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 struct platform_driver sun4v_rtc_driver = {
96	.driver		= {
97		.name	= "rtc-sun4v",
98		.owner	= THIS_MODULE,
99	},
100};
101
102module_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
103
104MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
105MODULE_DESCRIPTION("SUN4V RTC driver");
106MODULE_LICENSE("GPL");
107