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
43 static struct i2c_driver em3027_driver;
44
em3027_get_time(struct device * dev,struct rtc_time * tm)45 static 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
em3027_set_time(struct device * dev,struct rtc_time * tm)83 static 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
112 static const struct rtc_class_ops em3027_rtc_ops = {
113 .read_time = em3027_get_time,
114 .set_time = em3027_set_time,
115 };
116
em3027_probe(struct i2c_client * client,const struct i2c_device_id * id)117 static 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
135 static const struct i2c_device_id em3027_id[] = {
136 { "em3027", 0 },
137 { }
138 };
139 MODULE_DEVICE_TABLE(i2c, em3027_id);
140
141 #ifdef CONFIG_OF
142 static const struct of_device_id em3027_of_match[] = {
143 { .compatible = "emmicro,em3027", },
144 {}
145 };
146 MODULE_DEVICE_TABLE(of, em3027_of_match);
147 #endif
148
149 static 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
158 module_i2c_driver(em3027_driver);
159
160 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
161 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
162 MODULE_LICENSE("GPL");
163