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 devm_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