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	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
22static 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
53static 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
80static const struct rtc_class_ops aspeed_rtc_ops = {
81	.read_time = aspeed_rtc_read_time,
82	.set_time = aspeed_rtc_set_time,
83};
84
85static 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
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	{}
115};
116MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
117
118static struct platform_driver aspeed_rtc_driver = {
119	.driver = {
120		.name = "aspeed-rtc",
121		.of_match_table = aspeed_rtc_match,
122	},
123};
124
125module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
126
127MODULE_DESCRIPTION("ASPEED RTC driver");
128MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
129MODULE_LICENSE("GPL");
130