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