linux/drivers/rtc/rtc-sun4v.c
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   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
  15static unsigned long hypervisor_get_time(void)
  16{
  17        unsigned long ret, time;
  18        int retries = 10000;
  19
  20retry:
  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
  36static 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
  42static int hypervisor_set_time(unsigned long secs)
  43{
  44        unsigned long ret;
  45        int retries = 10000;
  46
  47retry:
  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
  63static 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
  75static const struct rtc_class_ops sun4v_rtc_ops = {
  76        .read_time      = sun4v_read_time,
  77        .set_time       = sun4v_set_time,
  78};
  79
  80static 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
  91static 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
  99static 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
 107static int __init sun4v_rtc_init(void)
 108{
 109        return platform_driver_probe(&sun4v_rtc_driver, sun4v_rtc_probe);
 110}
 111
 112static void __exit sun4v_rtc_exit(void)
 113{
 114        platform_driver_unregister(&sun4v_rtc_driver);
 115}
 116
 117module_init(sun4v_rtc_init);
 118module_exit(sun4v_rtc_exit);
 119
 120MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
 121MODULE_DESCRIPTION("SUN4V RTC driver");
 122MODULE_LICENSE("GPL");
 123
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