Input: sun4i-lradc-keys - add wakeup support

Allow the driver to wake the system on key press if the "wakeup-source"
property is provided in the device tree. Using the LRADC as a wakeup
source requires keeping the AVCC domain active during sleep. Since this
has a nontrivial impact on power consumption (sometimes doubling it),
disable the LRADC wakeup source by default.
Signed-off-by: Ondrej Jirman <x@xff.cz>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20220424161328.61103-1-samuel@sholland.orgSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/sun4i-lradc-keys.c

@@ -22,6 +22,8 @@
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/pm_wakeup.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 
@@ -226,8 +228,7 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 {
 	struct sun4i_lradc_data *lradc;
 	struct device *dev = &pdev->dev;
-	int i;
-	int error;
+	int error, i, irq;
 
 	lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
 	if (!lradc)
@@ -272,8 +273,11 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 	if (IS_ERR(lradc->base))
 		return PTR_ERR(lradc->base);
 
-	error = devm_request_irq(dev, platform_get_irq(pdev, 0),
-				 sun4i_lradc_irq, 0,
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	error = devm_request_irq(dev, irq, sun4i_lradc_irq, 0,
 				 "sun4i-a10-lradc-keys", lradc);
 	if (error)
 		return error;
@@ -282,6 +286,16 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
+	if (device_property_read_bool(dev, "wakeup-source")) {
+		error = dev_pm_set_wake_irq(dev, irq);
+		if (error)
+			dev_warn(dev,
+				 "Failed to set IRQ %d as a wake IRQ: %d\n",
+				 irq, error);
+		else
+			device_set_wakeup_capable(dev, true);
+	}
+
 	return 0;
 }