/* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.

   *
   * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/delay.h>
  #include <linux/init.h>

  #include <linux/rtc.h>
  #include <linux/platform_device.h>
  
  #include <asm/hypervisor.h>

  static unsigned long hypervisor_get_time(void)
  {
  	unsigned long ret, time;
  	int retries = 10000;
  
  retry:
  	ret = sun4v_tod_get(&time);
  	if (ret == HV_EOK)
  		return time;
  	if (ret == HV_EWOULDBLOCK) {
  		if (--retries > 0) {
  			udelay(100);
  			goto retry;
  		}
  		printk(KERN_WARNING "SUN4V: tod_get() timed out.
  ");
  		return 0;
  	}
  	printk(KERN_WARNING "SUN4V: tod_get() not supported.
  ");
  	return 0;
  }
  
  static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
  {

  	rtc_time_to_tm(hypervisor_get_time(), tm);

  	return 0;
  }
  
  static int hypervisor_set_time(unsigned long secs)
  {
  	unsigned long ret;
  	int retries = 10000;
  
  retry:
  	ret = sun4v_tod_set(secs);
  	if (ret == HV_EOK)
  		return 0;
  	if (ret == HV_EWOULDBLOCK) {
  		if (--retries > 0) {
  			udelay(100);
  			goto retry;
  		}
  		printk(KERN_WARNING "SUN4V: tod_set() timed out.
  ");
  		return -EAGAIN;
  	}
  	printk(KERN_WARNING "SUN4V: tod_set() not supported.
  ");
  	return -EOPNOTSUPP;
  }
  
  static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
  {

  	unsigned long secs;

  	int err;
  
  	err = rtc_tm_to_time(tm, &secs);
  	if (err)
  		return err;

  	return hypervisor_set_time(secs);

  }
  
  static const struct rtc_class_ops sun4v_rtc_ops = {
  	.read_time	= sun4v_read_time,
  	.set_time	= sun4v_set_time,
  };

  static int __init sun4v_rtc_probe(struct platform_device *pdev)

  {

  	struct rtc_device *rtc = rtc_device_register("sun4v", &pdev->dev,

  				     &sun4v_rtc_ops, THIS_MODULE);

  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);
  
  	platform_set_drvdata(pdev, rtc);

  	return 0;
  }

  static int __exit sun4v_rtc_remove(struct platform_device *pdev)

  {

  	struct rtc_device *rtc = platform_get_drvdata(pdev);

  	rtc_device_unregister(rtc);

  	return 0;
  }
  
  static struct platform_driver sun4v_rtc_driver = {
  	.driver		= {
  		.name	= "rtc-sun4v",
  		.owner	= THIS_MODULE,
  	},

  	.remove		= __exit_p(sun4v_rtc_remove),

  };
  
  static int __init sun4v_rtc_init(void)
  {

  	return platform_driver_probe(&sun4v_rtc_driver, sun4v_rtc_probe);

  }
  
  static void __exit sun4v_rtc_exit(void)
  {
  	platform_driver_unregister(&sun4v_rtc_driver);
  }
  
  module_init(sun4v_rtc_init);
  module_exit(sun4v_rtc_exit);

  
  MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  MODULE_DESCRIPTION("SUN4V RTC driver");
  MODULE_LICENSE("GPL");