regulator: core: Allow use of "status = disabled" in regulator dts nodes

The axp20x and axp22x pmics have ldo regulators which are muxed to the outside via gpio pins. Unfortunately regulator enable / disable is implemented in the hardware via selecting a specific pin-mux option.

So if we want to use these pins as gpio pins we must not register a regulator for these pins at all, otherwise any gpio use (switching to input, or writing a value) gets undone when the regulator subsys disables unused regulators at the end of kernel-init.

This commits allows the use of "status = disabled" in regulator dts nodes and makes regulator_register return ENODEV when this is set.

Note that this commit changes the loop to find the of-node in regulator_of_get_init_data from using for_each_available_child_of_node to using for_each_child_of_node. regulator_register is the only user of regulator_of_get_init_data and the use of for_each_available_child... makes little sense there since this will only cause the constraints from regulator dts nodes marked as disabled to not be used, the actual registration of the regulator would still continue.

So in a way this patch could be seen as a bugfix as it actually makes regulators with an of_node which is marked as not available not register, but this behavior change may cause some issues in some places.

Note that individual regulator drivers / callers of regulator_register which may encounter disabled regulator (child) nodes need to be patched to handle ENODEV (to not make it fail their probe method).

---
 drivers/regulator/core.c         | 6 ++++++
 drivers/regulator/of_regulator.c | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

index 744c988..5589203 100644
@@ -3894,6 +3894,12 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		rdev->dev.of_node = of_node_get(config->of_node);
 	}
 
+	if (rdev->dev.of_node && !of_device_is_available(rdev->dev.of_node)) {
+		kfree(config);
+		kfree(rdev);
+		return ERR_PTR(-ENODEV);
+	}
+
 	mutex_lock(&regulator_list_mutex);
 
 	mutex_init(&rdev->mutex);

index 499e437..06ad766 100644
@@ -310,7 +310,7 @@ struct regulator_init_data *regulator_of_get_init_data(struct device *dev,
 		return NULL;
 	}
 
-	for_each_available_child_of_node(search, child) {
+	for_each_child_of_node(search, child) {
 		name = of_get_property(child, "regulator-compatible", NULL);
 		if (!name)
 			name = child->name;

2.7.2

Handle regulator_register returning ENODEV, this may happen when the dts node for the regulator contains "status = disabled" which is useful for the ldo_io regulators, to avoid the regulator code getting in the way of gpio use of these pins.

---
 drivers/regulator/axp20x-regulator.c | 3 +++
 1 file changed, 3 insertions(+)

index 679018c..4250b1b 100644
@@ -421,6 +421,9 @@ static int axp20x_regulator_probe(struct platform_device *pdev)
 
 		rdev = devm_regulator_register(&pdev->dev, desc, &config);
 		if (IS_ERR(rdev)) {
+			if (PTR_ERR(rdev) == -ENODEV)
+				continue;
+
 			dev_err(&pdev->dev, "Failed to register %s\n",
 				regulators[i].name);
 

2.7.2

Use of these as regulators conflicts with use of the gpio pins as gpios, so disabled the ldo_io# regulators by default.

---
 arch/arm/boot/dts/axp22x.dtsi | 2 ++
 1 file changed, 2 insertions(+)

index 76302f5..0cfec50 100644
@@ -126,10 +126,12 @@
 
 		reg_ldo_io0: ldo_io0 {
 			regulator-name = "ldo_io0";
+			status = "disabled";
 		};
 
 		reg_ldo_io1: ldo_io1 {
 			regulator-name = "ldo_io1";
+			status = "disabled";
 		};
 
 		reg_rtc_ldo: rtc_ldo {

2.7.2

Hi Mark,

Any comments on this one?

Thanks,
Maxime

Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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