Input: elan_i2c - use PM subsystem to manage wake irq

The Elan I2C touchpad driver is currently manually managing the wake
IRQ. This change removes the explicit enable_irq_wake/disable_irq_wake
and instead relies on the PM subsystem. This is done by calling
dev_pm_set_wake_irq.

i2c_device_probe already calls dev_pm_set_wake_irq when using device
tree, and i2c_device_remove also already calls dev_pm_clear_wake_irq.
There could be some device tree systems that have incorrectly declared
`wake` capabilities, so this change will set the wake irq if one is
missing. This matches the previous behavior.

I tested this on an ACPI system where the touchpad doesn't have _PRW
defined. I verified I can still wake the system and that the wake source
was the touchpad IRQ GPIO.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Link: https://lore.kernel.org/r/20220929093200.v6.2.Id022caf53d01112188308520915798f08a33cd3e@changeidSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elan_i2c_core.c

@@ -33,6 +33,7 @@
 #include <linux/jiffies.h>
 #include <linux/completion.h>
 #include <linux/of.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <asm/unaligned.h>
@@ -86,8 +87,6 @@ struct elan_tp_data {
 	u16			fw_page_size;
 	u32			fw_signature_address;
 
-	bool			irq_wake;
-
 	u8			min_baseline;
 	u8			max_baseline;
 	bool			baseline_ready;
@@ -1334,6 +1333,15 @@ static int elan_probe(struct i2c_client *client,
 	if (!dev->of_node)
 		device_init_wakeup(dev, true);
 
+	/*
+	 * The wake IRQ should be declared via device tree instead of assuming
+	 * the IRQ can wake the system. This is here for legacy reasons and
+	 * will be removed once the i2c-core supports querying ACPI for wake
+	 * capabilities.
+	 */
+	if (!dev->power.wakeirq)
+		dev_pm_set_wake_irq(dev, client->irq);
+
 	return 0;
 }
 
@@ -1356,8 +1364,6 @@ static int __maybe_unused elan_suspend(struct device *dev)
 
 	if (device_may_wakeup(dev)) {
 		ret = elan_sleep(data);
-		/* Enable wake from IRQ */
-		data->irq_wake = (enable_irq_wake(client->irq) == 0);
 	} else {
 		ret = elan_set_power(data, false);
 		if (ret)
@@ -1388,9 +1394,6 @@ static int __maybe_unused elan_resume(struct device *dev)
 			dev_err(dev, "error %d enabling regulator\n", error);
 			goto err;
 		}
-	} else if (data->irq_wake) {
-		disable_irq_wake(client->irq);
-		data->irq_wake = false;
 	}
 
 	error = elan_set_power(data, true);