power: supply: axp20x_ac_power: Add wakeup control

The AC power supply input can be used as a wakeup source. Hook up the
ACIN_PLUGIN IRQ to trigger wakeup based on userspace configuration.

To do this, we must remember the list of IRQs for the life of the
device. To know how much space to allocate for the flexible array
member, we switch from using a NULL sentinel to using an array length.

Because we now depend on the specific order of the IRQs (we assume
ACIN_PLUGIN is first and always present), failing to acquire an IRQ
during probe must be a fatal error.

To avoid spuriously waking up the system when the AC power supply is
not configured as a wakeup source, we must explicitly disable all non-
wake IRQs during system suspend. This is because the SoC's NMI input is
shared among all IRQs on the AXP PMIC. Due to the use of regmap-irq, the
individual IRQs within the PMIC are nested threaded interrupts, and are
therefore not automatically disabled during system suspend.

The upshot is that if any other device within the MFD (such as the power
key) is an enabled wakeup source, all enabled IRQs within the PMIC will
cause wakeup. We still need to call enable_irq_wake() when we *do* want
wakeup, in case those other wakeup sources on the PMIC are all disabled.
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/axp20x_ac_power.c

@@ -15,6 +15,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/power_supply.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
@@ -44,6 +45,8 @@ struct axp20x_ac_power {
 	struct iio_channel *acin_v;
 	struct iio_channel *acin_i;
 	bool has_acin_path_sel;
+	unsigned int num_irqs;
+	unsigned int irqs[];
 };
 
 static irqreturn_t axp20x_ac_power_irq(int irq, void *devid)
@@ -242,38 +245,86 @@ static const struct power_supply_desc axp813_ac_power_desc = {
 	.set_property = axp813_ac_power_set_property,
 };
 
+static const char * const axp20x_irq_names[] = {
+	"ACIN_PLUGIN",
+	"ACIN_REMOVAL",
+};
+
 struct axp_data {
 	const struct power_supply_desc	*power_desc;
+	const char * const		*irq_names;
+	unsigned int			num_irq_names;
 	bool				acin_adc;
 	bool				acin_path_sel;
 };
 
 static const struct axp_data axp20x_data = {
 	.power_desc	= &axp20x_ac_power_desc,
+	.irq_names	= axp20x_irq_names,
+	.num_irq_names	= ARRAY_SIZE(axp20x_irq_names),
 	.acin_adc	= true,
 	.acin_path_sel	= false,
 };
 
 static const struct axp_data axp22x_data = {
 	.power_desc	= &axp22x_ac_power_desc,
+	.irq_names	= axp20x_irq_names,
+	.num_irq_names	= ARRAY_SIZE(axp20x_irq_names),
 	.acin_adc	= false,
 	.acin_path_sel	= false,
 };
 
 static const struct axp_data axp813_data = {
 	.power_desc	= &axp813_ac_power_desc,
+	.irq_names	= axp20x_irq_names,
+	.num_irq_names	= ARRAY_SIZE(axp20x_irq_names),
 	.acin_adc	= false,
 	.acin_path_sel	= true,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static int axp20x_ac_power_suspend(struct device *dev)
+{
+	struct axp20x_ac_power *power = dev_get_drvdata(dev);
+	int i = 0;
+
+	/*
+	 * Allow wake via ACIN_PLUGIN only.
+	 *
+	 * As nested threaded IRQs are not automatically disabled during
+	 * suspend, we must explicitly disable the remainder of the IRQs.
+	 */
+	if (device_may_wakeup(&power->supply->dev))
+		enable_irq_wake(power->irqs[i++]);
+	while (i < power->num_irqs)
+		disable_irq(power->irqs[i++]);
+
+	return 0;
+}
+
+static int axp20x_ac_power_resume(struct device *dev)
+{
+	struct axp20x_ac_power *power = dev_get_drvdata(dev);
+	int i = 0;
+
+	if (device_may_wakeup(&power->supply->dev))
+		disable_irq_wake(power->irqs[i++]);
+	while (i < power->num_irqs)
+		enable_irq(power->irqs[i++]);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(axp20x_ac_power_pm_ops, axp20x_ac_power_suspend,
+						 axp20x_ac_power_resume);
+
 static int axp20x_ac_power_probe(struct platform_device *pdev)
 {
 	struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
 	struct power_supply_config psy_cfg = {};
 	struct axp20x_ac_power *power;
 	const struct axp_data *axp_data;
-	static const char * const irq_names[] = { "ACIN_PLUGIN", "ACIN_REMOVAL",
-		NULL };
 	int i, irq, ret;
 
 	if (!of_device_is_available(pdev->dev.of_node))
@@ -284,12 +335,14 @@ static int axp20x_ac_power_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
+	axp_data = of_device_get_match_data(&pdev->dev);
+
+	power = devm_kzalloc(&pdev->dev,
+			     struct_size(power, irqs, axp_data->num_irq_names),
+			     GFP_KERNEL);
 	if (!power)
 		return -ENOMEM;
 
-	axp_data = of_device_get_match_data(&pdev->dev);
-
 	if (axp_data->acin_adc) {
 		power->acin_v = devm_iio_channel_get(&pdev->dev, "acin_v");
 		if (IS_ERR(power->acin_v)) {
@@ -308,6 +361,7 @@ static int axp20x_ac_power_probe(struct platform_device *pdev)
 
 	power->regmap = dev_get_regmap(pdev->dev.parent, NULL);
 	power->has_acin_path_sel = axp_data->acin_path_sel;
+	power->num_irqs = axp_data->num_irq_names;
 
 	platform_set_drvdata(pdev, power);
 
@@ -321,20 +375,22 @@ static int axp20x_ac_power_probe(struct platform_device *pdev)
 		return PTR_ERR(power->supply);
 
 	/* Request irqs after registering, as irqs may trigger immediately */
-	for (i = 0; irq_names[i]; i++) {
-		irq = platform_get_irq_byname(pdev, irq_names[i]);
+	for (i = 0; i < axp_data->num_irq_names; i++) {
+		irq = platform_get_irq_byname(pdev, axp_data->irq_names[i]);
 		if (irq < 0) {
-			dev_warn(&pdev->dev, "No IRQ for %s: %d\n",
-				 irq_names[i], irq);
-			continue;
+			dev_err(&pdev->dev, "No IRQ for %s: %d\n",
+				axp_data->irq_names[i], irq);
+			return irq;
 		}
-		irq = regmap_irq_get_virq(axp20x->regmap_irqc, irq);
-		ret = devm_request_any_context_irq(&pdev->dev, irq,
+		power->irqs[i] = regmap_irq_get_virq(axp20x->regmap_irqc, irq);
+		ret = devm_request_any_context_irq(&pdev->dev, power->irqs[i],
 						   axp20x_ac_power_irq, 0,
 						   DRVNAME, power);
-		if (ret < 0)
-			dev_warn(&pdev->dev, "Error requesting %s IRQ: %d\n",
-				 irq_names[i], ret);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "Error requesting %s IRQ: %d\n",
+				axp_data->irq_names[i], ret);
+			return ret;
+		}
 	}
 
 	return 0;
@@ -359,6 +415,7 @@ static struct platform_driver axp20x_ac_power_driver = {
 	.driver = {
 		.name		= DRVNAME,
 		.of_match_table	= axp20x_ac_power_match,
+		.pm		= &axp20x_ac_power_pm_ops,
 	},
 };