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#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
  17static unsigned long hypervisor_get_time(void)
  18{
  19        unsigned long ret, time;
  20        int retries = 10000;
  21
  22retry:
  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
  38static 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
  44static int hypervisor_set_time(unsigned long secs)
  45{
  46        unsigned long ret;
  47        int retries = 10000;
  48
  49retry:
  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
  65static 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
  77static const struct rtc_class_ops sun4v_rtc_ops = {
  78        .read_time      = sun4v_read_time,
  79        .set_time       = sun4v_set_time,
  80};
  81
  82static 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
  95static int __exit sun4v_rtc_remove(struct platform_device *pdev)
  96{
  97        return 0;
  98}
  99
 100static struct platform_driver sun4v_rtc_driver = {
 101        .driver         = {
 102                .name   = "rtc-sun4v",
 103                .owner  = THIS_MODULE,
 104        },
 105        .remove         = __exit_p(sun4v_rtc_remove),
 106};
 107
 108module_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
 109
 110MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
 111MODULE_DESCRIPTION("SUN4V RTC driver");
 112MODULE_LICENSE("GPL");
 113
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