1/*
2 * An rtc/i2c driver for the EM Microelectronic EM3027
3 * Copyright 2011 CompuLab, Ltd.
4 *
5 * Author: Mike Rapoport <mike@compulab.co.il>
6 *
7 * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14#include <linux/i2c.h>
15#include <linux/rtc.h>
16#include <linux/bcd.h>
17#include <linux/module.h>
18#include <linux/of.h>
19
20/* Registers */
21#define EM3027_REG_ON_OFF_CTRL	0x00
22#define EM3027_REG_IRQ_CTRL	0x01
23#define EM3027_REG_IRQ_FLAGS	0x02
24#define EM3027_REG_STATUS	0x03
25#define EM3027_REG_RST_CTRL	0x04
26
27#define EM3027_REG_WATCH_SEC	0x08
28#define EM3027_REG_WATCH_MIN	0x09
29#define EM3027_REG_WATCH_HOUR	0x0a
30#define EM3027_REG_WATCH_DATE	0x0b
31#define EM3027_REG_WATCH_DAY	0x0c
32#define EM3027_REG_WATCH_MON	0x0d
33#define EM3027_REG_WATCH_YEAR	0x0e
34
35#define EM3027_REG_ALARM_SEC	0x10
36#define EM3027_REG_ALARM_MIN	0x11
37#define EM3027_REG_ALARM_HOUR	0x12
38#define EM3027_REG_ALARM_DATE	0x13
39#define EM3027_REG_ALARM_DAY	0x14
40#define EM3027_REG_ALARM_MON	0x15
41#define EM3027_REG_ALARM_YEAR	0x16
42
43static struct i2c_driver em3027_driver;
44
45static int em3027_get_time(struct device *dev, struct rtc_time *tm)
46{
47	struct i2c_client *client = to_i2c_client(dev);
48
49	unsigned char addr = EM3027_REG_WATCH_SEC;
50	unsigned char buf[7];
51
52	struct i2c_msg msgs[] = {
53		{/* setup read addr */
54			.addr = client->addr,
55			.len = 1,
56			.buf = &addr
57		},
58		{/* read time/date */
59			.addr = client->addr,
60			.flags = I2C_M_RD,
61			.len = 7,
62			.buf = buf
63		},
64	};
65
66	/* read time/date registers */
67	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
68		dev_err(&client->dev, "%s: read error\n", __func__);
69		return -EIO;
70	}
71
72	tm->tm_sec	= bcd2bin(buf[0]);
73	tm->tm_min	= bcd2bin(buf[1]);
74	tm->tm_hour	= bcd2bin(buf[2]);
75	tm->tm_mday	= bcd2bin(buf[3]);
76	tm->tm_wday	= bcd2bin(buf[4]);
77	tm->tm_mon	= bcd2bin(buf[5]);
78	tm->tm_year	= bcd2bin(buf[6]) + 100;
79
80	return 0;
81}
82
83static int em3027_set_time(struct device *dev, struct rtc_time *tm)
84{
85	struct i2c_client *client = to_i2c_client(dev);
86	unsigned char buf[8];
87
88	struct i2c_msg msg = {
89		.addr = client->addr,
90		.len = 8,
91		.buf = buf,	/* write time/date */
92	};
93
94	buf[0] = EM3027_REG_WATCH_SEC;
95	buf[1] = bin2bcd(tm->tm_sec);
96	buf[2] = bin2bcd(tm->tm_min);
97	buf[3] = bin2bcd(tm->tm_hour);
98	buf[4] = bin2bcd(tm->tm_mday);
99	buf[5] = bin2bcd(tm->tm_wday);
100	buf[6] = bin2bcd(tm->tm_mon);
101	buf[7] = bin2bcd(tm->tm_year % 100);
102
103	/* write time/date registers */
104	if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
105		dev_err(&client->dev, "%s: write error\n", __func__);
106		return -EIO;
107	}
108
109	return 0;
110}
111
112static const struct rtc_class_ops em3027_rtc_ops = {
113	.read_time = em3027_get_time,
114	.set_time = em3027_set_time,
115};
116
117static int em3027_probe(struct i2c_client *client,
118			const struct i2c_device_id *id)
119{
120	struct rtc_device *rtc;
121
122	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
123		return -ENODEV;
124
125	rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
126				  &em3027_rtc_ops, THIS_MODULE);
127	if (IS_ERR(rtc))
128		return PTR_ERR(rtc);
129
130	i2c_set_clientdata(client, rtc);
131
132	return 0;
133}
134
135static struct i2c_device_id em3027_id[] = {
136	{ "em3027", 0 },
137	{ }
138};
139MODULE_DEVICE_TABLE(i2c, em3027_id);
140
141#ifdef CONFIG_OF
142static const struct of_device_id em3027_of_match[] = {
143	{ .compatible = "emmicro,em3027", },
144	{}
145};
146MODULE_DEVICE_TABLE(of, em3027_of_match);
147#endif
148
149static struct i2c_driver em3027_driver = {
150	.driver = {
151		   .name = "rtc-em3027",
152		   .of_match_table = of_match_ptr(em3027_of_match),
153	},
154	.probe = &em3027_probe,
155	.id_table = em3027_id,
156};
157
158module_i2c_driver(em3027_driver);
159
160MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
161MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
162MODULE_LICENSE("GPL");
163