On 09/10/2012 09:03 AM, Daniel Mack wrote:
> Add DT bindings for the gpio-regulator driver and some documentation on
> how to use it.
> +++ b/Documentation/devicetree/bindings/regulator/gpio-regulator.txt
> @@ -0,0 +1,58 @@
> +Device tree bindings for GPIO controlled voltages
> +
> +Voltage or current regulators on boards that are controlled by GPIOs can
> +be used by the gpio-regulator driver.
> +
> +Required properties:
> +
> + - "compatible": must be set to "gpio-regulator"
> + - "regulator-name": must be set to a string describing the name of
> this
> + regulator.
I'd expect the "gpios" property to be listed here.
> +Optional properties:
> +
> + - "startup-delay": Start-up time in microseconds
> + - "enable-high": Polarity of enable GPIO. Active high if
> + defined, otherwise active low
fixed-regulator.txt already has an "enable-active-high" property; it'd
be nice to be consistent.
> + - "enabled-at-boot": If set, the regulator has been enabled
> at boot
> + time
Isn't that regulator-boot-on, as defined in regulator.txt that you
mentioned?
> + - "regulator-type-voltage": The regulator controls a voltage
> + - "regulator-type-current": The regulator controls a current
I wonder if it'd be better to differentiate this using different
compatible values instead?
> + - "states": An array of possible states, describing the
> + GPIO states to reach a given value
> + - "value": The value of the state, in microvolts or
> + microamperes
A name like "microvolts", "voltage", "microamps", or "current" might be
more descriptive here.
> + - "gpios": bitfield of gpio target-states for the value
> + The n-th bit in the bitfield describes the
> + state of the n-th GPIO from the gpios-array
"gpios" sounds like the name of a property that defines which GPIOs are
used, rather than the value of those GPIOs. Perhaps "gpio-values" instead?
Actually, I wonder if we really even need to represent that values
explicitly; rather than have a big set of nodes, perhaps you can instead
have a single property that lists the voltage (or current) that each
combination of GPIO values gives; something like:
reg_gpio {
...
gpios = <&ggpio 23 0 &gpio 24 0>;
voltages = <0 1000000 2000000 3000000>;
};
(As inspiration for that, I looked at
Documentation/devicetree/bindings/net/mdio-mux-gpio.txt which doesn't
have a property defining the value of the GPIOs for each combination,
but rather a node per valid combination).
Perhaps represent and invalid GPIO combination with 0xffffffff?
> +Also, all properties described in
> +Documentation/devicetree/bindings/regulator/regulator.txt are supported as
> +well.
> +
> +Example:
> +
> + reg_gpio {
> + compatible = "gpio-regulator";
> + regulator-name = "voltage";
> + regulator-enable-high;
> + regulator-type-voltage;
> + regulator-min-microvolt = <3300000>;
> + regulator-max-microvolt = <3300000>;
> + regulator-always-on;
> +
> + gpios = <&gpio 23 0>;
> +
> + states {
> + state-on {
> + value = <3300000>;
> + gpios = <0x1>;
> + };
> +
> + state-off {
> + value = <0>;
> + gpios = <0x0>;
> + };
> + };
> + };
That particular example only has on/off states, and so might be better
covered using the existing fixed-regulator, with optional GPIO control.
Perhaps an example using 2 GPIOs for 4 voltage states would be more useful?
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