Information about this ACPI emulation

 CONFIGURATION

The kernel must be built with CONFIG_FRV_ACPI_EMU configured. It can
be built in or built as a module. It if is built as a module, the
module must be loaded before any of the ACPI emulation will fucntion.

 EVENTS

ACPI events are written to /proc/acpi/events. Events are not queued;
if nothing is reading /proc/acpi/events when an event occurs, the
event information is discarded.
The acpid program can be used to interpret and respond to
events. Running acpid with the "-d" option will show you what events
are being generated.

 AUTOSUSPEND AND AUTOSTANDBY TIMER EMULATION

Write any positive integer string to
/proc/acpi/bios_emulation/suspend_timeout to start the timer:

echo 60 > /proc/acpi/bios_emulation/suspend_timeout

will set a 60-second suspend timeout. Write a zero to stop the timer.
Read the timer to findout how many seconds remain before the timout
occurs. The timeout causes an ACPI event.

Autostandby works the same as autosuspend, using
/proc/acpi/bios_emulation/standby_timeout.

Write a non-zero integer string to
/proc/acpi/bios_emulation/restart_timeout to simulate activity. This
restarts the suspend and standby timeouts.

 POWERDOWM MODE

Write either "suspend" or "shutdown" to
/proc/acpi/bios_emulation/powerdown_mode to change the powerdown mode.

 POWERSAVE MODE IN AC-IN STATE

Write a zero or non-zero integer string to
/proc/acpi/bios_emulation/powersave_mode to emulate enabling or
disabling powersave mode in AC-in state.

 BATTERY ALARM AND DEAD VOLTAGE PARAMETERS

/proc/acpi/battery/BAT0/alarm and /proc/acpi/battery/BAT0/dead are
used to set the capacity at which battery low and battery dead events
are generated. Write ro /proc/acpi/battery/BAT0/emulatecapacity to set
an emulated battery capacity value. If you set it beloew the alarm or
dead thresholds, the ACPI daemon will generate battery events.

 CPU CONTROL FOR SUSPEND

Write the integer-value string "5" to /proc/sys/pm/suspend to suspend
the system. On the PDK, pressing any of the user pushbuttons will
resume the system.
Write to other /proc/sys/pm/ files to set the cm, cmode, and p0
values. Read /proc/cpuinfo to see the current values.

 SAMPLE POWER BUTTON DRIVER ON THE PDK

A power button driver has been implmented for user pushbutton 4 on the
PDK. Pushing button 4 on the PDK generates an ACPI event. The event is
either a power button event or a sleep button event, depending on the
setting of /proc/acpi/bios_emulation/powerdown_mode (see above).

acpid can be configured, for instance, to write 5 to
/proc/sys/pm/suspend when the suspend button event is generated.
