Re: [PATCH] ACPI: generate wakeup events on fixed power button

[Zhang Rui <rui.zhang@intel.com>]

On 四, 2012-04-12 at 17:35 +0100, Daniel Drake wrote:
> When the system is woken up by the ACPI fixed power button, currently there
> is no way of userspace becoming aware that the power button was pressed.
> 
> OLPC would like to know this, so that we can respond appropriately.
> For example, if the system was woken up by a network packet, we know
> we can go back to sleep very quickly. But if the user explicitly woke the
> system with the power button, we're going to want to stay awake for a
> while.
> 
> The wakeup count mechanism seems like a good fit for communicating this.
> Mark the fixed power button as wakeup-enabled, and increment its wakeup
> counter when the system is woken with the power button. (The wakeup counter
> is also incremented when the power button is pressed during system
> operation; this is already handled by an existing acpi-button codepath).
> 
> Signed-off-by: Daniel Drake <dsd@laptop.org>

Acked-by: Zhang Rui <rui.zhang@intel.com>

> ---
>  drivers/acpi/scan.c  |    1 +
>  drivers/acpi/sleep.c |   43 +++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 42 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 767e2dc..bf1f4f7 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1566,6 +1566,7 @@ static int acpi_bus_scan_fixed(void)
>  						ACPI_BUS_TYPE_POWER_BUTTON,
>  						ACPI_STA_DEFAULT,
>  						&ops);
> +		device_init_wakeup(&device->dev, true);
>  	}
>  
>  	if ((acpi_gbl_FADT.flags & ACPI_FADT_SLEEP_BUTTON) == 0) {
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 1d661b5..2c88796 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -47,6 +47,7 @@ static u8 wake_sleep_flags(void)
>  }
>  
>  static u8 sleep_states[ACPI_S_STATE_COUNT];
> +static bool pwr_btn_event_pending;
>  
>  static void acpi_sleep_tts_switch(u32 acpi_state)
>  {
> @@ -176,6 +177,14 @@ static int acpi_pm_prepare(void)
>  	return error;
>  }
>  
> +static int find_powerf_dev(struct device *dev, void *data)
> +{
> +	struct acpi_device *device = to_acpi_device(dev);
> +	const char *hid = acpi_device_hid(device);
> +
> +	return !strcmp(hid, ACPI_BUTTON_HID_POWERF);
> +}
> +
>  /**
>   *	acpi_pm_finish - Instruct the platform to leave a sleep state.
>   *
> @@ -184,6 +193,7 @@ static int acpi_pm_prepare(void)
>   */
>  static void acpi_pm_finish(void)
>  {
> +	struct device *pwr_btn_dev;
>  	u32 acpi_state = acpi_target_sleep_state;
>  
>  	acpi_ec_unblock_transactions();
> @@ -201,6 +211,21 @@ static void acpi_pm_finish(void)
>  	acpi_set_firmware_waking_vector((acpi_physical_address) 0);
>  
>  	acpi_target_sleep_state = ACPI_STATE_S0;
> +
> +	/* 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_dev = bus_find_device(&acpi_bus_type, NULL, NULL,
> +				      find_powerf_dev);
> +	if (pwr_btn_dev)
> +		pm_wakeup_event(pwr_btn_dev, 0);
>  }
>  
>  /**
> @@ -291,9 +316,23 @@ static int acpi_suspend_enter(suspend_state_t pm_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_clear_event(ACPI_EVENT_POWER_BUTTON);
> +	if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
> +		acpi_event_status pwr_btn_status;
> +
> +		acpi_get_event_status(ACPI_EVENT_POWER_BUTTON, &pwr_btn_status);
> +
> +		if (pwr_btn_status & ACPI_EVENT_FLAG_SET) {
> +			acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
> +			/* Flag for later */
> +			pwr_btn_event_pending = true;
> +		}
> +	}
>  
>  	/*
>  	 * Disable and clear GPE status before interrupt is enabled. Some GPEs


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