APM(4)

NAME
apm - advanced power management device interface

SYNOPSIS
apm0 at pxaip?

DESCRIPTION
The apm driver provides an interface which simulates the Advanced Power Management (APM) BIOS functions. The BIOS functions are translated into the appropriate Power Manager requests. Currently only battery level, AC connection, and charging status is available from the apm device, and no distinction is made between standby and suspend requests. Other power events are NOT YET SUPPORTED.

Configuration options:

APMDEBUG
    Enable various driver status messages.
DIAGNOSTIC
    Enable debugging messages.
DEBUG
    Enable other debugging messages.

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

APM_IOC_REJECT
    (struct apm_event_info) Not implemented. DO NOT USE.

APM_IOC_STANDBY
    (no parameters) Request “standby” mode.

APM_IOC_SUSPEND
    (no parameters) Request “suspend” mode.

APM_IOC_GETPOWER
    (struct apm_power_info) Request the current power state. The argument 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.

    APM_AC_BACKUP
        Backup power in use.

    APM_AC_UNKNOWN
        External power state unknown.

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

    The minutes_left value contains the estimated number of minutes of battery life remaining. If no time estimate is available, the minutes_left value is 0.

APM_IOC_NEXTEVENT
    NOT YET SUPPORTED on zaurus (struct apm_event_info) The APM driver stores up to APM_NEVENTS events. This was defined as 16 at the time this documentation was written. If the event list is full when a new event is detected the new event is lost. APM_IOC_NEXTEVENT ioctl returns the next event on the list or EAGAIN if the event list is empty. The format of the returned event is:

        struct apm_event_info {
        	u_int type;
        	u_int index;
        	u_int spare[8];
        };

    where index is a sequential count of events that can be used to check if any events were lost and type is one of:

    APM_STANDBY_REQ
    APM_SUSPEND_REQ
    APM_NORMAL_RESUME
    APM_CRIT_RESUME
    APM_BATTERY_LOW
    APM_POWER_CHANGE
    APM_UPDATE_TIME
    APM_CRIT_SUSPEND_REQ
    APM_USER_STANDBY_REQ
    APM_USER_SUSPEND_REQ
    APM_SYS_STANDBY_RESUME

APM_IOC_DEV_CTL
    NOT YET SUPPORTED on zaurus (struct apm_ctl) Allows an application to directly set the APM operating mode. The argument structure is as follows:

        struct apm_ctl {
        	u_int dev;
        	u_int mode;
        };

    dev indicates the device, typically APM_DEV_ALLDEVS.

    mode indicates the desired operating mode. Possible values are
    APM_SYS_READY
    APM_SYS_STANDBY
    APM_SYS_SUSPEND
    APM_SYS_OFF
    APM_LASTREQ_INPROG
    APM_LASTREQ_REJECTED

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 estimated battery life percentage changes.

    However, in no case will power status messages be displayed until the battery life goes below the percentage in the sysctl(8) state variable machdep.apmwarn. Setting machdep.apmwarn to zero disables all warnings regardless of the APM_IOC_PRN_CTL setting.

FILES

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

/dev/apmctl
    Power management 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), sysctl.conf(5), apm(8), apmd(8), halt(8), sysctl(8)

BUGS
Power events are not supported.

Reported battery life remaining and minutes left can be off by 25% or more, and are generally overestimated while the battery is charging.