xref: /openbmc/linux/drivers/misc/ds1682.c (revision f050bb8f)
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  */
ds1682_show(struct device * dev,struct device_attribute * attr,char * buf)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 
ds1682_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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  */
ds1682_eeprom_read(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)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 
ds1682_eeprom_write(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)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  */
ds1682_probe(struct i2c_client * client)203 static int ds1682_probe(struct i2c_client *client)
204 {
205 	int rc;
206 
207 	if (!i2c_check_functionality(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(&client->dev.kobj, &ds1682_group);
215 	if (rc)
216 		goto exit;
217 
218 	rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
219 	if (rc)
220 		goto exit_bin_attr;
221 
222 	return 0;
223 
224  exit_bin_attr:
225 	sysfs_remove_group(&client->dev.kobj, &ds1682_group);
226  exit:
227 	return rc;
228 }
229 
ds1682_remove(struct i2c_client * client)230 static void ds1682_remove(struct i2c_client *client)
231 {
232 	sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
233 	sysfs_remove_group(&client->dev.kobj, &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