Re: [PATCH v2 03/14] DEVICETREE: Add PIC32 clock binding documentation

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On Mon, Dec 14, 2015 at 03:42:05PM -0700, Joshua Henderson wrote:
> From: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
> 
> Document the devicetree bindings for the clock driver found on Microchip
> PIC32 class devices.
> 
> Signed-off-by: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
> Signed-off-by: Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>

A couple of nits on the example, otherwise:

Acked-by: Rob Herring <robh@xxxxxxxxxx>

> ---
>  .../devicetree/bindings/clock/microchip,pic32.txt  |  256 ++++++++++++++++++++
>  1 file changed, 256 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/microchip,pic32.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/microchip,pic32.txt b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> new file mode 100644
> index 0000000..f50c653
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> @@ -0,0 +1,256 @@
> +Binding for a Clock hardware block found on
> +certain Microchip PIC32 MCU devices.
> +
> +Microchip SoC clocks-node consists of few oscillators, PLL, multiplexer
> +and few divider nodes.
> +
> +We will find only the base address of the clock tree, this base
> +address is common for some of the subnodes, not all. If no address is
> +specified for any of subnode base address of the clock tree will be
> +treated as its base. Each of subnodes follow the same common clock
> +binding with some additional optional properties.
> +
> +	clocks_node {
> +		reg = <>;
> +
> +		spll_node {
> +			...
> +		};
> +
> +		frcdiv_node {
> +			...
> +		};
> +
> +		sysclk_mux_node {
> +			...
> +		};
> +
> +		pbdiv_node {
> +			...
> +		};
> +
> +		refoclk_node {
> +			...
> +		};
> +		...
> +	};
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible : should be one of "microchip,pic32mzda-clk",
> +    "microchip,pic32mzda-sosc", "microchip,pic32mzda-frcdivclk",
> +    "microchip,pic32mzda-syspll", "microchip,pic32mzda-sysclk-v2",
> +    "microchip,pic32mzda-pbclk", "microchip,pic32mzda-refoclk".
> +- reg : A Base address and length of the register set.
> +- interrupts : source of interrupt.
> +
> +Optional properties (for subnodes):
> +- #clock-cells: From common clock binding, should be 0.
> +- microchip,clock-indices: in multiplexer node clock sources always aren't linear
> +    and contiguous. This property helps define clock-sources with respect to
> +    the mux clock node.
> +- microchip,ignore-unused : ignore gate request even if the gated clock is unused.
> +- microchip,status-bit-mask: bitmask for status check. This will be used to confirm
> +    particular operation by clock sub-node is completed. It is dependent sub-node.
> +- microchip,bit-mask: enable mask, similar to microchip,status-bit-mask.
> +- microchip,slew-step: enable frequency slewing(stepping) during rate change;
> +    applicable only to sys-clock subnode.
> +
> +Example:
> +
> +/* PIC32 specific clks */
> +pic32_clktree {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	reg = <0x1f801200 0x200>;
> +	compatible = "microchip,pic32mzda-clk";
> +	ranges = <0 0x1f801200 0x200>;
> +
> +	/* secondary oscillator; external input on SOSCI pin */
> +	SOSC:sosc_clk {

For the ones with reg property, do clock@0 instead of sosc_clk.

> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-sosc";
> +		clock-frequency = <32768>;
> +		reg = <0x000 0x10>, /* enable reg */
> +		      <0x1d0 0x10>; /* status reg */
> +		microchip,bit-mask = <0x02>; /* enable mask */
> +		microchip,status-bit-mask = <0x10>; /* status-mask*/
> +	};
> +
> +	FRCDIV:frcdiv_clk {
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-frcdivclk";
> +		clocks = <&FRC>;
> +		clock-output-names = "frcdiv_clk";
> +	};
> +
> +	/* System PLL clock */
> +	SYSPLL:spll_clk {
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-syspll";
> +		reg = <0x020 0x10>, /* SPLL register */
> +		      <0x1d0 0x10>; /* CLKSTAT register */
> +		clocks = <&POSC>, <&FRC>;
> +		clock-output-names = "sys_pll";
> +		microchip,status-bit-mask = <0x80>; /* SPLLRDY */
> +	};
> +
> +	/* system clock; mux with postdiv & slew */
> +	SYSCLK:sys_clk {
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-sysclk-v2";
> +		reg = <0x1c0 0x04>; /* SLEWCON */
> +		clocks = <&FRCDIV>, <&SYSPLL>, <&POSC>, <&SOSC>,
> +				<&LPRC>, <&FRCDIV>;
> +		microchip,clock-indices = <0>, <1>, <2>, <4>, <5>, <7>;
> +		clock-output-names = "sys_clk";
> +	};
> +
> +	/* UPLL is integral part of USB PHY; UTMI clk for USBCORE */
> +	UPLL:usb_phy_clk {
> +		#clock-cells = <0>;
> +		compatible = "fixed-clocks";
> +		clock-frequency = <24000000>;
> +		clock-output-names = "usbphy_clk";
> +	};
> +
> +	/* Peripheral bus1 clock */
> +	PBCLK1:pb1_clk {
> +		reg = <0x140 0x10>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		clock-output-names = "pb1_clk";
> +		/* used by system modules, not gateable */
> +		microchip,ignore-unused;
> +	};
> +
> +	/* Peripheral bus2 clock */
> +	PBCLK2:pb2_clk {
> +		reg = <0x150 0x10>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		clock-output-names = "pb2_clk";
> +		/* avoid gating even if unused */
> +		microchip,ignore-unused;
> +	};
> +
> +	/* Peripheral bus3 clock */
> +	PBCLK3:pb3_clk {
> +		reg = <0x160 0x10>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		clock-output-names = "pb3_clk";
> +	};
> +
> +	/* Peripheral bus4 clock(I/O ports, GPIO) */
> +	PBCLK4:pb4_clk {
> +		reg = <0x170 0x10>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		clock-output-names = "pb4_clk";
> +	};
> +
> +	/* Peripheral bus clock */
> +	PBCLK5:pb5_clk {
> +		reg = <0x180 0x10>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		clock-output-names = "pb5_clk";
> +	};
> +
> +	/* Peripheral Bus6 clock; */
> +	PBCLK6:pb6_clk {
> +		reg = <0x190 0x10>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		clocks = <&SYSCLK>;
> +		#clock-cells = <0>;
> +	};
> +
> +	/* Peripheral bus7 clock */
> +	PBCLK7:pb7_clk {
> +		reg = <0x1A0 0x10>;

lower case

> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-pbclk";
> +		/* CPU is driven by this clock; so named */
> +		clock-output-names = "cpu_clk";
> +		clocks = <&SYSCLK>;
> +	};
> +
> +	/* Reference Oscillator clock for SPI/I2S */
> +	REFCLKO1:refo1_clk {
> +		reg = <0x080 0x20>;
> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-refoclk";
> +		clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> +			<&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> +		microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> +						<7>, <8>, <9>;
> +		clock-output-names = "refo1_clk";
> +	};
> +
> +	/* Reference Oscillator clock for SQI */
> +	REFCLKO2:refo2_clk {
> +		reg = <0x0A0 0x20>;

lower case

> +		#clock-cells = <0>;
> +		compatible = "microchip,pic32mzda-refoclk";
> +		clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> +			<&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> +		microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> +						<7>, <8>, <9>;
> +		clock-output-names = "refo2_clk";
> +	};
> +
> +	/* Reference Oscillator clock, ADC */
> +	REFCLKO3:refo3_clk {
> +		reg = <0x0C0 0x20>;

lower case

> +		compatible = "microchip,pic32mzda-refoclk";
> +		clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> +			<&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> +		microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> +						<7>, <8>, <9>;
> +		#clock-cells = <0>;
> +		clock-output-names = "refo3_clk";
> +	};
> +
> +	/* Reference Oscillator clock */
> +	REFCLKO4:refo4_clk {
> +		reg = <0x0E0 0x20>;
> +		compatible = "microchip,pic32mzda-refoclk";
> +		clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> +				<&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> +		microchip,clock-indices = <0>,<1>,<2>,<3>,<4>,<5>,<7>,
> +						<8>,<9>;
> +		#clock-cells = <0>;
> +		clock-output-names = "refo4_clk";
> +	};
> +
> +	/* Reference Oscillator clock, LCD */
> +	REFCLKO5:refo5_clk {
> +		reg = <0x100 0x20>;
> +		compatible = "microchip,pic32mzda-refoclk";
> +		clocks = <&SYSCLK>,<&PBCLK1>,<&POSC>,<&FRC>,<&LPRC>,
> +			<&SOSC>,<&SYSPLL>,<&REFIx>,<&BFRC>;
> +		microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> +					<7>, <8>,<9>;
> +		#clock-cells = <0>;
> +		clock-output-names = "refo5_clk";
> +	};
> +};
> +
> +The clock consumer should specify the desired clock by having the clocks in its
> +"clock" phandle cell. For example for UART:
> +
> +uart2: serial@<> {
> +	compatible = "microchip,pic32mzda-uart";
> +	reg = <>;
> +	interrupts = <>;
> +	clocks = <&PBCLK2>;
> +}
> -- 
> 1.7.9.5
> 
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