2
* bios-less APM driver for ARM Linux
3
* Jamey Hicks <jamey@crl.dec.com>
4
* adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
7
* Intel Corporation, Microsoft Corporation. Advanced Power Management
8
* (APM) BIOS Interface Specification, Revision 1.2, February 1996.
10
* This document is available from Microsoft at:
11
* http://www.microsoft.com/whdc/archive/amp_12.mspx
13
#include <linux/module.h>
14
#include <linux/poll.h>
15
#include <linux/slab.h>
16
#include <linux/mutex.h>
17
#include <linux/proc_fs.h>
18
#include <linux/seq_file.h>
19
#include <linux/miscdevice.h>
20
#include <linux/apm_bios.h>
21
#include <linux/capability.h>
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#include <linux/sched.h>
23
#include <linux/suspend.h>
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#include <linux/apm-emulation.h>
25
#include <linux/freezer.h>
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#include <linux/device.h>
27
#include <linux/kernel.h>
28
#include <linux/list.h>
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#include <linux/init.h>
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#include <linux/completion.h>
31
#include <linux/kthread.h>
32
#include <linux/delay.h>
34
#include <asm/system.h>
37
* The apm_bios device is one of the misc char devices.
38
* This is its minor number.
40
#define APM_MINOR_DEV 134
43
* One option can be changed at boot time as follows:
44
* apm=on/off enable/disable APM
48
* Maximum number of events stored
50
#define APM_MAX_EVENTS 16
53
unsigned int event_head;
54
unsigned int event_tail;
55
apm_event_t events[APM_MAX_EVENTS];
59
* thread states (for threads using a writable /dev/apm_bios fd):
61
* SUSPEND_NONE: nothing happening
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* SUSPEND_PENDING: suspend event queued for thread and pending to be read
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* SUSPEND_READ: suspend event read, pending acknowledgement
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* SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
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* SUSPEND_ACKTO: acknowledgement timeout
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* SUSPEND_DONE: thread had acked suspend and is now notified of
70
* SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
72
* A thread migrates in one of three paths:
73
* NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
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* -6-> ACKTO -7-> NONE
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* NONE -8-> WAIT -9-> NONE
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* While in PENDING or READ, the thread is accounted for in the
78
* suspend_acks_pending counter.
80
* The transitions are invoked as follows:
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* 1: suspend event is signalled from the core PM code
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* 2: the suspend event is read from the fd by the userspace thread
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* 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
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* 4: core PM code signals that we have resumed
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* 5: APM_IOC_SUSPEND ioctl returns
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* 6: the notifier invoked from the core PM code timed out waiting
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* for all relevant threds to enter ACKED state and puts those
89
* that haven't into ACKTO
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* 7: those threads issue APM_IOC_SUSPEND ioctl too late,
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* 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
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* ioctl code invokes pm_suspend()
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* 9: pm_suspend() returns indicating resume
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enum apm_suspend_state {
108
* The per-file APM data
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struct list_head list;
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unsigned int suser: 1;
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unsigned int writer: 1;
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unsigned int reader: 1;
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enum apm_suspend_state suspend_state;
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struct apm_queue queue;
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static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
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static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
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static int apm_disabled;
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static struct task_struct *kapmd_tsk;
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static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
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static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
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* This is a list of everyone who has opened /dev/apm_bios
137
static DECLARE_RWSEM(user_list_lock);
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static LIST_HEAD(apm_user_list);
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* kapmd info. kapmd provides us a process context to handle
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* "APM" events within - specifically necessary if we're going
143
* to be suspending the system.
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static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
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static DEFINE_SPINLOCK(kapmd_queue_lock);
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static struct apm_queue kapmd_queue;
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static DEFINE_MUTEX(state_lock);
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static const char driver_version[] = "1.13"; /* no spaces */
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* Compatibility cruft until the IPAQ people move over to the new
159
static void __apm_get_power_status(struct apm_power_info *info)
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* This allows machines to provide their own "apm get power status" function.
166
void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
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EXPORT_SYMBOL(apm_get_power_status);
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* APM event queue management.
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static inline int queue_empty(struct apm_queue *q)
175
return q->event_head == q->event_tail;
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static inline apm_event_t queue_get_event(struct apm_queue *q)
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q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
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return q->events[q->event_tail];
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static void queue_add_event(struct apm_queue *q, apm_event_t event)
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q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
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if (q->event_head == q->event_tail) {
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printk(KERN_ERR "apm: an event queue overflowed\n");
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q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
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q->events[q->event_head] = event;
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static void queue_event(apm_event_t event)
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down_read(&user_list_lock);
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list_for_each_entry(as, &apm_user_list, list) {
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queue_add_event(&as->queue, event);
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up_read(&user_list_lock);
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wake_up_interruptible(&apm_waitqueue);
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static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
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struct apm_user *as = fp->private_data;
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int i = count, ret = 0;
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if (count < sizeof(apm_event_t))
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if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
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wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
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while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
225
event = queue_get_event(&as->queue);
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if (copy_to_user(buf, &event, sizeof(event)))
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mutex_lock(&state_lock);
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if (as->suspend_state == SUSPEND_PENDING &&
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(event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
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as->suspend_state = SUSPEND_READ;
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mutex_unlock(&state_lock);
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buf += sizeof(event);
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static unsigned int apm_poll(struct file *fp, poll_table * wait)
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struct apm_user *as = fp->private_data;
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poll_wait(fp, &apm_waitqueue, wait);
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return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
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* apm_ioctl - handle APM ioctl
259
* This IOCTL is overloaded, and performs two functions. It is used to:
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* - initiate a suspend
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* - acknowledge a suspend read from /dev/apm_bios.
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* Only when everyone who has opened /dev/apm_bios with write permission
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* has acknowledge does the actual suspend happen.
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apm_ioctl(struct file *filp, u_int cmd, u_long arg)
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struct apm_user *as = filp->private_data;
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if (!as->suser || !as->writer)
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case APM_IOC_SUSPEND:
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mutex_lock(&state_lock);
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as->suspend_result = -EINTR;
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switch (as->suspend_state) {
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* If we read a suspend command from /dev/apm_bios,
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* then the corresponding APM_IOC_SUSPEND ioctl is
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* interpreted as an acknowledge.
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as->suspend_state = SUSPEND_ACKED;
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atomic_dec(&suspend_acks_pending);
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mutex_unlock(&state_lock);
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* suspend_acks_pending changed, the notifier needs to
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* be woken up for this
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wake_up(&apm_suspend_waitqueue);
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* Wait for the suspend/resume to complete. If there
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* are pending acknowledges, we wait here for them.
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* wait_event_freezable() is interruptible and pending
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* signal can cause busy looping. We aren't doing
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* anything critical, chill a bit on each iteration.
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while (wait_event_freezable(apm_suspend_waitqueue,
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as->suspend_state == SUSPEND_DONE))
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as->suspend_result = -ETIMEDOUT;
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mutex_unlock(&state_lock);
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as->suspend_state = SUSPEND_WAIT;
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mutex_unlock(&state_lock);
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* Otherwise it is a request to suspend the system.
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* Just invoke pm_suspend(), we'll handle it from
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* there via the notifier.
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as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
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mutex_lock(&state_lock);
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err = as->suspend_result;
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as->suspend_state = SUSPEND_NONE;
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mutex_unlock(&state_lock);
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static int apm_release(struct inode * inode, struct file * filp)
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struct apm_user *as = filp->private_data;
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filp->private_data = NULL;
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down_write(&user_list_lock);
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up_write(&user_list_lock);
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* We are now unhooked from the chain. As far as new
346
* events are concerned, we no longer exist.
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mutex_lock(&state_lock);
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if (as->suspend_state == SUSPEND_PENDING ||
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as->suspend_state == SUSPEND_READ)
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atomic_dec(&suspend_acks_pending);
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mutex_unlock(&state_lock);
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wake_up(&apm_suspend_waitqueue);
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static int apm_open(struct inode * inode, struct file * filp)
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as = kzalloc(sizeof(*as), GFP_KERNEL);
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* XXX - this is a tiny bit broken, when we consider BSD
368
* process accounting. If the device is opened by root, we
369
* instantly flag that we used superuser privs. Who knows,
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* we might close the device immediately without doing a
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* privileged operation -- cevans
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as->suser = capable(CAP_SYS_ADMIN);
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as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
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as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
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down_write(&user_list_lock);
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list_add(&as->list, &apm_user_list);
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up_write(&user_list_lock);
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filp->private_data = as;
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return as ? 0 : -ENOMEM;
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static const struct file_operations apm_bios_fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = apm_ioctl,
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.release = apm_release,
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.llseek = noop_llseek,
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static struct miscdevice apm_device = {
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.minor = APM_MINOR_DEV,
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.fops = &apm_bios_fops
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#ifdef CONFIG_PROC_FS
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* Arguments, with symbols from linux/apm_bios.h.
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* 0) Linux driver version (this will change if format changes)
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* 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
410
* 2) APM flags from APM Installation Check (0x00):
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* bit 0: APM_16_BIT_SUPPORT
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* bit 1: APM_32_BIT_SUPPORT
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* bit 2: APM_IDLE_SLOWS_CLOCK
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* bit 3: APM_BIOS_DISABLED
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* bit 4: APM_BIOS_DISENGAGED
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* 0x02: On backup power (BIOS >= 1.1 only)
426
* 0x04: Selected battery not present (BIOS >= 1.2 only)
433
* bit 7: No system battery
435
* 6) Remaining battery life (percentage of charge):
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* 7) Remaining battery life (time units):
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* Number of remaining minutes or seconds
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* 8) min = minutes; sec = seconds
443
static int proc_apm_show(struct seq_file *m, void *v)
445
struct apm_power_info info;
448
info.ac_line_status = 0xff;
449
info.battery_status = 0xff;
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info.battery_flag = 0xff;
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info.battery_life = -1;
455
if (apm_get_power_status)
456
apm_get_power_status(&info);
458
switch (info.units) {
459
default: units = "?"; break;
460
case 0: units = "min"; break;
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case 1: units = "sec"; break;
464
seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
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driver_version, APM_32_BIT_SUPPORT,
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info.ac_line_status, info.battery_status,
467
info.battery_flag, info.battery_life,
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static int proc_apm_open(struct inode *inode, struct file *file)
475
return single_open(file, proc_apm_show, NULL);
478
static const struct file_operations apm_proc_fops = {
479
.owner = THIS_MODULE,
480
.open = proc_apm_open,
483
.release = single_release,
487
static int kapmd(void *arg)
492
wait_event_interruptible(kapmd_wait,
493
!queue_empty(&kapmd_queue) || kthread_should_stop());
495
if (kthread_should_stop())
498
spin_lock_irq(&kapmd_queue_lock);
500
if (!queue_empty(&kapmd_queue))
501
event = queue_get_event(&kapmd_queue);
502
spin_unlock_irq(&kapmd_queue_lock);
508
case APM_LOW_BATTERY:
509
case APM_POWER_STATUS_CHANGE:
513
case APM_USER_SUSPEND:
514
case APM_SYS_SUSPEND:
515
pm_suspend(PM_SUSPEND_MEM);
518
case APM_CRITICAL_SUSPEND:
519
atomic_inc(&userspace_notification_inhibit);
520
pm_suspend(PM_SUSPEND_MEM);
521
atomic_dec(&userspace_notification_inhibit);
529
static int apm_suspend_notifier(struct notifier_block *nb,
536
/* short-cut emergency suspends */
537
if (atomic_read(&userspace_notification_inhibit))
541
case PM_SUSPEND_PREPARE:
543
* Queue an event to all "writer" users that we want
544
* to suspend and need their ack.
546
mutex_lock(&state_lock);
547
down_read(&user_list_lock);
549
list_for_each_entry(as, &apm_user_list, list) {
550
if (as->suspend_state != SUSPEND_WAIT && as->reader &&
551
as->writer && as->suser) {
552
as->suspend_state = SUSPEND_PENDING;
553
atomic_inc(&suspend_acks_pending);
554
queue_add_event(&as->queue, APM_USER_SUSPEND);
558
up_read(&user_list_lock);
559
mutex_unlock(&state_lock);
560
wake_up_interruptible(&apm_waitqueue);
563
* Wait for the the suspend_acks_pending variable to drop to
564
* zero, meaning everybody acked the suspend event (or the
565
* process was killed.)
567
* If the app won't answer within a short while we assume it
568
* locked up and ignore it.
570
err = wait_event_interruptible_timeout(
571
apm_suspend_waitqueue,
572
atomic_read(&suspend_acks_pending) == 0,
578
* Move anybody who timed out to "ack timeout" state.
580
* We could time out and the userspace does the ACK
581
* right after we time out but before we enter the
582
* locked section here, but that's fine.
584
mutex_lock(&state_lock);
585
down_read(&user_list_lock);
586
list_for_each_entry(as, &apm_user_list, list) {
587
if (as->suspend_state == SUSPEND_PENDING ||
588
as->suspend_state == SUSPEND_READ) {
589
as->suspend_state = SUSPEND_ACKTO;
590
atomic_dec(&suspend_acks_pending);
593
up_read(&user_list_lock);
594
mutex_unlock(&state_lock);
597
/* let suspend proceed */
601
/* interrupted by signal */
602
return notifier_from_errno(err);
604
case PM_POST_SUSPEND:
606
* Anyone on the APM queues will think we're still suspended.
607
* Send a message so everyone knows we're now awake again.
609
queue_event(APM_NORMAL_RESUME);
612
* Finally, wake up anyone who is sleeping on the suspend.
614
mutex_lock(&state_lock);
615
down_read(&user_list_lock);
616
list_for_each_entry(as, &apm_user_list, list) {
617
if (as->suspend_state == SUSPEND_ACKED) {
619
* TODO: maybe grab error code, needs core
620
* changes to push the error to the notifier
621
* chain (could use the second parameter if
624
as->suspend_result = 0;
625
as->suspend_state = SUSPEND_DONE;
628
up_read(&user_list_lock);
629
mutex_unlock(&state_lock);
631
wake_up(&apm_suspend_waitqueue);
639
static struct notifier_block apm_notif_block = {
640
.notifier_call = apm_suspend_notifier,
643
static int __init apm_init(void)
648
printk(KERN_NOTICE "apm: disabled on user request.\n");
652
kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
653
if (IS_ERR(kapmd_tsk)) {
654
ret = PTR_ERR(kapmd_tsk);
658
wake_up_process(kapmd_tsk);
660
#ifdef CONFIG_PROC_FS
661
proc_create("apm", 0, NULL, &apm_proc_fops);
664
ret = misc_register(&apm_device);
668
ret = register_pm_notifier(&apm_notif_block);
675
misc_deregister(&apm_device);
677
remove_proc_entry("apm", NULL);
678
kthread_stop(kapmd_tsk);
683
static void __exit apm_exit(void)
685
unregister_pm_notifier(&apm_notif_block);
686
misc_deregister(&apm_device);
687
remove_proc_entry("apm", NULL);
689
kthread_stop(kapmd_tsk);
692
module_init(apm_init);
693
module_exit(apm_exit);
695
MODULE_AUTHOR("Stephen Rothwell");
696
MODULE_DESCRIPTION("Advanced Power Management");
697
MODULE_LICENSE("GPL");
700
static int __init apm_setup(char *str)
702
while ((str != NULL) && (*str != '\0')) {
703
if (strncmp(str, "off", 3) == 0)
705
if (strncmp(str, "on", 2) == 0)
707
str = strchr(str, ',');
709
str += strspn(str, ", \t");
714
__setup("apm=", apm_setup);
718
* apm_queue_event - queue an APM event for kapmd
721
* Queue an APM event for kapmd to process and ultimately take the
722
* appropriate action. Only a subset of events are handled:
724
* %APM_POWER_STATUS_CHANGE
727
* %APM_CRITICAL_SUSPEND
729
void apm_queue_event(apm_event_t event)
733
spin_lock_irqsave(&kapmd_queue_lock, flags);
734
queue_add_event(&kapmd_queue, event);
735
spin_unlock_irqrestore(&kapmd_queue_lock, flags);
737
wake_up_interruptible(&kapmd_wait);
739
EXPORT_SYMBOL(apm_queue_event);