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
pm886_rtc_read_time(struct device * dev,struct rtc_time * tm)14 static 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
pm886_rtc_set_time(struct device * dev,struct rtc_time * tm)36 static 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
51 static const struct rtc_class_ops pm886_rtc_ops = {
52 .read_time = pm886_rtc_read_time,
53 .set_time = pm886_rtc_set_time,
54 };
55
pm886_rtc_probe(struct platform_device * pdev)56 static 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
80 static const struct platform_device_id pm886_rtc_id_table[] = {
81 { "88pm886-rtc", },
82 { }
83 };
84 MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table);
85
86 static 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 };
93 module_platform_driver(pm886_rtc_driver);
94
95 MODULE_DESCRIPTION("Marvell 88PM886 RTC driver");
96 MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
97 MODULE_LICENSE("GPL");
98