1 files changed, 726 insertions, 0 deletions

diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
new file mode 100644
index 0000000000..e795390b07
--- /dev/null
+++ b/drivers/char/apm-emulation.c
@@ -0,0 +1,726 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * bios-less APM driver for ARM Linux
+ *  Jamey Hicks <jamey@crl.dec.com>
+ *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
+ *
+ * APM 1.2 Reference:
+ *   Intel Corporation, Microsoft Corporation. Advanced Power Management
+ *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
+ *
+ * This document is available from Microsoft at:
+ *    http://www.microsoft.com/whdc/archive/amp_12.mspx
+ */
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/miscdevice.h>
+#include <linux/apm_bios.h>
+#include <linux/capability.h>
+#include <linux/sched.h>
+#include <linux/suspend.h>
+#include <linux/apm-emulation.h>
+#include <linux/freezer.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+/*
+ * One option can be changed at boot time as follows:
+ *	apm=on/off			enable/disable APM
+ */
+
+/*
+ * Maximum number of events stored
+ */
+#define APM_MAX_EVENTS		16
+
+struct apm_queue {
+	unsigned int		event_head;
+	unsigned int		event_tail;
+	apm_event_t		events[APM_MAX_EVENTS];
+};
+
+/*
+ * thread states (for threads using a writable /dev/apm_bios fd):
+ *
+ * SUSPEND_NONE:	nothing happening
+ * SUSPEND_PENDING:	suspend event queued for thread and pending to be read
+ * SUSPEND_READ:	suspend event read, pending acknowledgement
+ * SUSPEND_ACKED:	acknowledgement received from thread (via ioctl),
+ *			waiting for resume
+ * SUSPEND_ACKTO:	acknowledgement timeout
+ * SUSPEND_DONE:	thread had acked suspend and is now notified of
+ *			resume
+ *
+ * SUSPEND_WAIT:	this thread invoked suspend and is waiting for resume
+ *
+ * A thread migrates in one of three paths:
+ *	NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
+ *				    -6-> ACKTO -7-> NONE
+ *	NONE -8-> WAIT -9-> NONE
+ *
+ * While in PENDING or READ, the thread is accounted for in the
+ * suspend_acks_pending counter.
+ *
+ * The transitions are invoked as follows:
+ *	1: suspend event is signalled from the core PM code
+ *	2: the suspend event is read from the fd by the userspace thread
+ *	3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
+ *	4: core PM code signals that we have resumed
+ *	5: APM_IOC_SUSPEND ioctl returns
+ *
+ *	6: the notifier invoked from the core PM code timed out waiting
+ *	   for all relevant threds to enter ACKED state and puts those
+ *	   that haven't into ACKTO
+ *	7: those threads issue APM_IOC_SUSPEND ioctl too late,
+ *	   get an error
+ *
+ *	8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
+ *	   ioctl code invokes pm_suspend()
+ *	9: pm_suspend() returns indicating resume
+ */
+enum apm_suspend_state {
+	SUSPEND_NONE,
+	SUSPEND_PENDING,
+	SUSPEND_READ,
+	SUSPEND_ACKED,
+	SUSPEND_ACKTO,
+	SUSPEND_WAIT,
+	SUSPEND_DONE,
+};
+
+/*
+ * The per-file APM data
+ */
+struct apm_user {
+	struct list_head	list;
+
+	unsigned int		suser: 1;
+	unsigned int		writer: 1;
+	unsigned int		reader: 1;
+
+	int			suspend_result;
+	enum apm_suspend_state	suspend_state;
+
+	struct apm_queue	queue;
+};
+
+/*
+ * Local variables
+ */
+static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
+static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
+static int apm_disabled;
+static struct task_struct *kapmd_tsk;
+
+static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
+static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
+
+/*
+ * This is a list of everyone who has opened /dev/apm_bios
+ */
+static DECLARE_RWSEM(user_list_lock);
+static LIST_HEAD(apm_user_list);
+
+/*
+ * kapmd info.  kapmd provides us a process context to handle
+ * "APM" events within - specifically necessary if we're going
+ * to be suspending the system.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
+static DEFINE_SPINLOCK(kapmd_queue_lock);
+static struct apm_queue kapmd_queue;
+
+static DEFINE_MUTEX(state_lock);
+
+static const char driver_version[] = "1.13";	/* no spaces */
+
+
+
+/*
+ * Compatibility cruft until the IPAQ people move over to the new
+ * interface.
+ */
+static void __apm_get_power_status(struct apm_power_info *info)
+{
+}
+
+/*
+ * This allows machines to provide their own "apm get power status" function.
+ */
+void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
+EXPORT_SYMBOL(apm_get_power_status);
+
+
+/*
+ * APM event queue management.
+ */
+static inline int queue_empty(struct apm_queue *q)
+{
+	return q->event_head == q->event_tail;
+}
+
+static inline apm_event_t queue_get_event(struct apm_queue *q)
+{
+	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+	return q->events[q->event_tail];
+}
+
+static void queue_add_event(struct apm_queue *q, apm_event_t event)
+{
+	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
+	if (q->event_head == q->event_tail) {
+		static int notified;
+
+		if (notified++ == 0)
+		    printk(KERN_ERR "apm: an event queue overflowed\n");
+		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+	}
+	q->events[q->event_head] = event;
+}
+
+static void queue_event(apm_event_t event)
+{
+	struct apm_user *as;
+
+	down_read(&user_list_lock);
+	list_for_each_entry(as, &apm_user_list, list) {
+		if (as->reader)
+			queue_add_event(&as->queue, event);
+	}
+	up_read(&user_list_lock);
+	wake_up_interruptible(&apm_waitqueue);
+}
+
+static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct apm_user *as = fp->private_data;
+	apm_event_t event;
+	int i = count, ret = 0;
+
+	if (count < sizeof(apm_event_t))
+		return -EINVAL;
+
+	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
+		return -EAGAIN;
+
+	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
+
+	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
+		event = queue_get_event(&as->queue);
+
+		ret = -EFAULT;
+		if (copy_to_user(buf, &event, sizeof(event)))
+			break;
+
+		mutex_lock(&state_lock);
+		if (as->suspend_state == SUSPEND_PENDING &&
+		    (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
+			as->suspend_state = SUSPEND_READ;
+		mutex_unlock(&state_lock);
+
+		buf += sizeof(event);
+		i -= sizeof(event);
+	}
+
+	if (i < count)
+		ret = count - i;
+
+	return ret;
+}
+
+static __poll_t apm_poll(struct file *fp, poll_table * wait)
+{
+	struct apm_user *as = fp->private_data;
+
+	poll_wait(fp, &apm_waitqueue, wait);
+	return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;
+}
+
+/*
+ * apm_ioctl - handle APM ioctl
+ *
+ * APM_IOC_SUSPEND
+ *   This IOCTL is overloaded, and performs two functions.  It is used to:
+ *     - initiate a suspend
+ *     - acknowledge a suspend read from /dev/apm_bios.
+ *   Only when everyone who has opened /dev/apm_bios with write permission
+ *   has acknowledge does the actual suspend happen.
+ */
+static long
+apm_ioctl(struct file *filp, u_int cmd, u_long arg)
+{
+	struct apm_user *as = filp->private_data;
+	int err = -EINVAL;
+
+	if (!as->suser || !as->writer)
+		return -EPERM;
+
+	switch (cmd) {
+	case APM_IOC_SUSPEND:
+		mutex_lock(&state_lock);
+
+		as->suspend_result = -EINTR;
+
+		switch (as->suspend_state) {
+		case SUSPEND_READ:
+			/*
+			 * If we read a suspend command from /dev/apm_bios,
+			 * then the corresponding APM_IOC_SUSPEND ioctl is
+			 * interpreted as an acknowledge.
+			 */
+			as->suspend_state = SUSPEND_ACKED;
+			atomic_dec(&suspend_acks_pending);
+			mutex_unlock(&state_lock);
+
+			/*
+			 * suspend_acks_pending changed, the notifier needs to
+			 * be woken up for this
+			 */
+			wake_up(&apm_suspend_waitqueue);
+
+			/*
+			 * Wait for the suspend/resume to complete.  If there
+			 * are pending acknowledges, we wait here for them.
+			 * wait_event_freezable() is interruptible and pending
+			 * signal can cause busy looping.  We aren't doing
+			 * anything critical, chill a bit on each iteration.
+			 */
+			while (wait_event_freezable(apm_suspend_waitqueue,
+					as->suspend_state != SUSPEND_ACKED))
+				msleep(10);
+			break;
+		case SUSPEND_ACKTO:
+			as->suspend_result = -ETIMEDOUT;
+			mutex_unlock(&state_lock);
+			break;
+		default:
+			as->suspend_state = SUSPEND_WAIT;
+			mutex_unlock(&state_lock);
+
+			/*
+			 * Otherwise it is a request to suspend the system.
+			 * Just invoke pm_suspend(), we'll handle it from
+			 * there via the notifier.
+			 */
+			as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
+		}
+
+		mutex_lock(&state_lock);
+		err = as->suspend_result;
+		as->suspend_state = SUSPEND_NONE;
+		mutex_unlock(&state_lock);
+		break;
+	}
+
+	return err;
+}
+
+static int apm_release(struct inode * inode, struct file * filp)
+{
+	struct apm_user *as = filp->private_data;
+
+	filp->private_data = NULL;
+
+	down_write(&user_list_lock);
+	list_del(&as->list);
+	up_write(&user_list_lock);
+
+	/*
+	 * We are now unhooked from the chain.  As far as new
+	 * events are concerned, we no longer exist.
+	 */
+	mutex_lock(&state_lock);
+	if (as->suspend_state == SUSPEND_PENDING ||
+	    as->suspend_state == SUSPEND_READ)
+		atomic_dec(&suspend_acks_pending);
+	mutex_unlock(&state_lock);
+
+	wake_up(&apm_suspend_waitqueue);
+
+	kfree(as);
+	return 0;
+}
+
+static int apm_open(struct inode * inode, struct file * filp)
+{
+	struct apm_user *as;
+
+	as = kzalloc(sizeof(*as), GFP_KERNEL);
+	if (as) {
+		/*
+		 * XXX - this is a tiny bit broken, when we consider BSD
+		 * process accounting. If the device is opened by root, we
+		 * instantly flag that we used superuser privs. Who knows,
+		 * we might close the device immediately without doing a
+		 * privileged operation -- cevans
+		 */
+		as->suser = capable(CAP_SYS_ADMIN);
+		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
+		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
+
+		down_write(&user_list_lock);
+		list_add(&as->list, &apm_user_list);
+		up_write(&user_list_lock);
+
+		filp->private_data = as;
+	}
+
+	return as ? 0 : -ENOMEM;
+}
+
+static const struct file_operations apm_bios_fops = {
+	.owner		= THIS_MODULE,
+	.read		= apm_read,
+	.poll		= apm_poll,
+	.unlocked_ioctl	= apm_ioctl,
+	.open		= apm_open,
+	.release	= apm_release,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice apm_device = {
+	.minor		= APM_MINOR_DEV,
+	.name		= "apm_bios",
+	.fops		= &apm_bios_fops
+};
+
+
+#ifdef CONFIG_PROC_FS
+/*
+ * Arguments, with symbols from linux/apm_bios.h.
+ *
+ *   0) Linux driver version (this will change if format changes)
+ *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
+ *   2) APM flags from APM Installation Check (0x00):
+ *	bit 0: APM_16_BIT_SUPPORT
+ *	bit 1: APM_32_BIT_SUPPORT
+ *	bit 2: APM_IDLE_SLOWS_CLOCK
+ *	bit 3: APM_BIOS_DISABLED
+ *	bit 4: APM_BIOS_DISENGAGED
+ *   3) AC line status
+ *	0x00: Off-line
+ *	0x01: On-line
+ *	0x02: On backup power (BIOS >= 1.1 only)
+ *	0xff: Unknown
+ *   4) Battery status
+ *	0x00: High
+ *	0x01: Low
+ *	0x02: Critical
+ *	0x03: Charging
+ *	0x04: Selected battery not present (BIOS >= 1.2 only)
+ *	0xff: Unknown
+ *   5) Battery flag
+ *	bit 0: High
+ *	bit 1: Low
+ *	bit 2: Critical
+ *	bit 3: Charging
+ *	bit 7: No system battery
+ *	0xff: Unknown
+ *   6) Remaining battery life (percentage of charge):
+ *	0-100: valid
+ *	-1: Unknown
+ *   7) Remaining battery life (time units):
+ *	Number of remaining minutes or seconds
+ *	-1: Unknown
+ *   8) min = minutes; sec = seconds
+ */
+static int proc_apm_show(struct seq_file *m, void *v)
+{
+	struct apm_power_info info;
+	char *units;
+
+	info.ac_line_status = 0xff;
+	info.battery_status = 0xff;
+	info.battery_flag   = 0xff;
+	info.battery_life   = -1;
+	info.time	    = -1;
+	info.units	    = -1;
+
+	if (apm_get_power_status)
+		apm_get_power_status(&info);
+
+	switch (info.units) {
+	default:	units = "?";	break;
+	case 0: 	units = "min";	break;
+	case 1: 	units = "sec";	break;
+	}
+
+	seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
+		     driver_version, APM_32_BIT_SUPPORT,
+		     info.ac_line_status, info.battery_status,
+		     info.battery_flag, info.battery_life,
+		     info.time, units);
+
+	return 0;
+}
+#endif
+
+static int kapmd(void *arg)
+{
+	do {
+		apm_event_t event;
+
+		wait_event_interruptible(kapmd_wait,
+				!queue_empty(&kapmd_queue) || kthread_should_stop());
+
+		if (kthread_should_stop())
+			break;
+
+		spin_lock_irq(&kapmd_queue_lock);
+		event = 0;
+		if (!queue_empty(&kapmd_queue))
+			event = queue_get_event(&kapmd_queue);
+		spin_unlock_irq(&kapmd_queue_lock);
+
+		switch (event) {
+		case 0:
+			break;
+
+		case APM_LOW_BATTERY:
+		case APM_POWER_STATUS_CHANGE:
+			queue_event(event);
+			break;
+
+		case APM_USER_SUSPEND:
+		case APM_SYS_SUSPEND:
+			pm_suspend(PM_SUSPEND_MEM);
+			break;
+
+		case APM_CRITICAL_SUSPEND:
+			atomic_inc(&userspace_notification_inhibit);
+			pm_suspend(PM_SUSPEND_MEM);
+			atomic_dec(&userspace_notification_inhibit);
+			break;
+		}
+	} while (1);
+
+	return 0;
+}
+
+static int apm_suspend_notifier(struct notifier_block *nb,
+				unsigned long event,
+				void *dummy)
+{
+	struct apm_user *as;
+	int err;
+	unsigned long apm_event;
+
+	/* short-cut emergency suspends */
+	if (atomic_read(&userspace_notification_inhibit))
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case PM_SUSPEND_PREPARE:
+	case PM_HIBERNATION_PREPARE:
+		apm_event = (event == PM_SUSPEND_PREPARE) ?
+			APM_USER_SUSPEND : APM_USER_HIBERNATION;
+		/*
+		 * Queue an event to all "writer" users that we want
+		 * to suspend and need their ack.
+		 */
+		mutex_lock(&state_lock);
+		down_read(&user_list_lock);
+
+		list_for_each_entry(as, &apm_user_list, list) {
+			if (as->suspend_state != SUSPEND_WAIT && as->reader &&
+			    as->writer && as->suser) {
+				as->suspend_state = SUSPEND_PENDING;
+				atomic_inc(&suspend_acks_pending);
+				queue_add_event(&as->queue, apm_event);
+			}
+		}
+
+		up_read(&user_list_lock);
+		mutex_unlock(&state_lock);
+		wake_up_interruptible(&apm_waitqueue);
+
+		/*
+		 * Wait for the suspend_acks_pending variable to drop to
+		 * zero, meaning everybody acked the suspend event (or the
+		 * process was killed.)
+		 *
+		 * If the app won't answer within a short while we assume it
+		 * locked up and ignore it.
+		 */
+		err = wait_event_interruptible_timeout(
+			apm_suspend_waitqueue,
+			atomic_read(&suspend_acks_pending) == 0,
+			5*HZ);
+
+		/* timed out */
+		if (err == 0) {
+			/*
+			 * Move anybody who timed out to "ack timeout" state.
+			 *
+			 * We could time out and the userspace does the ACK
+			 * right after we time out but before we enter the
+			 * locked section here, but that's fine.
+			 */
+			mutex_lock(&state_lock);
+			down_read(&user_list_lock);
+			list_for_each_entry(as, &apm_user_list, list) {
+				if (as->suspend_state == SUSPEND_PENDING ||
+				    as->suspend_state == SUSPEND_READ) {
+					as->suspend_state = SUSPEND_ACKTO;
+					atomic_dec(&suspend_acks_pending);
+				}
+			}
+			up_read(&user_list_lock);
+			mutex_unlock(&state_lock);
+		}
+
+		/* let suspend proceed */
+		if (err >= 0)
+			return NOTIFY_OK;
+
+		/* interrupted by signal */
+		return notifier_from_errno(err);
+
+	case PM_POST_SUSPEND:
+	case PM_POST_HIBERNATION:
+		apm_event = (event == PM_POST_SUSPEND) ?
+			APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
+		/*
+		 * Anyone on the APM queues will think we're still suspended.
+		 * Send a message so everyone knows we're now awake again.
+		 */
+		queue_event(apm_event);
+
+		/*
+		 * Finally, wake up anyone who is sleeping on the suspend.
+		 */
+		mutex_lock(&state_lock);
+		down_read(&user_list_lock);
+		list_for_each_entry(as, &apm_user_list, list) {
+			if (as->suspend_state == SUSPEND_ACKED) {
+				/*
+				 * TODO: maybe grab error code, needs core
+				 * changes to push the error to the notifier
+				 * chain (could use the second parameter if
+				 * implemented)
+				 */
+				as->suspend_result = 0;
+				as->suspend_state = SUSPEND_DONE;
+			}
+		}
+		up_read(&user_list_lock);
+		mutex_unlock(&state_lock);
+
+		wake_up(&apm_suspend_waitqueue);
+		return NOTIFY_OK;
+
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static struct notifier_block apm_notif_block = {
+	.notifier_call = apm_suspend_notifier,
+};
+
+static int __init apm_init(void)
+{
+	int ret;
+
+	if (apm_disabled) {
+		printk(KERN_NOTICE "apm: disabled on user request.\n");
+		return -ENODEV;
+	}
+
+	kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
+	if (IS_ERR(kapmd_tsk)) {
+		ret = PTR_ERR(kapmd_tsk);
+		kapmd_tsk = NULL;
+		goto out;
+	}
+	wake_up_process(kapmd_tsk);
+
+#ifdef CONFIG_PROC_FS
+	proc_create_single("apm", 0, NULL, proc_apm_show);
+#endif
+
+	ret = misc_register(&apm_device);
+	if (ret)
+		goto out_stop;
+
+	ret = register_pm_notifier(&apm_notif_block);
+	if (ret)
+		goto out_unregister;
+
+	return 0;
+
+ out_unregister:
+	misc_deregister(&apm_device);
+ out_stop:
+	remove_proc_entry("apm", NULL);
+	kthread_stop(kapmd_tsk);
+ out:
+	return ret;
+}
+
+static void __exit apm_exit(void)
+{
+	unregister_pm_notifier(&apm_notif_block);
+	misc_deregister(&apm_device);
+	remove_proc_entry("apm", NULL);
+
+	kthread_stop(kapmd_tsk);
+}
+
+module_init(apm_init);
+module_exit(apm_exit);
+
+MODULE_AUTHOR("Stephen Rothwell");
+MODULE_DESCRIPTION("Advanced Power Management");
+MODULE_LICENSE("GPL");
+
+#ifndef MODULE
+static int __init apm_setup(char *str)
+{
+	while ((str != NULL) && (*str != '\0')) {
+		if (strncmp(str, "off", 3) == 0)
+			apm_disabled = 1;
+		if (strncmp(str, "on", 2) == 0)
+			apm_disabled = 0;
+		str = strchr(str, ',');
+		if (str != NULL)
+			str += strspn(str, ", \t");
+	}
+	return 1;
+}
+
+__setup("apm=", apm_setup);
+#endif
+
+/**
+ * apm_queue_event - queue an APM event for kapmd
+ * @event: APM event
+ *
+ * Queue an APM event for kapmd to process and ultimately take the
+ * appropriate action.  Only a subset of events are handled:
+ *   %APM_LOW_BATTERY
+ *   %APM_POWER_STATUS_CHANGE
+ *   %APM_USER_SUSPEND
+ *   %APM_SYS_SUSPEND
+ *   %APM_CRITICAL_SUSPEND
+ */
+void apm_queue_event(apm_event_t event)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&kapmd_queue_lock, flags);
+	queue_add_event(&kapmd_queue, event);
+	spin_unlock_irqrestore(&kapmd_queue_lock, flags);
+
+	wake_up_interruptible(&kapmd_wait);
+}
+EXPORT_SYMBOL(apm_queue_event);