1 // SPDX-License-Identifier: GPL-2.0-only
3  * bios-less APM driver for ARM Linux
24 #include <linux/suspend.h>
25 #include <linux/apm-emulation.h>
55  * SUSPEND_PENDING:	suspend event queued for thread and pending to be read
56  * SUSPEND_READ:	suspend event read, pending acknowledgement
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
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
86  *	8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
101  * The per-file APM data
135  * "APM" events within - specifically necessary if we're going
168 	return q->event_head == q->event_tail;  in queue_empty()
173 	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;  in queue_get_event()
174 	return q->events[q->event_tail];  in queue_get_event()
179 	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;  in queue_add_event()
180 	if (q->event_head == q->event_tail) {  in queue_add_event()
185 		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;  in queue_add_event()
187 	q->events[q->event_head] = event;  in queue_add_event()
196 		if (as->reader)  in queue_event()
197 			queue_add_event(&as->queue, event);  in queue_event()
205 	struct apm_user *as = fp->private_data;  in apm_read()
210 		return -EINVAL;  in apm_read()
212 	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)  in apm_read()
213 		return -EAGAIN;  in apm_read()
215 	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));  in apm_read()
217 	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {  in apm_read()
218 		event = queue_get_event(&as->queue);  in apm_read()
220 		ret = -EFAULT;  in apm_read()
225 		if (as->suspend_state == SUSPEND_PENDING &&  in apm_read()
227 			as->suspend_state = SUSPEND_READ;  in apm_read()
231 		i -= sizeof(event);  in apm_read()
235 		ret = count - i;  in apm_read()
240 static __poll_t apm_poll(struct file *fp, poll_table * wait)  in apm_poll()  argument
242 	struct apm_user *as = fp->private_data;  in apm_poll()
244 	poll_wait(fp, &apm_waitqueue, wait);  in apm_poll()
245 	return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;  in apm_poll()
249  * apm_ioctl - handle APM ioctl
253  *     - initiate a suspend
254  *     - acknowledge a suspend read from /dev/apm_bios.
256  *   has acknowledge does the actual suspend happen.
261 	struct apm_user *as = filp->private_data;  in apm_ioctl()
262 	int err = -EINVAL;  in apm_ioctl()
264 	if (!as->suser || !as->writer)  in apm_ioctl()
265 		return -EPERM;  in apm_ioctl()
271 		as->suspend_result = -EINTR;  in apm_ioctl()
273 		switch (as->suspend_state) {  in apm_ioctl()
276 			 * If we read a suspend command from /dev/apm_bios,  in apm_ioctl()
280 			as->suspend_state = SUSPEND_ACKED;  in apm_ioctl()
291 			 * Wait for the suspend/resume to complete.  If there  in apm_ioctl()
292 			 * are pending acknowledges, we wait here for them.  in apm_ioctl()
298 					as->suspend_state != SUSPEND_ACKED))  in apm_ioctl()
302 			as->suspend_result = -ETIMEDOUT;  in apm_ioctl()
306 			as->suspend_state = SUSPEND_WAIT;  in apm_ioctl()
310 			 * Otherwise it is a request to suspend the system.  in apm_ioctl()
314 			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);  in apm_ioctl()
318 		err = as->suspend_result;  in apm_ioctl()
319 		as->suspend_state = SUSPEND_NONE;  in apm_ioctl()
329 	struct apm_user *as = filp->private_data;  in apm_release()
331 	filp->private_data = NULL;  in apm_release()
334 	list_del(&as->list);  in apm_release()
342 	if (as->suspend_state == SUSPEND_PENDING ||  in apm_release()
343 	    as->suspend_state == SUSPEND_READ)  in apm_release()
360 		 * XXX - this is a tiny bit broken, when we consider BSD  in apm_open()
364 		 * privileged operation -- cevans  in apm_open()
366 		as->suser = capable(CAP_SYS_ADMIN);  in apm_open()
367 		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;  in apm_open()
368 		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;  in apm_open()
371 		list_add(&as->list, &apm_user_list);  in apm_open()
374 		filp->private_data = as;  in apm_open()
377 	return as ? 0 : -ENOMEM;  in apm_open()
410  *	0x00: Off-line
411  *	0x01: On-line
429  *	0-100: valid
430  *	-1: Unknown
433  *	-1: Unknown
444 	info.battery_life   = -1;  in proc_apm_show()
445 	info.time	    = -1;  in proc_apm_show()
446 	info.units	    = -1;  in proc_apm_show()
517 	/* short-cut emergency suspends */  in apm_suspend_notifier()
528 		 * to suspend and need their ack.  in apm_suspend_notifier()
534 			if (as->suspend_state != SUSPEND_WAIT && as->reader &&  in apm_suspend_notifier()
535 			    as->writer && as->suser) {  in apm_suspend_notifier()
536 				as->suspend_state = SUSPEND_PENDING;  in apm_suspend_notifier()
538 				queue_add_event(&as->queue, apm_event);  in apm_suspend_notifier()
547 		 * Wait for the suspend_acks_pending variable to drop to  in apm_suspend_notifier()
548 		 * zero, meaning everybody acked the suspend event (or the  in apm_suspend_notifier()
571 				if (as->suspend_state == SUSPEND_PENDING ||  in apm_suspend_notifier()
572 				    as->suspend_state == SUSPEND_READ) {  in apm_suspend_notifier()
573 					as->suspend_state = SUSPEND_ACKTO;  in apm_suspend_notifier()
581 		/* let suspend proceed */  in apm_suspend_notifier()
599 		 * Finally, wake up anyone who is sleeping on the suspend.  in apm_suspend_notifier()
604 			if (as->suspend_state == SUSPEND_ACKED) {  in apm_suspend_notifier()
611 				as->suspend_result = 0;  in apm_suspend_notifier()
612 				as->suspend_state = SUSPEND_DONE;  in apm_suspend_notifier()
636 		return -ENODEV;  in apm_init()
705  * apm_queue_event - queue an APM event for kapmd