kernel/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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/delay.h>
  11 #include <linux/init.h>
  12 #include <linux/rtc.h>
  13 #include <linux/platform_device.h>
  14
  15 #include <asm/hypervisor.h>
  16
  17 static unsigned long hypervisor_get_time(void)
  18 {
  19         unsigned long ret, time;
  20         int retries = 10000;
  21
  22 retry:
  23         ret = sun4v_tod_get(&time);
  24         if (ret == HV_EOK)
  25                 return time;
  26         if (ret == HV_EWOULDBLOCK) {
  27                 if (--retries > 0) {
  28                         udelay(100);
  29                         goto retry;
  30                 }
  31                 pr_warn("tod_get() timed out.\n");
  32                 return 0;
  33         }
  34         pr_warn("tod_get() not supported.\n");
  35         return 0;
  36 }
  37
  38 static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
  39 {
  40         rtc_time_to_tm(hypervisor_get_time(), tm);
  41         return 0;
  42 }
  43
  44 static int hypervisor_set_time(unsigned long secs)
  45 {
  46         unsigned long ret;
  47         int retries = 10000;
  48
  49 retry:
  50         ret = sun4v_tod_set(secs);
  51         if (ret == HV_EOK)
  52                 return 0;
  53         if (ret == HV_EWOULDBLOCK) {
  54                 if (--retries > 0) {
  55                         udelay(100);
  56                         goto retry;
  57                 }
  58                 pr_warn("tod_set() timed out.\n");
  59                 return -EAGAIN;
  60         }
  61         pr_warn("tod_set() not supported.\n");
  62         return -EOPNOTSUPP;
  63 }
  64
  65 static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
  66 {
  67         unsigned long secs;
  68         int err;
  69
  70         err = rtc_tm_to_time(tm, &secs);
  71         if (err)
  72                 return err;
  73
  74         return hypervisor_set_time(secs);
  75 }
  76
  77 static const struct rtc_class_ops sun4v_rtc_ops = {
  78         .read_time      = sun4v_read_time,
  79         .set_time       = sun4v_set_time,
  80 };
  81
  82 static int __init sun4v_rtc_probe(struct platform_device *pdev)
  83 {
  84         struct rtc_device *rtc;
  85
  86         rtc = devm_rtc_device_register(&pdev->dev, "sun4v",
  87                                 &sun4v_rtc_ops, THIS_MODULE);
  88         if (IS_ERR(rtc))
  89                 return PTR_ERR(rtc);
  90
  91         platform_set_drvdata(pdev, rtc);
  92         return 0;
  93 }
  94
  95 static struct platform_driver sun4v_rtc_driver = {
  96         .driver         = {
  97                 .name   = "rtc-sun4v",
  98         },
  99 };
 100
 101 module_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
 102
 103 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
 104 MODULE_DESCRIPTION("SUN4V RTC driver");
 105 MODULE_LICENSE("GPL");