drivers/rtc/rtc-sun4v.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.
0003  *
0004  * Author: David S. Miller
0005  *
0006  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
0007  */
0008
0009 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0010
0011 #include <linux/kernel.h>
0012 #include <linux/delay.h>
0013 #include <linux/init.h>
0014 #include <linux/rtc.h>
0015 #include <linux/platform_device.h>
0016
0017 #include <asm/hypervisor.h>
0018
0019 static unsigned long hypervisor_get_time(void)
0020 {
0021     unsigned long ret, time;
0022     int retries = 10000;
0023
0024 retry:
0025     ret = sun4v_tod_get(&time);
0026     if (ret == HV_EOK)
0027         return time;
0028     if (ret == HV_EWOULDBLOCK) {
0029         if (--retries > 0) {
0030             udelay(100);
0031             goto retry;
0032         }
0033         pr_warn("tod_get() timed out.\n");
0034         return 0;
0035     }
0036     pr_warn("tod_get() not supported.\n");
0037     return 0;
0038 }
0039
0040 static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
0041 {
0042     rtc_time64_to_tm(hypervisor_get_time(), tm);
0043     return 0;
0044 }
0045
0046 static int hypervisor_set_time(unsigned long secs)
0047 {
0048     unsigned long ret;
0049     int retries = 10000;
0050
0051 retry:
0052     ret = sun4v_tod_set(secs);
0053     if (ret == HV_EOK)
0054         return 0;
0055     if (ret == HV_EWOULDBLOCK) {
0056         if (--retries > 0) {
0057             udelay(100);
0058             goto retry;
0059         }
0060         pr_warn("tod_set() timed out.\n");
0061         return -EAGAIN;
0062     }
0063     pr_warn("tod_set() not supported.\n");
0064     return -EOPNOTSUPP;
0065 }
0066
0067 static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
0068 {
0069     return hypervisor_set_time(rtc_tm_to_time64(tm));
0070 }
0071
0072 static const struct rtc_class_ops sun4v_rtc_ops = {
0073     .read_time  = sun4v_read_time,
0074     .set_time   = sun4v_set_time,
0075 };
0076
0077 static int __init sun4v_rtc_probe(struct platform_device *pdev)
0078 {
0079     struct rtc_device *rtc;
0080
0081     rtc = devm_rtc_allocate_device(&pdev->dev);
0082     if (IS_ERR(rtc))
0083         return PTR_ERR(rtc);
0084
0085     rtc->ops = &sun4v_rtc_ops;
0086     rtc->range_max = U64_MAX;
0087     platform_set_drvdata(pdev, rtc);
0088
0089     return devm_rtc_register_device(rtc);
0090 }
0091
0092 static struct platform_driver sun4v_rtc_driver = {
0093     .driver     = {
0094         .name   = "rtc-sun4v",
0095     },
0096 };
0097
0098 builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);