drivers/rtc/rtc-sun4v.c

   1 /* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.
   2  *
   3  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/delay.h>
   9 #include <linux/init.h>
  10 #include <linux/rtc.h>
  11 #include <linux/platform_device.h>
  12
  13 #include <asm/hypervisor.h>
  14
  15 static unsigned long hypervisor_get_time(void)
  16 {
  17         unsigned long ret, time;
  18         int retries = 10000;
  19
  20 retry:
  21         ret = sun4v_tod_get(&time);
  22         if (ret == HV_EOK)
  23                 return time;
  24         if (ret == HV_EWOULDBLOCK) {
  25                 if (--retries > 0) {
  26                         udelay(100);
  27                         goto retry;
  28                 }
  29                 printk(KERN_WARNING "SUN4V: tod_get() timed out.\n");
  30                 return 0;
  31         }
  32         printk(KERN_WARNING "SUN4V: tod_get() not supported.\n");
  33         return 0;
  34 }
  35
  36 static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
  37 {
  38         rtc_time_to_tm(hypervisor_get_time(), tm);
  39         return 0;
  40 }
  41
  42 static int hypervisor_set_time(unsigned long secs)
  43 {
  44         unsigned long ret;
  45         int retries = 10000;
  46
  47 retry:
  48         ret = sun4v_tod_set(secs);
  49         if (ret == HV_EOK)
  50                 return 0;
  51         if (ret == HV_EWOULDBLOCK) {
  52                 if (--retries > 0) {
  53                         udelay(100);
  54                         goto retry;
  55                 }
  56                 printk(KERN_WARNING "SUN4V: tod_set() timed out.\n");
  57                 return -EAGAIN;
  58         }
  59         printk(KERN_WARNING "SUN4V: tod_set() not supported.\n");
  60         return -EOPNOTSUPP;
  61 }
  62
  63 static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
  64 {
  65         unsigned long secs;
  66         int err;
  67
  68         err = rtc_tm_to_time(tm, &secs);
  69         if (err)
  70                 return err;
  71
  72         return hypervisor_set_time(secs);
  73 }
  74
  75 static const struct rtc_class_ops sun4v_rtc_ops = {
  76         .read_time      = sun4v_read_time,
  77         .set_time       = sun4v_set_time,
  78 };
  79
  80 static int __init sun4v_rtc_probe(struct platform_device *pdev)
  81 {
  82         struct rtc_device *rtc = rtc_device_register("sun4v", &pdev->dev,
  83                                      &sun4v_rtc_ops, THIS_MODULE);
  84         if (IS_ERR(rtc))
  85                 return PTR_ERR(rtc);
  86
  87         platform_set_drvdata(pdev, rtc);
  88         return 0;
  89 }
  90
  91 static int __exit sun4v_rtc_remove(struct platform_device *pdev)
  92 {
  93         struct rtc_device *rtc = platform_get_drvdata(pdev);
  94
  95         rtc_device_unregister(rtc);
  96         return 0;
  97 }
  98
  99 static struct platform_driver sun4v_rtc_driver = {
 100         .driver         = {
 101                 .name   = "rtc-sun4v",
 102                 .owner  = THIS_MODULE,
 103         },
 104         .remove         = __exit_p(sun4v_rtc_remove),
 105 };
 106
 107 static int __init sun4v_rtc_init(void)
 108 {
 109         return platform_driver_probe(&sun4v_rtc_driver, sun4v_rtc_probe);
 110 }
 111
 112 static void __exit sun4v_rtc_exit(void)
 113 {
 114         platform_driver_unregister(&sun4v_rtc_driver);
 115 }
 116
 117 module_init(sun4v_rtc_init);
 118 module_exit(sun4v_rtc_exit);
 119
 120 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
 121 MODULE_DESCRIPTION("SUN4V RTC driver");
 122 MODULE_LICENSE("GPL");