1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * An rtc/i2c driver for the EM Microelectronic EM3027
4 * Copyright 2011 CompuLab, Ltd.
5 *
6 * Author: Mike Rapoport <mike@compulab.co.il>
7 *
8 * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it>
9 */
10
11#include <linux/i2c.h>
12#include <linux/rtc.h>
13#include <linux/bcd.h>
14#include <linux/module.h>
15#include <linux/of.h>
16
17/* Registers */
18#define EM3027_REG_ON_OFF_CTRL	0x00
19#define EM3027_REG_IRQ_CTRL	0x01
20#define EM3027_REG_IRQ_FLAGS	0x02
21#define EM3027_REG_STATUS	0x03
22#define EM3027_REG_RST_CTRL	0x04
23
24#define EM3027_REG_WATCH_SEC	0x08
25#define EM3027_REG_WATCH_MIN	0x09
26#define EM3027_REG_WATCH_HOUR	0x0a
27#define EM3027_REG_WATCH_DATE	0x0b
28#define EM3027_REG_WATCH_DAY	0x0c
29#define EM3027_REG_WATCH_MON	0x0d
30#define EM3027_REG_WATCH_YEAR	0x0e
31
32#define EM3027_REG_ALARM_SEC	0x10
33#define EM3027_REG_ALARM_MIN	0x11
34#define EM3027_REG_ALARM_HOUR	0x12
35#define EM3027_REG_ALARM_DATE	0x13
36#define EM3027_REG_ALARM_DAY	0x14
37#define EM3027_REG_ALARM_MON	0x15
38#define EM3027_REG_ALARM_YEAR	0x16
39
40static struct i2c_driver em3027_driver;
41
42static int em3027_get_time(struct device *dev, struct rtc_time *tm)
43{
44	struct i2c_client *client = to_i2c_client(dev);
45
46	unsigned char addr = EM3027_REG_WATCH_SEC;
47	unsigned char buf[7];
48
49	struct i2c_msg msgs[] = {
50		{/* setup read addr */
51			.addr = client->addr,
52			.len = 1,
53			.buf = &addr
54		},
55		{/* read time/date */
56			.addr = client->addr,
57			.flags = I2C_M_RD,
58			.len = 7,
59			.buf = buf
60		},
61	};
62
63	/* read time/date registers */
64	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
65		dev_err(&client->dev, "%s: read error\n", __func__);
66		return -EIO;
67	}
68
69	tm->tm_sec	= bcd2bin(buf[0]);
70	tm->tm_min	= bcd2bin(buf[1]);
71	tm->tm_hour	= bcd2bin(buf[2]);
72	tm->tm_mday	= bcd2bin(buf[3]);
73	tm->tm_wday	= bcd2bin(buf[4]);
74	tm->tm_mon	= bcd2bin(buf[5]) - 1;
75	tm->tm_year	= bcd2bin(buf[6]) + 100;
76
77	return 0;
78}
79
80static int em3027_set_time(struct device *dev, struct rtc_time *tm)
81{
82	struct i2c_client *client = to_i2c_client(dev);
83	unsigned char buf[8];
84
85	struct i2c_msg msg = {
86		.addr = client->addr,
87		.len = 8,
88		.buf = buf,	/* write time/date */
89	};
90
91	buf[0] = EM3027_REG_WATCH_SEC;
92	buf[1] = bin2bcd(tm->tm_sec);
93	buf[2] = bin2bcd(tm->tm_min);
94	buf[3] = bin2bcd(tm->tm_hour);
95	buf[4] = bin2bcd(tm->tm_mday);
96	buf[5] = bin2bcd(tm->tm_wday);
97	buf[6] = bin2bcd(tm->tm_mon + 1);
98	buf[7] = bin2bcd(tm->tm_year % 100);
99
100	/* write time/date registers */
101	if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
102		dev_err(&client->dev, "%s: write error\n", __func__);
103		return -EIO;
104	}
105
106	return 0;
107}
108
109static const struct rtc_class_ops em3027_rtc_ops = {
110	.read_time = em3027_get_time,
111	.set_time = em3027_set_time,
112};
113
114static int em3027_probe(struct i2c_client *client)
115{
116	struct rtc_device *rtc;
117
118	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
119		return -ENODEV;
120
121	rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
122				  &em3027_rtc_ops, THIS_MODULE);
123	if (IS_ERR(rtc))
124		return PTR_ERR(rtc);
125
126	i2c_set_clientdata(client, rtc);
127
128	return 0;
129}
130
131static const struct i2c_device_id em3027_id[] = {
132	{ "em3027", 0 },
133	{ }
134};
135MODULE_DEVICE_TABLE(i2c, em3027_id);
136
137#ifdef CONFIG_OF
138static const struct of_device_id em3027_of_match[] = {
139	{ .compatible = "emmicro,em3027", },
140	{}
141};
142MODULE_DEVICE_TABLE(of, em3027_of_match);
143#endif
144
145static struct i2c_driver em3027_driver = {
146	.driver = {
147		   .name = "rtc-em3027",
148		   .of_match_table = of_match_ptr(em3027_of_match),
149	},
150	.probe = em3027_probe,
151	.id_table = em3027_id,
152};
153
154module_i2c_driver(em3027_driver);
155
156MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
157MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
158MODULE_LICENSE("GPL");
159