APM(4)              OpenBSD Programmer's Manual (Loongson)              APM(4)

NAME
     apm - advanced power management device interface

SYNOPSIS
     apm0 at mainbus0

DESCRIPTION
     The apm driver provides generic power and battery control, relying on de-
     vice specific drivers to provide the actual information.

     The apm driver provides an interface which simulates the Advanced Power
     Management (APM) BIOS functions encountered on some x86 hardware.  The
     BIOS functions are translated into the appropriate microcontroller re-
     quests by the hardware specific drivers, like ykbec(4).  Currently only
     battery level, AC connection, and charging status are available from the
     apm device.  Suspend/resume and other power events are not yet supported.

     The apm driver implements the following ioctl(2) calls.  They are defined
     in <machine/apmvar.h>.

     APM_IOC_GETPOWER
             (struct apm_power_info) Request the current power state.  The ar-
             gument structure is as follows:

                   struct apm_power_info {
                           u_char battery_state;
                           u_char ac_state;
                           u_char battery_life;
                           u_char spare1;
                           u_int minutes_left;
                           u_int spare2[6];
                   };

             The following values are defined for battery_state:

             APM_BATT_HIGH
                     Battery has a high state of charge.

             APM_BATT_LOW
                     Battery has a low state of charge.

             APM_BATT_CRITICAL
                     Battery has a critical state of charge.

             APM_BATT_CHARGING
                     Battery is not high, low, or critical and is currently
                     charging.

             APM_BATT_UNKNOWN
                     Can not read the current battery state.

             APM_BATTERY_ABSENT
                     No battery installed.

             The following values are defined for ac_state:

             APM_AC_OFF
                     External power not detected.

             APM_AC_ON
                     External power detected.

             The battery_life value contains the estimated percentage of bat-
             tery life available.  100% indicates a full charge.

             The minutes_left value contains the estimated number of minutes
             of battery life remaining.

     APM_IOC_PRN_CTL
             (int) This ioctl(2) controls message output by the apm driver
             when a power change event is detected.  The integer parameter is
             one of:

             APM_PRINT_ON
                     All power change events result in a message.  This is the
                     normal operating mode for the driver.

             APM_PRINT_OFF
                     Power change event messages are suppressed.

             APM_PRINT_PCT
                     Power change event messages are suppressed unless the es-
                     timated battery life percentage changes.

FILES
     /dev/apm     APM data device.  May only be opened read-only.  May be
                  opened by multiple concurrent users.

     /dev/apmctl  APM control device.  May be opened read-write or write-only.
                  May only be opened by one user at a time.  An attempt to
                  open the file when in use will fail, returning EBUSY.

SEE ALSO
     intro(4), ykbec(4), apm(8), apmd(8)

BUGS
     Suspend and resume are not supported.

OpenBSD 4.7                    February 28, 2010                             2
