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