在 linux 设备树（arm）中定义由相同 GPIO 引脚控制的 3 个调节器

Question

I have a board for which I'm fixing/writing the device tree for, based on the rk3288 (rockchip). In the file there are currently the following definitions for three seperate regulators:

    dovdd_1v8: dovdd-1v8-regulator {
            compatible = "regulator-fixed";
            enable-active-high;
            gpio = <&gpio0 11 GPIO_ACTIVE_HIGH>;
            pinctrl-names = "default";
            pinctrl-0 = <&dvp_pwr>;
            regulator-name = "dovdd_1v8";
            regulator-min-microvolt = <1800000>;
            regulator-max-microvolt = <1800000>;
            vin-supply = <&vcc_io>;
    };

    vcc28_dvp: vcc28-dvp-regulator {
            compatible = "regulator-fixed";
            enable-active-high;
            gpio = <&gpio0 11 GPIO_ACTIVE_HIGH>;
            pinctrl-names = "default";
            pinctrl-0 = <&dvp_pwr>;
            regulator-name = "vcc28_dvp";
            regulator-min-microvolt = <2800000>;
            regulator-max-microvolt = <2800000>;
            vin-supply = <&vcc_io>;
    };

    af_28: af_28-regulator {
            compatible = "regulator-fixed";
            enable-active-high;
            gpio = <&gpio0 11 GPIO_ACTIVE_HIGH>;
            pinctrl-names = "default";
            pinctrl-0 = <&dvp_pwr>;
            regulator-name = "af_28";
            regulator-min-microvolt = <2800000>;
            regulator-max-microvolt = <2800000>;
            vin-supply = <&vcc_io>;
    };

The problem is that the kernel complains that it can't assign the same GPIO pin to these 3 regulators. In the schematic for the board the regulators are controlled by the same GPIO pin.

What is the right way to do this?

Thanks! B

EDIT: here is the error message I see on the serial console:

[    0.270507] rockchip-pinctrl pinctrl: pin gpio0-11 already requested 
by dovdd-1v8-regulator; cannot claim for vcc28-dvp-regulator
[    0.270570] rockchip-pinctrl pinctrl: pin-11 (vcc28-dvp-regulator) status -22
[    0.270611] rockchip-pinctrl pinctrl: could not request pin 11 (gpio0-11) from group dvp-pwr  on device rockchip-pinctrl
[    0.270663] reg-fixed-voltage vcc28-dvp-regulator: Error applying setting, reverse things back

Answer 1

The regulator subsystem allows a single GPIO to enable more than one regulator.
I can find no code in fixed.c or core.c that would inhibit several regulators to share one enabling GPIO.

Now that you have added the salient error message, the issue is clearer.
The error messages that you are getting are not from the GPIO resource management, but rather from the pinctrl subsystem.
The likely cause of this is improper declarations of the pinctrl group for each regulator. (You have not posted that portion of your Device Tree.)
Hence you get a pinctrl allocation error, which is not the same as a GPIO allocation error.
(The pinctrl subsystem is at a lower level than GPIO management, and can allocate pins for peripheral functions, aka pin multiplexing, as well as for GPIO.)

I'm not sure what the proper fix in the DT should be.
Assuming that there is just one pinctrl group declared for the enabling GPIO, you can try using it only once in one regulator node. IOW remove the pinctrl attributes in the other two regulators.