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 
hypervisor_get_time(void)19 static unsigned long hypervisor_get_time(void)
20 {
21 	unsigned long ret, time;
22 	int retries = 10000;
23 
24 retry:
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 
sun4v_read_time(struct device * dev,struct rtc_time * tm)40 static 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 
hypervisor_set_time(unsigned long secs)46 static int hypervisor_set_time(unsigned long secs)
47 {
48 	unsigned long ret;
49 	int retries = 10000;
50 
51 retry:
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 
sun4v_set_time(struct device * dev,struct rtc_time * tm)67 static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
68 {
69 	return hypervisor_set_time(rtc_tm_to_time64(tm));
70 }
71 
72 static const struct rtc_class_ops sun4v_rtc_ops = {
73 	.read_time	= sun4v_read_time,
74 	.set_time	= sun4v_set_time,
75 };
76 
sun4v_rtc_probe(struct platform_device * pdev)77 static 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 
92 static struct platform_driver sun4v_rtc_driver = {
93 	.driver		= {
94 		.name	= "rtc-sun4v",
95 	},
96 };
97 
98 builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
99