1// SPDX-License-Identifier: GPL-2.0-only
 2#include <linux/limits.h>
 3#include <linux/mod_devicetable.h>
 4#include <linux/platform_device.h>
 5#include <linux/rtc.h>
 6
 7#include <linux/mfd/88pm886.h>
 8
 9/*
10 * Time is calculated as the sum of a 32-bit read-only advancing counter and a
11 * writeable constant offset stored in the chip's spare registers.
12 */
13
14static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm)
15{
16	struct regmap *regmap = dev_get_drvdata(dev);
17	u32 time;
18	u32 buf;
19	int ret;
20
21	ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
22	if (ret)
23		return ret;
24	time = buf;
25
26	ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
27	if (ret)
28		return ret;
29	time += buf;
30
31	rtc_time64_to_tm(time, tm);
32
33	return 0;
34}
35
36static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm)
37{
38	struct regmap *regmap = dev_get_drvdata(dev);
39	u32 buf;
40	int ret;
41
42	ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
43	if (ret)
44		return ret;
45
46	buf = rtc_tm_to_time64(tm) - buf;
47
48	return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
49}
50
51static const struct rtc_class_ops pm886_rtc_ops = {
52	.read_time = pm886_rtc_read_time,
53	.set_time = pm886_rtc_set_time,
54};
55
56static int pm886_rtc_probe(struct platform_device *pdev)
57{
58	struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent);
59	struct device *dev = &pdev->dev;
60	struct rtc_device *rtc;
61	int ret;
62
63	platform_set_drvdata(pdev, chip->regmap);
64
65	rtc = devm_rtc_allocate_device(dev);
66	if (IS_ERR(rtc))
67		return dev_err_probe(dev, PTR_ERR(rtc),
68				"Failed to allocate RTC device\n");
69
70	rtc->ops = &pm886_rtc_ops;
71	rtc->range_max = U32_MAX;
72
73	ret = devm_rtc_register_device(rtc);
74	if (ret)
75		return dev_err_probe(dev, ret, "Failed to register RTC device\n");
76
77	return 0;
78}
79
80static const struct platform_device_id pm886_rtc_id_table[] = {
81	{ "88pm886-rtc", },
82	{ }
83};
84MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table);
85
86static struct platform_driver pm886_rtc_driver = {
87	.driver = {
88		.name = "88pm886-rtc",
89	},
90	.probe = pm886_rtc_probe,
91	.id_table = pm886_rtc_id_table,
92};
93module_platform_driver(pm886_rtc_driver);
94
95MODULE_DESCRIPTION("Marvell 88PM886 RTC driver");
96MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
97MODULE_LICENSE("GPL");