1 files changed, 483 insertions, 0 deletions

diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c
new file mode 100644
index 000000000000..43d962a9c210
--- /dev/null
+++ b/drivers/rtc/dev.c
@@ -0,0 +1,483 @@
+/*
+ * RTC subsystem, dev interface
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * based on arch/arm/common/rtctime.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/sched/signal.h>
+#include "rtc-core.h"
+
+static dev_t rtc_devt;
+
+#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
+
+static int rtc_dev_open(struct inode *inode, struct file *file)
+{
+	struct rtc_device *rtc = container_of(inode->i_cdev,
+					struct rtc_device, char_dev);
+
+	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
+		return -EBUSY;
+
+	file->private_data = rtc;
+
+	spin_lock_irq(&rtc->irq_lock);
+	rtc->irq_data = 0;
+	spin_unlock_irq(&rtc->irq_lock);
+
+	return 0;
+}
+
+#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
+/*
+ * Routine to poll RTC seconds field for change as often as possible,
+ * after first RTC_UIE use timer to reduce polling
+ */
+static void rtc_uie_task(struct work_struct *work)
+{
+	struct rtc_device *rtc =
+		container_of(work, struct rtc_device, uie_task);
+	struct rtc_time tm;
+	int num = 0;
+	int err;
+
+	err = rtc_read_time(rtc, &tm);
+
+	spin_lock_irq(&rtc->irq_lock);
+	if (rtc->stop_uie_polling || err) {
+		rtc->uie_task_active = 0;
+	} else if (rtc->oldsecs != tm.tm_sec) {
+		num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
+		rtc->oldsecs = tm.tm_sec;
+		rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
+		rtc->uie_timer_active = 1;
+		rtc->uie_task_active = 0;
+		add_timer(&rtc->uie_timer);
+	} else if (schedule_work(&rtc->uie_task) == 0) {
+		rtc->uie_task_active = 0;
+	}
+	spin_unlock_irq(&rtc->irq_lock);
+	if (num)
+		rtc_handle_legacy_irq(rtc, num, RTC_UF);
+}
+static void rtc_uie_timer(struct timer_list *t)
+{
+	struct rtc_device *rtc = from_timer(rtc, t, uie_timer);
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc->irq_lock, flags);
+	rtc->uie_timer_active = 0;
+	rtc->uie_task_active = 1;
+	if ((schedule_work(&rtc->uie_task) == 0))
+		rtc->uie_task_active = 0;
+	spin_unlock_irqrestore(&rtc->irq_lock, flags);
+}
+
+static int clear_uie(struct rtc_device *rtc)
+{
+	spin_lock_irq(&rtc->irq_lock);
+	if (rtc->uie_irq_active) {
+		rtc->stop_uie_polling = 1;
+		if (rtc->uie_timer_active) {
+			spin_unlock_irq(&rtc->irq_lock);
+			del_timer_sync(&rtc->uie_timer);
+			spin_lock_irq(&rtc->irq_lock);
+			rtc->uie_timer_active = 0;
+		}
+		if (rtc->uie_task_active) {
+			spin_unlock_irq(&rtc->irq_lock);
+			flush_scheduled_work();
+			spin_lock_irq(&rtc->irq_lock);
+		}
+		rtc->uie_irq_active = 0;
+	}
+	spin_unlock_irq(&rtc->irq_lock);
+	return 0;
+}
+
+static int set_uie(struct rtc_device *rtc)
+{
+	struct rtc_time tm;
+	int err;
+
+	err = rtc_read_time(rtc, &tm);
+	if (err)
+		return err;
+	spin_lock_irq(&rtc->irq_lock);
+	if (!rtc->uie_irq_active) {
+		rtc->uie_irq_active = 1;
+		rtc->stop_uie_polling = 0;
+		rtc->oldsecs = tm.tm_sec;
+		rtc->uie_task_active = 1;
+		if (schedule_work(&rtc->uie_task) == 0)
+			rtc->uie_task_active = 0;
+	}
+	rtc->irq_data = 0;
+	spin_unlock_irq(&rtc->irq_lock);
+	return 0;
+}
+
+int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
+{
+	if (enabled)
+		return set_uie(rtc);
+	else
+		return clear_uie(rtc);
+}
+EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
+
+#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
+
+static ssize_t
+rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct rtc_device *rtc = file->private_data;
+
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long data;
+	ssize_t ret;
+
+	if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
+		return -EINVAL;
+
+	add_wait_queue(&rtc->irq_queue, &wait);
+	do {
+		__set_current_state(TASK_INTERRUPTIBLE);
+
+		spin_lock_irq(&rtc->irq_lock);
+		data = rtc->irq_data;
+		rtc->irq_data = 0;
+		spin_unlock_irq(&rtc->irq_lock);
+
+		if (data != 0) {
+			ret = 0;
+			break;
+		}
+		if (file->f_flags & O_NONBLOCK) {
+			ret = -EAGAIN;
+			break;
+		}
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+		schedule();
+	} while (1);
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rtc->irq_queue, &wait);
+
+	if (ret == 0) {
+		/* Check for any data updates */
+		if (rtc->ops->read_callback)
+			data = rtc->ops->read_callback(rtc->dev.parent,
+						       data);
+
+		if (sizeof(int) != sizeof(long) &&
+		    count == sizeof(unsigned int))
+			ret = put_user(data, (unsigned int __user *)buf) ?:
+				sizeof(unsigned int);
+		else
+			ret = put_user(data, (unsigned long __user *)buf) ?:
+				sizeof(unsigned long);
+	}
+	return ret;
+}
+
+static __poll_t rtc_dev_poll(struct file *file, poll_table *wait)
+{
+	struct rtc_device *rtc = file->private_data;
+	unsigned long data;
+
+	poll_wait(file, &rtc->irq_queue, wait);
+
+	data = rtc->irq_data;
+
+	return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0;
+}
+
+static long rtc_dev_ioctl(struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	int err = 0;
+	struct rtc_device *rtc = file->private_data;
+	const struct rtc_class_ops *ops = rtc->ops;
+	struct rtc_time tm;
+	struct rtc_wkalrm alarm;
+	void __user *uarg = (void __user *) arg;
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return err;
+
+	/* check that the calling task has appropriate permissions
+	 * for certain ioctls. doing this check here is useful
+	 * to avoid duplicate code in each driver.
+	 */
+	switch (cmd) {
+	case RTC_EPOCH_SET:
+	case RTC_SET_TIME:
+		if (!capable(CAP_SYS_TIME))
+			err = -EACCES;
+		break;
+
+	case RTC_IRQP_SET:
+		if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
+			err = -EACCES;
+		break;
+
+	case RTC_PIE_ON:
+		if (rtc->irq_freq > rtc->max_user_freq &&
+				!capable(CAP_SYS_RESOURCE))
+			err = -EACCES;
+		break;
+	}
+
+	if (err)
+		goto done;
+
+	/*
+	 * Drivers *SHOULD NOT* provide ioctl implementations
+	 * for these requests.  Instead, provide methods to
+	 * support the following code, so that the RTC's main
+	 * features are accessible without using ioctls.
+	 *
+	 * RTC and alarm times will be in UTC, by preference,
+	 * but dual-booting with MS-Windows implies RTCs must
+	 * use the local wall clock time.
+	 */
+
+	switch (cmd) {
+	case RTC_ALM_READ:
+		mutex_unlock(&rtc->ops_lock);
+
+		err = rtc_read_alarm(rtc, &alarm);
+		if (err < 0)
+			return err;
+
+		if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
+			err = -EFAULT;
+		return err;
+
+	case RTC_ALM_SET:
+		mutex_unlock(&rtc->ops_lock);
+
+		if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
+			return -EFAULT;
+
+		alarm.enabled = 0;
+		alarm.pending = 0;
+		alarm.time.tm_wday = -1;
+		alarm.time.tm_yday = -1;
+		alarm.time.tm_isdst = -1;
+
+		/* RTC_ALM_SET alarms may be up to 24 hours in the future.
+		 * Rather than expecting every RTC to implement "don't care"
+		 * for day/month/year fields, just force the alarm to have
+		 * the right values for those fields.
+		 *
+		 * RTC_WKALM_SET should be used instead.  Not only does it
+		 * eliminate the need for a separate RTC_AIE_ON call, it
+		 * doesn't have the "alarm 23:59:59 in the future" race.
+		 *
+		 * NOTE:  some legacy code may have used invalid fields as
+		 * wildcards, exposing hardware "periodic alarm" capabilities.
+		 * Not supported here.
+		 */
+		{
+			time64_t now, then;
+
+			err = rtc_read_time(rtc, &tm);
+			if (err < 0)
+				return err;
+			now = rtc_tm_to_time64(&tm);
+
+			alarm.time.tm_mday = tm.tm_mday;
+			alarm.time.tm_mon = tm.tm_mon;
+			alarm.time.tm_year = tm.tm_year;
+			err  = rtc_valid_tm(&alarm.time);
+			if (err < 0)
+				return err;
+			then = rtc_tm_to_time64(&alarm.time);
+
+			/* alarm may need to wrap into tomorrow */
+			if (then < now) {
+				rtc_time64_to_tm(now + 24 * 60 * 60, &tm);
+				alarm.time.tm_mday = tm.tm_mday;
+				alarm.time.tm_mon = tm.tm_mon;
+				alarm.time.tm_year = tm.tm_year;
+			}
+		}
+
+		return rtc_set_alarm(rtc, &alarm);
+
+	case RTC_RD_TIME:
+		mutex_unlock(&rtc->ops_lock);
+
+		err = rtc_read_time(rtc, &tm);
+		if (err < 0)
+			return err;
+
+		if (copy_to_user(uarg, &tm, sizeof(tm)))
+			err = -EFAULT;
+		return err;
+
+	case RTC_SET_TIME:
+		mutex_unlock(&rtc->ops_lock);
+
+		if (copy_from_user(&tm, uarg, sizeof(tm)))
+			return -EFAULT;
+
+		return rtc_set_time(rtc, &tm);
+
+	case RTC_PIE_ON:
+		err = rtc_irq_set_state(rtc, 1);
+		break;
+
+	case RTC_PIE_OFF:
+		err = rtc_irq_set_state(rtc, 0);
+		break;
+
+	case RTC_AIE_ON:
+		mutex_unlock(&rtc->ops_lock);
+		return rtc_alarm_irq_enable(rtc, 1);
+
+	case RTC_AIE_OFF:
+		mutex_unlock(&rtc->ops_lock);
+		return rtc_alarm_irq_enable(rtc, 0);
+
+	case RTC_UIE_ON:
+		mutex_unlock(&rtc->ops_lock);
+		return rtc_update_irq_enable(rtc, 1);
+
+	case RTC_UIE_OFF:
+		mutex_unlock(&rtc->ops_lock);
+		return rtc_update_irq_enable(rtc, 0);
+
+	case RTC_IRQP_SET:
+		err = rtc_irq_set_freq(rtc, arg);
+		break;
+
+	case RTC_IRQP_READ:
+		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
+		break;
+
+	case RTC_WKALM_SET:
+		mutex_unlock(&rtc->ops_lock);
+		if (copy_from_user(&alarm, uarg, sizeof(alarm)))
+			return -EFAULT;
+
+		return rtc_set_alarm(rtc, &alarm);
+
+	case RTC_WKALM_RD:
+		mutex_unlock(&rtc->ops_lock);
+		err = rtc_read_alarm(rtc, &alarm);
+		if (err < 0)
+			return err;
+
+		if (copy_to_user(uarg, &alarm, sizeof(alarm)))
+			err = -EFAULT;
+		return err;
+
+	default:
+		/* Finally try the driver's ioctl interface */
+		if (ops->ioctl) {
+			err = ops->ioctl(rtc->dev.parent, cmd, arg);
+			if (err == -ENOIOCTLCMD)
+				err = -ENOTTY;
+		} else
+			err = -ENOTTY;
+		break;
+	}
+
+done:
+	mutex_unlock(&rtc->ops_lock);
+	return err;
+}
+
+static int rtc_dev_fasync(int fd, struct file *file, int on)
+{
+	struct rtc_device *rtc = file->private_data;
+	return fasync_helper(fd, file, on, &rtc->async_queue);
+}
+
+static int rtc_dev_release(struct inode *inode, struct file *file)
+{
+	struct rtc_device *rtc = file->private_data;
+
+	/* We shut down the repeating IRQs that userspace enabled,
+	 * since nothing is listening to them.
+	 *  - Update (UIE) ... currently only managed through ioctls
+	 *  - Periodic (PIE) ... also used through rtc_*() interface calls
+	 *
+	 * Leave the alarm alone; it may be set to trigger a system wakeup
+	 * later, or be used by kernel code, and is a one-shot event anyway.
+	 */
+
+	/* Keep ioctl until all drivers are converted */
+	rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
+	rtc_update_irq_enable(rtc, 0);
+	rtc_irq_set_state(rtc, 0);
+
+	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
+	return 0;
+}
+
+static const struct file_operations rtc_dev_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.read		= rtc_dev_read,
+	.poll		= rtc_dev_poll,
+	.unlocked_ioctl	= rtc_dev_ioctl,
+	.open		= rtc_dev_open,
+	.release	= rtc_dev_release,
+	.fasync		= rtc_dev_fasync,
+};
+
+/* insertion/removal hooks */
+
+void rtc_dev_prepare(struct rtc_device *rtc)
+{
+	if (!rtc_devt)
+		return;
+
+	if (rtc->id >= RTC_DEV_MAX) {
+		dev_dbg(&rtc->dev, "too many RTC devices\n");
+		return;
+	}
+
+	rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
+
+#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
+	INIT_WORK(&rtc->uie_task, rtc_uie_task);
+	timer_setup(&rtc->uie_timer, rtc_uie_timer, 0);
+#endif
+
+	cdev_init(&rtc->char_dev, &rtc_dev_fops);
+	rtc->char_dev.owner = rtc->owner;
+}
+
+void __init rtc_dev_init(void)
+{
+	int err;
+
+	err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
+	if (err < 0)
+		pr_err("failed to allocate char dev region\n");
+}
+
+void __exit rtc_dev_exit(void)
+{
+	if (rtc_devt)
+		unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
+}