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, command: sattr->index, length: sattr->nr, |
67 | values: (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, command: sattr->index, |
79 | length: sattr->nr, |
80 | values: (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, fmt: "%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(s: buf, base: 0, res: &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, command: sattr->index, length: sattr->nr, |
123 | values: (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 | length: count, values: 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 | length: count, values: 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 | { |
205 | int rc; |
206 | |
207 | if (!i2c_check_functionality(adap: 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(kobj: &client->dev.kobj, grp: &ds1682_group); |
215 | if (rc) |
216 | goto exit; |
217 | |
218 | rc = sysfs_create_bin_file(kobj: &client->dev.kobj, attr: &ds1682_eeprom_attr); |
219 | if (rc) |
220 | goto exit_bin_attr; |
221 | |
222 | return 0; |
223 | |
224 | exit_bin_attr: |
225 | sysfs_remove_group(kobj: &client->dev.kobj, grp: &ds1682_group); |
226 | exit: |
227 | return rc; |
228 | } |
229 | |
230 | static void ds1682_remove(struct i2c_client *client) |
231 | { |
232 | sysfs_remove_bin_file(kobj: &client->dev.kobj, attr: &ds1682_eeprom_attr); |
233 | sysfs_remove_group(kobj: &client->dev.kobj, grp: &ds1682_group); |
234 | } |
235 | |
236 | static const struct i2c_device_id ds1682_id[] = { |
237 | { "ds1682" , 0 }, |
238 | { } |
239 | }; |
240 | MODULE_DEVICE_TABLE(i2c, ds1682_id); |
241 | |
242 | static const struct of_device_id ds1682_of_match[] = { |
243 | { .compatible = "dallas,ds1682" , }, |
244 | {} |
245 | }; |
246 | MODULE_DEVICE_TABLE(of, ds1682_of_match); |
247 | |
248 | static struct i2c_driver ds1682_driver = { |
249 | .driver = { |
250 | .name = "ds1682" , |
251 | .of_match_table = ds1682_of_match, |
252 | }, |
253 | .probe = ds1682_probe, |
254 | .remove = ds1682_remove, |
255 | .id_table = ds1682_id, |
256 | }; |
257 | |
258 | module_i2c_driver(ds1682_driver); |
259 | |
260 | MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>" ); |
261 | MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver" ); |
262 | MODULE_LICENSE("GPL" ); |
263 | |