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 */
54static 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
97static 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 */
136static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
137			    ds1682_store, 4, DS1682_REG_ELAPSED);
138static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
139			    ds1682_store, 4, DS1682_REG_ALARM);
140static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
141			    ds1682_store, 2, DS1682_REG_EVT_CNTR);
142
143static 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 */
155static 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
173static 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
190static 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 */
203static 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
230static 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
236static const struct i2c_device_id ds1682_id[] = {
237	{ "ds1682", 0 },
238	{ }
239};
240MODULE_DEVICE_TABLE(i2c, ds1682_id);
241
242static const struct of_device_id ds1682_of_match[] = {
243	{ .compatible = "dallas,ds1682", },
244	{}
245};
246MODULE_DEVICE_TABLE(of, ds1682_of_match);
247
248static 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
258module_i2c_driver(ds1682_driver);
259
260MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
261MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
262MODULE_LICENSE("GPL");
263