APM(4) - Device Drivers Manual (i386)

APM(4) - Device Drivers Manual (i386) #

APM(4) - Device Drivers Manual (i386)

NAME #

apm - advanced power management device interface

SYNOPSIS #

apm0 at bios0 flags 0x0000

DESCRIPTION #

The apm driver provides an interface to the Advanced Power Management (APM) BIOS functions. The driver supports versions 1.0, 1.1, and 1.2 interface specifications.

This driver also provides an interface to acpi(4) on some machines.

The low two bytes of the flags specify the version of the specification driver should conform to in binary decimal notation. The value of 0x0101 would specify version 1.1 of the interface specification to be used.

The value of 0x10000 specifies whether to leave interrupts enabled when calling APM BIOS routines. This is needed for some IBM laptops, the symptoms are hangs and freezes on suspend, stand by, and hibernation activities.

The value of 0x20000 specifies to swap the bytes of the battery life estimation (the DX register) as given from the APM BIOS. This is needed for some SONY VAIO laptops, such as some 505 models.

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

Not implemented. DO NOT USE.

APM_IOC_STANDBY

(no parameters) Request “standby” mode.

APM_IOC_SUSPEND

(no parameters) Request “suspend” mode.

APM_IOC_HIBERNATE

(no parameters) Request “hibernate” 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

Cannot 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.

APM_IOC_DEV_CTL

(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.

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 #

acpi(4), intro(4), apm(8), apmd(8), halt(8)

HISTORY #

The apm driver source code contains these copyrights:

Copyright (c) 1995 John T. Kohl. All rights reserved.
Copyright (C) 1994 by HOSOKAWA Tatsumi <hosokawa@mt.cs.keio.ac.jp>

…and has been hacked on by many others since.

BUGS #

Not all the BIOSes support power down the way we are attempting to execute it.

Not all BIOS vendors even read the specification.

OpenBSD 7.5 - January 30, 2023