1 // SPDX-License-Identifier: GPL-2.0-only
3  * bios-less APM driver for ARM Linux
8  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
25 #include <linux/apm-emulation.h>
36  * One option can be changed at boot time as follows:
37  *	apm=on/off			enable/disable APM
66  *	NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
67  *				    -6-> ACKTO -7-> NONE
68  *	NONE -8-> WAIT -9-> NONE
101  * The per-file APM data
135  * "APM" events within - specifically necessary if we're going
154  * This allows machines to provide their own "apm get power status" function.
165 	return q->event_head == q->event_tail;  in queue_empty()
170 	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;  in queue_get_event()
171 	return q->events[q->event_tail];  in queue_get_event()
176 	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;  in queue_add_event()
177 	if (q->event_head == q->event_tail) {  in queue_add_event()
182 		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;  in queue_add_event()
184 	q->events[q->event_head] = event;  in queue_add_event()
193 		if (as->reader)  in queue_event()
194 			queue_add_event(&as->queue, event);  in queue_event()
202 	struct apm_user *as = fp->private_data;  in apm_read()
207 		return -EINVAL;  in apm_read()
209 	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)  in apm_read()
210 		return -EAGAIN;  in apm_read()
212 	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));  in apm_read()
214 	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {  in apm_read()
215 		event = queue_get_event(&as->queue);  in apm_read()
217 		ret = -EFAULT;  in apm_read()
222 		if (as->suspend_state == SUSPEND_PENDING &&  in apm_read()
224 			as->suspend_state = SUSPEND_READ;  in apm_read()
228 		i -= sizeof(event);  in apm_read()
232 		ret = count - i;  in apm_read()
239 	struct apm_user *as = fp->private_data;  in apm_poll()
242 	return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;  in apm_poll()
246  * apm_ioctl - handle APM ioctl
250  *     - initiate a suspend
251  *     - acknowledge a suspend read from /dev/apm_bios.
258 	struct apm_user *as = filp->private_data;  in apm_ioctl()
259 	int err = -EINVAL;  in apm_ioctl()
261 	if (!as->suser || !as->writer)  in apm_ioctl()
262 		return -EPERM;  in apm_ioctl()
268 		as->suspend_result = -EINTR;  in apm_ioctl()
270 		switch (as->suspend_state) {  in apm_ioctl()
277 			as->suspend_state = SUSPEND_ACKED;  in apm_ioctl()
295 					as->suspend_state != SUSPEND_ACKED))  in apm_ioctl()
299 			as->suspend_result = -ETIMEDOUT;  in apm_ioctl()
303 			as->suspend_state = SUSPEND_WAIT;  in apm_ioctl()
311 			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);  in apm_ioctl()
315 		err = as->suspend_result;  in apm_ioctl()
316 		as->suspend_state = SUSPEND_NONE;  in apm_ioctl()
326 	struct apm_user *as = filp->private_data;  in apm_release()
328 	filp->private_data = NULL;  in apm_release()
331 	list_del(&as->list);  in apm_release()
339 	if (as->suspend_state == SUSPEND_PENDING ||  in apm_release()
340 	    as->suspend_state == SUSPEND_READ)  in apm_release()
357 		 * XXX - this is a tiny bit broken, when we consider BSD  in apm_open()
361 		 * privileged operation -- cevans  in apm_open()
363 		as->suser = capable(CAP_SYS_ADMIN);  in apm_open()
364 		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;  in apm_open()
365 		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;  in apm_open()
368 		list_add(&as->list, &apm_user_list);  in apm_open()
371 		filp->private_data = as;  in apm_open()
374 	return as ? 0 : -ENOMEM;  in apm_open()
407  *	0x00: Off-line
408  *	0x01: On-line
409  *	0x02: On backup power (BIOS >= 1.1 only)
426  *	0-100: valid
427  *	-1: Unknown
428  *   7) Remaining battery life (time units):
430  *	-1: Unknown
431  *   8) min = minutes; sec = seconds
443 	info.battery_life   = -1;  in proc_apm_show()
444 	info.time	    = -1;  in proc_apm_show()
445 	info.units	    = -1;  in proc_apm_show()
453 	case 1: 	units = "sec";	break;  in proc_apm_show()
460 		     info.time, units);  in proc_apm_show()
516 	/* short-cut emergency suspends */  in apm_suspend_notifier()
533 			if (as->suspend_state != SUSPEND_WAIT && as->reader &&  in apm_suspend_notifier()
534 			    as->writer && as->suser) {  in apm_suspend_notifier()
535 				as->suspend_state = SUSPEND_PENDING;  in apm_suspend_notifier()
537 				queue_add_event(&as->queue, apm_event);  in apm_suspend_notifier()
563 			 * We could time out and the userspace does the ACK  in apm_suspend_notifier()
564 			 * right after we time out but before we enter the  in apm_suspend_notifier()
570 				if (as->suspend_state == SUSPEND_PENDING ||  in apm_suspend_notifier()
571 				    as->suspend_state == SUSPEND_READ) {  in apm_suspend_notifier()
572 					as->suspend_state = SUSPEND_ACKTO;  in apm_suspend_notifier()
603 			if (as->suspend_state == SUSPEND_ACKED) {  in apm_suspend_notifier()
610 				as->suspend_result = 0;  in apm_suspend_notifier()
611 				as->suspend_state = SUSPEND_DONE;  in apm_suspend_notifier()
635 		return -ENODEV;  in apm_init()
682 MODULE_DESCRIPTION("Advanced Power Management");
689 		if (strncmp(str, "off", 3) == 0)  in apm_setup()
704  * apm_queue_event - queue an APM event for kapmd