LXR linux/drivers/rtc/rtc-sun4v.c

   1// SPDX-License-Identifier: GPL-2.0
   2/* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.
   3 *
   4 * Author: David S. Miller
   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
  19static unsigned long hypervisor_get_time(void)
  20{
  21        unsigned long ret, time;
  22        int retries = 10000;
  23
  24retry:
  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
  40static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
  41{
  42        rtc_time64_to_tm(hypervisor_get_time(), tm);
  43        return 0;
  44}
  45
  46static int hypervisor_set_time(unsigned long secs)
  47{
  48        unsigned long ret;
  49        int retries = 10000;
  50
  51retry:
  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
  67static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
  68{
  69        return hypervisor_set_time(rtc_tm_to_time64(tm));
  70}
  71
  72static const struct rtc_class_ops sun4v_rtc_ops = {
  73        .read_time      = sun4v_read_time,
  74        .set_time       = sun4v_set_time,
  75};
  76
  77static int __init sun4v_rtc_probe(struct platform_device *pdev)
  78{
  79        struct rtc_device *rtc;
  80
  81        rtc = devm_rtc_allocate_device(&pdev->dev);
  82        if (IS_ERR(rtc))
  83                return PTR_ERR(rtc);
  84
  85        rtc->ops = &sun4v_rtc_ops;
  86        rtc->range_max = U64_MAX;
  87        platform_set_drvdata(pdev, rtc);
  88
  89        return rtc_register_device(rtc);
  90}
  91
  92static struct platform_driver sun4v_rtc_driver = {
  93        .driver         = {
  94                .name   = "rtc-sun4v",
  95        },
  96};
  97
  98builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
  99