Re: [Patch v9] driver/clk/clk-si5338: Add common clock framework driver for si5338

[Rob Herring <robh@kernel.org>]

On Fri, Aug 26, 2016 at 02:45:49PM -0700, York Sun wrote:
> From: York Sun <yorksun@freescale.com>
> 
> SI5338 is a programmable clock generator. It has 4 sets of inputs,
> PLL, multisynth and dividers to make 4 outputs. This driver splits
> them into multiple clocks to comply with common clock framework.
> 
> See Documentation/devicetree/bindings/clock/silabs,si5338.txt for
> details.
> 
> Signed-off-by: York Sun <yorksun@freescale.com>
> CC: Mike Turquette <mturquette@baylibre.com>
> CC: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
> CC: Guenter Roeck <linux@roeck-us.net>
> CC: Andrey Filippov <andrey@elphel.com>
> CC: Paul Bolle <pebolle@tiscali.nl>

7 versions before you decide to start cc'ing DT list?

[...]

> diff --git a/Documentation/devicetree/bindings/clock/silabs,si5338.txt b/Documentation/devicetree/bindings/clock/silabs,si5338.txt
> new file mode 100644
> index 0000000..cc7ae8e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/silabs,si5338.txt
> @@ -0,0 +1,192 @@
> +Binding for Silicon Labs Si5338 programmable i2c clock generator.
> +
> +Reference
> +[1] Si5338 Data Sheet
> +    http://www.silabs.com/Support%20Documents/TechnicalDocs/Si5338.pdf
> +
> +The Si5338 is a programmable i2c clock generators with up to 4 output
> +clocks. It has 4 sets of possible input clocks
> +
> +IN1/IN2: differential
> +IN3: single-ended
> +IN4: single-ended
> +IN5/IN6: differential
> +
> +Additionally, IN1/IN2 can be used as XTAL with different setting.
> +The clock tree looks like below (without support of zero-delay)
> +
> +
> +      IN1/IN2 IN3         IN4 IN5/IN6
> +         |     |           |     |
> +   ------|     |           |     |
> +   |     |     |           |     |
> +   |     \     /           \     /
> +   |      \   /             \   /
> +   |       \ /               \ /
> + XTAL     REFCLK            FBCLK
> +   |       |  \             /   |
> +   |       |   \           /    |
> +   |       | DIVREFCLK DIVFBCLK |
> +   |       |     \       /      |
> +   |       |      \     /       |
> +   |       |       \   /        |
> +   |       |        PLL         |
> +   |       |      / | | \       |
> +   |       |     /  / \  \      |
> +   |       |    /  /   \  \     |
> +   |       |   /   |   |   \    |
> +   |       |   |   |   |   |    |
> +   |       |  MS0 MS1 MS2 MS3   |
> +   |       |   |   |   |   |    |
> +
> +       OUT0  OUT1  OUT2  OUT3
> +
> +The output clock can choose from any of the above clock as its source, with
> +exceptions: MS1 can only be used for OUT1, MS2 can only be used for OUT2, MS3
> +can only be used for OUT3.
> +
> +==I2C device node==
> +
> +Required properties:
> +- compatible: shall be "silabs,si5338".
> +- reg: i2c device address, shall be 0x60, 0x61, 0x70, or 0x71
> +- #clock-cells: shall be set to 1 for multiple outputs
> +- clocks: list of parent clocks in the order of <xtal>, <in1/2>, <in3>, <in4>,
> +	 <in5/6>.
> +	Note, xtal and in1/2 are mutually exclusive. Only one can be set.
> +- clock-names: The name of the clocks in the same order.
> +- #address-cells: shall be set to 1.
> +- #size-cells: shall be set to 0.
> +- silabs,pll-master: If PLL is used, pick one MS (0, 1, 2, or 3) to allow
> +	chaning PLL rate. This is arbitrary since MS0/1/2/3 share one PLL.
> +	PLL can be calculated backward to satisfy MS. This node is not
> +	required if PLL is not used, or if silabs,pll-vco is set.
> +
> +Optional properties if not set by platform driver:
> +- silab,name-prefix: name prefix for si5338
> +        If multiple si5338 chips exist, use name-prefix to form unique names.
> +	If omitted, i2c bus name will be used as the prefix.

Drop this please. There should not be any need for it.

> +- silab,ref-source: source of refclk, valid value is defined as
> +	#define SI5338_REF_SRC_CLKIN12          0
> +	#define SI5338_REF_SRC_CLKIN3           1
> +	#define SI5338_REF_SRC_XTAL             4
> +- silab,fb-source:  source of fbclk, valid value is defined as
> +	#define SI5338_FB_SRC_CLKIN4            2
> +	#define SI5338_FB_SRC_CLKIN56           3
> +	#define SI5338_FB_SRC_NOCLK             5
> +- silabs,pll-source: source of pll, valid value is defined as
> +	#define SI5338_PFD_IN_REF_REFCLK           0
> +	#define SI5338_PFD_IN_REF_FBCLK            1
> +	#define SI5338_PFD_IN_REF_DIVREFCLK        2
> +	#define SI5338_PFD_IN_REF_DIVFBCLK         3
> +	#define SI5338_PFD_IN_REF_XOCLK            4
> +	#define SI5338_PFD_IN_REF_NOCLK            5
> +- silabs,pll-vco: Specify VCO frequency for optimal ratios for all outputs.
> +	If specified, silabs,pll-master is ignored.
> +
> +==Child nodes==
> +
> +Each of the clock outputs can be configured individually by
> +using a child node to the I2C device node. If a child node for a clock
> +output is not set, platform driver has to set up.
> +
> +Required child node properties:
> +- name: name for the child node
> +        It has to be unique. The name prefix is ignored.
> +	If using platform data and the name is not specificed,
> +        clkout0/1/2/3 will be used with name prefix.
> +- reg: number of clock output.
> +
> +Optional child node properties:
> +- silabs,drive-config: the configuration of output driver
> +  The valid value list is long. Please refer to soruce code.

May be long, but needs to be documented here. I don't follow why you are 
using strings for the values here.

> +- silabs,clock-source: source clock of the output divider
> +	#define SI5338_OUT_MUX_FBCLK            0
> +	#define SI5338_OUT_MUX_REFCLK           1
> +	#deinfe SI5338_OUT_MUX_DIVFBCLK         2
> +	#deinfe SI5338_OUT_MUX_DIVREFCLK        3
> +	#deinfe SI5338_OUT_MUX_XOCLK            4
> +	#deinfe SI5338_OUT_MUX_MS0              5
> +	#deinfe SI5338_OUT_MUX_MSN              6 /* MS0/1/2/3 */
> +	#deinfe SI5338_OUT_MUX_NOCLK            7
> +- silabs,disable-state : clock output disable state, shall be
> +	#define SI5338_OUT_DIS_HIZ              0
> +	#define SI5338_OUT_DIS_LOW              1
> +	#define SI5338_OUT_DIS_HI               2
> +	#define SI5338_OUT_DIS_ALWAYS_ON        3
> +- enabled: the output is enabled by default
> +	The existence of this node enables the output when the driver is loaded
> +	otherwise the clock is only enabled when used

Drop this. Either platform code should claim this and enable the clock 
or use the critical clocks binding.

> +
> +==Example==
> +
> +/* 25MHz reference crystal */
> +ref25: ref25M {
> +	compatible = "fixed-clock";
> +	#clock-cells = <0>;
> +	clock-frequency = <25000000>;
> +};
> +clkin56: ref100M {
> +	compatible = "fixed-clock";
> +	#clock-cells = <0>;
> +	clock-frequency = <100000000>;
> +};
> +i2c-master-node {
> +	si5338: clock-generator@70 {
> +		compatible = "silabs,si5338";
> +		reg = <0x70>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		#clock-cells = <1>;
> +
> +		/* connect xtal to 25MHz, in5/in6 to 100MHz */
> +		clocks = <&ref25>, <0>, <0>, <0>, <&clkin56>;
> +		clock-names = "xtal", "in12", "in3", "in4", "in56";
> +
> +		/* connect xtal as source of refclk */
> +		silab,ref-source = <SI5338_REF_SRC_XTAL>;
> +
> +		/* connect in5/in6 as source of fbclk */
> +		silab,fb-source = <SI5338_FB_SRC_CLKIN56>;
> +
> +		/* connect divrefclk as source of pll */
> +		silab,pll-source = <SI5338_PFD_IN_REF_DIVREFCLK>;
> +
> +		/* Choose one MS for pll master */
> +		silabs,pll-master = <0>;
> +
> +		/* Specify pll-vco frequency. pll-master is ignored. */
> +		silabs,pll-vco = <2450000000>;
> +
> +		/* output */
> +		clkout0 {

reg property means you need a unit address.

> +			reg = <0>;
> +			silabs,drive-config = "1V8_LVDS";
> +			silabs,clock-source = <SI5338_OUT_MUX_MS0>;
> +			silabs,disable-state = <SI5338_OUT_DIS_HIZ>;
> +			clock-frequency = <125000000>;
> +		};
> +		clkout1 {
> +			reg = <1>;
> +			silabs,drive-config = "1V8_LVDS";
> +			silabs,clock-source = <SI5338_OUT_MUX_MSN>;
> +			silabs,disable-state = <SI5338_OUT_DIS_HIZ>;
> +			clock-frequency = <125000000>;
> +		};
> +		clkout2 {
> +			reg = <2>;
> +			silabs,drive-config = "1V8_LVDS";
> +			silabs,clock-source = <SI5338_OUT_MUX_MSN>;
> +			silabs,disable-state = <SI5338_OUT_DIS_HIZ>;
> +			clock-frequency = <125000000>;
> +		};
> +		clkout3 {
> +			reg = <3>;
> +			silabs,drive-config = "1V8_LVDS";
> +			silabs,clock-source = <SI5338_OUT_MUX_MSN>;
> +			silabs,disable-state = <SI5338_OUT_DIS_HIZ>;
> +			clock-frequency = <125000000>;
> +		};
> +
> +	};
> +};