[PATCH v2 1/1] 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 | 38 ++++++++++++++++-------------
 drivers/acpi/sleep.c  | 56 +++----------------------------------------
 include/acpi/button.h |  5 ----
 3 files changed, 24 insertions(+), 75 deletions(-)

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 8d2843bece29..f9b6b7fff5bd 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -175,6 +175,7 @@ struct acpi_button {
 	int last_state;
 	ktime_t last_time;
 	bool suspended;
+	bool wakeup_pending;
 	bool lid_state_initialized;
 };
 
@@ -452,6 +453,9 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
 	acpi_pm_wakeup_event(&device->dev);
 
 	button = acpi_driver_data(device);
+	if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+		button->wakeup_pending = true;
+
 	if (button->suspended)
 		return;
 
@@ -468,23 +472,6 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
 					event, ++button->pushed);
 }
 
-void acpi_power_button_wakeup(struct acpi_device *device)
-{
-       struct acpi_button *button = acpi_driver_data(device);
-       struct input_dev *input;
-
-       if (button->type == ACPI_BUTTON_TYPE_POWER) {
-               input = button->input;
-               input_report_key(input, KEY_WAKEUP, 1);
-               input_sync(input);
-               input_report_key(input, KEY_WAKEUP, 0);
-               input_sync(input);
-       }
-
-       return;
-}
-EXPORT_SYMBOL(acpi_power_button_wakeup);
-
 static void acpi_button_notify_run(void *data)
 {
 	acpi_button_notify(NULL, ACPI_BUTTON_NOTIFY_STATUS, data);
@@ -492,6 +479,12 @@ static void acpi_button_notify_run(void *data)
 
 static u32 acpi_button_event(void *data)
 {
+	struct acpi_device *device = data;
+	struct acpi_button *button = acpi_driver_data(device);
+
+	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;
 }
@@ -503,11 +496,13 @@ static int acpi_button_suspend(struct device *dev)
 	struct acpi_button *button = acpi_driver_data(device);
 
 	button->suspended = true;
+	button->wakeup_pending = false;
 	return 0;
 }
 
 static int acpi_button_resume(struct device *dev)
 {
+	struct input_dev *input;
 	struct acpi_device *device = to_acpi_device(dev);
 	struct acpi_button *button = acpi_driver_data(device);
 
@@ -518,6 +513,15 @@ static int acpi_button_resume(struct device *dev)
 		acpi_lid_initialize_state(device);
 	}
 
+	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;
 }
 #endif
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 0adfcd0fb55e..d655248c20d4 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -22,7 +22,6 @@
 #include <linux/syscore_ops.h>
 #include <asm/io.h>
 #include <trace/events/power.h>
-#include <acpi/button.h>
 
 #include "internal.h"
 #include "sleep.h"
@@ -105,8 +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
@@ -463,7 +460,6 @@ 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();
@@ -482,24 +478,6 @@ 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_power_button_wakeup(pwr_btn_adev);
-		acpi_dev_put(pwr_btn_adev);
-	}
 }
 
 /**
@@ -604,27 +582,6 @@ 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
@@ -797,19 +754,12 @@ bool acpi_s2idle_wake(void)
 
 void acpi_s2idle_restore_check_powerkey(void)
 {
-	struct acpi_device *pwr_btn_adev;
 	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) {
-		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_power_button_wakeup(pwr_btn_adev);
-			acpi_dev_put(pwr_btn_adev);
-		}
-	}
+	if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET)
+		acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
 }
 
 void acpi_s2idle_restore(void)
diff --git a/include/acpi/button.h b/include/acpi/button.h
index be02d3ff2896..af2fce5d2ee3 100644
--- a/include/acpi/button.h
+++ b/include/acpi/button.h
@@ -8,16 +8,11 @@
 
 #if IS_ENABLED(CONFIG_ACPI_BUTTON)
 extern int acpi_lid_open(void);
-extern void acpi_power_button_wakeup(struct acpi_device *device);
 #else
 static inline int acpi_lid_open(void)
 {
 	return 1;
 }
-static inline void acpi_power_button_wakeup(struct acpi_device *device)
-{
-       return;
-}
 #endif /* IS_ENABLED(CONFIG_ACPI_BUTTON) */
 
 #endif /* ACPI_BUTTON_H */
-- 
2.34.1