drivers/rtc/rtc-sun4v.c

   1 /* rtc-sun4c.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/time.h>
  11 #include <linux/rtc.h>
  12 #include <linux/platform_device.h>
  13
  14 #include <asm/hypervisor.h>
  15
  16 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  17 MODULE_DESCRIPTION("SUN4V RTC driver");
  18 MODULE_LICENSE("GPL");
  19
  20 struct sun4v_rtc {
  21         struct rtc_device       *rtc;
  22         spinlock_t              lock;
  23 };
  24
  25 static unsigned long hypervisor_get_time(void)
  26 {
  27         unsigned long ret, time;
  28         int retries = 10000;
  29
  30 retry:
  31         ret = sun4v_tod_get(&time);
  32         if (ret == HV_EOK)
  33                 return time;
  34         if (ret == HV_EWOULDBLOCK) {
  35                 if (--retries > 0) {
  36                         udelay(100);
  37                         goto retry;
  38                 }
  39                 printk(KERN_WARNING "SUN4V: tod_get() timed out.\n");
  40                 return 0;
  41         }
  42         printk(KERN_WARNING "SUN4V: tod_get() not supported.\n");
  43         return 0;
  44 }
  45
  46 static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
  47 {
  48         struct sun4v_rtc *p = dev_get_drvdata(dev);
  49         unsigned long flags, secs;
  50
  51         spin_lock_irqsave(&p->lock, flags);
  52         secs = hypervisor_get_time();
  53         spin_unlock_irqrestore(&p->lock, flags);
  54
  55         rtc_time_to_tm(secs, tm);
  56
  57         return 0;
  58 }
  59
  60 static int hypervisor_set_time(unsigned long secs)
  61 {
  62         unsigned long ret;
  63         int retries = 10000;
  64
  65 retry:
  66         ret = sun4v_tod_set(secs);
  67         if (ret == HV_EOK)
  68                 return 0;
  69         if (ret == HV_EWOULDBLOCK) {
  70                 if (--retries > 0) {
  71                         udelay(100);
  72                         goto retry;
  73                 }
  74                 printk(KERN_WARNING "SUN4V: tod_set() timed out.\n");
  75                 return -EAGAIN;
  76         }
  77         printk(KERN_WARNING "SUN4V: tod_set() not supported.\n");
  78         return -EOPNOTSUPP;
  79 }
  80
  81 static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
  82 {
  83         struct sun4v_rtc *p = dev_get_drvdata(dev);
  84         unsigned long flags, secs;
  85         int err;
  86
  87         err = rtc_tm_to_time(tm, &secs);
  88         if (err)
  89                 return err;
  90
  91         spin_lock_irqsave(&p->lock, flags);
  92         err = hypervisor_set_time(secs);
  93         spin_unlock_irqrestore(&p->lock, flags);
  94
  95         return err;
  96 }
  97
  98 static const struct rtc_class_ops sun4v_rtc_ops = {
  99         .read_time      = sun4v_read_time,
 100         .set_time       = sun4v_set_time,
 101 };
 102
 103 static int __devinit sun4v_rtc_probe(struct platform_device *pdev)
 104 {
 105         struct sun4v_rtc *p = kzalloc(sizeof(*p), GFP_KERNEL);
 106
 107         if (!p)
 108                 return -ENOMEM;
 109
 110         spin_lock_init(&p->lock);
 111
 112         p->rtc = rtc_device_register("sun4v", &pdev->dev,
 113                                      &sun4v_rtc_ops, THIS_MODULE);
 114         if (IS_ERR(p->rtc)) {
 115                 int err = PTR_ERR(p->rtc);
 116                 kfree(p);
 117                 return err;
 118         }
 119         platform_set_drvdata(pdev, p);
 120         return 0;
 121 }
 122
 123 static int __devexit sun4v_rtc_remove(struct platform_device *pdev)
 124 {
 125         struct sun4v_rtc *p = platform_get_drvdata(pdev);
 126
 127         rtc_device_unregister(p->rtc);
 128         kfree(p);
 129
 130         return 0;
 131 }
 132
 133 static struct platform_driver sun4v_rtc_driver = {
 134         .driver         = {
 135                 .name   = "rtc-sun4v",
 136                 .owner  = THIS_MODULE,
 137         },
 138         .probe          = sun4v_rtc_probe,
 139         .remove         = __devexit_p(sun4v_rtc_remove),
 140 };
 141
 142 static int __init sun4v_rtc_init(void)
 143 {
 144         return platform_driver_register(&sun4v_rtc_driver);
 145 }
 146
 147 static void __exit sun4v_rtc_exit(void)
 148 {
 149         platform_driver_unregister(&sun4v_rtc_driver);
 150 }
 151
 152 module_init(sun4v_rtc_init);
 153 module_exit(sun4v_rtc_exit);