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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * bios-less APM driver for ARM Linux4 * Jamey Hicks <jamey@crl.dec.com>5 * adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)6 *7 * APM 1.2 Reference:8 * Intel Corporation, Microsoft Corporation. Advanced Power Management9 * (APM) BIOS Interface Specification, Revision 1.2, February 1996.10 *11 * This document is available from Microsoft at:12 * http://www.microsoft.com/whdc/archive/amp_12.mspx13 */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>34 35/*36 * One option can be changed at boot time as follows:37 * apm=on/off enable/disable APM38 */39 40/*41 * Maximum number of events stored42 */43#define APM_MAX_EVENTS 1644 45struct apm_queue {46 unsigned int event_head;47 unsigned int event_tail;48 apm_event_t events[APM_MAX_EVENTS];49};50 51/*52 * thread states (for threads using a writable /dev/apm_bios fd):53 *54 * SUSPEND_NONE: nothing happening55 * SUSPEND_PENDING: suspend event queued for thread and pending to be read56 * SUSPEND_READ: suspend event read, pending acknowledgement57 * SUSPEND_ACKED: acknowledgement received from thread (via ioctl),58 * waiting for resume59 * SUSPEND_ACKTO: acknowledgement timeout60 * SUSPEND_DONE: thread had acked suspend and is now notified of61 * resume62 *63 * SUSPEND_WAIT: this thread invoked suspend and is waiting for resume64 *65 * A thread migrates in one of three paths:66 * NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE67 * -6-> ACKTO -7-> NONE68 * NONE -8-> WAIT -9-> NONE69 *70 * While in PENDING or READ, the thread is accounted for in the71 * suspend_acks_pending counter.72 *73 * The transitions are invoked as follows:74 * 1: suspend event is signalled from the core PM code75 * 2: the suspend event is read from the fd by the userspace thread76 * 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)77 * 4: core PM code signals that we have resumed78 * 5: APM_IOC_SUSPEND ioctl returns79 *80 * 6: the notifier invoked from the core PM code timed out waiting81 * for all relevant threds to enter ACKED state and puts those82 * that haven't into ACKTO83 * 7: those threads issue APM_IOC_SUSPEND ioctl too late,84 * get an error85 *86 * 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),87 * ioctl code invokes pm_suspend()88 * 9: pm_suspend() returns indicating resume89 */90enum apm_suspend_state {91 SUSPEND_NONE,92 SUSPEND_PENDING,93 SUSPEND_READ,94 SUSPEND_ACKED,95 SUSPEND_ACKTO,96 SUSPEND_WAIT,97 SUSPEND_DONE,98};99 100/*101 * The per-file APM data102 */103struct apm_user {104 struct list_head list;105 106 unsigned int suser: 1;107 unsigned int writer: 1;108 unsigned int reader: 1;109 110 int suspend_result;111 enum apm_suspend_state suspend_state;112 113 struct apm_queue queue;114};115 116/*117 * Local variables118 */119static atomic_t suspend_acks_pending = ATOMIC_INIT(0);120static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);121static int apm_disabled;122static struct task_struct *kapmd_tsk;123 124static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);125static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);126 127/*128 * This is a list of everyone who has opened /dev/apm_bios129 */130static DECLARE_RWSEM(user_list_lock);131static LIST_HEAD(apm_user_list);132 133/*134 * kapmd info. kapmd provides us a process context to handle135 * "APM" events within - specifically necessary if we're going136 * to be suspending the system.137 */138static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);139static DEFINE_SPINLOCK(kapmd_queue_lock);140static struct apm_queue kapmd_queue;141 142static DEFINE_MUTEX(state_lock);143 144static const char driver_version[] = "1.13"; /* no spaces */145 146 147 148/*149 * Compatibility cruft until the IPAQ people move over to the new150 * interface.151 */152static void __apm_get_power_status(struct apm_power_info *info)153{154}155 156/*157 * This allows machines to provide their own "apm get power status" function.158 */159void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;160EXPORT_SYMBOL(apm_get_power_status);161 162 163/*164 * APM event queue management.165 */166static inline int queue_empty(struct apm_queue *q)167{168 return q->event_head == q->event_tail;169}170 171static inline apm_event_t queue_get_event(struct apm_queue *q)172{173 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;174 return q->events[q->event_tail];175}176 177static void queue_add_event(struct apm_queue *q, apm_event_t event)178{179 q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;180 if (q->event_head == q->event_tail) {181 static int notified;182 183 if (notified++ == 0)184 printk(KERN_ERR "apm: an event queue overflowed\n");185 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;186 }187 q->events[q->event_head] = event;188}189 190static void queue_event(apm_event_t event)191{192 struct apm_user *as;193 194 down_read(&user_list_lock);195 list_for_each_entry(as, &apm_user_list, list) {196 if (as->reader)197 queue_add_event(&as->queue, event);198 }199 up_read(&user_list_lock);200 wake_up_interruptible(&apm_waitqueue);201}202 203static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)204{205 struct apm_user *as = fp->private_data;206 apm_event_t event;207 int i = count, ret = 0;208 209 if (count < sizeof(apm_event_t))210 return -EINVAL;211 212 if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)213 return -EAGAIN;214 215 wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));216 217 while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {218 event = queue_get_event(&as->queue);219 220 ret = -EFAULT;221 if (copy_to_user(buf, &event, sizeof(event)))222 break;223 224 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);229 230 buf += sizeof(event);231 i -= sizeof(event);232 }233 234 if (i < count)235 ret = count - i;236 237 return ret;238}239 240static __poll_t apm_poll(struct file *fp, poll_table * wait)241{242 struct apm_user *as = fp->private_data;243 244 poll_wait(fp, &apm_waitqueue, wait);245 return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;246}247 248/*249 * apm_ioctl - handle APM ioctl250 *251 * APM_IOC_SUSPEND252 * This IOCTL is overloaded, and performs two functions. It is used to:253 * - initiate a suspend254 * - acknowledge a suspend read from /dev/apm_bios.255 * Only when everyone who has opened /dev/apm_bios with write permission256 * has acknowledge does the actual suspend happen.257 */258static long259apm_ioctl(struct file *filp, u_int cmd, u_long arg)260{261 struct apm_user *as = filp->private_data;262 int err = -EINVAL;263 264 if (!as->suser || !as->writer)265 return -EPERM;266 267 switch (cmd) {268 case APM_IOC_SUSPEND:269 mutex_lock(&state_lock);270 271 as->suspend_result = -EINTR;272 273 switch (as->suspend_state) {274 case SUSPEND_READ:275 /*276 * If we read a suspend command from /dev/apm_bios,277 * then the corresponding APM_IOC_SUSPEND ioctl is278 * interpreted as an acknowledge.279 */280 as->suspend_state = SUSPEND_ACKED;281 atomic_dec(&suspend_acks_pending);282 mutex_unlock(&state_lock);283 284 /*285 * suspend_acks_pending changed, the notifier needs to286 * be woken up for this287 */288 wake_up(&apm_suspend_waitqueue);289 290 /*291 * Wait for the suspend/resume to complete. If there292 * are pending acknowledges, we wait here for them.293 * wait_event_freezable() is interruptible and pending294 * signal can cause busy looping. We aren't doing295 * anything critical, chill a bit on each iteration.296 */297 while (wait_event_freezable(apm_suspend_waitqueue,298 as->suspend_state != SUSPEND_ACKED))299 msleep(10);300 break;301 case SUSPEND_ACKTO:302 as->suspend_result = -ETIMEDOUT;303 mutex_unlock(&state_lock);304 break;305 default:306 as->suspend_state = SUSPEND_WAIT;307 mutex_unlock(&state_lock);308 309 /*310 * Otherwise it is a request to suspend the system.311 * Just invoke pm_suspend(), we'll handle it from312 * there via the notifier.313 */314 as->suspend_result = pm_suspend(PM_SUSPEND_MEM);315 }316 317 mutex_lock(&state_lock);318 err = as->suspend_result;319 as->suspend_state = SUSPEND_NONE;320 mutex_unlock(&state_lock);321 break;322 }323 324 return err;325}326 327static int apm_release(struct inode * inode, struct file * filp)328{329 struct apm_user *as = filp->private_data;330 331 filp->private_data = NULL;332 333 down_write(&user_list_lock);334 list_del(&as->list);335 up_write(&user_list_lock);336 337 /*338 * We are now unhooked from the chain. As far as new339 * events are concerned, we no longer exist.340 */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);346 347 wake_up(&apm_suspend_waitqueue);348 349 kfree(as);350 return 0;351}352 353static int apm_open(struct inode * inode, struct file * filp)354{355 struct apm_user *as;356 357 as = kzalloc(sizeof(*as), GFP_KERNEL);358 if (as) {359 /*360 * XXX - this is a tiny bit broken, when we consider BSD361 * process accounting. If the device is opened by root, we362 * instantly flag that we used superuser privs. Who knows,363 * we might close the device immediately without doing a364 * privileged operation -- cevans365 */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;369 370 down_write(&user_list_lock);371 list_add(&as->list, &apm_user_list);372 up_write(&user_list_lock);373 374 filp->private_data = as;375 }376 377 return as ? 0 : -ENOMEM;378}379 380static const struct file_operations apm_bios_fops = {381 .owner = THIS_MODULE,382 .read = apm_read,383 .poll = apm_poll,384 .unlocked_ioctl = apm_ioctl,385 .open = apm_open,386 .release = apm_release,387 .llseek = noop_llseek,388};389 390static struct miscdevice apm_device = {391 .minor = APM_MINOR_DEV,392 .name = "apm_bios",393 .fops = &apm_bios_fops394};395 396 397#ifdef CONFIG_PROC_FS398/*399 * Arguments, with symbols from linux/apm_bios.h.400 *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_SUPPORT405 * bit 1: APM_32_BIT_SUPPORT406 * bit 2: APM_IDLE_SLOWS_CLOCK407 * bit 3: APM_BIOS_DISABLED408 * bit 4: APM_BIOS_DISENGAGED409 * 3) AC line status410 * 0x00: Off-line411 * 0x01: On-line412 * 0x02: On backup power (BIOS >= 1.1 only)413 * 0xff: Unknown414 * 4) Battery status415 * 0x00: High416 * 0x01: Low417 * 0x02: Critical418 * 0x03: Charging419 * 0x04: Selected battery not present (BIOS >= 1.2 only)420 * 0xff: Unknown421 * 5) Battery flag422 * bit 0: High423 * bit 1: Low424 * bit 2: Critical425 * bit 3: Charging426 * bit 7: No system battery427 * 0xff: Unknown428 * 6) Remaining battery life (percentage of charge):429 * 0-100: valid430 * -1: Unknown431 * 7) Remaining battery life (time units):432 * Number of remaining minutes or seconds433 * -1: Unknown434 * 8) min = minutes; sec = seconds435 */436static int proc_apm_show(struct seq_file *m, void *v)437{438 struct apm_power_info info;439 char *units;440 441 info.ac_line_status = 0xff;442 info.battery_status = 0xff;443 info.battery_flag = 0xff;444 info.battery_life = -1;445 info.time = -1;446 info.units = -1;447 448 if (apm_get_power_status)449 apm_get_power_status(&info);450 451 switch (info.units) {452 default: units = "?"; break;453 case 0: units = "min"; break;454 case 1: units = "sec"; break;455 }456 457 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,461 info.time, units);462 463 return 0;464}465#endif466 467static int kapmd(void *arg)468{469 do {470 apm_event_t event;471 472 wait_event_interruptible(kapmd_wait,473 !queue_empty(&kapmd_queue) || kthread_should_stop());474 475 if (kthread_should_stop())476 break;477 478 spin_lock_irq(&kapmd_queue_lock);479 event = 0;480 if (!queue_empty(&kapmd_queue))481 event = queue_get_event(&kapmd_queue);482 spin_unlock_irq(&kapmd_queue_lock);483 484 switch (event) {485 case 0:486 break;487 488 case APM_LOW_BATTERY:489 case APM_POWER_STATUS_CHANGE:490 queue_event(event);491 break;492 493 case APM_USER_SUSPEND:494 case APM_SYS_SUSPEND:495 pm_suspend(PM_SUSPEND_MEM);496 break;497 498 case APM_CRITICAL_SUSPEND:499 atomic_inc(&userspace_notification_inhibit);500 pm_suspend(PM_SUSPEND_MEM);501 atomic_dec(&userspace_notification_inhibit);502 break;503 }504 } while (1);505 506 return 0;507}508 509static int apm_suspend_notifier(struct notifier_block *nb,510 unsigned long event,511 void *dummy)512{513 struct apm_user *as;514 int err;515 unsigned long apm_event;516 517 /* short-cut emergency suspends */518 if (atomic_read(&userspace_notification_inhibit))519 return NOTIFY_DONE;520 521 switch (event) {522 case PM_SUSPEND_PREPARE:523 case PM_HIBERNATION_PREPARE:524 apm_event = (event == PM_SUSPEND_PREPARE) ?525 APM_USER_SUSPEND : APM_USER_HIBERNATION;526 /*527 * Queue an event to all "writer" users that we want528 * to suspend and need their ack.529 */530 mutex_lock(&state_lock);531 down_read(&user_list_lock);532 533 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);539 }540 }541 542 up_read(&user_list_lock);543 mutex_unlock(&state_lock);544 wake_up_interruptible(&apm_waitqueue);545 546 /*547 * Wait for the suspend_acks_pending variable to drop to548 * zero, meaning everybody acked the suspend event (or the549 * process was killed.)550 *551 * If the app won't answer within a short while we assume it552 * locked up and ignore it.553 */554 err = wait_event_interruptible_timeout(555 apm_suspend_waitqueue,556 atomic_read(&suspend_acks_pending) == 0,557 5*HZ);558 559 /* timed out */560 if (err == 0) {561 /*562 * Move anybody who timed out to "ack timeout" state.563 *564 * We could time out and the userspace does the ACK565 * right after we time out but before we enter the566 * locked section here, but that's fine.567 */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);575 }576 }577 up_read(&user_list_lock);578 mutex_unlock(&state_lock);579 }580 581 /* let suspend proceed */582 if (err >= 0)583 return NOTIFY_OK;584 585 /* interrupted by signal */586 return notifier_from_errno(err);587 588 case PM_POST_SUSPEND:589 case PM_POST_HIBERNATION:590 apm_event = (event == PM_POST_SUSPEND) ?591 APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;592 /*593 * Anyone on the APM queues will think we're still suspended.594 * Send a message so everyone knows we're now awake again.595 */596 queue_event(apm_event);597 598 /*599 * Finally, wake up anyone who is sleeping on the suspend.600 */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) {605 /*606 * TODO: maybe grab error code, needs core607 * changes to push the error to the notifier608 * chain (could use the second parameter if609 * implemented)610 */611 as->suspend_result = 0;612 as->suspend_state = SUSPEND_DONE;613 }614 }615 up_read(&user_list_lock);616 mutex_unlock(&state_lock);617 618 wake_up(&apm_suspend_waitqueue);619 return NOTIFY_OK;620 621 default:622 return NOTIFY_DONE;623 }624}625 626static struct notifier_block apm_notif_block = {627 .notifier_call = apm_suspend_notifier,628};629 630static int __init apm_init(void)631{632 int ret;633 634 if (apm_disabled) {635 printk(KERN_NOTICE "apm: disabled on user request.\n");636 return -ENODEV;637 }638 639 kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");640 if (IS_ERR(kapmd_tsk)) {641 ret = PTR_ERR(kapmd_tsk);642 kapmd_tsk = NULL;643 goto out;644 }645 wake_up_process(kapmd_tsk);646 647#ifdef CONFIG_PROC_FS648 proc_create_single("apm", 0, NULL, proc_apm_show);649#endif650 651 ret = misc_register(&apm_device);652 if (ret)653 goto out_stop;654 655 ret = register_pm_notifier(&apm_notif_block);656 if (ret)657 goto out_unregister;658 659 return 0;660 661 out_unregister:662 misc_deregister(&apm_device);663 out_stop:664 remove_proc_entry("apm", NULL);665 kthread_stop(kapmd_tsk);666 out:667 return ret;668}669 670static void __exit apm_exit(void)671{672 unregister_pm_notifier(&apm_notif_block);673 misc_deregister(&apm_device);674 remove_proc_entry("apm", NULL);675 676 kthread_stop(kapmd_tsk);677}678 679module_init(apm_init);680module_exit(apm_exit);681 682MODULE_AUTHOR("Stephen Rothwell");683MODULE_DESCRIPTION("Advanced Power Management");684MODULE_LICENSE("GPL");685 686#ifndef MODULE687static int __init apm_setup(char *str)688{689 while ((str != NULL) && (*str != '\0')) {690 if (strncmp(str, "off", 3) == 0)691 apm_disabled = 1;692 if (strncmp(str, "on", 2) == 0)693 apm_disabled = 0;694 str = strchr(str, ',');695 if (str != NULL)696 str += strspn(str, ", \t");697 }698 return 1;699}700 701__setup("apm=", apm_setup);702#endif703 704/**705 * apm_queue_event - queue an APM event for kapmd706 * @event: APM event707 *708 * Queue an APM event for kapmd to process and ultimately take the709 * appropriate action. Only a subset of events are handled:710 * %APM_LOW_BATTERY711 * %APM_POWER_STATUS_CHANGE712 * %APM_USER_SUSPEND713 * %APM_SYS_SUSPEND714 * %APM_CRITICAL_SUSPEND715 */716void apm_queue_event(apm_event_t event)717{718 unsigned long flags;719 720 spin_lock_irqsave(&kapmd_queue_lock, flags);721 queue_add_event(&kapmd_queue, event);722 spin_unlock_irqrestore(&kapmd_queue_lock, flags);723 724 wake_up_interruptible(&kapmd_wait);725}726EXPORT_SYMBOL(apm_queue_event);727