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Linux/drivers/rtc/rtc-sun4v.c

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

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