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 
40 static struct i2c_driver em3027_driver;
41 
em3027_get_time(struct device * dev,struct rtc_time * tm)42 static 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 
em3027_set_time(struct device * dev,struct rtc_time * tm)80 static 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 
109 static const struct rtc_class_ops em3027_rtc_ops = {
110 	.read_time = em3027_get_time,
111 	.set_time = em3027_set_time,
112 };
113 
em3027_probe(struct i2c_client * client)114 static 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 
131 static const struct i2c_device_id em3027_id[] = {
132 	{ "em3027", 0 },
133 	{ }
134 };
135 MODULE_DEVICE_TABLE(i2c, em3027_id);
136 
137 #ifdef CONFIG_OF
138 static const struct of_device_id em3027_of_match[] = {
139 	{ .compatible = "emmicro,em3027", },
140 	{}
141 };
142 MODULE_DEVICE_TABLE(of, em3027_of_match);
143 #endif
144 
145 static 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 
154 module_i2c_driver(em3027_driver);
155 
156 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
157 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
158 MODULE_LICENSE("GPL");
159