2 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
4 * Written by: Grant Likely <grant.likely@secretlab.ca>
6 * Copyright (C) 2007 Secret Lab Technologies Ltd.
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.
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.
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
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.
34 #include <linux/module.h>
35 #include <linux/init.h>
36 #include <linux/i2c.h>
37 #include <linux/string.h>
38 #include <linux/list.h>
39 #include <linux/sysfs.h>
40 #include <linux/ctype.h>
41 #include <linux/hwmon-sysfs.h>
43 /* Device registers */
44 #define DS1682_REG_CONFIG 0x00
45 #define DS1682_REG_ALARM 0x01
46 #define DS1682_REG_ELAPSED 0x05
47 #define DS1682_REG_EVT_CNTR 0x09
48 #define DS1682_REG_EEPROM 0x0b
49 #define DS1682_REG_RESET 0x1d
50 #define DS1682_REG_WRITE_DISABLE 0x1e
51 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f
53 #define DS1682_EEPROM_SIZE 10
56 * Generic counter attributes
58 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
61 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
62 struct i2c_client *client = to_i2c_client(dev);
66 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
68 /* Read the register */
69 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
74 /* Special case: the 32 bit regs are time values with 1/4s
75 * resolution, scale them up to milliseconds */
77 return sprintf(buf, "%llu\n",
78 ((unsigned long long)le32_to_cpu(val)) * 250);
80 /* Format the output string and return # of bytes */
81 return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
84 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
85 const char *buf, size_t count)
87 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
88 struct i2c_client *client = to_i2c_client(dev);
94 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
97 val = simple_strtoull(buf, &endp, 0);
99 dev_dbg(dev, "input string not a number\n");
103 /* Special case: the 32 bit regs are time values with 1/4s
104 * resolution, scale input down to quarter-seconds */
108 /* write out the value */
109 val_le = cpu_to_le32(val);
110 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
113 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
114 sattr->index, sattr->nr);
122 * Simple register attributes
124 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
125 ds1682_store, 4, DS1682_REG_ELAPSED);
126 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
127 ds1682_store, 4, DS1682_REG_ALARM);
128 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
129 ds1682_store, 2, DS1682_REG_EVT_CNTR);
131 static const struct attribute_group ds1682_group = {
132 .attrs = (struct attribute *[]) {
133 &sensor_dev_attr_elapsed_time.dev_attr.attr,
134 &sensor_dev_attr_alarm_time.dev_attr.attr,
135 &sensor_dev_attr_event_count.dev_attr.attr,
141 * User data attribute
143 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
144 struct bin_attribute *attr,
145 char *buf, loff_t off, size_t count)
147 struct i2c_client *client = kobj_to_i2c_client(kobj);
150 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
153 if (off >= DS1682_EEPROM_SIZE)
156 if (off + count > DS1682_EEPROM_SIZE)
157 count = DS1682_EEPROM_SIZE - off;
159 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
167 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
168 struct bin_attribute *attr,
169 char *buf, loff_t off, size_t count)
171 struct i2c_client *client = kobj_to_i2c_client(kobj);
173 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
176 if (off >= DS1682_EEPROM_SIZE)
179 if (off + count > DS1682_EEPROM_SIZE)
180 count = DS1682_EEPROM_SIZE - off;
182 /* Write out to the device */
183 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
190 static struct bin_attribute ds1682_eeprom_attr = {
193 .mode = S_IRUGO | S_IWUSR,
195 .size = DS1682_EEPROM_SIZE,
196 .read = ds1682_eeprom_read,
197 .write = ds1682_eeprom_write,
201 * Called when a ds1682 device is matched with this driver
203 static int ds1682_probe(struct i2c_client *client,
204 const struct i2c_device_id *id)
208 if (!i2c_check_functionality(client->adapter,
209 I2C_FUNC_SMBUS_I2C_BLOCK)) {
210 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
215 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
219 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
226 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
231 static int ds1682_remove(struct i2c_client *client)
233 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
234 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
238 static const struct i2c_device_id ds1682_id[] = {
242 MODULE_DEVICE_TABLE(i2c, ds1682_id);
244 static struct i2c_driver ds1682_driver = {
248 .probe = ds1682_probe,
249 .remove = ds1682_remove,
250 .id_table = ds1682_id,
253 static int __init ds1682_init(void)
255 return i2c_add_driver(&ds1682_driver);
258 static void __exit ds1682_exit(void)
260 i2c_del_driver(&ds1682_driver);
263 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
264 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
265 MODULE_LICENSE("GPL");
267 module_init(ds1682_init);
268 module_exit(ds1682_exit);