GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / misc / ds1682.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
4  *
5  * Written by: Grant Likely <grant.likely@secretlab.ca>
6  *
7  * Copyright (C) 2007 Secret Lab Technologies Ltd.
8  */
9
10 /*
11  * The DS1682 elapsed timer recorder is a simple device that implements
12  * one elapsed time counter, one event counter, an alarm signal and 10
13  * bytes of general purpose EEPROM.
14  *
15  * This driver provides access to the DS1682 counters and user data via
16  * the sysfs.  The following attributes are added to the device node:
17  *     elapsed_time (u32): Total elapsed event time in ms resolution
18  *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
19  *                       then the alarm pin is asserted.
20  *     event_count (u16): number of times the event pin has gone low.
21  *     eeprom (u8[10]): general purpose EEPROM
22  *
23  * Counter registers and user data are both read/write unless the device
24  * has been write protected.  This driver does not support turning off write
25  * protection.  Once write protection is turned on, it is impossible to
26  * turn it off again, so I have left the feature out of this driver to avoid
27  * accidental enabling, but it is trivial to add write protect support.
28  *
29  */
30
31 #include <linux/module.h>
32 #include <linux/i2c.h>
33 #include <linux/string.h>
34 #include <linux/list.h>
35 #include <linux/sysfs.h>
36 #include <linux/ctype.h>
37 #include <linux/hwmon-sysfs.h>
38
39 /* Device registers */
40 #define DS1682_REG_CONFIG               0x00
41 #define DS1682_REG_ALARM                0x01
42 #define DS1682_REG_ELAPSED              0x05
43 #define DS1682_REG_EVT_CNTR             0x09
44 #define DS1682_REG_EEPROM               0x0b
45 #define DS1682_REG_RESET                0x1d
46 #define DS1682_REG_WRITE_DISABLE        0x1e
47 #define DS1682_REG_WRITE_MEM_DISABLE    0x1f
48
49 #define DS1682_EEPROM_SIZE              10
50
51 /*
52  * Generic counter attributes
53  */
54 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
55                            char *buf)
56 {
57         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
58         struct i2c_client *client = to_i2c_client(dev);
59         unsigned long long val, check;
60         __le32 val_le = 0;
61         int rc;
62
63         dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
64
65         /* Read the register */
66         rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
67                                            (u8 *)&val_le);
68         if (rc < 0)
69                 return -EIO;
70
71         val = le32_to_cpu(val_le);
72
73         if (sattr->index == DS1682_REG_ELAPSED) {
74                 int retries = 5;
75
76                 /* Detect and retry when a tick occurs mid-read */
77                 do {
78                         rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
79                                                            sattr->nr,
80                                                            (u8 *)&val_le);
81                         if (rc < 0 || retries <= 0)
82                                 return -EIO;
83
84                         check = val;
85                         val = le32_to_cpu(val_le);
86                         retries--;
87                 } while (val != check && val != (check + 1));
88         }
89
90         /* Format the output string and return # of bytes
91          * Special case: the 32 bit regs are time values with 1/4s
92          * resolution, scale them up to milliseconds
93          */
94         return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
95 }
96
97 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
98                             const char *buf, size_t count)
99 {
100         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
101         struct i2c_client *client = to_i2c_client(dev);
102         u64 val;
103         __le32 val_le;
104         int rc;
105
106         dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
107
108         /* Decode input */
109         rc = kstrtoull(buf, 0, &val);
110         if (rc < 0) {
111                 dev_dbg(dev, "input string not a number\n");
112                 return -EINVAL;
113         }
114
115         /* Special case: the 32 bit regs are time values with 1/4s
116          * resolution, scale input down to quarter-seconds */
117         if (sattr->nr == 4)
118                 do_div(val, 250);
119
120         /* write out the value */
121         val_le = cpu_to_le32(val);
122         rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
123                                             (u8 *) & val_le);
124         if (rc < 0) {
125                 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
126                         sattr->index, sattr->nr);
127                 return -EIO;
128         }
129
130         return count;
131 }
132
133 /*
134  * Simple register attributes
135  */
136 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
137                             ds1682_store, 4, DS1682_REG_ELAPSED);
138 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
139                             ds1682_store, 4, DS1682_REG_ALARM);
140 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
141                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
142
143 static const struct attribute_group ds1682_group = {
144         .attrs = (struct attribute *[]) {
145                 &sensor_dev_attr_elapsed_time.dev_attr.attr,
146                 &sensor_dev_attr_alarm_time.dev_attr.attr,
147                 &sensor_dev_attr_event_count.dev_attr.attr,
148                 NULL,
149         },
150 };
151
152 /*
153  * User data attribute
154  */
155 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
156                                   struct bin_attribute *attr,
157                                   char *buf, loff_t off, size_t count)
158 {
159         struct i2c_client *client = kobj_to_i2c_client(kobj);
160         int rc;
161
162         dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
163                 buf, off, count);
164
165         rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
166                                            count, buf);
167         if (rc < 0)
168                 return -EIO;
169
170         return count;
171 }
172
173 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
174                                    struct bin_attribute *attr,
175                                    char *buf, loff_t off, size_t count)
176 {
177         struct i2c_client *client = kobj_to_i2c_client(kobj);
178
179         dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
180                 buf, off, count);
181
182         /* Write out to the device */
183         if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
184                                            count, buf) < 0)
185                 return -EIO;
186
187         return count;
188 }
189
190 static const struct bin_attribute ds1682_eeprom_attr = {
191         .attr = {
192                 .name = "eeprom",
193                 .mode = S_IRUGO | S_IWUSR,
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                         const struct i2c_device_id *id)
205 {
206         int rc;
207
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");
211                 rc = -ENODEV;
212                 goto exit;
213         }
214
215         rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
216         if (rc)
217                 goto exit;
218
219         rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
220         if (rc)
221                 goto exit_bin_attr;
222
223         return 0;
224
225  exit_bin_attr:
226         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
227  exit:
228         return rc;
229 }
230
231 static int ds1682_remove(struct i2c_client *client)
232 {
233         sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
234         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
235         return 0;
236 }
237
238 static const struct i2c_device_id ds1682_id[] = {
239         { "ds1682", 0 },
240         { }
241 };
242 MODULE_DEVICE_TABLE(i2c, ds1682_id);
243
244 static const struct of_device_id ds1682_of_match[] = {
245         { .compatible = "dallas,ds1682", },
246         {}
247 };
248 MODULE_DEVICE_TABLE(of, ds1682_of_match);
249
250 static struct i2c_driver ds1682_driver = {
251         .driver = {
252                 .name = "ds1682",
253                 .of_match_table = ds1682_of_match,
254         },
255         .probe = ds1682_probe,
256         .remove = ds1682_remove,
257         .id_table = ds1682_id,
258 };
259
260 module_i2c_driver(ds1682_driver);
261
262 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
263 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
264 MODULE_LICENSE("GPL");