xref: /openbmc/linux/drivers/rtc/rtc-aspeed.c (revision 4f3688dc)
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