[PATCH v3] ACPI: button: Report wakeup key only for power button wakeups

[Baorui.Liu <baorliu@amd.com>]

The ACPI button driver reports KEY_WAKEUP from the Power Button input
device to let userspace know that the system was resumed by a power
button wakeup.

However, reporting KEY_WAKEUP from generic system resume paths can make
userspace observe a Power Button wakeup even when the system was resumed
by a different wake source.

This is reproducible on an AMD Android 15 Xen guest. With a kernel
without this fix, a non-power-button S3 resume:

  echo mem > /sys/power/state
  xl trigger android s3resume

makes the Power Button input device report KEY_WAKEUP. The same test on
a kernel with this fix no longer reports KEY_WAKEUP from the Power Button
input device.

Track whether a power button event/notify is observed while the ACPI
button device is suspended, and report KEY_WAKEUP on resume only in that
case. Do not synthesize a Power Button input event from generic ACPI
sleep resume code.

Signed-off-by: Baorui.Liu <baorliu@amd.com>
---
 drivers/acpi/button.c | 13 ++++++++++++-
 drivers/acpi/sleep.c  | 41 -----------------------------------------
 2 files changed, 12 insertions(+), 42 deletions(-)

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index cdbb1023a8ee..7a708fe351fb 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -191,6 +191,7 @@ struct acpi_button {
 	bool last_state;
 	ktime_t last_time;
 	bool suspended;
+	bool wakeup_pending;
 	bool lid_state_initialized;
 	bool gpe_enabled;
 };
@@ -476,6 +477,9 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
 
 	acpi_pm_wakeup_event(button->dev);
 
+	if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+		button->wakeup_pending = true;
+
 	if (button->suspended || event == ACPI_BUTTON_NOTIFY_WAKE)
 		return;
 
@@ -498,6 +502,11 @@ static void acpi_button_notify_run(void *data)
 
 static u32 acpi_button_event(void *data)
 {
+	struct acpi_button *button = data;
+
+	if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+		button->wakeup_pending = true;
+
 	acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_button_notify_run, data);
 	return ACPI_INTERRUPT_HANDLED;
 }
@@ -508,6 +517,7 @@ static int acpi_button_suspend(struct device *dev)
 	struct acpi_button *button = dev_get_drvdata(dev);
 
 	button->suspended = true;
+	button->wakeup_pending = false;
 	return 0;
 }
 
@@ -523,12 +533,13 @@ static int acpi_button_resume(struct device *dev)
 		acpi_lid_initialize_state(button);
 	}
 
-	if (button->type == ACPI_BUTTON_TYPE_POWER) {
+	if (button->type == ACPI_BUTTON_TYPE_POWER && button->wakeup_pending) {
 		input = button->input;
 		input_report_key(input, KEY_WAKEUP, 1);
 		input_sync(input);
 		input_report_key(input, KEY_WAKEUP, 0);
 		input_sync(input);
+		button->wakeup_pending = false;
 	}
 	return 0;
 }
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 132a9df98471..7296e4bb0e4d 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -104,8 +104,6 @@ u32 acpi_target_system_state(void)
 }
 EXPORT_SYMBOL_GPL(acpi_target_system_state);
 
-static bool pwr_btn_event_pending;
-
 /*
  * The ACPI specification wants us to save NVS memory regions during hibernation
  * and to restore them during the subsequent resume.  Windows does that also for
@@ -484,7 +482,6 @@ static int acpi_pm_prepare(void)
  */
 static void acpi_pm_finish(void)
 {
-	struct acpi_device *pwr_btn_adev;
 	u32 acpi_state = acpi_target_sleep_state;
 
 	acpi_ec_unblock_transactions();
@@ -503,23 +500,6 @@ static void acpi_pm_finish(void)
 	acpi_target_sleep_state = ACPI_STATE_S0;
 
 	acpi_resume_power_resources();
-
-	/* If we were woken with the fixed power button, provide a small
-	 * hint to userspace in the form of a wakeup event on the fixed power
-	 * button device (if it can be found).
-	 *
-	 * We delay the event generation til now, as the PM layer requires
-	 * timekeeping to be running before we generate events. */
-	if (!pwr_btn_event_pending)
-		return;
-
-	pwr_btn_event_pending = false;
-	pwr_btn_adev = acpi_dev_get_first_match_dev(ACPI_BUTTON_HID_POWERF,
-						    NULL, -1);
-	if (pwr_btn_adev) {
-		pm_wakeup_event(&pwr_btn_adev->dev, 0);
-		acpi_dev_put(pwr_btn_adev);
-	}
 }
 
 /**
@@ -626,27 +606,6 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
 	/* Reprogram control registers */
 	acpi_leave_sleep_state_prep(acpi_state);
 
-	/* ACPI 3.0 specs (P62) says that it's the responsibility
-	 * of the OSPM to clear the status bit [ implying that the
-	 * POWER_BUTTON event should not reach userspace ]
-	 *
-	 * However, we do generate a small hint for userspace in the form of
-	 * a wakeup event. We flag this condition for now and generate the
-	 * event later, as we're currently too early in resume to be able to
-	 * generate wakeup events.
-	 */
-	if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
-		acpi_event_status pwr_btn_status = ACPI_EVENT_FLAG_DISABLED;
-
-		acpi_get_event_status(ACPI_EVENT_POWER_BUTTON, &pwr_btn_status);
-
-		if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET) {
-			acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
-			/* Flag for later */
-			pwr_btn_event_pending = true;
-		}
-	}
-
 	/*
 	 * Disable all GPE and clear their status bits before interrupts are
 	 * enabled. Some GPEs (like wakeup GPEs) have no handlers and this can
-- 
2.34.1