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/i2c.h>
36 #include <linux/string.h>
37 #include <linux/list.h>
38 #include <linux/sysfs.h>
39 #include <linux/ctype.h>
40 #include <linux/hwmon-sysfs.h>
41
42 /* Device registers */
43 #define DS1682_REG_CONFIG 0x00
44 #define DS1682_REG_ALARM 0x01
45 #define DS1682_REG_ELAPSED 0x05
46 #define DS1682_REG_EVT_CNTR 0x09
47 #define DS1682_REG_EEPROM 0x0b
48 #define DS1682_REG_RESET 0x1d
49 #define DS1682_REG_WRITE_DISABLE 0x1e
50 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f
51
52 #define DS1682_EEPROM_SIZE 10
53
54 /*
55 * Generic counter attributes
56 */
ds1682_show(struct device * dev,struct device_attribute * attr,char * buf)57 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
58 char *buf)
59 {
60 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
61 struct i2c_client *client = to_i2c_client(dev);
62 unsigned long long val, check;
63 __le32 val_le = 0;
64 int rc;
65
66 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
67
68 /* Read the register */
69 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
70 (u8 *)&val_le);
71 if (rc < 0)
72 return -EIO;
73
74 val = le32_to_cpu(val_le);
75
76 if (sattr->index == DS1682_REG_ELAPSED) {
77 int retries = 5;
78
79 /* Detect and retry when a tick occurs mid-read */
80 do {
81 rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
82 sattr->nr,
83 (u8 *)&val_le);
84 if (rc < 0 || retries <= 0)
85 return -EIO;
86
87 check = val;
88 val = le32_to_cpu(val_le);
89 retries--;
90 } while (val != check && val != (check + 1));
91 }
92
93 /* Format the output string and return # of bytes
94 * Special case: the 32 bit regs are time values with 1/4s
95 * resolution, scale them up to milliseconds
96 */
97 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
98 }
99
ds1682_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)100 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
101 const char *buf, size_t count)
102 {
103 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
104 struct i2c_client *client = to_i2c_client(dev);
105 u64 val;
106 __le32 val_le;
107 int rc;
108
109 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
110
111 /* Decode input */
112 rc = kstrtoull(buf, 0, &val);
113 if (rc < 0) {
114 dev_dbg(dev, "input string not a number\n");
115 return -EINVAL;
116 }
117
118 /* Special case: the 32 bit regs are time values with 1/4s
119 * resolution, scale input down to quarter-seconds */
120 if (sattr->nr == 4)
121 do_div(val, 250);
122
123 /* write out the value */
124 val_le = cpu_to_le32(val);
125 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
126 (u8 *) & val_le);
127 if (rc < 0) {
128 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
129 sattr->index, sattr->nr);
130 return -EIO;
131 }
132
133 return count;
134 }
135
136 /*
137 * Simple register attributes
138 */
139 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
140 ds1682_store, 4, DS1682_REG_ELAPSED);
141 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
142 ds1682_store, 4, DS1682_REG_ALARM);
143 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
144 ds1682_store, 2, DS1682_REG_EVT_CNTR);
145
146 static const struct attribute_group ds1682_group = {
147 .attrs = (struct attribute *[]) {
148 &sensor_dev_attr_elapsed_time.dev_attr.attr,
149 &sensor_dev_attr_alarm_time.dev_attr.attr,
150 &sensor_dev_attr_event_count.dev_attr.attr,
151 NULL,
152 },
153 };
154
155 /*
156 * User data attribute
157 */
ds1682_eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)158 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
159 struct bin_attribute *attr,
160 char *buf, loff_t off, size_t count)
161 {
162 struct i2c_client *client = kobj_to_i2c_client(kobj);
163 int rc;
164
165 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
166 buf, off, count);
167
168 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
169 count, buf);
170 if (rc < 0)
171 return -EIO;
172
173 return count;
174 }
175
ds1682_eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)176 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
177 struct bin_attribute *attr,
178 char *buf, loff_t off, size_t count)
179 {
180 struct i2c_client *client = kobj_to_i2c_client(kobj);
181
182 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
183 buf, off, count);
184
185 /* Write out to the device */
186 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
187 count, buf) < 0)
188 return -EIO;
189
190 return count;
191 }
192
193 static const struct bin_attribute ds1682_eeprom_attr = {
194 .attr = {
195 .name = "eeprom",
196 .mode = S_IRUGO | S_IWUSR,
197 },
198 .size = DS1682_EEPROM_SIZE,
199 .read = ds1682_eeprom_read,
200 .write = ds1682_eeprom_write,
201 };
202
203 /*
204 * Called when a ds1682 device is matched with this driver
205 */
ds1682_probe(struct i2c_client * client,const struct i2c_device_id * id)206 static int ds1682_probe(struct i2c_client *client,
207 const struct i2c_device_id *id)
208 {
209 int rc;
210
211 if (!i2c_check_functionality(client->adapter,
212 I2C_FUNC_SMBUS_I2C_BLOCK)) {
213 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
214 rc = -ENODEV;
215 goto exit;
216 }
217
218 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
219 if (rc)
220 goto exit;
221
222 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
223 if (rc)
224 goto exit_bin_attr;
225
226 return 0;
227
228 exit_bin_attr:
229 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
230 exit:
231 return rc;
232 }
233
ds1682_remove(struct i2c_client * client)234 static int ds1682_remove(struct i2c_client *client)
235 {
236 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
237 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
238 return 0;
239 }
240
241 static const struct i2c_device_id ds1682_id[] = {
242 { "ds1682", 0 },
243 { }
244 };
245 MODULE_DEVICE_TABLE(i2c, ds1682_id);
246
247 static const struct of_device_id ds1682_of_match[] = {
248 { .compatible = "dallas,ds1682", },
249 {}
250 };
251 MODULE_DEVICE_TABLE(of, ds1682_of_match);
252
253 static struct i2c_driver ds1682_driver = {
254 .driver = {
255 .name = "ds1682",
256 .of_match_table = ds1682_of_match,
257 },
258 .probe = ds1682_probe,
259 .remove = ds1682_remove,
260 .id_table = ds1682_id,
261 };
262
263 module_i2c_driver(ds1682_driver);
264
265 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
266 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
267 MODULE_LICENSE("GPL");
268