ACPI / PM: Generate wakeup events on fixed power button

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>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
rtc-cmos / PM: report wakeup event on ACPI RTC alarm

When the ACPI-driven RTC alarm wakes the system, report it as a wakeup
event. This allows userspace to determine that the reason for system
wakeup was RTC alarm.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ACPI / PM: Fix error messages in drivers/acpi/bus.c

After recent changes of the ACPI device low-power states definitions
kernel messages in drivers/acpi/bus.c need to be updated so that they
include the correct names of the states in question (currently is
"D3" for D3hot and "D4" for D3cold, which is incorrect).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ACPI / PM: Make __acpi_bus_get_power() cover D3cold correctly

After recent changes of the ACPI device power states definitions, if
power resources are not used for the device's power management, the
state returned by __acpi_bus_get_power() cannot exceed D3hot, because
the return values of _PSC are 0 through 3.  However, if the _PR3
method is not present for the device and _PS3 returns 3, we have to
assume that the device is in D3cold, so the value returned by
__acpi_bus_get_power() in that case should be 4.

Similarly, acpi_power_get_inferred_state() should take the power
resources for the D3hot state into account in general, so that it
can return 3 if those resources are "on" or 4 (D3cold) otherwise.

Fix the the above two issues and make sure that if both _PSC and
_PR3 are present for the device, the power resources listed by _PR3
will be used to determine if the number 3 returned by _PSC is meant
to represent D3cold or D3hot.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ACPI / PM: Make acpi_pm_device_sleep_state() follow the specification

The comparison between the system sleep state being entered
and the lowest system sleep state the given device may wake up
from in acpi_pm_device_sleep_state() is reversed, because the
specification (ACPI 5.0) says that for wakeup to work:

"The sleeping state being entered must be less than or equal to the
 power state declared in element 1 of the _PRW object."

In other words, the state returned by _PRW is the deepest
(lowest-power) system sleep state the device is capable of waking up
the system from.

Moreover, acpi_pm_device_sleep_state() also should check if the
wakeup capability is supported through ACPI, because in principle it
may be done via native PCIe PME, for example, in which case _SxW
should not be evaluated.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>