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130 lines · 3.1 KiB

1// SPDX-License-Identifier: GPL-2.0+
2// Copyright 2015 IBM Corp.
3
4#include <linux/module.h>
5#include <linux/of.h>
6#include <linux/platform_device.h>
7#include <linux/rtc.h>
8#include <linux/io.h>
9
10struct aspeed_rtc {
11 void __iomem *base;
12};
13
14#define RTC_TIME 0x00
15#define RTC_YEAR 0x04
16#define RTC_CTRL 0x10
17
18#define RTC_UNLOCK BIT(1)
19#define RTC_ENABLE BIT(0)
20
21static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
22{
23 struct aspeed_rtc *rtc = dev_get_drvdata(dev);
24 unsigned int cent, year;
25 u32 reg1, reg2;
26
27 if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
28 dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
29 return -EINVAL;
30 }
31
32 do {
33 reg2 = readl(rtc->base + RTC_YEAR);
34 reg1 = readl(rtc->base + RTC_TIME);
35 } while (reg2 != readl(rtc->base + RTC_YEAR));
36
37 tm->tm_mday = (reg1 >> 24) & 0x1f;
38 tm->tm_hour = (reg1 >> 16) & 0x1f;
39 tm->tm_min = (reg1 >> 8) & 0x3f;
40 tm->tm_sec = (reg1 >> 0) & 0x3f;
41
42 cent = (reg2 >> 16) & 0x1f;
43 year = (reg2 >> 8) & 0x7f;
44 tm->tm_mon = ((reg2 >> 0) & 0x0f) - 1;
45 tm->tm_year = year + (cent * 100) - 1900;
46
47 dev_dbg(dev, "%s %ptR", __func__, tm);
48
49 return 0;
50}
51
52static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
53{
54 struct aspeed_rtc *rtc = dev_get_drvdata(dev);
55 u32 reg1, reg2, ctrl;
56 int year, cent;
57
58 cent = (tm->tm_year + 1900) / 100;
59 year = tm->tm_year % 100;
60
61 reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
62 tm->tm_sec;
63
64 reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
65 ((tm->tm_mon + 1) & 0xf);
66
67 ctrl = readl(rtc->base + RTC_CTRL);
68 writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
69
70 writel(reg1, rtc->base + RTC_TIME);
71 writel(reg2, rtc->base + RTC_YEAR);
72
73 /* Re-lock and ensure enable is set now that a time is programmed */
74 writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
75
76 return 0;
77}
78
79static const struct rtc_class_ops aspeed_rtc_ops = {
80 .read_time = aspeed_rtc_read_time,
81 .set_time = aspeed_rtc_set_time,
82};
83
84static int aspeed_rtc_probe(struct platform_device *pdev)
85{
86 struct aspeed_rtc *rtc;
87 struct rtc_device *rtc_dev;
88
89 rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
90 if (!rtc)
91 return -ENOMEM;
92
93 rtc->base = devm_platform_ioremap_resource(pdev, 0);
94 if (IS_ERR(rtc->base))
95 return PTR_ERR(rtc->base);
96
97 rtc_dev = devm_rtc_allocate_device(&pdev->dev);
98 if (IS_ERR(rtc_dev))
99 return PTR_ERR(rtc_dev);
100
101 platform_set_drvdata(pdev, rtc);
102
103 rtc_dev->ops = &aspeed_rtc_ops;
104 rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
105 rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
106
107 return devm_rtc_register_device(rtc_dev);
108}
109
110static const struct of_device_id aspeed_rtc_match[] = {
111 { .compatible = "aspeed,ast2400-rtc", },
112 { .compatible = "aspeed,ast2500-rtc", },
113 { .compatible = "aspeed,ast2600-rtc", },
114 { .compatible = "aspeed,ast2700-rtc", },
115 {}
116};
117MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
118
119static struct platform_driver aspeed_rtc_driver = {
120 .driver = {
121 .name = "aspeed-rtc",
122 .of_match_table = aspeed_rtc_match,
123 },
124};
125
126module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
127
128MODULE_DESCRIPTION("ASPEED RTC driver");
129MODULE_AUTHOR("Joel Stanley <[email protected]>");
130MODULE_LICENSE("GPL");