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Linux/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                 .owner  = THIS_MODULE,
 99         },
100 };
101 
102 module_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
103 
104 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
105 MODULE_DESCRIPTION("SUN4V RTC driver");
106 MODULE_LICENSE("GPL");
107 

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