/*
   * 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.
  */
  
  #include <linux/module.h>
  #include <linux/rtc.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)
  {
  	int err;
  	struct rtc_device *rtc = container_of(inode->i_cdev,
  					struct rtc_device, char_dev);

  	const struct rtc_class_ops *ops = rtc->ops;

  	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  		return -EBUSY;

  	file->private_data = rtc;

  	err = ops->open ? ops->open(rtc->dev.parent) : 0;

  	if (err == 0) {
  		spin_lock_irq(&rtc->irq_lock);
  		rtc->irq_data = 0;
  		spin_unlock_irq(&rtc->irq_lock);

  		return 0;

  	}

  	/* something has gone wrong */

  	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);

  	return err;
  }

  #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);

  
  	local_irq_disable();
  	spin_lock(&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(&rtc->irq_lock);

  	if (num)

  		rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);

  	local_irq_enable();

  }

  static void rtc_uie_timer(unsigned long data)
  {
  	struct rtc_device *rtc = (struct rtc_device *)data;
  	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 unsigned int 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) ? (POLLIN | POLLRDNORM) : 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;

  	/* try the driver's ioctl interface */
  	if (ops->ioctl) {

  		err = ops->ioctl(rtc->dev.parent, cmd, arg);

  		if (err != -ENOIOCTLCMD) {
  			mutex_unlock(&rtc->ops_lock);

  			return err;

  		}

  	}
  
  	/* if the driver does not provide the ioctl interface
  	 * or if that particular ioctl was not implemented

  	 * (-ENOIOCTLCMD), we will try to emulate here.

  	 *
  	 * 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.
  		 */
  		{
  			unsigned long now, then;
  
  			err = rtc_read_time(rtc, &tm);
  			if (err < 0)
  				return err;
  			rtc_tm_to_time(&tm, &now);
  
  			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;
  			rtc_tm_to_time(&alarm.time, &then);
  
  			/* alarm may need to wrap into tomorrow */
  			if (then < now) {
  				rtc_time_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, NULL, 1);
  		break;
  
  	case RTC_PIE_OFF:
  		err = rtc_irq_set_state(rtc, NULL, 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, NULL, arg);
  		break;
  
  	case RTC_IRQP_READ:
  		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);

  		break;

  #if 0
  	case RTC_EPOCH_SET:
  #ifndef rtc_epoch
  		/*
  		 * There were no RTC clocks before 1900.
  		 */
  		if (arg < 1900) {
  			err = -EINVAL;
  			break;
  		}

  		rtc_epoch = arg;
  		err = 0;
  #endif
  		break;
  
  	case RTC_EPOCH_READ:
  		err = put_user(rtc_epoch, (unsigned long __user *)uarg);
  		break;
  #endif
  	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:

  		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, NULL, 0);

  	if (rtc->ops->release)

  		rtc->ops->release(rtc->dev.parent);

  	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) {

  		pr_debug("%s: too many RTC devices
  ", rtc->name);
  		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);

  	setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
  #endif

  
  	cdev_init(&rtc->char_dev, &rtc_dev_fops);
  	rtc->char_dev.owner = rtc->owner;

  }

  void rtc_dev_add_device(struct rtc_device *rtc)
  {

  	if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))

  		printk(KERN_WARNING "%s: failed to add char device %d:%d
  ",
  			rtc->name, MAJOR(rtc_devt), rtc->id);
  	else
  		pr_debug("%s: dev (%d:%d)
  ", rtc->name,

  			MAJOR(rtc_devt), rtc->id);

  }

  void rtc_dev_del_device(struct rtc_device *rtc)

  {

  	if (rtc->dev.devt)

  		cdev_del(&rtc->char_dev);

  }

  void __init rtc_dev_init(void)

  {
  	int err;

  	err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");

  	if (err < 0)

  		printk(KERN_ERR "%s: failed to allocate char dev region
  ",
  			__FILE__);

  }

  void __exit rtc_dev_exit(void)

  {

  	if (rtc_devt)
  		unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);

  }