4 files changed, 762 insertions, 0 deletions

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 0326ca1a848a..ae8567cc529c 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -60,6 +60,8 @@ obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
 obj-$(CONFIG_PRINTER)           += lp.o
 obj-$(CONFIG_TIPAR)             += tipar.o
 
+obj-$(CONFIG_APM_EMULATION)     += apm-emulation.o
+
 obj-$(CONFIG_DTLK)              += dtlk.o
 obj-$(CONFIG_R3964)             += n_r3964.o
 obj-$(CONFIG_APPLICOM)          += applicom.o
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
new file mode 100644
index 000000000000..179c7a3b6e75
--- /dev/null
+++ b/drivers/char/apm-emulation.c
@@ -0,0 +1,672 @@
+/*
+ * bios-less APM driver for ARM Linux
+ *  Jamey Hicks <jamey@crl.dec.com>
+ *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
+ *
+ * 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/module.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/miscdevice.h>
+#include <linux/apm_bios.h>
+#include <linux/capability.h>
+#include <linux/sched.h>
+#include <linux/pm.h>
+#include <linux/apm-emulation.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+#include <asm/system.h>
+
+/*
+ * 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
+ */
+
+/*
+ * Maximum number of events stored
+ */
+#define APM_MAX_EVENTS          16
+
+struct apm_queue {
+        unsigned int            event_head;
+        unsigned int            event_tail;
+        apm_event_t             events[APM_MAX_EVENTS];
+};
+
+/*
+ * The per-file APM data
+ */
+struct apm_user {
+        struct list_head        list;
+
+        unsigned int            suser: 1;
+        unsigned int            writer: 1;
+        unsigned int            reader: 1;
+
+        int                     suspend_result;
+        unsigned int            suspend_state;
+#define SUSPEND_NONE    0               /* no suspend pending */
+#define SUSPEND_PENDING 1               /* suspend pending read */
+#define SUSPEND_READ    2               /* suspend read, pending ack */
+#define SUSPEND_ACKED   3               /* suspend acked */
+#define SUSPEND_WAIT    4               /* waiting for suspend */
+#define SUSPEND_DONE    5               /* suspend completed */
+
+        struct apm_queue        queue;
+};
+
+/*
+ * Local variables
+ */
+static int suspends_pending;
+static int apm_disabled;
+static struct task_struct *kapmd_tsk;
+
+static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
+static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
+
+/*
+ * This is a list of everyone who has opened /dev/apm_bios
+ */
+static DECLARE_RWSEM(user_list_lock);
+static LIST_HEAD(apm_user_list);
+
+/*
+ * kapmd info.  kapmd provides us a process context to handle
+ * "APM" events within - specifically necessary if we're going
+ * to be suspending the system.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
+static DEFINE_SPINLOCK(kapmd_queue_lock);
+static struct apm_queue kapmd_queue;
+
+static DEFINE_MUTEX(state_lock);
+
+static const char driver_version[] = "1.13";    /* no spaces */
+
+
+
+/*
+ * Compatibility cruft until the IPAQ people move over to the new
+ * interface.
+ */
+static void __apm_get_power_status(struct apm_power_info *info)
+{
+}
+
+/*
+ * This allows machines to provide their own "apm get power status" function.
+ */
+void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
+EXPORT_SYMBOL(apm_get_power_status);
+
+
+/*
+ * APM event queue management.
+ */
+static inline int queue_empty(struct apm_queue *q)
+{
+        return q->event_head == q->event_tail;
+}
+
+static inline apm_event_t queue_get_event(struct apm_queue *q)
+{
+        q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+        return q->events[q->event_tail];
+}
+
+static void queue_add_event(struct apm_queue *q, apm_event_t event)
+{
+        q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
+        if (q->event_head == q->event_tail) {
+                static int notified;
+
+                if (notified++ == 0)
+                    printk(KERN_ERR "apm: an event queue overflowed\n");
+                q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+        }
+        q->events[q->event_head] = event;
+}
+
+static void queue_event(apm_event_t event)
+{
+        struct apm_user *as;
+
+        down_read(&user_list_lock);
+        list_for_each_entry(as, &apm_user_list, list) {
+                if (as->reader)
+                        queue_add_event(&as->queue, event);
+        }
+        up_read(&user_list_lock);
+        wake_up_interruptible(&apm_waitqueue);
+}
+
+/*
+ * queue_suspend_event - queue an APM suspend event.
+ *
+ * Check that we're in a state where we can suspend.  If not,
+ * return -EBUSY.  Otherwise, queue an event to all "writer"
+ * users.  If there are no "writer" users, return '1' to
+ * indicate that we can immediately suspend.
+ */
+static int queue_suspend_event(apm_event_t event, struct apm_user *sender)
+{
+        struct apm_user *as;
+        int ret = 1;
+
+        mutex_lock(&state_lock);
+        down_read(&user_list_lock);
+
+        /*
+         * If a thread is still processing, we can't suspend, so reject
+         * the request.
+         */
+        list_for_each_entry(as, &apm_user_list, list) {
+                if (as != sender && as->reader && as->writer && as->suser &&
+                    as->suspend_state != SUSPEND_NONE) {
+                        ret = -EBUSY;
+                        goto out;
+                }
+        }
+
+        list_for_each_entry(as, &apm_user_list, list) {
+                if (as != sender && as->reader && as->writer && as->suser) {
+                        as->suspend_state = SUSPEND_PENDING;
+                        suspends_pending++;
+                        queue_add_event(&as->queue, event);
+                        ret = 0;
+                }
+        }
+ out:
+        up_read(&user_list_lock);
+        mutex_unlock(&state_lock);
+        wake_up_interruptible(&apm_waitqueue);
+        return ret;
+}
+
+static void apm_suspend(void)
+{
+        struct apm_user *as;
+        int err = pm_suspend(PM_SUSPEND_MEM);
+
+        /*
+         * Anyone on the APM queues will think we're still suspended.
+         * Send a message so everyone knows we're now awake again.
+         */
+        queue_event(APM_NORMAL_RESUME);
+
+        /*
+         * Finally, wake up anyone who is sleeping on the suspend.
+         */
+        mutex_lock(&state_lock);
+        down_read(&user_list_lock);
+        list_for_each_entry(as, &apm_user_list, list) {
+                if (as->suspend_state == SUSPEND_WAIT ||
+                    as->suspend_state == SUSPEND_ACKED) {
+                        as->suspend_result = err;
+                        as->suspend_state = SUSPEND_DONE;
+                }
+        }
+        up_read(&user_list_lock);
+        mutex_unlock(&state_lock);
+
+        wake_up(&apm_suspend_waitqueue);
+}
+
+static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct apm_user *as = fp->private_data;
+        apm_event_t event;
+        int i = count, ret = 0;
+
+        if (count < sizeof(apm_event_t))
+                return -EINVAL;
+
+        if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
+                return -EAGAIN;
+
+        wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
+
+        while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
+                event = queue_get_event(&as->queue);
+
+                ret = -EFAULT;
+                if (copy_to_user(buf, &event, sizeof(event)))
+                        break;
+
+                mutex_lock(&state_lock);
+                if (as->suspend_state == SUSPEND_PENDING &&
+                    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
+                        as->suspend_state = SUSPEND_READ;
+                mutex_unlock(&state_lock);
+
+                buf += sizeof(event);
+                i -= sizeof(event);
+        }
+
+        if (i < count)
+                ret = count - i;
+
+        return ret;
+}
+
+static unsigned int apm_poll(struct file *fp, poll_table * wait)
+{
+        struct apm_user *as = fp->private_data;
+
+        poll_wait(fp, &apm_waitqueue, wait);
+        return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
+}
+
+/*
+ * apm_ioctl - handle APM ioctl
+ *
+ * APM_IOC_SUSPEND
+ *   This IOCTL is overloaded, and performs two functions.  It is used to:
+ *     - initiate a suspend
+ *     - acknowledge a suspend read from /dev/apm_bios.
+ *   Only when everyone who has opened /dev/apm_bios with write permission
+ *   has acknowledge does the actual suspend happen.
+ */
+static int
+apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
+{
+        struct apm_user *as = filp->private_data;
+        unsigned long flags;
+        int err = -EINVAL;
+
+        if (!as->suser || !as->writer)
+                return -EPERM;
+
+        switch (cmd) {
+        case APM_IOC_SUSPEND:
+                mutex_lock(&state_lock);
+
+                as->suspend_result = -EINTR;
+
+                if (as->suspend_state == SUSPEND_READ) {
+                        int pending;
+
+                        /*
+                         * If we read a suspend command from /dev/apm_bios,
+                         * then the corresponding APM_IOC_SUSPEND ioctl is
+                         * interpreted as an acknowledge.
+                         */
+                        as->suspend_state = SUSPEND_ACKED;
+                        suspends_pending--;
+                        pending = suspends_pending == 0;
+                        mutex_unlock(&state_lock);
+
+                        /*
+                         * If there are no further acknowledges required,
+                         * suspend the system.
+                         */
+                        if (pending)
+                                apm_suspend();
+
+                        /*
+                         * Wait for the suspend/resume to complete.  If there
+                         * are pending acknowledges, we wait here for them.
+                         *
+                         * Note: we need to ensure that the PM subsystem does
+                         * not kick us out of the wait when it suspends the
+                         * threads.
+                         */
+                        flags = current->flags;
+                        current->flags |= PF_NOFREEZE;
+
+                        wait_event(apm_suspend_waitqueue,
+                                   as->suspend_state == SUSPEND_DONE);
+                } else {
+                        as->suspend_state = SUSPEND_WAIT;
+                        mutex_unlock(&state_lock);
+
+                        /*
+                         * Otherwise it is a request to suspend the system.
+                         * Queue an event for all readers, and expect an
+                         * acknowledge from all writers who haven't already
+                         * acknowledged.
+                         */
+                        err = queue_suspend_event(APM_USER_SUSPEND, as);
+                        if (err < 0) {
+                                /*
+                                 * Avoid taking the lock here - this
+                                 * should be fine.
+                                 */
+                                as->suspend_state = SUSPEND_NONE;
+                                break;
+                        }
+
+                        if (err > 0)
+                                apm_suspend();
+
+                        /*
+                         * Wait for the suspend/resume to complete.  If there
+                         * are pending acknowledges, we wait here for them.
+                         *
+                         * Note: we need to ensure that the PM subsystem does
+                         * not kick us out of the wait when it suspends the
+                         * threads.
+                         */
+                        flags = current->flags;
+                        current->flags |= PF_NOFREEZE;
+
+                        wait_event_interruptible(apm_suspend_waitqueue,
+                                         as->suspend_state == SUSPEND_DONE);
+                }
+
+                current->flags = flags;
+
+                mutex_lock(&state_lock);
+                err = as->suspend_result;
+                as->suspend_state = SUSPEND_NONE;
+                mutex_unlock(&state_lock);
+                break;
+        }
+
+        return err;
+}
+
+static int apm_release(struct inode * inode, struct file * filp)
+{
+        struct apm_user *as = filp->private_data;
+        int pending = 0;
+
+        filp->private_data = NULL;
+
+        down_write(&user_list_lock);
+        list_del(&as->list);
+        up_write(&user_list_lock);
+
+        /*
+         * We are now unhooked from the chain.  As far as new
+         * events are concerned, we no longer exist.  However, we
+         * need to balance suspends_pending, which means the
+         * possibility of sleeping.
+         */
+        mutex_lock(&state_lock);
+        if (as->suspend_state != SUSPEND_NONE) {
+                suspends_pending -= 1;
+                pending = suspends_pending == 0;
+        }
+        mutex_unlock(&state_lock);
+        if (pending)
+                apm_suspend();
+
+        kfree(as);
+        return 0;
+}
+
+static int apm_open(struct inode * inode, struct file * filp)
+{
+        struct apm_user *as;
+
+        as = kzalloc(sizeof(*as), GFP_KERNEL);
+        if (as) {
+                /*
+                 * 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;
+
+                down_write(&user_list_lock);
+                list_add(&as->list, &apm_user_list);
+                up_write(&user_list_lock);
+
+                filp->private_data = as;
+        }
+
+        return as ? 0 : -ENOMEM;
+}
+
+static struct file_operations apm_bios_fops = {
+        .owner          = THIS_MODULE,
+        .read           = apm_read,
+        .poll           = apm_poll,
+        .ioctl          = apm_ioctl,
+        .open           = apm_open,
+        .release        = apm_release,
+};
+
+static struct miscdevice apm_device = {
+        .minor          = APM_MINOR_DEV,
+        .name           = "apm_bios",
+        .fops           = &apm_bios_fops
+};
+
+
+#ifdef CONFIG_PROC_FS
+/*
+ * Arguments, with symbols from linux/apm_bios.h.
+ *
+ *   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
+ */
+static int apm_get_info(char *buf, char **start, off_t fpos, int length)
+{
+        struct apm_power_info info;
+        char *units;
+        int ret;
+
+        info.ac_line_status = 0xff;
+        info.battery_status = 0xff;
+        info.battery_flag   = 0xff;
+        info.battery_life   = -1;
+        info.time           = -1;
+        info.units          = -1;
+
+        if (apm_get_power_status)
+                apm_get_power_status(&info);
+
+        switch (info.units) {
+        default:        units = "?";    break;
+        case 0:         units = "min";  break;
+        case 1:         units = "sec";  break;
+        }
+
+        ret = sprintf(buf, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
+                     driver_version, APM_32_BIT_SUPPORT,
+                     info.ac_line_status, info.battery_status,
+                     info.battery_flag, info.battery_life,
+                     info.time, units);
+
+        return ret;
+}
+#endif
+
+static int kapmd(void *arg)
+{
+        do {
+                apm_event_t event;
+                int ret;
+
+                wait_event_interruptible(kapmd_wait,
+                                !queue_empty(&kapmd_queue) || kthread_should_stop());
+
+                if (kthread_should_stop())
+                        break;
+
+                spin_lock_irq(&kapmd_queue_lock);
+                event = 0;
+                if (!queue_empty(&kapmd_queue))
+                        event = queue_get_event(&kapmd_queue);
+                spin_unlock_irq(&kapmd_queue_lock);
+
+                switch (event) {
+                case 0:
+                        break;
+
+                case APM_LOW_BATTERY:
+                case APM_POWER_STATUS_CHANGE:
+                        queue_event(event);
+                        break;
+
+                case APM_USER_SUSPEND:
+                case APM_SYS_SUSPEND:
+                        ret = queue_suspend_event(event, NULL);
+                        if (ret < 0) {
+                                /*
+                                 * We were busy.  Try again in 50ms.
+                                 */
+                                queue_add_event(&kapmd_queue, event);
+                                msleep(50);
+                        }
+                        if (ret > 0)
+                                apm_suspend();
+                        break;
+
+                case APM_CRITICAL_SUSPEND:
+                        apm_suspend();
+                        break;
+                }
+        } while (1);
+
+        return 0;
+}
+
+static int __init apm_init(void)
+{
+        int ret;
+
+        if (apm_disabled) {
+                printk(KERN_NOTICE "apm: disabled on user request.\n");
+                return -ENODEV;
+        }
+
+        kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
+        if (IS_ERR(kapmd_tsk)) {
+                ret = PTR_ERR(kapmd_tsk);
+                kapmd_tsk = NULL;
+                return ret;
+        }
+        kapmd_tsk->flags |= PF_NOFREEZE;
+        wake_up_process(kapmd_tsk);
+
+#ifdef CONFIG_PROC_FS
+        create_proc_info_entry("apm", 0, NULL, apm_get_info);
+#endif
+
+        ret = misc_register(&apm_device);
+        if (ret != 0) {
+                remove_proc_entry("apm", NULL);
+                kthread_stop(kapmd_tsk);
+        }
+
+        return ret;
+}
+
+static void __exit apm_exit(void)
+{
+        misc_deregister(&apm_device);
+        remove_proc_entry("apm", NULL);
+
+        kthread_stop(kapmd_tsk);
+}
+
+module_init(apm_init);
+module_exit(apm_exit);
+
+MODULE_AUTHOR("Stephen Rothwell");
+MODULE_DESCRIPTION("Advanced Power Management");
+MODULE_LICENSE("GPL");
+
+#ifndef MODULE
+static int __init apm_setup(char *str)
+{
+        while ((str != NULL) && (*str != '\0')) {
+                if (strncmp(str, "off", 3) == 0)
+                        apm_disabled = 1;
+                if (strncmp(str, "on", 2) == 0)
+                        apm_disabled = 0;
+                str = strchr(str, ',');
+                if (str != NULL)
+                        str += strspn(str, ", \t");
+        }
+        return 1;
+}
+
+__setup("apm=", apm_setup);
+#endif
+
+/**
+ * apm_queue_event - queue an APM event for kapmd
+ * @event: APM event
+ *
+ * Queue an APM event for kapmd to process and ultimately take the
+ * appropriate action.  Only a subset of events are handled:
+ *   %APM_LOW_BATTERY
+ *   %APM_POWER_STATUS_CHANGE
+ *   %APM_USER_SUSPEND
+ *   %APM_SYS_SUSPEND
+ *   %APM_CRITICAL_SUSPEND
+ */
+void apm_queue_event(apm_event_t event)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&kapmd_queue_lock, flags);
+        queue_add_event(&kapmd_queue, event);
+        spin_unlock_irqrestore(&kapmd_queue_lock, flags);
+
+        wake_up_interruptible(&kapmd_wait);
+}
+EXPORT_SYMBOL(apm_queue_event);
diff --git a/include/linux/apm-emulation.h b/include/linux/apm-emulation.h
new file mode 100644
index 000000000000..e6d800358dd6
--- /dev/null
+++ b/include/linux/apm-emulation.h
@@ -0,0 +1,62 @@
+/* -*- linux-c -*-
+ *
+ * (C) 2003 zecke@handhelds.org
+ *
+ * GPL version 2
+ *
+ * based on arch/arm/kernel/apm.c
+ * factor out the information needed by architectures to provide
+ * apm status
+ */
+#ifndef __LINUX_APM_EMULATION_H
+#define __LINUX_APM_EMULATION_H
+
+#include <linux/apm_bios.h>
+
+/*
+ * This structure gets filled in by the machine specific 'get_power_status'
+ * implementation.  Any fields which are not set default to a safe value.
+ */
+struct apm_power_info {
+        unsigned char   ac_line_status;
+#define APM_AC_OFFLINE                  0
+#define APM_AC_ONLINE                   1
+#define APM_AC_BACKUP                   2
+#define APM_AC_UNKNOWN                  0xff
+
+        unsigned char   battery_status;
+#define APM_BATTERY_STATUS_HIGH         0
+#define APM_BATTERY_STATUS_LOW          1
+#define APM_BATTERY_STATUS_CRITICAL     2
+#define APM_BATTERY_STATUS_CHARGING     3
+#define APM_BATTERY_STATUS_NOT_PRESENT  4
+#define APM_BATTERY_STATUS_UNKNOWN      0xff
+
+        unsigned char   battery_flag;
+#define APM_BATTERY_FLAG_HIGH           (1 << 0)
+#define APM_BATTERY_FLAG_LOW            (1 << 1)
+#define APM_BATTERY_FLAG_CRITICAL       (1 << 2)
+#define APM_BATTERY_FLAG_CHARGING       (1 << 3)
+#define APM_BATTERY_FLAG_NOT_PRESENT    (1 << 7)
+#define APM_BATTERY_FLAG_UNKNOWN        0xff
+
+        int             battery_life;
+        int             time;
+        int             units;
+#define APM_UNITS_MINS                  0
+#define APM_UNITS_SECS                  1
+#define APM_UNITS_UNKNOWN               -1
+
+};
+
+/*
+ * This allows machines to provide their own "apm get power status" function.
+ */
+extern void (*apm_get_power_status)(struct apm_power_info *);
+
+/*
+ * Queue an event (APM_SYS_SUSPEND or APM_CRITICAL_SUSPEND)
+ */
+void apm_queue_event(apm_event_t event);
+
+#endif /* __LINUX_APM_EMULATION_H */
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index ed296225dcd4..95f6657fff73 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -131,3 +131,29 @@ config SUSPEND_SMP
         bool
         depends on HOTPLUG_CPU && X86 && PM
         default y
+
+config APM_EMULATION
+        tristate "Advanced Power Management Emulation"
+        depends on PM && SYS_SUPPORTS_APM_EMULATION
+        help
+          APM is a BIOS specification for saving power using several different
+          techniques. This is mostly useful for battery powered laptops with
+          APM compliant BIOSes. If you say Y here, the system time will be
+          reset after a RESUME operation, the /proc/apm device will provide
+          battery status information, and user-space programs will receive
+          notification of APM "events" (e.g. battery status change).
+
+          In order to use APM, you will need supporting software. For location
+          and more information, read <file:Documentation/pm.txt> and the
+          Battery Powered Linux mini-HOWTO, available from
+          <http://www.tldp.org/docs.html#howto>.
+
+          This driver does not spin down disk drives (see the hdparm(8)
+          manpage ("man 8 hdparm") for that), and it doesn't turn off
+          VESA-compliant "green" monitors.
+
+          Generally, if you don't have a battery in your machine, there isn't
+          much point in using this driver and you should say N. If you get
+          random kernel OOPSes or reboots that don't seem to be related to
+          anything, try disabling/enabling this option (or disabling/enabling
+          APM in your BIOS).