UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.git] / drivers / rtc / rtc-sun4v.c
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
17 static unsigned long hypervisor_get_time(void)
18 {
19         unsigned long ret, time;
20         int retries = 10000;
21
22 retry:
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
38 static 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
44 static int hypervisor_set_time(unsigned long secs)
45 {
46         unsigned long ret;
47         int retries = 10000;
48
49 retry:
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
65 static 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
77 static const struct rtc_class_ops sun4v_rtc_ops = {
78         .read_time      = sun4v_read_time,
79         .set_time       = sun4v_set_time,
80 };
81
82 static 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
95 static int __exit sun4v_rtc_remove(struct platform_device *pdev)
96 {
97         return 0;
98 }
99
100 static struct platform_driver sun4v_rtc_driver = {
101         .driver         = {
102                 .name   = "rtc-sun4v",
103                 .owner  = THIS_MODULE,
104         },
105         .remove         = __exit_p(sun4v_rtc_remove),
106 };
107
108 module_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
109
110 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
111 MODULE_DESCRIPTION("SUN4V RTC driver");
112 MODULE_LICENSE("GPL");