1 /*
2 * An rtc/i2c driver for the Dallas DS1672
3 * Copyright 2005-06 Tower Technologies
4 *
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/i2c.h>
13 #include <linux/rtc.h>
14 #include <linux/module.h>
15
16 #define DRV_VERSION "0.4"
17
18 /* Registers */
19
20 #define DS1672_REG_CNT_BASE 0
21 #define DS1672_REG_CONTROL 4
22 #define DS1672_REG_TRICKLE 5
23
24 #define DS1672_REG_CONTROL_EOSC 0x80
25
26 static struct i2c_driver ds1672_driver;
27
28 /*
29 * In the routines that deal directly with the ds1672 hardware, we use
30 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
31 * Epoch is initialized as 2000. Time is set to UTC.
32 */
ds1672_get_datetime(struct i2c_client * client,struct rtc_time * tm)33 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
34 {
35 unsigned long time;
36 unsigned char addr = DS1672_REG_CNT_BASE;
37 unsigned char buf[4];
38
39 struct i2c_msg msgs[] = {
40 {/* setup read ptr */
41 .addr = client->addr,
42 .len = 1,
43 .buf = &addr
44 },
45 {/* read date */
46 .addr = client->addr,
47 .flags = I2C_M_RD,
48 .len = 4,
49 .buf = buf
50 },
51 };
52
53 /* read date registers */
54 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
55 dev_err(&client->dev, "%s: read error\n", __func__);
56 return -EIO;
57 }
58
59 dev_dbg(&client->dev,
60 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
61 __func__, buf[0], buf[1], buf[2], buf[3]);
62
63 time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
64 (buf[1] << 8) | buf[0];
65
66 rtc_time_to_tm(time, tm);
67
68 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
69 "mday=%d, mon=%d, year=%d, wday=%d\n",
70 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
71 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
72
73 return 0;
74 }
75
ds1672_set_mmss(struct i2c_client * client,unsigned long secs)76 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
77 {
78 int xfer;
79 unsigned char buf[6];
80
81 buf[0] = DS1672_REG_CNT_BASE;
82 buf[1] = secs & 0x000000FF;
83 buf[2] = (secs & 0x0000FF00) >> 8;
84 buf[3] = (secs & 0x00FF0000) >> 16;
85 buf[4] = (secs & 0xFF000000) >> 24;
86 buf[5] = 0; /* set control reg to enable counting */
87
88 xfer = i2c_master_send(client, buf, 6);
89 if (xfer != 6) {
90 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
91 return -EIO;
92 }
93
94 return 0;
95 }
96
ds1672_rtc_read_time(struct device * dev,struct rtc_time * tm)97 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
98 {
99 return ds1672_get_datetime(to_i2c_client(dev), tm);
100 }
101
ds1672_rtc_set_mmss(struct device * dev,unsigned long secs)102 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
103 {
104 return ds1672_set_mmss(to_i2c_client(dev), secs);
105 }
106
ds1672_get_control(struct i2c_client * client,u8 * status)107 static int ds1672_get_control(struct i2c_client *client, u8 *status)
108 {
109 unsigned char addr = DS1672_REG_CONTROL;
110
111 struct i2c_msg msgs[] = {
112 {/* setup read ptr */
113 .addr = client->addr,
114 .len = 1,
115 .buf = &addr
116 },
117 {/* read control */
118 .addr = client->addr,
119 .flags = I2C_M_RD,
120 .len = 1,
121 .buf = status
122 },
123 };
124
125 /* read control register */
126 if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
127 dev_err(&client->dev, "%s: read error\n", __func__);
128 return -EIO;
129 }
130
131 return 0;
132 }
133
134 /* following are the sysfs callback functions */
show_control(struct device * dev,struct device_attribute * attr,char * buf)135 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
136 char *buf)
137 {
138 struct i2c_client *client = to_i2c_client(dev);
139 u8 control;
140 int err;
141
142 err = ds1672_get_control(client, &control);
143 if (err)
144 return err;
145
146 return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
147 ? "disabled" : "enabled");
148 }
149
150 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
151
152 static const struct rtc_class_ops ds1672_rtc_ops = {
153 .read_time = ds1672_rtc_read_time,
154 .set_mmss = ds1672_rtc_set_mmss,
155 };
156
ds1672_probe(struct i2c_client * client,const struct i2c_device_id * id)157 static int ds1672_probe(struct i2c_client *client,
158 const struct i2c_device_id *id)
159 {
160 int err = 0;
161 u8 control;
162 struct rtc_device *rtc;
163
164 dev_dbg(&client->dev, "%s\n", __func__);
165
166 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
167 return -ENODEV;
168
169 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
170
171 rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name,
172 &ds1672_rtc_ops, THIS_MODULE);
173
174 if (IS_ERR(rtc))
175 return PTR_ERR(rtc);
176
177 i2c_set_clientdata(client, rtc);
178
179 /* read control register */
180 err = ds1672_get_control(client, &control);
181 if (err) {
182 dev_warn(&client->dev, "Unable to read the control register\n");
183 }
184
185 if (control & DS1672_REG_CONTROL_EOSC)
186 dev_warn(&client->dev, "Oscillator not enabled. "
187 "Set time to enable.\n");
188
189 /* Register sysfs hooks */
190 err = device_create_file(&client->dev, &dev_attr_control);
191 if (err)
192 dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
193 dev_attr_control.attr.name);
194
195 return 0;
196 }
197
198 static struct i2c_device_id ds1672_id[] = {
199 { "ds1672", 0 },
200 { }
201 };
202 MODULE_DEVICE_TABLE(i2c, ds1672_id);
203
204 static struct i2c_driver ds1672_driver = {
205 .driver = {
206 .name = "rtc-ds1672",
207 },
208 .probe = &ds1672_probe,
209 .id_table = ds1672_id,
210 };
211
212 module_i2c_driver(ds1672_driver);
213
214 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
215 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
216 MODULE_LICENSE("GPL");
217 MODULE_VERSION(DRV_VERSION);
218