Re: [PATCH v8 1/6] mfd: AXP20x: Add bindings documentation

[Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On Tue, 23 Dec 2014, Chen-Yu Tsai wrote:

> From: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
> 
> Bindings documentation for the AXP20x driver. In this file also
> sub-nodes are documented.
> 
> Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
> Acked-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> [wens-jdAy2FN1RRM@public.gmane.org: clarify interrupt source for the axp PMIC]
> [wens-jdAy2FN1RRM@public.gmane.org: explain dcdc-workmode in detail and trim lines to 80 chars]
> [wens-jdAy2FN1RRM@public.gmane.org: make regulator supplies optional if using unregulated input]
> [wens-jdAy2FN1RRM@public.gmane.org: use cubieboard2 regulator nodes as example]
> Signed-off-by: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
> ---
>  Documentation/devicetree/bindings/mfd/axp20x.txt | 97 ++++++++++++++++++++++++
>  1 file changed, 97 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/axp20x.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/axp20x.txt b/Documentation/devicetree/bindings/mfd/axp20x.txt
> new file mode 100644
> index 000000000000..b775d8ccbc7c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/axp20x.txt
> @@ -0,0 +1,97 @@
> +AXP202/AXP209 device tree bindings
> +
> +The axp20x family current members :
> +axp202 (X-Powers)
> +axp209 (X-Powers)
> +
> +Required properties:
> +- compatible: "x-powers,axp202" or "x-powers,axp209"
> +- reg: The I2C slave address for the AXP chip
> +- interrupt-parent: The parent interrupt controller
> +- interrupts: SoC NMI / GPIO interrupt connected to the PMIC's IRQ pin
> +- interrupt-controller: axp20x has its own internal IRQs
> +- #interrupt-cells: Should be set to 1
> +- regulators: A node that houses a sub-node for each regulator. The regulators
> +	      are bound using their name as listed here: dcdc2, dcdc3, ldo1,
> +	      ldo2, ldo3, ldo4, ldo5.  The bindings details of individual
> +	      regulator device can be found in:
> +	      Documentation/devicetree/bindings/regulator/regulator.txt with
> +	      the exception of x-powers,dcdc-freq. Regulators not used should
> +	      still be listed for completeness and that the regulator subsystem
> +	      properly registers them.
> +
> +- x-powers,dcdc-freq: defines the work frequency of DC-DC in KHz
> +		      (range: 750-1875). Default: 1.5MHz

I'm not keen on defining new properties when existing properties would
suffice.  How about using clock-frequency here instead?  Also it's not
common to issue this stuff using metric prefixes (KHz, MHz, etc).
Please use HZ.

> +Optional properties:
> +- regulator supplies - may be omitted if inputs are unregulated, such as using
> +		       the IPSOUT output from the PMIC
> +  - acin-supply: The input supply for LDO1
> +  - vin2-supply: The input supply for DCDC2
> +  - vin3-supply: The input supply for DCDC3
> +  - ldo24in-supply: The input supply for LDO2, LDO4
> +  - ldo3in-supply: The input supply for LDO3
> +  - ldo5in-supply: The input supply for LDO5
> +
> +Optional properties for DCDC regulators:
> +- x-powers,dcdc-workmode: 1 for PWM mode, 0 for AUTO (PWM/PFM) mode

If there only two options, please use bool.

'x-powers,dcdc-workmode-pwm' and default to auto if it's not present.

> +			  Default: AUTO mode
> +			  The DCDC regulators work in a mixed PWM/PFM mode,
> +			  using PFM under light loads and switching to PWM
> +			  for heavier loads. Forcing PWM mode trades efficiency
> +			  under light loads for lower output noise. This
> +			  probably makes sense for HiFi audio related
> +			  applications that aren't battery constrained.
> +
> +Example:
> +
> +axp209: pmic@34 {
> +	compatible = "x-powers,axp209";
> +	reg = <0x34>;
> +	interrupt-parent = <&nmi_intc>;
> +	interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
> +	interrupt-controller;
> +	#interrupt-cells = <1>;
> +
> +	regulators {
> +		x-powers,dcdc-freq = <1500>;
> +
> +		vdd_cpu: dcdc2 {
> +			regulator-always-on;
> +			regulator-min-microvolt = <1000000>;
> +			regulator-max-microvolt = <1450000>;
> +			regulator-name = "vdd-cpu";
> +		};
> +
> +		vdd_int_dll: dcdc3 {
> +			regulator-always-on;
> +			regulator-min-microvolt = <1000000>;
> +			regulator-max-microvolt = <1400000>;
> +			regulator-name = "vdd-int-dll";
> +		};
> +
> +		vdd_rtc: ldo1 {
> +			regulator-always-on;
> +			regulator-min-microvolt = <1200000>;
> +			regulator-max-microvolt = <1400000>;
> +			regulator-name = "vdd-rtc";
> +		};
> +
> +		avcc: ldo2 {
> +			regulator-always-on;
> +			regulator-min-microvolt = <2700000>;
> +			regulator-max-microvolt = <3300000>;
> +			regulator-name = "avcc";
> +		};
> +
> +		ldo3 {
> +			/* unused */
> +		};

Does this need to be in the example?

> +		csi1_io_2v8: ldo4 {
> +			/* output on extension headers */
> +			regulator-name = "csi1-io-2v8";
> +		};
> +	};
> +};
> +

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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