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

   *

   * Author: David S. Miller
   * License: GPL
   *

   * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.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;
  		}

  		pr_warn("tod_get() timed out.
  ");

  		return 0;
  	}

  	pr_warn("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;
  		}

  		pr_warn("tod_set() timed out.
  ");

  		return -EAGAIN;
  	}

  	pr_warn("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 = devm_rtc_device_register(&pdev->dev, "sun4v",
  				&sun4v_rtc_ops, THIS_MODULE);

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

  	return 0;
  }

  static struct platform_driver sun4v_rtc_driver = {
  	.driver		= {
  		.name	= "rtc-sun4v",

  	},

  };

  builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);