/* -*- linux-c -*-
 * APM BIOS driver for Linux
 * Copyright 1994-2001 Stephen Rothwell (sfr@canb.auug.org.au)
 *
 * Initial development of this driver was funded by NEC Australia P/L
 *      and NEC Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * October 1995, Rik Faith (faith@cs.unc.edu):
 *    Minor enhancements and updates (to the patch set) for 1.3.x
 *    Documentation
 * January 1996, Rik Faith (faith@cs.unc.edu):
 *    Make /proc/apm easy to format (bump driver version)
 * March 1996, Rik Faith (faith@cs.unc.edu):
 *    Prohibit APM BIOS calls unless apm_enabled.
 *    (Thanks to Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>)
 * April 1996, Stephen Rothwell (sfr@canb.auug.org.au)
 *    Version 1.0 and 1.1
 * May 1996, Version 1.2
 * Feb 1998, Version 1.3
 * Feb 1998, Version 1.4
 * Aug 1998, Version 1.5
 * Sep 1998, Version 1.6
 * Nov 1998, Version 1.7
 * Jan 1999, Version 1.8
 * Jan 1999, Version 1.9
 * Oct 1999, Version 1.10
 * Nov 1999, Version 1.11
 * Jan 2000, Version 1.12
 * Feb 2000, Version 1.13
 * Nov 2000, Version 1.14
 * Oct 2001, Version 1.15
 * Jan 2002, Version 1.16
 *
 * History:
 *    0.6b: first version in official kernel, Linux 1.3.46
 *    0.7: changed /proc/apm format, Linux 1.3.58
 *    0.8: fixed gcc 2.7.[12] compilation problems, Linux 1.3.59
 *    0.9: only call bios if bios is present, Linux 1.3.72
 *    1.0: use fixed device number, consolidate /proc/apm into this file,
 *         Linux 1.3.85
 *    1.1: support user-space standby and suspend, power off after system
 *         halted, Linux 1.3.98
 *    1.2: When resetting RTC after resume, take care so that the time
 *         is only incorrect by 30-60mS (vs. 1S previously) (Gabor J. Toth
 *         <jtoth@princeton.edu>); improve interaction between
 *         screen-blanking and gpm (Stephen Rothwell); Linux 1.99.4
 *    1.2a:Simple change to stop mysterious bug reports with SMP also added
 *         levels to the printk calls. APM is not defined for SMP machines.
 *         The new replacment for it is, but Linux doesn't yet support this.
 *         Alan Cox Linux 2.1.55
 *    1.3: Set up a valid data descriptor 0x40 for buggy BIOS's
 *    1.4: Upgraded to support APM 1.2. Integrated ThinkPad suspend patch by
 *         Dean Gaudet <dgaudet@arctic.org>.
 *         C. Scott Ananian <cananian@alumni.princeton.edu> Linux 2.1.87
 *    1.5: Fix segment register reloading (in case of bad segments saved
 *         across BIOS call).
 *         Stephen Rothwell
 *    1.6: Cope with complier/assembler differences.
 *         Only try to turn off the first display device.
 *         Fix OOPS at power off with no APM BIOS by Jan Echternach
 *                   <echter@informatik.uni-rostock.de>
 *         Stephen Rothwell
 *    1.7: Modify driver's cached copy of the disabled/disengaged flags
 *         to reflect current state of APM BIOS.
 *         Chris Rankin <rankinc@bellsouth.net>
 *         Reset interrupt 0 timer to 100Hz after suspend
 *         Chad Miller <cmiller@surfsouth.com>
 *         Add CONFIG_APM_IGNORE_SUSPEND_BOUNCE
 *         Richard Gooch <rgooch@atnf.csiro.au>
 *         Allow boot time disabling of APM
 *         Make boot messages far less verbose by default
 *         Make asm safer
 *         Stephen Rothwell
 *    1.8: Add CONFIG_APM_RTC_IS_GMT
 *         Richard Gooch <rgooch@atnf.csiro.au>
 *         change APM_NOINTS to CONFIG_APM_ALLOW_INTS
 *         remove dependency on CONFIG_PROC_FS
 *         Stephen Rothwell
 *    1.9: Fix small typo.  <laslo@wodip.opole.pl>
 *         Try to cope with BIOS's that need to have all display
 *         devices blanked and not just the first one.
 *         Ross Paterson <ross@soi.city.ac.uk>
 *         Fix segment limit setting it has always been wrong as
 *         the segments needed to have byte granularity.
 *         Mark a few things __init.
 *         Add hack to allow power off of SMP systems by popular request.
 *         Use CONFIG_SMP instead of __SMP__
 *         Ignore BOUNCES for three seconds.
 *         Stephen Rothwell
 *   1.10: Fix for Thinkpad return code.
 *         Merge 2.2 and 2.3 drivers.
 *         Remove APM dependencies in arch/i386/kernel/process.c
 *         Remove APM dependencies in drivers/char/sysrq.c
 *         Reset time across standby.
 *         Allow more inititialisation on SMP.
 *         Remove CONFIG_APM_POWER_OFF and make it boot time
 *         configurable (default on).
 *         Make debug only a boot time parameter (remove APM_DEBUG).
 *         Try to blank all devices on any error.
 *   1.11: Remove APM dependencies in drivers/char/console.c
 *         Check nr_running to detect if we are idle (from
 *         Borislav Deianov <borislav@lix.polytechnique.fr>)
 *         Fix for bioses that don't zero the top part of the
 *         entrypoint offset (Mario Sitta <sitta@al.unipmn.it>)
 *         (reported by Panos Katsaloulis <teras@writeme.com>).
 *         Real mode power off patch (Walter Hofmann
 *         <Walter.Hofmann@physik.stud.uni-erlangen.de>).
 *   1.12: Remove CONFIG_SMP as the compiler will optimize
 *         the code away anyway (smp_num_cpus == 1 in UP)
 *         noted by Artur Skawina <skawina@geocities.com>.
 *         Make power off under SMP work again.
 *         Fix thinko with initial engaging of BIOS.
 *         Make sure power off only happens on CPU 0
 *         (Paul "Rusty" Russell <rusty@rustcorp.com.au>).
 *         Do error notification to user mode if BIOS calls fail.
 *         Move entrypoint offset fix to ...boot/setup.S
 *         where it belongs (Cosmos <gis88564@cis.nctu.edu.tw>).
 *         Remove smp-power-off. SMP users must now specify
 *         "apm=power-off" on the kernel command line. Suggested
 *         by Jim Avera <jima@hal.com>, modified by Alan Cox
 *         <alan@lxorguk.ukuu.org.uk>.
 *         Register the /proc/apm entry even on SMP so that
 *         scripts that check for it before doing power off
 *         work (Jim Avera <jima@hal.com>).
 *   1.13: Changes for new pm_ interfaces (Andy Henroid
 *         <andy_henroid@yahoo.com>).
 *         Modularize the code.
 *         Fix the Thinkpad (again) :-( (CONFIG_APM_IGNORE_MULTIPLE_SUSPENDS
 *         is now the way life works).
 *         Fix thinko in suspend() (wrong return).
 *         Notify drivers on critical suspend.
 *         Make kapmd absorb more idle time (Pavel Machek <pavel@suse.cz>
 *         modified by sfr).
 *         Disable interrupts while we are suspended (Andy Henroid
 *         <andy_henroid@yahoo.com> fixed by sfr).
 *         Make power off work on SMP again (Tony Hoyle
 *         <tmh@magenta-logic.com> and <zlatko@iskon.hr>) modified by sfr.
 *         Remove CONFIG_APM_SUSPEND_BOUNCE.  The bounce ignore
 *         interval is now configurable.
 *   1.14: Make connection version persist across module unload/load.
 *         Enable and engage power management earlier.
 *         Disengage power management on module unload.
 *         Changed to use the sysrq-register hack for registering the
 *         power off function called by magic sysrq based upon discussions
 *         in irc://irc.openprojects.net/#kernelnewbies
 *         (Crutcher Dunnavant <crutcher+kernel@datastacks.com>).
 *         Make CONFIG_APM_REAL_MODE_POWER_OFF run time configurable.
 *         (Arjan van de Ven <arjanv@redhat.com>) modified by sfr.
 *         Work around byte swap bug in one of the Vaio's BIOS's
 *         (Marc Boucher <marc@mbsi.ca>).
 *         Exposed the disable flag to dmi so that we can handle known
 *         broken APM (Alan Cox <alan@redhat.com>).
 *   1.14ac: If the BIOS says "I slowed the CPU down" then don't spin
 *         calling it - instead idle. (Alan Cox <alan@redhat.com>)
 *         If an APM idle fails log it and idle sensibly
 *   1.15: Don't queue events to clients who open the device O_WRONLY.
 *         Don't expect replies from clients who open the device O_RDONLY.
 *         (Idea from Thomas Hood <jdthood@mail.com>)
 *         Minor waitqueue cleanups. (John Fremlin <chief@bandits.org>)
 *   1.16: Fix idle calling. (Andreas Steinmetz <ast@domdv.de> et al.)
 *         Notify listeners of standby or suspend events before notifying
 *         drivers. Return EBUSY to ioctl() if suspend is rejected.
 *         (Russell King <rmk@arm.linux.org.uk> and Thomas Hood)
 *         Ignore first resume after we generate our own resume event
 *         after a suspend (Thomas Hood <jdthood@mail.com>)
 *         Daemonize now gets rid of our controlling terminal (sfr).
 *         CONFIG_APM_CPU_IDLE now just affects the default value of
 *         idle_threshold (sfr).
 *         Change name of kernel apm daemon (as it no longer idles) (sfr).
 *
 * APM 1.1 Reference:
 *
 *   Intel Corporation, Microsoft Corporation. Advanced Power Management
 *   (APM) BIOS Interface Specification, Revision 1.1, September 1993.
 *   Intel Order Number 241704-001.  Microsoft Part Number 781-110-X01.
 *
 * [This document is available free from Intel by calling 800.628.8686 (fax
 * 916.356.6100) or 800.548.4725; or via anonymous ftp from
 * ftp://ftp.intel.com/pub/IAL/software_specs/apmv11.doc.  It is also
 * available from Microsoft by calling 206.882.8080.]
 *
 * APM 1.2 Reference:
 *   Intel Corporation, Microsoft Corporation. Advanced Power Management
 *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
 *
 * [This document is available from Microsoft at:
 *    http://www.microsoft.com/hwdev/busbios/amp_12.htm]
 */

#include <linux/config.h>
#include <linux/module.h>

#include <linux/poll.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/timer.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/proc_fs.h>
#include <linux/miscdevice.h>
#include <linux/apm_bios.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/kernel.h>
#include <linux/smp_lock.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/desc.h>

#include <linux/sysrq.h>

extern unsigned long get_cmos_time(void);
extern void machine_real_restart(unsigned char *, int);

#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
extern int (*console_blank_hook)(int);
#endif

/*
 * The apm_bios device is one of the misc char devices.
 * This is its minor number.
 */
#define APM_MINOR_DEV   134

/*
 * See Documentation/Config.help for the configuration options.
 *
 * Various options can be changed at boot time as follows:
 * (We allow underscores for compatibility with the modules code)
 *      apm=on/off                      enable/disable APM
 *          [no-]allow[-_]ints          allow interrupts during BIOS calls
 *          [no-]broken[-_]psr          BIOS has a broken GetPowerStatus call
 *          [no-]realmode[-_]power[-_]off       switch to real mode before
 *                                              powering off
 *          [no-]debug                  log some debugging messages
 *          [no-]power[-_]off           power off on shutdown
 *          [no-]smp                    Use apm even on an SMP box
 *          bounce[-_]interval=<n>      number of ticks to ignore suspend
 *                                      bounces
 *          idle[-_]threshold=<n>       System idle percentage above which to
 *                                      make APM BIOS idle calls. Set it to
 *                                      100 to disable.
 *          idle[-_]period=<n>          Period (in 1/100s of a second) over
 *                                      which the idle percentage is
 *                                      calculated.
 */

/* KNOWN PROBLEM MACHINES:
 *
 * U: TI 4000M TravelMate: BIOS is *NOT* APM compliant
 *                         [Confirmed by TI representative]
 * ?: ACER 486DX4/75: uses dseg 0040, in violation of APM specification
 *                    [Confirmed by BIOS disassembly]
 *                    [This may work now ...]
 * P: Toshiba 1950S: battery life information only gets updated after resume
 * P: Midwest Micro Soundbook Elite DX2/66 monochrome: screen blanking
 *      broken in BIOS [Reported by Garst R. Reese <reese@isn.net>]
 * ?: AcerNote-950: oops on reading /proc/apm - workaround is a WIP
 *      Neale Banks <neale@lowendale.com.au> December 2000
 *
 * Legend: U = unusable with APM patches
 *         P = partially usable with APM patches
 */

/*
 * Define as 1 to make the driver always call the APM BIOS busy
 * routine even if the clock was not reported as slowed by the
 * idle routine.  Otherwise, define as 0.
 */
#define ALWAYS_CALL_BUSY   1

/*
 * Define to make the APM BIOS calls zero all data segment registers (so
 * that an incorrect BIOS implementation will cause a kernel panic if it
 * tries to write to arbitrary memory).
 */
#define APM_ZERO_SEGS

/*
 * Define to make all _set_limit calls use 64k limits.  The APM 1.1 BIOS is
 * supposed to provide limit information that it recognizes.  Many machines
 * do this correctly, but many others do not restrict themselves to their
 * claimed limit.  When this happens, they will cause a segmentation
 * violation in the kernel at boot time.  Most BIOS's, however, will
 * respect a 64k limit, so we use that.  If you want to be pedantic and
 * hold your BIOS to its claims, then undefine this.
 */
#define APM_RELAX_SEGMENTS

/*
 * Define to re-initialize the interrupt 0 timer to 100 Hz after a suspend.
 * This patched by Chad Miller <cmiller@surfsouth.com>, original code by
 * David Chen <chen@ctpa04.mit.edu>
 */
#undef INIT_TIMER_AFTER_SUSPEND

#ifdef INIT_TIMER_AFTER_SUSPEND
#include <linux/timex.h>
#include <asm/io.h>
#include <linux/delay.h>
#endif

/*
 * Need to poll the APM BIOS every second
 */
#define APM_CHECK_TIMEOUT       (HZ)

/*
 * Ignore suspend events for this amount of time after a resume
 */
#define DEFAULT_BOUNCE_INTERVAL         (3 * HZ)

/*
 * Save a segment register away
 */
#define savesegment(seg, where) \
                __asm__ __volatile__("movl %%" #seg ",%0" : "=m" (where))

/*
 * Maximum number of events stored
 */
#define APM_MAX_EVENTS          20

/*
 * The per-file APM data
 */
struct apm_user {
        int             magic;
        struct apm_user *       next;
        int             suser: 1;
        int             writer: 1;
        int             reader: 1;
        int             suspend_wait: 1;
        int             suspend_result;
        int             suspends_pending;
        int             standbys_pending;
        int             suspends_read;
        int             standbys_read;
        int             event_head;
        int             event_tail;
        apm_event_t     events[APM_MAX_EVENTS];
};

/*
 * The magic number in apm_user
 */
#define APM_BIOS_MAGIC          0x4101

/*
 * idle percentage above which bios idle calls are done
 */
#ifdef CONFIG_APM_CPU_IDLE
#define DEFAULT_IDLE_THRESHOLD  95
#else
#define DEFAULT_IDLE_THRESHOLD  100
#endif
#define DEFAULT_IDLE_PERIOD     (100 / 3)

/*
 * Local variables
 */
static struct {
        unsigned long   offset;
        unsigned short  segment;
}                               apm_bios_entry;
static int                      clock_slowed;
static int                      idle_threshold = DEFAULT_IDLE_THRESHOLD;
static int                      idle_period = DEFAULT_IDLE_PERIOD;
static int                      set_pm_idle;
static int                      suspends_pending;
static int                      standbys_pending;
static int                      ignore_sys_suspend;
static int                      ignore_normal_resume;
static int                      bounce_interval = DEFAULT_BOUNCE_INTERVAL;

#ifdef CONFIG_APM_RTC_IS_GMT
#       define  clock_cmos_diff 0
#       define  got_clock_diff  1
#else
static long                     clock_cmos_diff;
static int                      got_clock_diff;
#endif
static int                      debug;
static int                      smp = 0;
static int                      apm_disabled = -1;
#ifdef CONFIG_SMP
static int                      power_off;
#else
static int                      power_off = 1;
#endif
#ifdef CONFIG_APM_REAL_MODE_POWER_OFF
static int                      realmode_power_off = 1;
#else
static int                      realmode_power_off;
#endif
static int                      exit_kapmd;
static int                      kapmd_running;
#ifdef CONFIG_APM_ALLOW_INTS
static int                      allow_ints = 1;
#else
static int                      allow_ints;
#endif
static int                      broken_psr;

static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
static struct apm_user *        user_list;

static char                     driver_version[] = "1.16";      /* no spaces */

/*
 *      APM event names taken from the APM 1.2 specification. These are
 *      the message codes that the BIOS uses to tell us about events
 */
static char *   apm_event_name[] = {
        "system standby",
        "system suspend",
        "normal resume",
        "critical resume",
        "low battery",
        "power status change",
        "update time",
        "critical suspend",
        "user standby",
        "user suspend",
        "system standby resume",
        "capabilities change"
};
#define NR_APM_EVENT_NAME       \
                (sizeof(apm_event_name) / sizeof(apm_event_name[0]))

typedef struct lookup_t {
        int     key;
        char *  msg;
} lookup_t;

/*
 *      The BIOS returns a set of standard error codes in AX when the
 *      carry flag is set.
 */
 
static const lookup_t error_table[] = {
/* N/A  { APM_SUCCESS,          "Operation succeeded" }, */
        { APM_DISABLED,         "Power management disabled" },
        { APM_CONNECTED,        "Real mode interface already connected" },
        { APM_NOT_CONNECTED,    "Interface not connected" },
        { APM_16_CONNECTED,     "16 bit interface already connected" },
/* N/A  { APM_16_UNSUPPORTED,   "16 bit interface not supported" }, */
        { APM_32_CONNECTED,     "32 bit interface already connected" },
        { APM_32_UNSUPPORTED,   "32 bit interface not supported" },
        { APM_BAD_DEVICE,       "Unrecognized device ID" },
        { APM_BAD_PARAM,        "Parameter out of range" },
        { APM_NOT_ENGAGED,      "Interface not engaged" },
        { APM_BAD_FUNCTION,     "Function not supported" },
        { APM_RESUME_DISABLED,  "Resume timer disabled" },
        { APM_BAD_STATE,        "Unable to enter requested state" },
/* N/A  { APM_NO_EVENTS,        "No events pending" }, */
        { APM_NO_ERROR,         "BIOS did not set a return code" },
        { APM_NOT_PRESENT,      "No APM present" }
};
#define ERROR_COUNT     (sizeof(error_table)/sizeof(lookup_t))

/**
 *      apm_error       -       display an APM error
 *      @str: information string
 *      @err: APM BIOS return code
 *
 *      Write a meaningful log entry to the kernel log in the event of
 *      an APM error.
 */
 
static void apm_error(char *str, int err)
{
        int     i;

        for (i = 0; i < ERROR_COUNT; i++)
                if (error_table[i].key == err) break;
        if (i < ERROR_COUNT)
                printk(KERN_NOTICE "apm: %s: %s\n", str, error_table[i].msg);
        else
                printk(KERN_NOTICE "apm: %s: unknown error code %#2.2x\n",
                        str, err);
}

/*
 * Lock APM functionality to physical CPU 0
 */
 
#ifdef CONFIG_SMP

static unsigned long apm_save_cpus(void)
{
        unsigned long x = current->cpus_allowed;
        /* Some bioses don't like being called from CPU != 0 */
        if (cpu_number_map(smp_processor_id()) != 0) {
                set_cpus_allowed(current, 1 << cpu_logical_map(0));
                if (unlikely(cpu_number_map(smp_processor_id()) != 0))
                        BUG();
        }
        return x;
}

static inline void apm_restore_cpus(unsigned long mask)
{
        set_cpus_allowed(current, mask);
}

#else

/*
 *      No CPU lockdown needed on a uniprocessor
 */
 
#define apm_save_cpus() 0
#define apm_restore_cpus(x)     (void)(x)

#endif

/*
 * These are the actual BIOS calls.  Depending on APM_ZERO_SEGS and
 * apm_info.allow_ints, we are being really paranoid here!  Not only
 * are interrupts disabled, but all the segment registers (except SS)
 * are saved and zeroed this means that if the BIOS tries to reference
 * any data without explicitly loading the segment registers, the kernel
 * will fault immediately rather than have some unforeseen circumstances
 * for the rest of the kernel.  And it will be very obvious!  :-) Doing
 * this depends on CS referring to the same physical memory as DS so that
 * DS can be zeroed before the call. Unfortunately, we can't do anything
 * about the stack segment/pointer.  Also, we tell the compiler that
 * everything could change.
 *
 * Also, we KNOW that for the non error case of apm_bios_call, there
 * is no useful data returned in the low order 8 bits of eax.
 */
#define APM_DO_CLI      \
        if (apm_info.allow_ints) \
                __sti(); \
        else \
                __cli();

#ifdef APM_ZERO_SEGS
#       define APM_DECL_SEGS \
                unsigned int saved_fs; unsigned int saved_gs;
#       define APM_DO_SAVE_SEGS \
                savesegment(fs, saved_fs); savesegment(gs, saved_gs)
#       define APM_DO_ZERO_SEGS \
                "pushl %%ds\n\t" \
                "pushl %%es\n\t" \
                "xorl %%edx, %%edx\n\t" \
                "mov %%dx, %%ds\n\t" \
                "mov %%dx, %%es\n\t" \
                "mov %%dx, %%fs\n\t" \
                "mov %%dx, %%gs\n\t"
#       define APM_DO_POP_SEGS \
                "popl %%es\n\t" \
                "popl %%ds\n\t"
#       define APM_DO_RESTORE_SEGS \
                loadsegment(fs, saved_fs); loadsegment(gs, saved_gs)
#else
#       define APM_DECL_SEGS
#       define APM_DO_SAVE_SEGS
#       define APM_DO_ZERO_SEGS
#       define APM_DO_POP_SEGS
#       define APM_DO_RESTORE_SEGS
#endif

/**
 *      apm_bios_call   -       Make an APM BIOS 32bit call
 *      @func: APM function to execute
 *      @ebx_in: EBX register for call entry
 *      @ecx_in: ECX register for call entry
 *      @eax: EAX register return
 *      @ebx: EBX register return
 *      @ecx: ECX register return
 *      @edx: EDX register return
 *      @esi: ESI register return
 *
 *      Make an APM call using the 32bit protected mode interface. The
 *      caller is responsible for knowing if APM BIOS is configured and
 *      enabled. This call can disable interrupts for a long period of
 *      time on some laptops.  The return value is in AH and the carry
 *      flag is loaded into AL.  If there is an error, then the error
 *      code is returned in AH (bits 8-15 of eax) and this function
 *      returns non-zero.
 */
 
static u8 apm_bios_call(u32 func, u32 ebx_in, u32 ecx_in,
        u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, u32 *esi)
{
        APM_DECL_SEGS
        unsigned long   flags;
        unsigned long cpus = apm_save_cpus();
        
        __save_flags(flags);
        APM_DO_CLI;
        APM_DO_SAVE_SEGS;
        /*
         * N.B. We do NOT need a cld after the BIOS call
         * because we always save and restore the flags.
         */
        __asm__ __volatile__(APM_DO_ZERO_SEGS
                "pushl %%edi\n\t"
                "pushl %%ebp\n\t"
                "lcall %%cs:" SYMBOL_NAME_STR(apm_bios_entry) "\n\t"
                "setc %%al\n\t"
                "popl %%ebp\n\t"
                "popl %%edi\n\t"
                APM_DO_POP_SEGS
                : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx),
                  "=S" (*esi)
                : "a" (func), "b" (ebx_in), "c" (ecx_in)
                : "memory", "cc");
        APM_DO_RESTORE_SEGS;
        __restore_flags(flags);
        
        apm_restore_cpus(cpus);
        
        return *eax & 0xff;
}

/**
 *      apm_bios_call_simple    -       make a simple APM BIOS 32bit call
 *      @func: APM function to invoke
 *      @ebx_in: EBX register value for BIOS call
 *      @ecx_in: ECX register value for BIOS call
 *      @eax: EAX register on return from the BIOS call
 *
 *      Make a BIOS call that does only returns one value, or just status.
 *      If there is an error, then the error code is returned in AH
 *      (bits 8-15 of eax) and this function returns non-zero. This is
 *      used for simpler BIOS operations. This call may hold interrupts
 *      off for a long time on some laptops.
 */

static u8 apm_bios_call_simple(u32 func, u32 ebx_in, u32 ecx_in, u32 *eax)
{
        u8              error;
        APM_DECL_SEGS
        unsigned long   flags;

        unsigned long cpus = apm_save_cpus();
        
        __save_flags(flags);
        APM_DO_CLI;
        APM_DO_SAVE_SEGS;
        {
                int     cx, dx, si;

                /*
                 * N.B. We do NOT need a cld after the BIOS call
                 * because we always save and restore the flags.
                 */
                __asm__ __volatile__(APM_DO_ZERO_SEGS
                        "pushl %%edi\n\t"
                        "pushl %%ebp\n\t"
                        "lcall %%cs:" SYMBOL_NAME_STR(apm_bios_entry) "\n\t"
                        "setc %%bl\n\t"
                        "popl %%ebp\n\t"
                        "popl %%edi\n\t"
                        APM_DO_POP_SEGS
                        : "=a" (*eax), "=b" (error), "=c" (cx), "=d" (dx),
                          "=S" (si)
                        : "a" (func), "b" (ebx_in), "c" (ecx_in)
                        : "memory", "cc");
        }
        APM_DO_RESTORE_SEGS;
        __restore_flags(flags);

        apm_restore_cpus(cpus);
        
        return error;
}

/**
 *      apm_driver_version      -       APM driver version
 *      @val:   loaded with the APM version on return
 *
 *      Retrieve the APM version supported by the BIOS. This is only
 *      supported for APM 1.1 or higher. An error indicates APM 1.0 is
 *      probably present.
 *
 *      On entry val should point to a value indicating the APM driver
 *      version with the high byte being the major and the low byte the
 *      minor number both in BCD
 *
 *      On return it will hold the BIOS revision supported in the
 *      same format.
 */

static int __init apm_driver_version(u_short *val)
{
        u32     eax;

        if (apm_bios_call_simple(APM_FUNC_VERSION, 0, *val, &eax))
                return (eax >> 8) & 0xff;
        *val = eax;
        return APM_SUCCESS;
}

/**
 *      apm_get_event   -       get an APM event from the BIOS
 *      @event: pointer to the event
 *      @info: point to the event information
 *
 *      The APM BIOS provides a polled information for event
 *      reporting. The BIOS expects to be polled at least every second
 *      when events are pending. When a message is found the caller should
 *      poll until no more messages are present.  However, this causes
 *      problems on some laptops where a suspend event notification is
 *      not cleared until it is acknowledged.
 *
 *      Additional information is returned in the info pointer, providing
 *      that APM 1.2 is in use. If no messges are pending the value 0x80
 *      is returned (No power management events pending).
 */
 
static int apm_get_event(apm_event_t *event, apm_eventinfo_t *info)
{
        u32     eax;
        u32     ebx;
        u32     ecx;
        u32     dummy;

        if (apm_bios_call(APM_FUNC_GET_EVENT, 0, 0, &eax, &ebx, &ecx,
                        &dummy, &dummy))
                return (eax >> 8) & 0xff;
        *event = ebx;
        if (apm_info.connection_version < 0x0102)
                *info = ~0; /* indicate info not valid */
        else
                *info = ecx;
        return APM_SUCCESS;
}

/**
 *      set_power_state -       set the power management state
 *      @what: which items to transition
 *      @state: state to transition to
 *
 *      Request an APM change of state for one or more system devices. The
 *      processor state must be transitioned last of all. what holds the
 *      class of device in the upper byte and the device number (0xFF for
 *      all) for the object to be transitioned.
 *
 *      The state holds the state to transition to, which may in fact
 *      be an acceptance of a BIOS requested state change.
 */
 
static int set_power_state(u_short what, u_short state)
{
        u32     eax;

        if (apm_bios_call_simple(APM_FUNC_SET_STATE, what, state, &eax))
                return (eax >> 8) & 0xff;
        return APM_SUCCESS;
}

/**
 *      set_system_power_state - set system wide power state
 *      @state: which state to enter
 *
 *      Transition the entire system into a new APM power state.
 */
 
static int set_system_power_state(u_short state)
{
        return set_power_state(APM_DEVICE_ALL, state);
}

/**
 *      apm_do_idle     -       perform power saving
 *
 *      This function notifies the BIOS that the processor is (in the view
 *      of the OS) idle. It returns -1 in the event that the BIOS refuses
 *      to handle the idle request. On a success the function returns 1
 *      if the BIOS did clock slowing or 0 otherwise.
 */
 
static int apm_do_idle(void)
{
        u32     eax;

        if (apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax)) {
                static unsigned long t;

                /* This always fails on some SMP boards running UP kernels.
                 * Only report the failure the first 5 times.
                 */
                if (++t < 5) {
                        printk(KERN_DEBUG "apm_do_idle failed (%d)\n",
                                        (eax >> 8) & 0xff);
                }
                return -1;
        }
        clock_slowed = (apm_info.bios.flags & APM_IDLE_SLOWS_CLOCK) != 0;
        return clock_slowed;
}

/**
 *      apm_do_busy     -       inform the BIOS the CPU is busy
 *
 *      Request that the BIOS brings the CPU back to full performance. 
 */
 
static void apm_do_busy(void)
{
        u32     dummy;

        if (clock_slowed || ALWAYS_CALL_BUSY) {
                (void) apm_bios_call_simple(APM_FUNC_BUSY, 0, 0, &dummy);
                clock_slowed = 0;
        }
}

/*
 * If no process has really been interested in
 * the CPU for some time, we want to call BIOS
 * power management - we probably want
 * to conserve power.
 */
#define IDLE_CALC_LIMIT   (HZ * 100)
#define IDLE_LEAKY_MAX    16

static void (*original_pm_idle)(void);

extern void default_idle(void);

/**
 * apm_cpu_idle         -       cpu idling for APM capable Linux
 *
 * This is the idling function the kernel executes when APM is available. It 
 * tries to do BIOS powermanagement based on the average system idle time.
 * Furthermore it calls the system default idle routine.
 */

static void apm_cpu_idle(void)
{
        static int use_apm_idle; /* = 0 */
        static unsigned int last_jiffies; /* = 0 */
        static unsigned int last_stime; /* = 0 */

        int apm_idle_done = 0;
        unsigned int jiffies_since_last_check = jiffies - last_jiffies;
        unsigned int bucket;

recalc:
        if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
                use_apm_idle = 0;
                last_jiffies = jiffies;
                last_stime = current->times.tms_stime;
        } else if (jiffies_since_last_check > idle_period) {
                unsigned int idle_percentage;

                idle_percentage = current->times.tms_stime - last_stime;
                idle_percentage *= 100;
                idle_percentage /= jiffies_since_last_check;
                use_apm_idle = (idle_percentage > idle_threshold);
                if (apm_info.forbid_idle)
                        use_apm_idle = 0;
                last_jiffies = jiffies;
                last_stime = current->times.tms_stime;
        }

        bucket = IDLE_LEAKY_MAX;

        while (!current->need_resched) {
                if (use_apm_idle) {
                        unsigned int t;

                        t = jiffies;
                        switch (apm_do_idle()) {
                        case 0: apm_idle_done = 1;
                                if (t != jiffies) {
                                        if (bucket) {
                                                bucket = IDLE_LEAKY_MAX;
                                                continue;
                                        }
                                } else if (bucket) {
                                        bucket--;
                                        continue;
                                }
                                break;
                        case 1: apm_idle_done = 1;
                                break;
                        default: /* BIOS refused */
                                break;
                        }
                }
                if (original_pm_idle)
                        original_pm_idle();
                else
                        default_idle();
                jiffies_since_last_check = jiffies - last_jiffies;
                if (jiffies_since_last_check > idle_period)
                        goto recalc;
        }

        if (apm_idle_done)
                apm_do_busy();
}

/**
 *      apm_power_off   -       ask the BIOS to power off
 *
 *      Handle the power off sequence. This is the one piece of code we
 *      will execute even on SMP machines. In order to deal with BIOS
 *      bugs we support real mode APM BIOS power off calls. We also make
 *      the SMP call on CPU0 as some systems will only honour this call
 *      on their first cpu.
 */
 
static void apm_power_off(void)
{
        unsigned char   po_bios_call[] = {
                0xb8, 0x00, 0x10,       /* movw  $0x1000,ax  */
                0x8e, 0xd0,             /* movw  ax,ss       */
                0xbc, 0x00, 0xf0,       /* movw  $0xf000,sp  */
                0xb8, 0x07, 0x53,       /* movw  $0x5307,ax  */
                0xbb, 0x01, 0x00,       /* movw  $0x0001,bx  */
                0xb9, 0x03, 0x00,       /* movw  $0x0003,cx  */
                0xcd, 0x15              /* int   $0x15       */
        };

        /*
         * This may be called on an SMP machine.
         */
        if (apm_info.realmode_power_off)
        {
                (void)apm_save_cpus();
                machine_real_restart(po_bios_call, sizeof(po_bios_call));
                /* Never returns */
        }
        else
                (void) set_system_power_state(APM_STATE_OFF);
}

/**
 * handle_poweroff      -       sysrq callback for power down
 * @key: key pressed (unused)
 * @pt_regs: register state (unused)
 * @kbd: keyboard state (unused)
 * @tty: tty involved (unused)
 *
 * When the user hits Sys-Rq o to power down the machine this is the
 * callback we use.
 */

void handle_poweroff (int key, struct pt_regs *pt_regs,
                struct kbd_struct *kbd, struct tty_struct *tty) {
        apm_power_off();
}

struct sysrq_key_op     sysrq_poweroff_op = {
        handler:        handle_poweroff,
        help_msg:       "Off",
        action_msg:     "Power Off\n"
};


#ifdef CONFIG_APM_DO_ENABLE

/**
 *      apm_enable_power_management - enable BIOS APM power management
 *      @enable: enable yes/no
 *
 *      Enable or disable the APM BIOS power services. 
 */
 
static int apm_enable_power_management(int enable)
{
        u32     eax;

        if ((enable == 0) && (apm_info.bios.flags & APM_BIOS_DISENGAGED))
                return APM_NOT_ENGAGED;
        if (apm_bios_call_simple(APM_FUNC_ENABLE_PM, APM_DEVICE_BALL,
                        enable, &eax))
                return (eax >> 8) & 0xff;
        if (enable)
                apm_info.bios.flags &= ~APM_BIOS_DISABLED;
        else
                apm_info.bios.flags |= APM_BIOS_DISABLED;
        return APM_SUCCESS;
}
#endif

/**
 *      apm_get_power_status    -       get current power state

 *      @status: returned status
 *      @bat: battery info
 *      @life: estimated life
 *
 *      Obtain the current power status from the APM BIOS. We return a
 *      status which gives the rough battery status, and current power
 *      source. The bat value returned give an estimate as a percentage
 *      of life and a status value for the battery. The estimated life
 *      if reported is a lifetime in secodnds/minutes at current powwer
 *      consumption.
 */
 
static int apm_get_power_status(u_short *status, u_short *bat, u_short *life)
{
        u32     eax;
        u32     ebx;
        u32     ecx;
        u32     edx;
        u32     dummy;

        if (apm_info.get_power_status_broken)
                return APM_32_UNSUPPORTED;
        if (apm_bios_call(APM_FUNC_GET_STATUS, APM_DEVICE_ALL, 0,
                        &eax, &ebx, &ecx, &edx, &dummy))
                return (eax >> 8) & 0xff;
        *status = ebx;
        *bat = ecx;
        if (apm_info.get_power_status_swabinminutes) {
                *life = swab16((u16)edx);
                *life |= 0x8000;
        } else
                *life = edx;
        return APM_SUCCESS;
}

#if 0
static int apm_get_battery_status(u_short which, u_short *status,
                                  u_short *bat, u_short *life, u_short *nbat)
{
        u32     eax;
        u32     ebx;
        u32     ecx;
        u32     edx;
        u32     esi;

        if (apm_info.connection_version < 0x0102) {
                /* pretend we only have one battery. */
                if (which != 1)
                        return APM_BAD_DEVICE;
                *nbat = 1;
                return apm_get_power_status(status, bat, life);
        }

        if (apm_bios_call(APM_FUNC_GET_STATUS, (0x8000 | (which)), 0, &eax,
                        &ebx, &ecx, &edx, &esi))
                return (eax >> 8) & 0xff;
        *status = ebx;
        *bat = ecx;
        *life = edx;
        *nbat = esi;
        return APM_SUCCESS;
}
#endif

/**
 *      apm_engage_power_management     -       enable PM on a device
 *      @device: identity of device
 *      @enable: on/off
 *
 *      Activate or deactive power management on either a specific device
 *      or the entire system (%APM_DEVICE_ALL).
 */
 
static int apm_engage_power_management(u_short device, int enable)
{
        u32     eax;

        if ((enable == 0) && (device == APM_DEVICE_ALL)
            && (apm_info.bios.flags & APM_BIOS_DISABLED))
                return APM_DISABLED;
        if (apm_bios_call_simple(APM_FUNC_ENGAGE_PM, device, enable, &eax))
                return (eax >> 8) & 0xff;
        if (device == APM_DEVICE_ALL) {
                if (enable)
                        apm_info.bios.flags &= ~APM_BIOS_DISENGAGED;
                else
                        apm_info.bios.flags |= APM_BIOS_DISENGAGED;
        }
        return APM_SUCCESS;
}

#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)

/**
 *      apm_console_blank       -       blank the display
 *      @blank: on/off
 *
 *      Attempt to blank the console, firstly by blanking just video device
 *      zero, and if that fails (some BIOSes dont support it) then it blanks
 *      all video devices. Typically the BIOS will do laptop backlight and
 *      monitor powerdown for us.
 */
 
static int apm_console_blank(int blank)
{
        int     error;
        u_short state;

        state = blank ? APM_STATE_STANDBY : APM_STATE_READY;
        /* Blank the first display device */
        error = set_power_state(0x100, state);
        if ((error != APM_SUCCESS) && (error != APM_NO_ERROR)) {
                /* try to blank them all instead */
                error = set_power_state(0x1ff, state);
                if ((error != APM_SUCCESS) && (error != APM_NO_ERROR))
                        /* try to blank device one instead */
                        error = set_power_state(0x101, state);
        }
        if ((error == APM_SUCCESS) || (error == APM_NO_ERROR))
                return 1;
        if (error == APM_NOT_ENGAGED) {
                static int tried;
                int eng_error;
                if (tried++ == 0) {
                        eng_error = apm_engage_power_management(APM_DEVICE_ALL, 1);
                        if (eng_error) {
                                apm_error("set display", error);
                                apm_error("engage interface", eng_error);
                                return 0;
                        } else
                                return apm_console_blank(blank);
                }
        }
        apm_error("set display", error);
        return 0;
}
#endif

static int queue_empty(struct apm_user *as)
{
        return as->event_head == as->event_tail;
}

static apm_event_t get_queued_event(struct apm_user *as)
{
        as->event_tail = (as->event_tail + 1) % APM_MAX_EVENTS;
        return as->events[as->event_tail];
}

static void queue_event(apm_event_t event, struct apm_user *sender)
{
        struct apm_user *       as;

        if (user_list == NULL)
                return;
        for (as = user_list; as != NULL; as = as->next) {
                if ((as == sender) || (!as->reader))
                        continue;
                as->event_head = (as->event_head + 1) % APM_MAX_EVENTS;
                if (as->event_head == as->event_tail) {
                        static int notified;

                        if (notified++ == 0)
                            printk(KERN_ERR "apm: an event queue overflowed\n");
                        as->event_tail = (as->event_tail + 1) % APM_MAX_EVENTS;
                }
                as->events[as->event_head] = event;
                if ((!as->suser) || (!as->writer))
                        continue;
                switch (event) {
                case APM_SYS_SUSPEND:
                case APM_USER_SUSPEND:
                        as->suspends_pending++;
                        suspends_pending++;
                        break;

                case APM_SYS_STANDBY:
                case APM_USER_STANDBY:
                        as->standbys_pending++;
                        standbys_pending++;
                        break;
                }
        }
        wake_up_interruptible(&apm_waitqueue);
}

static void set_time(void)
{
        unsigned long   flags;

        if (got_clock_diff) {   /* Must know time zone in order to set clock */
                save_flags(flags);
                cli();
                CURRENT_TIME = get_cmos_time() + clock_cmos_diff;
                restore_flags(flags);
        }
}

static void get_time_diff(void)
{
#ifndef CONFIG_APM_RTC_IS_GMT
        unsigned long   flags;

        /*
         * Estimate time zone so that set_time can update the clock
         */
        save_flags(flags);
        clock_cmos_diff = -get_cmos_time();
        cli();
        clock_cmos_diff += CURRENT_TIME;
        got_clock_diff = 1;
        restore_flags(flags);
#endif
}

static void reinit_timer(void)
{
#ifdef INIT_TIMER_AFTER_SUSPEND
        unsigned long   flags;

        save_flags(flags);
        cli();
        /* set the clock to 100 Hz */
        outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
        udelay(10);
        outb_p(LATCH & 0xff , 0x40);    /* LSB */
        udelay(10);
        outb(LATCH >> 8 , 0x40);        /* MSB */
        udelay(10);
        restore_flags(flags);
#endif
}

static int suspend(int vetoable)
{
        int             err;
        struct apm_user *as;

        if (pm_send_all(PM_SUSPEND, (void *)3)) {
                /* Vetoed */
                if (vetoable) {
                        if (apm_info.connection_version > 0x100)
                                set_system_power_state(APM_STATE_REJECT);
                        err = -EBUSY;
                        ignore_sys_suspend = 0;
                        printk(KERN_WARNING "apm: suspend was vetoed.\n");
                        goto out;
                }
                printk(KERN_CRIT "apm: suspend was vetoed, but suspending anyway.\n");
        }
        get_time_diff();
        __cli();
        err = set_system_power_state(APM_STATE_SUSPEND);
        reinit_timer();
        set_time();
        ignore_normal_resume = 1;
        __sti();
        if (err == APM_NO_ERROR)
                err = APM_SUCCESS;
        if (err != APM_SUCCESS)
                apm_error("suspend", err);
        err = (err == APM_SUCCESS) ? 0 : -EIO;
        pm_send_all(PM_RESUME, (void *)0);
        queue_event(APM_NORMAL_RESUME, NULL);
 out:
        for (as = user_list; as != NULL; as = as->next) {
                as->suspend_wait = 0;
                as->suspend_result = err;
        }
        wake_up_interruptible(&apm_suspend_waitqueue);
        return err;
}

static void standby(void)
{
        int     err;

        /* If needed, notify drivers here */
        get_time_diff();
        err = set_system_power_state(APM_STATE_STANDBY);
        if ((err != APM_SUCCESS) && (err != APM_NO_ERROR))
                apm_error("standby", err);
}

static apm_event_t get_event(void)
{
        int             error;
        apm_event_t     event;
        apm_eventinfo_t info;

        static int notified;

        /* we don't use the eventinfo */
        error = apm_get_event(&event, &info);
        if (error == APM_SUCCESS)
                return event;

        if ((error != APM_NO_EVENTS) && (notified++ == 0))
                apm_error("get_event", error);

        return 0;
}

static void check_events(void)
{
        apm_event_t             event;
        static unsigned long    last_resume;
        static int              ignore_bounce;

        while ((event = get_event()) != 0) {
                if (debug) {
                        if (event <= NR_APM_EVENT_NAME)
                                printk(KERN_DEBUG "apm: received %s notify\n",
                                       apm_event_name[event - 1]);
                        else
                                printk(KERN_DEBUG "apm: received unknown "
                                       "event 0x%02x\n", event);
                }
                if (ignore_bounce
                    && ((jiffies - last_resume) > bounce_interval))
                        ignore_bounce = 0;

                switch (event) {
                case APM_SYS_STANDBY:
                case APM_USER_STANDBY:
                        queue_event(event, NULL);
                        if (standbys_pending <= 0)
                                standby();
                        break;

                case APM_USER_SUSPEND:
#ifdef CONFIG_APM_IGNORE_USER_SUSPEND
                        if (apm_info.connection_version > 0x100)
                                set_system_power_state(APM_STATE_REJECT);
                        break;
#endif
                case APM_SYS_SUSPEND:
                        if (ignore_bounce) {
                                if (apm_info.connection_version > 0x100)
                                        set_system_power_state(APM_STATE_REJECT);
                                break;
                        }
                        /*
                         * If we are already processing a SUSPEND,
                         * then further SUSPEND events from the BIOS
                         * will be ignored.  We also return here to
                         * cope with the fact that the Thinkpads keep
                         * sending a SUSPEND event until something else
                         * happens!
                         */
                        if (ignore_sys_suspend)
                                return;
                        ignore_sys_suspend = 1;
                        queue_event(event, NULL);
                        if (suspends_pending <= 0)
                                (void) suspend(1);
                        break;

                case APM_NORMAL_RESUME:
                case APM_CRITICAL_RESUME:
                case APM_STANDBY_RESUME:
                        ignore_sys_suspend = 0;
                        last_resume = jiffies;
                        ignore_bounce = 1;
                        if ((event != APM_NORMAL_RESUME)
                            || (ignore_normal_resume == 0)) {
                                set_time();
                                pm_send_all(PM_RESUME, (void *)0);
                                queue_event(event, NULL);
                        }
                        ignore_normal_resume = 0;
                        break;

                case APM_CAPABILITY_CHANGE:
                case APM_LOW_BATTERY:
                case APM_POWER_STATUS_CHANGE:
                        queue_event(event, NULL);
                        /* If needed, notify drivers here */
                        break;

                case APM_UPDATE_TIME:
                        set_time();
                        break;

                case APM_CRITICAL_SUSPEND:
                        /*
                         * We are not allowed to reject a critical suspend.
                         */
                        (void) suspend(0);
                        break;
                }
        }
}

static void apm_event_handler(void)
{
        static int      pending_count = 4;
        int             err;

        if ((standbys_pending > 0) || (suspends_pending > 0)) {
                if ((apm_info.connection_version > 0x100) &&
                                (pending_count-- <= 0)) {
                        pending_count = 4;
                        if (debug)
                                printk(KERN_DEBUG "apm: setting state busy\n");
                        err = set_system_power_state(APM_STATE_BUSY);
                        if (err)
                                apm_error("busy", err);
                }
        } else
                pending_count = 4;
        check_events();
}

/*
 * This is the APM thread main loop.
 */

static void apm_mainloop(void)
{
        DECLARE_WAITQUEUE(wait, current);

        add_wait_queue(&apm_waitqueue, &wait);
        set_current_state(TASK_INTERRUPTIBLE);
        for (;;) {
                schedule_timeout(APM_CHECK_TIMEOUT);
                if (exit_kapmd)
                        break;
                /*
                 * Ok, check all events, check for idle (and mark us sleeping
                 * so as not to count towards the load average)..
                 */
                set_current_state(TASK_INTERRUPTIBLE);
                apm_event_handler();
        }
        remove_wait_queue(&apm_waitqueue, &wait);
}

static int check_apm_user(struct apm_user *as, const char *func)
{
        if ((as == NULL) || (as->magic != APM_BIOS_MAGIC)) {
                printk(KERN_ERR "apm: %s passed bad filp\n", func);
                return 1;
        }
        return 0;
}

static ssize_t do_read(struct file *fp, char *buf, size_t count, loff_t *ppos)
{
        struct apm_user *       as;
        int                     i;
        apm_event_t             event;

        as = fp->private_data;
        if (check_apm_user(as, "read"))
                return -EIO;
        if ((int)count < sizeof(apm_event_t))
                return -EINVAL;
        if ((queue_empty(as)) && (fp->f_flags & O_NONBLOCK))
                return -EAGAIN;
        wait_event_interruptible(apm_waitqueue, !queue_empty(as));
        i = count;
        while ((i >= sizeof(event)) && !queue_empty(as)) {
                event = get_queued_event(as);
                if (copy_to_user(buf, &event, sizeof(event))) {
                        if (i < count)
                                break;
                        return -EFAULT;
                }
                switch (event) {
                case APM_SYS_SUSPEND:
                case APM_USER_SUSPEND:
                        as->suspends_read++;
                        break;

                case APM_SYS_STANDBY:
                case APM_USER_STANDBY:
                        as->standbys_read++;
                        break;
                }
                buf += sizeof(event);
                i -= sizeof(event);
        }
        if (i < count)
                return count - i;
        if (signal_pending(current))
                return -ERESTARTSYS;
        return 0;
}

static unsigned int do_poll(struct file *fp, poll_table * wait)
{
        struct apm_user * as;

        as = fp->private_data;
        if (check_apm_user(as, "poll"))
                return 0;
        poll_wait(fp, &apm_waitqueue, wait);
        if (!queue_empty(as))
                return POLLIN | POLLRDNORM;
        return 0;
}

static int do_ioctl(struct inode * inode, struct file *filp,
                    u_int cmd, u_long arg)
{
        struct apm_user *       as;

        as = filp->private_data;
        if (check_apm_user(as, "ioctl"))
                return -EIO;
        if ((!as->suser) || (!as->writer))
                return -EPERM;
        switch (cmd) {
        case APM_IOC_STANDBY:
                if (as->standbys_read > 0) {
                        as->standbys_read--;
                        as->standbys_pending--;
                        standbys_pending--;
                } else
                        queue_event(APM_USER_STANDBY, as);
                if (standbys_pending <= 0)
                        standby();
                break;
        case APM_IOC_SUSPEND:
                if (as->suspends_read > 0) {
                        as->suspends_read--;
                        as->suspends_pending--;
                        suspends_pending--;
                } else
                        queue_event(APM_USER_SUSPEND, as);
                if (suspends_pending <= 0) {
                        return suspend(1);
                } else {
                        as->suspend_wait = 1;
                        wait_event_interruptible(apm_suspend_waitqueue,
                                        as->suspend_wait == 0);
                        return as->suspend_result;
                }
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

static int do_release(struct inode * inode, struct file * filp)
{
        struct apm_user *       as;

        as = filp->private_data;
        if (check_apm_user(as, "release"))
                return 0;
        filp->private_data = NULL;
        lock_kernel();
        if (as->standbys_pending > 0) {
                standbys_pending -= as->standbys_pending;
                if (standbys_pending <= 0)
                        standby();
        }
        if (as->suspends_pending > 0) {
                suspends_pending -= as->suspends_pending;
                if (suspends_pending <= 0)
                        (void) suspend(1);
        }
        if (user_list == as)
                user_list = as->next;
        else {
                struct apm_user *       as1;

                for (as1 = user_list;
                     (as1 != NULL) && (as1->next != as);
                     as1 = as1->next)
                        ;
                if (as1 == NULL)
                        printk(KERN_ERR "apm: filp not in user list\n");
                else
                        as1->next = as->next;
        }
        unlock_kernel();
        kfree(as);
        return 0;
}

static int do_open(struct inode * inode, struct file * filp)
{
        struct apm_user *       as;

        as = (struct apm_user *)kmalloc(sizeof(*as), GFP_KERNEL);
        if (as == NULL) {
                printk(KERN_ERR "apm: cannot allocate struct of size %d bytes\n",
                       sizeof(*as));
                return -ENOMEM;
        }
        as->magic = APM_BIOS_MAGIC;
        as->event_tail = as->event_head = 0;
        as->suspends_pending = as->standbys_pending = 0;
        as->suspends_read = as->standbys_read = 0;
        /*
         * XXX - this is a tiny bit broken, when we consider BSD
         * process accounting. If the device is opened by root, we
         * instantly flag that we used superuser privs. Who knows,
         * we might close the device immediately without doing a
         * privileged operation -- cevans
         */
        as->suser = capable(CAP_SYS_ADMIN);
        as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
        as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
        as->next = user_list;
        user_list = as;
        filp->private_data = as;
        return 0;
}

static int apm_get_info(char *buf, char **start, off_t fpos, int length)
{
        char *          p;
        unsigned short  bx;
        unsigned short  cx;
        unsigned short  dx;
        int             error;
        unsigned short  ac_line_status = 0xff;
        unsigned short  battery_status = 0xff;
        unsigned short  battery_flag   = 0xff;
        int             percentage     = -1;
        int             time_units     = -1;
        char            *units         = "?";

        p = buf;

        if ((smp_num_cpus == 1 || smp) &&
            !(error = apm_get_power_status(&bx, &cx, &dx))) {
                ac_line_status = (bx >> 8) & 0xff;
                battery_status = bx & 0xff;
                if ((cx & 0xff) != 0xff)
                        percentage = cx & 0xff;

                if (apm_info.connection_version > 0x100) {
                        battery_flag = (cx >> 8) & 0xff;
                        if (dx != 0xffff) {
                                units = (dx & 0x8000) ? "min" : "sec";
                                time_units = dx & 0x7fff;
                        }
                }
        }
        /* Arguments, with symbols from linux/apm_bios.h.  Information is
           from the Get Power Status (0x0a) call unless otherwise noted.

           0) Linux driver version (this will change if format changes)
           1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
           2) APM flags from APM Installation Check (0x00):
              bit 0: APM_16_BIT_SUPPORT
              bit 1: APM_32_BIT_SUPPORT
              bit 2: APM_IDLE_SLOWS_CLOCK
              bit 3: APM_BIOS_DISABLED
              bit 4: APM_BIOS_DISENGAGED
           3) AC line status
              0x00: Off-line
              0x01: On-line
              0x02: On backup power (BIOS >= 1.1 only)
              0xff: Unknown
           4) Battery status
              0x00: High
              0x01: Low
              0x02: Critical
              0x03: Charging
              0x04: Selected battery not present (BIOS >= 1.2 only)
              0xff: Unknown
           5) Battery flag
              bit 0: High
              bit 1: Low
              bit 2: Critical
              bit 3: Charging
              bit 7: No system battery
              0xff: Unknown
           6) Remaining battery life (percentage of charge):
              0-100: valid
              -1: Unknown
           7) Remaining battery life (time units):
              Number of remaining minutes or seconds
              -1: Unknown
           8) min = minutes; sec = seconds */

        p += sprintf(p, "%s %d.%d 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
                     driver_version,
                     (apm_info.bios.version >> 8) & 0xff,
                     apm_info.bios.version & 0xff,
                     apm_info.bios.flags,
                     ac_line_status,
                     battery_status,
                     battery_flag,
                     percentage,
                     time_units,
                     units);

        return p - buf;
}

static int apm(void *unused)
{
        unsigned short  bx;
        unsigned short  cx;
        unsigned short  dx;
        int             error;
        char *          power_stat;
        char *          bat_stat;

        kapmd_running = 1;

        daemonize();

        strcpy(current->comm, "kapmd");
        sigfillset(&current->blocked);

#ifdef CONFIG_SMP
        /* 2002/08/01 - WT
         * This is to avoid random crashes at boot time during initialization
         * on SMP systems in case of "apm=power-off" mode. Seen on ASUS A7M266D.
         * Some bioses don't like being called from CPU != 0.
         * Method suggested by Ingo Molnar.
         */
        if (cpu_number_map(smp_processor_id()) != 0) {
                current->cpus_allowed = 1;
                schedule();
                if (unlikely(cpu_number_map(smp_processor_id()) != 0))
                        BUG();
        }
#endif
        
        if (apm_info.connection_version == 0) {
                apm_info.connection_version = apm_info.bios.version;
                if (apm_info.connection_version > 0x100) {
                        /*
                         * We only support BIOSs up to version 1.2
                         */
                        if (apm_info.connection_version > 0x0102)
                                apm_info.connection_version = 0x0102;
                        error = apm_driver_version(&apm_info.connection_version);
                        if (error != APM_SUCCESS) {
                                apm_error("driver version", error);
                                /* Fall back to an APM 1.0 connection. */
                                apm_info.connection_version = 0x100;
                        }
                }
        }

        if (debug)
                printk(KERN_INFO "apm: Connection version %d.%d\n",
                        (apm_info.connection_version >> 8) & 0xff,
                        apm_info.connection_version & 0xff);

#ifdef CONFIG_APM_DO_ENABLE
        if (apm_info.bios.flags & APM_BIOS_DISABLED) {
                /*
                 * This call causes my NEC UltraLite Versa 33/C to hang if it
                 * is booted with PM disabled but not in the docking station.
                 * Unfortunate ...
                 */
                error = apm_enable_power_management(1);
                if (error) {
                        apm_error("enable power management", error);
                        return -1;
                }
        }
#endif

        if ((apm_info.bios.flags & APM_BIOS_DISENGAGED)
            && (apm_info.connection_version > 0x0100)) {
                error = apm_engage_power_management(APM_DEVICE_ALL, 1);
                if (error) {
                        apm_error("engage power management", error);
                        return -1;
                }
        }

        if (debug && (smp_num_cpus == 1 || smp )) {
                error = apm_get_power_status(&bx, &cx, &dx);
                if (error)
                        printk(KERN_INFO "apm: power status not available\n");
                else {
                        switch ((bx >> 8) & 0xff) {
                        case 0: power_stat = "off line"; break;
                        case 1: power_stat = "on line"; break;
                        case 2: power_stat = "on backup power"; break;
                        default: power_stat = "unknown"; break;
                        }
                        switch (bx & 0xff) {
                        case 0: bat_stat = "high"; break;
                        case 1: bat_stat = "low"; break;
                        case 2: bat_stat = "critical"; break;
                        case 3: bat_stat = "charging"; break;
                        default: bat_stat = "unknown"; break;
                        }
                        printk(KERN_INFO
                               "apm: AC %s, battery status %s, battery life ",
                               power_stat, bat_stat);
                        if ((cx & 0xff) == 0xff)
                                printk("unknown\n");
                        else
                                printk("%d%%\n", cx & 0xff);
                        if (apm_info.connection_version > 0x100) {
                                printk(KERN_INFO
                                       "apm: battery flag 0x%02x, battery life ",
                                       (cx >> 8) & 0xff);
                                if (dx == 0xffff)
                                        printk("unknown\n");
                                else
                                        printk("%d %s\n", dx & 0x7fff,
                                                (dx & 0x8000) ?
                                                "minutes" : "seconds");
                        }
                }
        }

        /* Install our power off handler.. */
        if (power_off)
                pm_power_off = apm_power_off;
        register_sysrq_key('o', &sysrq_poweroff_op);

        if (smp_num_cpus == 1 || smp) {
#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
                console_blank_hook = apm_console_blank;
#endif
                apm_mainloop();
#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
                console_blank_hook = NULL;
#endif
        }
        kapmd_running = 0;

        return 0;
}

#ifndef MODULE
static int __init apm_setup(char *str)
{
        int     invert;

        while ((str != NULL) && (*str != '\0')) {
                if (strncmp(str, "off", 3) == 0)
                        apm_disabled = 1;
                if (strncmp(str, "on", 2) == 0)
                        apm_disabled = 0;
                if ((strncmp(str, "bounce-interval=", 16) == 0) ||
                    (strncmp(str, "bounce_interval=", 16) == 0))
                        bounce_interval = simple_strtol(str + 16, NULL, 0);
                if ((strncmp(str, "idle-threshold=", 15) == 0) ||
                    (strncmp(str, "idle_threshold=", 15) == 0))
                        idle_threshold = simple_strtol(str + 15, NULL, 0);
                if ((strncmp(str, "idle-period=", 12) == 0) ||
                    (strncmp(str, "idle_period=", 12) == 0))
                        idle_period = simple_strtol(str + 12, NULL, 0);
                invert = (strncmp(str, "no-", 3) == 0) ||
                        (strncmp(str, "no_", 3) == 0);
                if (invert)
                        str += 3;
                if (strncmp(str, "debug", 5) == 0)
                        debug = !invert;
                if (strncmp(str, "smp", 3) == 0)
                {
                        smp = !invert;
                        idle_threshold = 100;
                }
                if ((strncmp(str, "power-off", 9) == 0) ||
                    (strncmp(str, "power_off", 9) == 0))
                        power_off = !invert;
                if ((strncmp(str, "allow-ints", 10) == 0) ||
                    (strncmp(str, "allow_ints", 10) == 0))
                        apm_info.allow_ints = !invert;
                if ((strncmp(str, "broken-psr", 10) == 0) ||
                    (strncmp(str, "broken_psr", 10) == 0))
                        apm_info.get_power_status_broken = !invert;
                if ((strncmp(str, "realmode-power-off", 18) == 0) ||
                    (strncmp(str, "realmode_power_off", 18) == 0))
                        apm_info.realmode_power_off = !invert;
                str = strchr(str, ',');
                if (str != NULL)
                        str += strspn(str, ", \t");
        }
        return 1;
}

__setup("apm=", apm_setup);
#endif

static struct file_operations apm_bios_fops = {
        owner:          THIS_MODULE,
        read:           do_read,
        poll:           do_poll,
        ioctl:          do_ioctl,
        open:           do_open,
        release:        do_release,
};

static struct miscdevice apm_device = {
        APM_MINOR_DEV,
        "apm_bios",
        &apm_bios_fops
};

/*
 * Just start the APM thread. We do NOT want to do APM BIOS
 * calls from anything but the APM thread, if for no other reason
 * than the fact that we don't trust the APM BIOS. This way,
 * most common APM BIOS problems that lead to protection errors
 * etc will have at least some level of being contained...
 *
 * In short, if something bad happens, at least we have a choice
 * of just killing the apm thread..
 */
static int __init apm_init(void)
{
        struct proc_dir_entry *apm_proc;

        if (apm_info.bios.version == 0) {
                printk(KERN_INFO "apm: BIOS not found.\n");
                return -ENODEV;
        }
        printk(KERN_INFO
                "apm: BIOS version %d.%d Flags 0x%02x (Driver version %s)\n",
                ((apm_info.bios.version >> 8) & 0xff),
                (apm_info.bios.version & 0xff),
                apm_info.bios.flags,
                driver_version);
        if ((apm_info.bios.flags & APM_32_BIT_SUPPORT) == 0) {
                printk(KERN_INFO "apm: no 32 bit BIOS support\n");
                return -ENODEV;
        }

        if (allow_ints)
                apm_info.allow_ints = 1;
        if (broken_psr)
                apm_info.get_power_status_broken = 1;
        if (realmode_power_off)
                apm_info.realmode_power_off = 1;
        /* User can override, but default is to trust DMI */
        if (apm_disabled != -1)
                apm_info.disabled = apm_disabled;

        /*
         * Fix for the Compaq Contura 3/25c which reports BIOS version 0.1
         * but is reportedly a 1.0 BIOS.
         */
        if (apm_info.bios.version == 0x001)
                apm_info.bios.version = 0x100;

        /* BIOS < 1.2 doesn't set cseg_16_len */
        if (apm_info.bios.version < 0x102)
                apm_info.bios.cseg_16_len = 0; /* 64k */

        if (debug) {
                printk(KERN_INFO "apm: entry %x:%lx cseg16 %x dseg %x",
                        apm_info.bios.cseg, apm_info.bios.offset,
                        apm_info.bios.cseg_16, apm_info.bios.dseg);
                if (apm_info.bios.version > 0x100)
                        printk(" cseg len %x, dseg len %x",
                                apm_info.bios.cseg_len,
                                apm_info.bios.dseg_len);
                if (apm_info.bios.version > 0x101)
                        printk(" cseg16 len %x", apm_info.bios.cseg_16_len);
                printk("\n");
        }

        if (apm_info.disabled) {
                printk(KERN_NOTICE "apm: disabled on user request.\n");
                return -ENODEV;
        }
        if ((smp_num_cpus > 1) && !power_off && !smp) {
                printk(KERN_NOTICE "apm: disabled - APM is not SMP safe.\n");
                return -ENODEV;
        }
        if (PM_IS_ACTIVE()) {
                printk(KERN_NOTICE "apm: overridden by ACPI.\n");
                return -ENODEV;
        }
        pm_active = 1;

        /*
         * Set up a segment that references the real mode segment 0x40
         * that extends up to the end of page zero (that we have reserved).
         * This is for buggy BIOS's that refer to (real mode) segment 0x40
         * even though they are called in protected mode.
         */
        set_base(gdt[APM_40 >> 3],
                 __va((unsigned long)0x40 << 4));
        _set_limit((char *)&gdt[APM_40 >> 3], 4095 - (0x40 << 4));

        apm_bios_entry.offset = apm_info.bios.offset;
        apm_bios_entry.segment = APM_CS;
        set_base(gdt[APM_CS >> 3],
                 __va((unsigned long)apm_info.bios.cseg << 4));
        set_base(gdt[APM_CS_16 >> 3],
                 __va((unsigned long)apm_info.bios.cseg_16 << 4));
        set_base(gdt[APM_DS >> 3],
                 __va((unsigned long)apm_info.bios.dseg << 4));
#ifndef APM_RELAX_SEGMENTS
        if (apm_info.bios.version == 0x100) {
#endif
                /* For ASUS motherboard, Award BIOS rev 110 (and others?) */
                _set_limit((char *)&gdt[APM_CS >> 3], 64 * 1024 - 1);

                /* For some unknown machine. */
                _set_limit((char *)&gdt[APM_CS_16 >> 3], 64 * 1024 - 1);
                /* For the DEC Hinote Ultra CT475 (and others?) */
                _set_limit((char *)&gdt[APM_DS >> 3], 64 * 1024 - 1);
#ifndef APM_RELAX_SEGMENTS
        } else {
                _set_limit((char *)&gdt[APM_CS >> 3],
                        (apm_info.bios.cseg_len - 1) & 0xffff);
                _set_limit((char *)&gdt[APM_CS_16 >> 3],
                        (apm_info.bios.cseg_16_len - 1) & 0xffff);
                _set_limit((char *)&gdt[APM_DS >> 3],
                        (apm_info.bios.dseg_len - 1) & 0xffff);
        }
#endif

        apm_proc = create_proc_info_entry("apm", 0, NULL, apm_get_info);
        if (apm_proc)
                SET_MODULE_OWNER(apm_proc);

        kernel_thread(apm, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD);

        if (smp_num_cpus > 1 && !smp) {
                printk(KERN_NOTICE
                   "apm: disabled - APM is not SMP safe (power off active).\n");
                return 0;
        }

        misc_register(&apm_device);

        if (HZ != 100)
                idle_period = (idle_period * HZ) / 100;
        if (idle_threshold < 100) {
                original_pm_idle = pm_idle;
                pm_idle  = apm_cpu_idle;
                set_pm_idle = 1;
        }

        return 0;
}

static void __exit apm_exit(void)
{
        int     error;

        if (set_pm_idle)
                pm_idle = original_pm_idle;
        if (((apm_info.bios.flags & APM_BIOS_DISENGAGED) == 0)
            && (apm_info.connection_version > 0x0100)) {
                error = apm_engage_power_management(APM_DEVICE_ALL, 0);
                if (error)
                        apm_error("disengage power management", error);
        }
        misc_deregister(&apm_device);
        remove_proc_entry("apm", NULL);
        unregister_sysrq_key('o',&sysrq_poweroff_op);
        if (power_off)
                pm_power_off = NULL;
        exit_kapmd = 1;
        while (kapmd_running)
                schedule();
        pm_active = 0;
}

module_init(apm_init);
module_exit(apm_exit);

MODULE_AUTHOR("Stephen Rothwell");
MODULE_DESCRIPTION("Advanced Power Management");
MODULE_LICENSE("GPL");
MODULE_PARM(debug, "i");
MODULE_PARM_DESC(debug, "Enable debug mode");
MODULE_PARM(power_off, "i");
MODULE_PARM_DESC(power_off, "Enable power off");
MODULE_PARM(bounce_interval, "i");
MODULE_PARM_DESC(bounce_interval,
                "Set the number of ticks to ignore suspend bounces");
MODULE_PARM(allow_ints, "i");
MODULE_PARM_DESC(allow_ints, "Allow interrupts during BIOS calls");
MODULE_PARM(broken_psr, "i");
MODULE_PARM_DESC(broken_psr, "BIOS has a broken GetPowerStatus call");
MODULE_PARM(realmode_power_off, "i");
MODULE_PARM_DESC(realmode_power_off,
                "Switch to real mode before powering off");
MODULE_PARM(idle_threshold, "i");
MODULE_PARM_DESC(idle_threshold,
        "System idle percentage above which to make APM BIOS idle calls");
MODULE_PARM(idle_period, "i");
MODULE_PARM_DESC(idle_period,
        "Period (in sec/100) over which to caculate the idle percentage");
MODULE_PARM(smp, "i");
MODULE_PARM_DESC(smp,
        "Set this to enable APM use on an SMP platform. Use with caution on older systems");

EXPORT_NO_SYMBOLS;