells = <0>;
+		#address-cells = <1>;
+		clocks = <&mck>;
+
+		ssc0_clk {
+			#clock-cells = <0>;
+			reg = <2>;
+			atmel,clk-output-range = <0 133000000>;
+		};
+
+		usart0_clk {
+			#clock-cells = <0>;
+			reg = <3>;
+			atmel,clk-output-range = <0 66000000>;
+		};
+	};
+
+
+Required properties for pll clocks:
+- interrupt-parent : must reference the PMC node.
+- interrupts : shall be set to "<1>".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the main clock phandle.
+- reg : pll id.
+	0 -> PLL A
+	1 -> PLL B
+- atmel,clk-input-range : minimum and maximum source clock frequency (two u32
+			  fields).
+	  e.g. input = <1 32000000>; <=> 1 to 32MHz.
+- #atmel,pll-clk-output-range-cells : number of cells reserved for pll output
+				      range description. Sould be set to 2, 3
+				      or 4.
+	* 1st and 2nd cells represent the frequency range (min-max).
+	* 3rd cell is optional and represents the OUT field value for the given
+	  range.
+	* 4th cell is optional and represents the ICPLL field (PLLICPR
+	  register)
+- atmel,pll-clk-output-ranges : pll output frequency ranges + optional parameter
+				depending on #atmel,pll-output-range-cells
+				property value.
+
+For example:
+	plla: pllack {
+		compatible = "atmel,at91sam9g45-clk-pll";
+		interrupt-parent = <&pmc>;
+		interrupts = <1>;
+		#clock-cells = <0>;
+		clocks = <&main>;
+		reg = <0>;
+		atmel,clk-input-range = <2000000 32000000>;
+		#atmel,pll-clk-output-range-cells = <4>;
+		atmel,pll-clk-output-ranges = <74500000 800000000 0 0
+					       69500000 750000000 1 0
+					       64500000 700000000 2 0
+					       59500000 650000000 3 0
+					       54500000 600000000 0 1
+					       49500000 550000000 1 1
+					       44500000 500000000 2 1
+					       40000000 450000000 3 1>;
+	};
+
+Required properties for plldiv clocks (plldiv = pll / 2):
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the plla clock phandle.
+
+The pll divisor is equal to 2 and cannot be changed.
+
+For example:
+	plladiv: plladivck {
+		compatible = "atmel,at91sam9x5-clk-plldiv";
+		#clock-cells = <0>;
+		clocks = <&plla>;
+	};
+
+Required properties for programmable clocks:
+- interrupt-parent : must reference the PMC node.
+- #size-cells : shall be 0 (reg is used to encode clk id).
+- #address-cells : shall be 1 (reg is used to encode clk id).
+- clocks : shall be the programmable clock source phandles.
+	e.g. clocks = <&clk32k>, <&main>, <&plla>, <&pllb>;
+- name: device tree node describing a specific prog clock.
+	* #clock-cells : from common clock binding; shall be set to 0.
+	* reg : programmable clock id (register offset from  PCKx
+			 register).
+	* interrupts : shall be set to "<(8 + id)>".
+
+For example:
+	prog: progck {
+		compatible = "atmel,at91sam9g45-clk-programmable";
+		#size-cells = <0>;
+		#address-cells = <1>;
+		interrupt-parent = <&pmc>;
+		clocks = <&clk32k>, <&main>, <&plladiv>, <&utmi>, <&mck>;
+
+		prog0 {
+			#clock-cells = <0>;
+			reg = <0>;
+			interrupts = <8>;
+		};
+
+		prog1 {
+			#clock-cells = <0>;
+			reg = <1>;
+			interrupts = <9>;
+		};
+	};
+
+
+Required properties for smd clock:
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the smd clock source phandles.
+	e.g. clocks = <&plladiv>, <&utmi>;
+
+For example:
+	smd: smdck {
+		compatible = "atmel,at91sam9x5-clk-smd";
+		#clock-cells = <0>;
+		clocks = <&plladiv>, <&utmi>;
+	};
+
+Required properties for system clocks:
+- #size-cells : shall be 0 (reg is used to encode clk id).
+- #address-cells : shall be 1 (reg is used to encode clk id).
+- name: device tree node describing a specific system clock.
+	* #clock-cells : from common clock binding; shall be set to 0.
+	* reg: system clock id (bit position in SCER/SCDR/SCSR registers).
+	      See Atmel's datasheet to get a full list of system clock ids.
+
+For example:
+	system: systemck {
+		compatible = "atmel,at91rm9200-clk-system";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		ddrck {
+			#clock-cells = <0>;
+			reg = <2>;
+			clocks = <&mck>;
+		};
+
+		uhpck {
+			#clock-cells = <0>;
+			reg = <6>;
+			clocks = <&usb>;
+		};
+
+		udpck {
+			#clock-cells = <0>;
+			reg = <7>;
+			clocks = <&usb>;
+		};
+	};
+
+
+Required properties for usb clock:
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the smd clock source phandles.
+	e.g. clocks = <&pllb>;
+- atmel,clk-divisors (only available for "atmel,at91rm9200-clk-usb"):
+	usb clock divisor table.
+	e.g. divisors = <1 2 4 0>;
+
+For example:
+	usb: usbck {
+		compatible = "atmel,at91sam9x5-clk-usb";
+		#clock-cells = <0>;
+		clocks = <&plladiv>, <&utmi>;
+	};
+
+	usb: usbck {
+		compatible = "atmel,at91rm9200-clk-usb";
+		#clock-cells = <0>;
+		clocks = <&pllb>;
+		atmel,clk-divisors = <1 2 4 0>;
+	};
+
+
+Required properties for utmi clock:
+- interrupt-parent : must reference the PMC node.
+- interrupts : shall be set to "<AT91_PMC_LOCKU IRQ_TYPE_LEVEL_HIGH>".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the main clock source phandle.
+
+For example:
+	utmi: utmick {
+		compatible = "atmel,at91sam9x5-clk-utmi";
+		interrupt-parent = <&pmc>;
+		interrupts = <AT91_PMC_LOCKU IRQ_TYPE_LEVEL_HIGH>;
+		#clock-cells = <0>;
+		clocks = <&main>;
+	};