Input: elants_i2c - use PM subsystem to manage wake irq

The Elan I2C touchscreen 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.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Link: https://lore.kernel.org/r/20220929093200.v6.3.I5862429ee3e4de0f9ad5ba01ce07ad99eec10cf0@changeidSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/elants_i2c.c

@@ -36,6 +36,7 @@
 #include <linux/input/touchscreen.h>
 #include <linux/acpi.h>
 #include <linux/of.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 #include <linux/uuid.h>
@@ -180,7 +181,6 @@ struct elants_data {
 	u8 cmd_resp[HEADER_SIZE];
 	struct completion cmd_done;
 
-	bool wake_irq_enabled;
 	bool keep_power_in_suspend;
 
 	/* Must be last to be used for DMA operations */
@@ -1571,6 +1571,15 @@ static int elants_i2c_probe(struct i2c_client *client)
 	if (!client->dev.of_node)
 		device_init_wakeup(&client->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 (!client->dev.power.wakeirq)
+		dev_pm_set_wake_irq(&client->dev, client->irq);
+
 	error = devm_device_add_group(&client->dev, &elants_attribute_group);
 	if (error) {
 		dev_err(&client->dev, "failed to create sysfs attributes: %d\n",
@@ -1602,7 +1611,7 @@ static int __maybe_unused elants_i2c_suspend(struct device *dev)
 		 * The device will automatically enter idle mode
 		 * that has reduced power consumption.
 		 */
-		ts->wake_irq_enabled = (enable_irq_wake(client->irq) == 0);
+		return 0;
 	} else if (ts->keep_power_in_suspend) {
 		for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {
 			error = elants_i2c_send(client, set_sleep_cmd,
@@ -1631,8 +1640,6 @@ static int __maybe_unused elants_i2c_resume(struct device *dev)
 	int error;
 
 	if (device_may_wakeup(dev)) {
-		if (ts->wake_irq_enabled)
-			disable_irq_wake(client->irq);
 		elants_i2c_sw_reset(client);
 	} else if (ts->keep_power_in_suspend) {
 		for (retry_cnt = 0; retry_cnt < MAX_RETRIES; retry_cnt++) {