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
19/* Registers */
20#define EM3027_REG_ON_OFF_CTRL	0x00
21#define EM3027_REG_IRQ_CTRL	0x01
22#define EM3027_REG_IRQ_FLAGS	0x02
23#define EM3027_REG_STATUS	0x03
24#define EM3027_REG_RST_CTRL	0x04
25
26#define EM3027_REG_WATCH_SEC	0x08
27#define EM3027_REG_WATCH_MIN	0x09
28#define EM3027_REG_WATCH_HOUR	0x0a
29#define EM3027_REG_WATCH_DATE	0x0b
30#define EM3027_REG_WATCH_DAY	0x0c
31#define EM3027_REG_WATCH_MON	0x0d
32#define EM3027_REG_WATCH_YEAR	0x0e
33
34#define EM3027_REG_ALARM_SEC	0x10
35#define EM3027_REG_ALARM_MIN	0x11
36#define EM3027_REG_ALARM_HOUR	0x12
37#define EM3027_REG_ALARM_DATE	0x13
38#define EM3027_REG_ALARM_DAY	0x14
39#define EM3027_REG_ALARM_MON	0x15
40#define EM3027_REG_ALARM_YEAR	0x16
41
42static struct i2c_driver em3027_driver;
43
44static int em3027_get_time(struct device *dev, struct rtc_time *tm)
45{
46	struct i2c_client *client = to_i2c_client(dev);
47
48	unsigned char addr = EM3027_REG_WATCH_SEC;
49	unsigned char buf[7];
50
51	struct i2c_msg msgs[] = {
52		{client->addr, 0, 1, &addr},		/* setup read addr */
53		{client->addr, I2C_M_RD, 7, buf},	/* read time/date */
54	};
55
56	/* read time/date registers */
57	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
58		dev_err(&client->dev, "%s: read error\n", __func__);
59		return -EIO;
60	}
61
62	tm->tm_sec	= bcd2bin(buf[0]);
63	tm->tm_min	= bcd2bin(buf[1]);
64	tm->tm_hour	= bcd2bin(buf[2]);
65	tm->tm_mday	= bcd2bin(buf[3]);
66	tm->tm_wday	= bcd2bin(buf[4]);
67	tm->tm_mon	= bcd2bin(buf[5]);
68	tm->tm_year	= bcd2bin(buf[6]) + 100;
69
70	return 0;
71}
72
73static int em3027_set_time(struct device *dev, struct rtc_time *tm)
74{
75	struct i2c_client *client = to_i2c_client(dev);
76	unsigned char buf[8];
77
78	struct i2c_msg msg = {
79		client->addr, 0, 8, buf,	/* write time/date */
80	};
81
82	buf[0] = EM3027_REG_WATCH_SEC;
83	buf[1] = bin2bcd(tm->tm_sec);
84	buf[2] = bin2bcd(tm->tm_min);
85	buf[3] = bin2bcd(tm->tm_hour);
86	buf[4] = bin2bcd(tm->tm_mday);
87	buf[5] = bin2bcd(tm->tm_wday);
88	buf[6] = bin2bcd(tm->tm_mon);
89	buf[7] = bin2bcd(tm->tm_year % 100);
90
91	/* write time/date registers */
92	if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
93		dev_err(&client->dev, "%s: write error\n", __func__);
94		return -EIO;
95	}
96
97	return 0;
98}
99
100static const struct rtc_class_ops em3027_rtc_ops = {
101	.read_time = em3027_get_time,
102	.set_time = em3027_set_time,
103};
104
105static int em3027_probe(struct i2c_client *client,
106			const struct i2c_device_id *id)
107{
108	struct rtc_device *rtc;
109
110	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
111		return -ENODEV;
112
113	rtc = rtc_device_register(em3027_driver.driver.name, &client->dev,
114				  &em3027_rtc_ops, THIS_MODULE);
115	if (IS_ERR(rtc))
116		return PTR_ERR(rtc);
117
118	i2c_set_clientdata(client, rtc);
119
120	return 0;
121}
122
123static int em3027_remove(struct i2c_client *client)
124{
125	struct rtc_device *rtc = i2c_get_clientdata(client);
126
127	if (rtc)
128		rtc_device_unregister(rtc);
129
130	return 0;
131}
132
133static struct i2c_device_id em3027_id[] = {
134	{ "em3027", 0 },
135	{ }
136};
137
138static struct i2c_driver em3027_driver = {
139	.driver = {
140		   .name = "rtc-em3027",
141	},
142	.probe = &em3027_probe,
143	.remove = &em3027_remove,
144	.id_table = em3027_id,
145};
146
147static int __init em3027_init(void)
148{
149	return i2c_add_driver(&em3027_driver);
150}
151
152static void __exit em3027_exit(void)
153{
154	i2c_del_driver(&em3027_driver);
155}
156
157MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
158MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
159MODULE_LICENSE("GPL");
160
161module_init(em3027_init);
162module_exit(em3027_exit);
163