1 /*
2 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
3 *
4 * Written by: Grant Likely <grant.likely@secretlab.ca>
5 *
6 * Copyright (C) 2007 Secret Lab Technologies Ltd.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13 /*
14 * The DS1682 elapsed timer recorder is a simple device that implements
15 * one elapsed time counter, one event counter, an alarm signal and 10
16 * bytes of general purpose EEPROM.
17 *
18 * This driver provides access to the DS1682 counters and user data via
19 * the sysfs. The following attributes are added to the device node:
20 * elapsed_time (u32): Total elapsed event time in ms resolution
21 * alarm_time (u32): When elapsed time exceeds the value in alarm_time,
22 * then the alarm pin is asserted.
23 * event_count (u16): number of times the event pin has gone low.
24 * eeprom (u8[10]): general purpose EEPROM
25 *
26 * Counter registers and user data are both read/write unless the device
27 * has been write protected. This driver does not support turning off write
28 * protection. Once write protection is turned on, it is impossible to
29 * turn it off again, so I have left the feature out of this driver to avoid
30 * accidental enabling, but it is trivial to add write protect support.
31 *
32 */
33
34 #include <linux/module.h>
35 #include <linux/init.h>
36 #include <linux/slab.h>
37 #include <linux/i2c.h>
38 #include <linux/string.h>
39 #include <linux/list.h>
40 #include <linux/sysfs.h>
41 #include <linux/ctype.h>
42 #include <linux/hwmon-sysfs.h>
43
44 /* Device registers */
45 #define DS1682_REG_CONFIG 0x00
46 #define DS1682_REG_ALARM 0x01
47 #define DS1682_REG_ELAPSED 0x05
48 #define DS1682_REG_EVT_CNTR 0x09
49 #define DS1682_REG_EEPROM 0x0b
50 #define DS1682_REG_RESET 0x1d
51 #define DS1682_REG_WRITE_DISABLE 0x1e
52 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f
53
54 #define DS1682_EEPROM_SIZE 10
55
56 /*
57 * Generic counter attributes
58 */
59 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
60 char *buf)
61 {
62 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
63 struct i2c_client *client = to_i2c_client(dev);
64 __le32 val = 0;
65 int rc;
66
67 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
68
69 /* Read the register */
70 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
71 (u8 *) & val);
72 if (rc < 0)
73 return -EIO;
74
75 /* Special case: the 32 bit regs are time values with 1/4s
76 * resolution, scale them up to milliseconds */
77 if (sattr->nr == 4)
78 return sprintf(buf, "%llu\n",
79 ((unsigned long long)le32_to_cpu(val)) * 250);
80
81 /* Format the output string and return # of bytes */
82 return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
83 }
84
85 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
86 const char *buf, size_t count)
87 {
88 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
89 struct i2c_client *client = to_i2c_client(dev);
90 char *endp;
91 u64 val;
92 __le32 val_le;
93 int rc;
94
95 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
96
97 /* Decode input */
98 val = simple_strtoull(buf, &endp, 0);
99 if (buf == endp) {
100 dev_dbg(dev, "input string not a number\n");
101 return -EINVAL;
102 }
103
104 /* Special case: the 32 bit regs are time values with 1/4s
105 * resolution, scale input down to quarter-seconds */
106 if (sattr->nr == 4)
107 do_div(val, 250);
108
109 /* write out the value */
110 val_le = cpu_to_le32(val);
111 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
112 (u8 *) & val_le);
113 if (rc < 0) {
114 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
115 sattr->index, sattr->nr);
116 return -EIO;
117 }
118
119 return count;
120 }
121
122 /*
123 * Simple register attributes
124 */
125 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
126 ds1682_store, 4, DS1682_REG_ELAPSED);
127 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
128 ds1682_store, 4, DS1682_REG_ALARM);
129 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
130 ds1682_store, 2, DS1682_REG_EVT_CNTR);
131
132 static const struct attribute_group ds1682_group = {
133 .attrs = (struct attribute *[]) {
134 &sensor_dev_attr_elapsed_time.dev_attr.attr,
135 &sensor_dev_attr_alarm_time.dev_attr.attr,
136 &sensor_dev_attr_event_count.dev_attr.attr,
137 NULL,
138 },
139 };
140
141 /*
142 * User data attribute
143 */
144 static ssize_t ds1682_eeprom_read(struct kobject *kobj, struct bin_attribute *attr,
145 char *buf, loff_t off, size_t count)
146 {
147 struct i2c_client *client = kobj_to_i2c_client(kobj);
148 int rc;
149
150 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
151 buf, off, count);
152
153 if (off >= DS1682_EEPROM_SIZE)
154 return 0;
155
156 if (off + count > DS1682_EEPROM_SIZE)
157 count = DS1682_EEPROM_SIZE - off;
158
159 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
160 count, buf);
161 if (rc < 0)
162 return -EIO;
163
164 return count;
165 }
166
167 static ssize_t ds1682_eeprom_write(struct kobject *kobj, struct bin_attribute *attr,
168 char *buf, loff_t off, size_t count)
169 {
170 struct i2c_client *client = kobj_to_i2c_client(kobj);
171
172 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
173 buf, off, count);
174
175 if (off >= DS1682_EEPROM_SIZE)
176 return -ENOSPC;
177
178 if (off + count > DS1682_EEPROM_SIZE)
179 count = DS1682_EEPROM_SIZE - off;
180
181 /* Write out to the device */
182 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
183 count, buf) < 0)
184 return -EIO;
185
186 return count;
187 }
188
189 static struct bin_attribute ds1682_eeprom_attr = {
190 .attr = {
191 .name = "eeprom",
192 .mode = S_IRUGO | S_IWUSR,
193 .owner = THIS_MODULE,
194 },
195 .size = DS1682_EEPROM_SIZE,
196 .read = ds1682_eeprom_read,
197 .write = ds1682_eeprom_write,
198 };
199
200 /*
201 * Called when a ds1682 device is matched with this driver
202 */
203 static int ds1682_probe(struct i2c_client *client)
204 {
205 int rc;
206
207 if (!i2c_check_functionality(client->adapter,
208 I2C_FUNC_SMBUS_I2C_BLOCK)) {
209 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
210 rc = -ENODEV;
211 goto exit;
212 }
213
214 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
215 if (rc)
216 goto exit;
217
218 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
219 if (rc)
220 goto exit_bin_attr;
221
222 return 0;
223
224 exit_bin_attr:
225 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
226 exit:
227 return rc;
228 }
229
230 static int ds1682_remove(struct i2c_client *client)
231 {
232 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
233 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
234 return 0;
235 }
236
237 static struct i2c_driver ds1682_driver = {
238 .driver = {
239 .name = "ds1682",
240 },
241 .probe = ds1682_probe,
242 .remove = ds1682_remove,
243 };
244
245 static int __init ds1682_init(void)
246 {
247 return i2c_add_driver(&ds1682_driver);
248 }
249
250 static void __exit ds1682_exit(void)
251 {
252 i2c_del_driver(&ds1682_driver);
253 }
254
255 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
256 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
257 MODULE_LICENSE("GPL");
258
259 module_init(ds1682_init);
260 module_exit(ds1682_exit);
261
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