1 // SPDX-License-Identifier: GPL-2.0-only
3 * bios-less APM driver for ARM Linux
4 * Jamey Hicks <jamey@crl.dec.com>
5 * adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
8 * Intel Corporation, Microsoft Corporation. Advanced Power Management
9 * (APM) BIOS Interface Specification, Revision 1.2, February 1996.
11 * This document is available from Microsoft at:
12 * http://www.microsoft.com/whdc/archive/amp_12.mspx
14 #include <linux/module.h>
15 #include <linux/poll.h>
16 #include <linux/slab.h>
17 #include <linux/mutex.h>
18 #include <linux/proc_fs.h>
19 #include <linux/seq_file.h>
20 #include <linux/miscdevice.h>
21 #include <linux/apm_bios.h>
22 #include <linux/capability.h>
23 #include <linux/sched.h>
24 #include <linux/suspend.h>
25 #include <linux/apm-emulation.h>
26 #include <linux/freezer.h>
27 #include <linux/device.h>
28 #include <linux/kernel.h>
29 #include <linux/list.h>
30 #include <linux/init.h>
31 #include <linux/completion.h>
32 #include <linux/kthread.h>
33 #include <linux/delay.h>
36 * One option can be changed at boot time as follows:
37 * apm=on/off enable/disable APM
41 * Maximum number of events stored
43 #define APM_MAX_EVENTS 16
46 unsigned int event_head
;
47 unsigned int event_tail
;
48 apm_event_t events
[APM_MAX_EVENTS
];
52 * thread states (for threads using a writable /dev/apm_bios fd):
54 * SUSPEND_NONE: nothing happening
55 * SUSPEND_PENDING: suspend event queued for thread and pending to be read
56 * SUSPEND_READ: suspend event read, pending acknowledgement
57 * SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
59 * SUSPEND_ACKTO: acknowledgement timeout
60 * SUSPEND_DONE: thread had acked suspend and is now notified of
63 * SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
65 * A thread migrates in one of three paths:
66 * NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
67 * -6-> ACKTO -7-> NONE
68 * NONE -8-> WAIT -9-> NONE
70 * While in PENDING or READ, the thread is accounted for in the
71 * suspend_acks_pending counter.
73 * The transitions are invoked as follows:
74 * 1: suspend event is signalled from the core PM code
75 * 2: the suspend event is read from the fd by the userspace thread
76 * 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
77 * 4: core PM code signals that we have resumed
78 * 5: APM_IOC_SUSPEND ioctl returns
80 * 6: the notifier invoked from the core PM code timed out waiting
81 * for all relevant threds to enter ACKED state and puts those
82 * that haven't into ACKTO
83 * 7: those threads issue APM_IOC_SUSPEND ioctl too late,
86 * 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
87 * ioctl code invokes pm_suspend()
88 * 9: pm_suspend() returns indicating resume
90 enum apm_suspend_state
{
101 * The per-file APM data
104 struct list_head list
;
106 unsigned int suser
: 1;
107 unsigned int writer
: 1;
108 unsigned int reader
: 1;
111 enum apm_suspend_state suspend_state
;
113 struct apm_queue queue
;
119 static atomic_t suspend_acks_pending
= ATOMIC_INIT(0);
120 static atomic_t userspace_notification_inhibit
= ATOMIC_INIT(0);
121 static int apm_disabled
;
122 static struct task_struct
*kapmd_tsk
;
124 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue
);
125 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue
);
128 * This is a list of everyone who has opened /dev/apm_bios
130 static DECLARE_RWSEM(user_list_lock
);
131 static LIST_HEAD(apm_user_list
);
134 * kapmd info. kapmd provides us a process context to handle
135 * "APM" events within - specifically necessary if we're going
136 * to be suspending the system.
138 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait
);
139 static DEFINE_SPINLOCK(kapmd_queue_lock
);
140 static struct apm_queue kapmd_queue
;
142 static DEFINE_MUTEX(state_lock
);
144 static const char driver_version
[] = "1.13"; /* no spaces */
149 * Compatibility cruft until the IPAQ people move over to the new
152 static void __apm_get_power_status(struct apm_power_info
*info
)
157 * This allows machines to provide their own "apm get power status" function.
159 void (*apm_get_power_status
)(struct apm_power_info
*) = __apm_get_power_status
;
160 EXPORT_SYMBOL(apm_get_power_status
);
164 * APM event queue management.
166 static inline int queue_empty(struct apm_queue
*q
)
168 return q
->event_head
== q
->event_tail
;
171 static inline apm_event_t
queue_get_event(struct apm_queue
*q
)
173 q
->event_tail
= (q
->event_tail
+ 1) % APM_MAX_EVENTS
;
174 return q
->events
[q
->event_tail
];
177 static void queue_add_event(struct apm_queue
*q
, apm_event_t event
)
179 q
->event_head
= (q
->event_head
+ 1) % APM_MAX_EVENTS
;
180 if (q
->event_head
== q
->event_tail
) {
184 printk(KERN_ERR
"apm: an event queue overflowed\n");
185 q
->event_tail
= (q
->event_tail
+ 1) % APM_MAX_EVENTS
;
187 q
->events
[q
->event_head
] = event
;
190 static void queue_event(apm_event_t event
)
194 down_read(&user_list_lock
);
195 list_for_each_entry(as
, &apm_user_list
, list
) {
197 queue_add_event(&as
->queue
, event
);
199 up_read(&user_list_lock
);
200 wake_up_interruptible(&apm_waitqueue
);
203 static ssize_t
apm_read(struct file
*fp
, char __user
*buf
, size_t count
, loff_t
*ppos
)
205 struct apm_user
*as
= fp
->private_data
;
207 int i
= count
, ret
= 0;
209 if (count
< sizeof(apm_event_t
))
212 if (queue_empty(&as
->queue
) && fp
->f_flags
& O_NONBLOCK
)
215 wait_event_interruptible(apm_waitqueue
, !queue_empty(&as
->queue
));
217 while ((i
>= sizeof(event
)) && !queue_empty(&as
->queue
)) {
218 event
= queue_get_event(&as
->queue
);
221 if (copy_to_user(buf
, &event
, sizeof(event
)))
224 mutex_lock(&state_lock
);
225 if (as
->suspend_state
== SUSPEND_PENDING
&&
226 (event
== APM_SYS_SUSPEND
|| event
== APM_USER_SUSPEND
))
227 as
->suspend_state
= SUSPEND_READ
;
228 mutex_unlock(&state_lock
);
230 buf
+= sizeof(event
);
240 static __poll_t
apm_poll(struct file
*fp
, poll_table
* wait
)
242 struct apm_user
*as
= fp
->private_data
;
244 poll_wait(fp
, &apm_waitqueue
, wait
);
245 return queue_empty(&as
->queue
) ? 0 : EPOLLIN
| EPOLLRDNORM
;
249 * apm_ioctl - handle APM ioctl
252 * This IOCTL is overloaded, and performs two functions. It is used to:
253 * - initiate a suspend
254 * - acknowledge a suspend read from /dev/apm_bios.
255 * Only when everyone who has opened /dev/apm_bios with write permission
256 * has acknowledge does the actual suspend happen.
259 apm_ioctl(struct file
*filp
, u_int cmd
, u_long arg
)
261 struct apm_user
*as
= filp
->private_data
;
264 if (!as
->suser
|| !as
->writer
)
268 case APM_IOC_SUSPEND
:
269 mutex_lock(&state_lock
);
271 as
->suspend_result
= -EINTR
;
273 switch (as
->suspend_state
) {
276 * If we read a suspend command from /dev/apm_bios,
277 * then the corresponding APM_IOC_SUSPEND ioctl is
278 * interpreted as an acknowledge.
280 as
->suspend_state
= SUSPEND_ACKED
;
281 atomic_dec(&suspend_acks_pending
);
282 mutex_unlock(&state_lock
);
285 * suspend_acks_pending changed, the notifier needs to
286 * be woken up for this
288 wake_up(&apm_suspend_waitqueue
);
291 * Wait for the suspend/resume to complete. If there
292 * are pending acknowledges, we wait here for them.
293 * wait_event_freezable() is interruptible and pending
294 * signal can cause busy looping. We aren't doing
295 * anything critical, chill a bit on each iteration.
297 while (wait_event_freezable(apm_suspend_waitqueue
,
298 as
->suspend_state
!= SUSPEND_ACKED
))
302 as
->suspend_result
= -ETIMEDOUT
;
303 mutex_unlock(&state_lock
);
306 as
->suspend_state
= SUSPEND_WAIT
;
307 mutex_unlock(&state_lock
);
310 * Otherwise it is a request to suspend the system.
311 * Just invoke pm_suspend(), we'll handle it from
312 * there via the notifier.
314 as
->suspend_result
= pm_suspend(PM_SUSPEND_MEM
);
317 mutex_lock(&state_lock
);
318 err
= as
->suspend_result
;
319 as
->suspend_state
= SUSPEND_NONE
;
320 mutex_unlock(&state_lock
);
327 static int apm_release(struct inode
* inode
, struct file
* filp
)
329 struct apm_user
*as
= filp
->private_data
;
331 filp
->private_data
= NULL
;
333 down_write(&user_list_lock
);
335 up_write(&user_list_lock
);
338 * We are now unhooked from the chain. As far as new
339 * events are concerned, we no longer exist.
341 mutex_lock(&state_lock
);
342 if (as
->suspend_state
== SUSPEND_PENDING
||
343 as
->suspend_state
== SUSPEND_READ
)
344 atomic_dec(&suspend_acks_pending
);
345 mutex_unlock(&state_lock
);
347 wake_up(&apm_suspend_waitqueue
);
353 static int apm_open(struct inode
* inode
, struct file
* filp
)
357 as
= kzalloc(sizeof(*as
), GFP_KERNEL
);
360 * XXX - this is a tiny bit broken, when we consider BSD
361 * process accounting. If the device is opened by root, we
362 * instantly flag that we used superuser privs. Who knows,
363 * we might close the device immediately without doing a
364 * privileged operation -- cevans
366 as
->suser
= capable(CAP_SYS_ADMIN
);
367 as
->writer
= (filp
->f_mode
& FMODE_WRITE
) == FMODE_WRITE
;
368 as
->reader
= (filp
->f_mode
& FMODE_READ
) == FMODE_READ
;
370 down_write(&user_list_lock
);
371 list_add(&as
->list
, &apm_user_list
);
372 up_write(&user_list_lock
);
374 filp
->private_data
= as
;
377 return as
? 0 : -ENOMEM
;
380 static const struct file_operations apm_bios_fops
= {
381 .owner
= THIS_MODULE
,
384 .unlocked_ioctl
= apm_ioctl
,
386 .release
= apm_release
,
387 .llseek
= noop_llseek
,
390 static struct miscdevice apm_device
= {
391 .minor
= APM_MINOR_DEV
,
393 .fops
= &apm_bios_fops
397 #ifdef CONFIG_PROC_FS
399 * Arguments, with symbols from linux/apm_bios.h.
401 * 0) Linux driver version (this will change if format changes)
402 * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2.
403 * 2) APM flags from APM Installation Check (0x00):
404 * bit 0: APM_16_BIT_SUPPORT
405 * bit 1: APM_32_BIT_SUPPORT
406 * bit 2: APM_IDLE_SLOWS_CLOCK
407 * bit 3: APM_BIOS_DISABLED
408 * bit 4: APM_BIOS_DISENGAGED
412 * 0x02: On backup power (BIOS >= 1.1 only)
419 * 0x04: Selected battery not present (BIOS >= 1.2 only)
426 * bit 7: No system battery
428 * 6) Remaining battery life (percentage of charge):
431 * 7) Remaining battery life (time units):
432 * Number of remaining minutes or seconds
434 * 8) min = minutes; sec = seconds
436 static int proc_apm_show(struct seq_file
*m
, void *v
)
438 struct apm_power_info info
;
441 info
.ac_line_status
= 0xff;
442 info
.battery_status
= 0xff;
443 info
.battery_flag
= 0xff;
444 info
.battery_life
= -1;
448 if (apm_get_power_status
)
449 apm_get_power_status(&info
);
451 switch (info
.units
) {
452 default: units
= "?"; break;
453 case 0: units
= "min"; break;
454 case 1: units
= "sec"; break;
457 seq_printf(m
, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
458 driver_version
, APM_32_BIT_SUPPORT
,
459 info
.ac_line_status
, info
.battery_status
,
460 info
.battery_flag
, info
.battery_life
,
467 static int kapmd(void *arg
)
472 wait_event_interruptible(kapmd_wait
,
473 !queue_empty(&kapmd_queue
) || kthread_should_stop());
475 if (kthread_should_stop())
478 spin_lock_irq(&kapmd_queue_lock
);
480 if (!queue_empty(&kapmd_queue
))
481 event
= queue_get_event(&kapmd_queue
);
482 spin_unlock_irq(&kapmd_queue_lock
);
488 case APM_LOW_BATTERY
:
489 case APM_POWER_STATUS_CHANGE
:
493 case APM_USER_SUSPEND
:
494 case APM_SYS_SUSPEND
:
495 pm_suspend(PM_SUSPEND_MEM
);
498 case APM_CRITICAL_SUSPEND
:
499 atomic_inc(&userspace_notification_inhibit
);
500 pm_suspend(PM_SUSPEND_MEM
);
501 atomic_dec(&userspace_notification_inhibit
);
509 static int apm_suspend_notifier(struct notifier_block
*nb
,
515 unsigned long apm_event
;
517 /* short-cut emergency suspends */
518 if (atomic_read(&userspace_notification_inhibit
))
522 case PM_SUSPEND_PREPARE
:
523 case PM_HIBERNATION_PREPARE
:
524 apm_event
= (event
== PM_SUSPEND_PREPARE
) ?
525 APM_USER_SUSPEND
: APM_USER_HIBERNATION
;
527 * Queue an event to all "writer" users that we want
528 * to suspend and need their ack.
530 mutex_lock(&state_lock
);
531 down_read(&user_list_lock
);
533 list_for_each_entry(as
, &apm_user_list
, list
) {
534 if (as
->suspend_state
!= SUSPEND_WAIT
&& as
->reader
&&
535 as
->writer
&& as
->suser
) {
536 as
->suspend_state
= SUSPEND_PENDING
;
537 atomic_inc(&suspend_acks_pending
);
538 queue_add_event(&as
->queue
, apm_event
);
542 up_read(&user_list_lock
);
543 mutex_unlock(&state_lock
);
544 wake_up_interruptible(&apm_waitqueue
);
547 * Wait for the the suspend_acks_pending variable to drop to
548 * zero, meaning everybody acked the suspend event (or the
549 * process was killed.)
551 * If the app won't answer within a short while we assume it
552 * locked up and ignore it.
554 err
= wait_event_interruptible_timeout(
555 apm_suspend_waitqueue
,
556 atomic_read(&suspend_acks_pending
) == 0,
562 * Move anybody who timed out to "ack timeout" state.
564 * We could time out and the userspace does the ACK
565 * right after we time out but before we enter the
566 * locked section here, but that's fine.
568 mutex_lock(&state_lock
);
569 down_read(&user_list_lock
);
570 list_for_each_entry(as
, &apm_user_list
, list
) {
571 if (as
->suspend_state
== SUSPEND_PENDING
||
572 as
->suspend_state
== SUSPEND_READ
) {
573 as
->suspend_state
= SUSPEND_ACKTO
;
574 atomic_dec(&suspend_acks_pending
);
577 up_read(&user_list_lock
);
578 mutex_unlock(&state_lock
);
581 /* let suspend proceed */
585 /* interrupted by signal */
586 return notifier_from_errno(err
);
588 case PM_POST_SUSPEND
:
589 case PM_POST_HIBERNATION
:
590 apm_event
= (event
== PM_POST_SUSPEND
) ?
591 APM_NORMAL_RESUME
: APM_HIBERNATION_RESUME
;
593 * Anyone on the APM queues will think we're still suspended.
594 * Send a message so everyone knows we're now awake again.
596 queue_event(apm_event
);
599 * Finally, wake up anyone who is sleeping on the suspend.
601 mutex_lock(&state_lock
);
602 down_read(&user_list_lock
);
603 list_for_each_entry(as
, &apm_user_list
, list
) {
604 if (as
->suspend_state
== SUSPEND_ACKED
) {
606 * TODO: maybe grab error code, needs core
607 * changes to push the error to the notifier
608 * chain (could use the second parameter if
611 as
->suspend_result
= 0;
612 as
->suspend_state
= SUSPEND_DONE
;
615 up_read(&user_list_lock
);
616 mutex_unlock(&state_lock
);
618 wake_up(&apm_suspend_waitqueue
);
626 static struct notifier_block apm_notif_block
= {
627 .notifier_call
= apm_suspend_notifier
,
630 static int __init
apm_init(void)
635 printk(KERN_NOTICE
"apm: disabled on user request.\n");
639 kapmd_tsk
= kthread_create(kapmd
, NULL
, "kapmd");
640 if (IS_ERR(kapmd_tsk
)) {
641 ret
= PTR_ERR(kapmd_tsk
);
645 wake_up_process(kapmd_tsk
);
647 #ifdef CONFIG_PROC_FS
648 proc_create_single("apm", 0, NULL
, proc_apm_show
);
651 ret
= misc_register(&apm_device
);
655 ret
= register_pm_notifier(&apm_notif_block
);
662 misc_deregister(&apm_device
);
664 remove_proc_entry("apm", NULL
);
665 kthread_stop(kapmd_tsk
);
670 static void __exit
apm_exit(void)
672 unregister_pm_notifier(&apm_notif_block
);
673 misc_deregister(&apm_device
);
674 remove_proc_entry("apm", NULL
);
676 kthread_stop(kapmd_tsk
);
679 module_init(apm_init
);
680 module_exit(apm_exit
);
682 MODULE_AUTHOR("Stephen Rothwell");
683 MODULE_DESCRIPTION("Advanced Power Management");
684 MODULE_LICENSE("GPL");
687 static int __init
apm_setup(char *str
)
689 while ((str
!= NULL
) && (*str
!= '\0')) {
690 if (strncmp(str
, "off", 3) == 0)
692 if (strncmp(str
, "on", 2) == 0)
694 str
= strchr(str
, ',');
696 str
+= strspn(str
, ", \t");
701 __setup("apm=", apm_setup
);
705 * apm_queue_event - queue an APM event for kapmd
708 * Queue an APM event for kapmd to process and ultimately take the
709 * appropriate action. Only a subset of events are handled:
711 * %APM_POWER_STATUS_CHANGE
714 * %APM_CRITICAL_SUSPEND
716 void apm_queue_event(apm_event_t event
)
720 spin_lock_irqsave(&kapmd_queue_lock
, flags
);
721 queue_add_event(&kapmd_queue
, event
);
722 spin_unlock_irqrestore(&kapmd_queue_lock
, flags
);
724 wake_up_interruptible(&kapmd_wait
);
726 EXPORT_SYMBOL(apm_queue_event
);