projects/linux·blob master · refs

299 lines · 7.9 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
4 *
5 * Written by: Grant Likely <[email protected]>
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/nvmem-provider.h>
36#include <linux/sysfs.h>
37#include <linux/ctype.h>
38#include <linux/hwmon-sysfs.h>
39
40/* Device registers */
41#define DS1682_REG_CONFIG 0x00
42#define DS1682_REG_ALARM 0x01
43#define DS1682_REG_ELAPSED 0x05
44#define DS1682_REG_EVT_CNTR 0x09
45#define DS1682_REG_EEPROM 0x0b
46#define DS1682_REG_RESET 0x1d
47#define DS1682_REG_WRITE_DISABLE 0x1e
48#define DS1682_REG_WRITE_MEM_DISABLE 0x1f
49
50#define DS1682_EEPROM_SIZE 10
51
52/*
53 * Generic counter attributes
54 */
55static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
56 char *buf)
57{
58 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
59 struct i2c_client *client = to_i2c_client(dev);
60 unsigned long long val, check;
61 __le32 val_le = 0;
62 int rc;
63
64 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
65
66 /* Read the register */
67 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
68 (u8 *)&val_le);
69 if (rc < 0)
70 return -EIO;
71
72 val = le32_to_cpu(val_le);
73
74 if (sattr->index == DS1682_REG_ELAPSED) {
75 int retries = 5;
76
77 /* Detect and retry when a tick occurs mid-read */
78 do {
79 rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
80 sattr->nr,
81 (u8 *)&val_le);
82 if (rc < 0 || retries <= 0)
83 return -EIO;
84
85 check = val;
86 val = le32_to_cpu(val_le);
87 retries--;
88 } while (val != check && val != (check + 1));
89 }
90
91 /* Format the output string and return # of bytes
92 * Special case: the 32 bit regs are time values with 1/4s
93 * resolution, scale them up to milliseconds
94 */
95 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
96}
97
98static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
99 const char *buf, size_t count)
100{
101 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
102 struct i2c_client *client = to_i2c_client(dev);
103 u64 val;
104 __le32 val_le;
105 int rc;
106
107 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
108
109 /* Decode input */
110 rc = kstrtoull(buf, 0, &val);
111 if (rc < 0) {
112 dev_dbg(dev, "input string not a number\n");
113 return -EINVAL;
114 }
115
116 /* Special case: the 32 bit regs are time values with 1/4s
117 * resolution, scale input down to quarter-seconds */
118 if (sattr->nr == 4)
119 do_div(val, 250);
120
121 /* write out the value */
122 val_le = cpu_to_le32(val);
123 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
124 (u8 *) & val_le);
125 if (rc < 0) {
126 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
127 sattr->index, sattr->nr);
128 return -EIO;
129 }
130
131 return count;
132}
133
134/*
135 * Simple register attributes
136 */
137static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
138 ds1682_store, 4, DS1682_REG_ELAPSED);
139static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
140 ds1682_store, 4, DS1682_REG_ALARM);
141static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
142 ds1682_store, 2, DS1682_REG_EVT_CNTR);
143
144static const struct attribute_group ds1682_group = {
145 .attrs = (struct attribute *[]) {
146 &sensor_dev_attr_elapsed_time.dev_attr.attr,
147 &sensor_dev_attr_alarm_time.dev_attr.attr,
148 &sensor_dev_attr_event_count.dev_attr.attr,
149 NULL,
150 },
151};
152
153/*
154 * User data attribute
155 */
156static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
157 const struct bin_attribute *attr,
158 char *buf, loff_t off, size_t count)
159{
160 struct i2c_client *client = kobj_to_i2c_client(kobj);
161 int rc;
162
163 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
164 buf, off, count);
165
166 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
167 count, buf);
168 if (rc < 0)
169 return -EIO;
170
171 return count;
172}
173
174static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
175 const struct bin_attribute *attr,
176 char *buf, loff_t off, size_t count)
177{
178 struct i2c_client *client = kobj_to_i2c_client(kobj);
179
180 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
181 buf, off, count);
182
183 /* Write out to the device */
184 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
185 count, buf) < 0)
186 return -EIO;
187
188 return count;
189}
190
191static const struct bin_attribute ds1682_eeprom_attr = {
192 .attr = {
193 .name = "eeprom",
194 .mode = S_IRUGO | S_IWUSR,
195 },
196 .size = DS1682_EEPROM_SIZE,
197 .read = ds1682_eeprom_read,
198 .write = ds1682_eeprom_write,
199};
200
201static int ds1682_nvmem_read(void *priv, unsigned int offset, void *val,
202 size_t bytes)
203{
204 struct i2c_client *client = priv;
205 int ret;
206
207 ret = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + offset,
208 bytes, val);
209 return ret < 0 ? ret : 0;
210}
211
212static int ds1682_nvmem_write(void *priv, unsigned int offset, void *val,
213 size_t bytes)
214{
215 struct i2c_client *client = priv;
216 int ret;
217
218 ret = i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + offset,
219 bytes, val);
220 return ret < 0 ? ret : 0;
221}
222
223/*
224 * Called when a ds1682 device is matched with this driver
225 */
226static int ds1682_probe(struct i2c_client *client)
227{
228 struct nvmem_config config = {
229 .dev = &client->dev,
230 .owner = THIS_MODULE,
231 .type = NVMEM_TYPE_EEPROM,
232 .reg_read = ds1682_nvmem_read,
233 .reg_write = ds1682_nvmem_write,
234 .size = DS1682_EEPROM_SIZE,
235 .priv = client,
236 };
237 struct nvmem_device *nvmem;
238 int rc;
239
240 if (!i2c_check_functionality(client->adapter,
241 I2C_FUNC_SMBUS_I2C_BLOCK)) {
242 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
243 rc = -ENODEV;
244 goto exit;
245 }
246
247 nvmem = devm_nvmem_register(&client->dev, &config);
248 if (IS_ENABLED(CONFIG_NVMEM) && IS_ERR(nvmem))
249 return PTR_ERR(nvmem);
250
251 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
252 if (rc)
253 goto exit;
254
255 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
256 if (rc)
257 goto exit_bin_attr;
258
259 return 0;
260
261 exit_bin_attr:
262 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
263 exit:
264 return rc;
265}
266
267static void ds1682_remove(struct i2c_client *client)
268{
269 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
270 sysfs_remove_group(&client->dev.kobj, &ds1682_group);
271}
272
273static const struct i2c_device_id ds1682_id[] = {
274 { .name = "ds1682" },
275 { }
276};
277MODULE_DEVICE_TABLE(i2c, ds1682_id);
278
279static const struct of_device_id ds1682_of_match[] = {
280 { .compatible = "dallas,ds1682" },
281 { }
282};
283MODULE_DEVICE_TABLE(of, ds1682_of_match);
284
285static struct i2c_driver ds1682_driver = {
286 .driver = {
287 .name = "ds1682",
288 .of_match_table = ds1682_of_match,
289 },
290 .probe = ds1682_probe,
291 .remove = ds1682_remove,
292 .id_table = ds1682_id,
293};
294
295module_i2c_driver(ds1682_driver);
296
297MODULE_AUTHOR("Grant Likely <[email protected]>");
298MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
299MODULE_LICENSE("GPL");