1/*
2 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
3 *
4 * Written by: Grant Likely <grant.likely@secretlab.ca>
5 *
6 * Copyright (C) 2007 Secret Lab Technologies Ltd.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13/*
14 * The DS1682 elapsed timer recorder is a simple device that implements
15 * one elapsed time counter, one event counter, an alarm signal and 10
16 * bytes of general purpose EEPROM.
17 *
18 * This driver provides access to the DS1682 counters and user data via
19 * the sysfs.  The following attributes are added to the device node:
20 *     elapsed_time (u32): Total elapsed event time in ms resolution
21 *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
22 *                       then the alarm pin is asserted.
23 *     event_count (u16): number of times the event pin has gone low.
24 *     eeprom (u8[10]): general purpose EEPROM
25 *
26 * Counter registers and user data are both read/write unless the device
27 * has been write protected.  This driver does not support turning off write
28 * protection.  Once write protection is turned on, it is impossible to
29 * turn it off again, so I have left the feature out of this driver to avoid
30 * accidental enabling, but it is trivial to add write protect support.
31 *
32 */
33
34#include <linux/module.h>
35#include <linux/i2c.h>
36#include <linux/string.h>
37#include <linux/list.h>
38#include <linux/sysfs.h>
39#include <linux/ctype.h>
40#include <linux/hwmon-sysfs.h>
41
42/* Device registers */
43#define DS1682_REG_CONFIG		0x00
44#define DS1682_REG_ALARM		0x01
45#define DS1682_REG_ELAPSED		0x05
46#define DS1682_REG_EVT_CNTR		0x09
47#define DS1682_REG_EEPROM		0x0b
48#define DS1682_REG_RESET		0x1d
49#define DS1682_REG_WRITE_DISABLE	0x1e
50#define DS1682_REG_WRITE_MEM_DISABLE	0x1f
51
52#define DS1682_EEPROM_SIZE		10
53
54/*
55 * Generic counter attributes
56 */
57static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
58			   char *buf)
59{
60	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
61	struct i2c_client *client = to_i2c_client(dev);
62	__le32 val = 0;
63	int rc;
64
65	dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
66
67	/* Read the register */
68	rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
69					   (u8 *) & val);
70	if (rc < 0)
71		return -EIO;
72
73	/* Special case: the 32 bit regs are time values with 1/4s
74	 * resolution, scale them up to milliseconds */
75	if (sattr->nr == 4)
76		return sprintf(buf, "%llu\n",
77			((unsigned long long)le32_to_cpu(val)) * 250);
78
79	/* Format the output string and return # of bytes */
80	return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
81}
82
83static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
84			    const char *buf, size_t count)
85{
86	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
87	struct i2c_client *client = to_i2c_client(dev);
88	u64 val;
89	__le32 val_le;
90	int rc;
91
92	dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
93
94	/* Decode input */
95	rc = kstrtoull(buf, 0, &val);
96	if (rc < 0) {
97		dev_dbg(dev, "input string not a number\n");
98		return -EINVAL;
99	}
100
101	/* Special case: the 32 bit regs are time values with 1/4s
102	 * resolution, scale input down to quarter-seconds */
103	if (sattr->nr == 4)
104		do_div(val, 250);
105
106	/* write out the value */
107	val_le = cpu_to_le32(val);
108	rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
109					    (u8 *) & val_le);
110	if (rc < 0) {
111		dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
112			sattr->index, sattr->nr);
113		return -EIO;
114	}
115
116	return count;
117}
118
119/*
120 * Simple register attributes
121 */
122static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
123			    ds1682_store, 4, DS1682_REG_ELAPSED);
124static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
125			    ds1682_store, 4, DS1682_REG_ALARM);
126static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
127			    ds1682_store, 2, DS1682_REG_EVT_CNTR);
128
129static const struct attribute_group ds1682_group = {
130	.attrs = (struct attribute *[]) {
131		&sensor_dev_attr_elapsed_time.dev_attr.attr,
132		&sensor_dev_attr_alarm_time.dev_attr.attr,
133		&sensor_dev_attr_event_count.dev_attr.attr,
134		NULL,
135	},
136};
137
138/*
139 * User data attribute
140 */
141static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
142				  struct bin_attribute *attr,
143				  char *buf, loff_t off, size_t count)
144{
145	struct i2c_client *client = kobj_to_i2c_client(kobj);
146	int rc;
147
148	dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
149		buf, off, count);
150
151	if (off >= DS1682_EEPROM_SIZE)
152		return 0;
153
154	if (off + count > DS1682_EEPROM_SIZE)
155		count = DS1682_EEPROM_SIZE - off;
156
157	rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
158					   count, buf);
159	if (rc < 0)
160		return -EIO;
161
162	return count;
163}
164
165static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
166				   struct bin_attribute *attr,
167				   char *buf, loff_t off, size_t count)
168{
169	struct i2c_client *client = kobj_to_i2c_client(kobj);
170
171	dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
172		buf, off, count);
173
174	if (off >= DS1682_EEPROM_SIZE)
175		return -ENOSPC;
176
177	if (off + count > DS1682_EEPROM_SIZE)
178		count = DS1682_EEPROM_SIZE - off;
179
180	/* Write out to the device */
181	if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
182					   count, buf) < 0)
183		return -EIO;
184
185	return count;
186}
187
188static struct bin_attribute ds1682_eeprom_attr = {
189	.attr = {
190		.name = "eeprom",
191		.mode = S_IRUGO | S_IWUSR,
192	},
193	.size = DS1682_EEPROM_SIZE,
194	.read = ds1682_eeprom_read,
195	.write = ds1682_eeprom_write,
196};
197
198/*
199 * Called when a ds1682 device is matched with this driver
200 */
201static int ds1682_probe(struct i2c_client *client,
202			const struct i2c_device_id *id)
203{
204	int rc;
205
206	if (!i2c_check_functionality(client->adapter,
207				     I2C_FUNC_SMBUS_I2C_BLOCK)) {
208		dev_err(&client->dev, "i2c bus does not support the ds1682\n");
209		rc = -ENODEV;
210		goto exit;
211	}
212
213	rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
214	if (rc)
215		goto exit;
216
217	rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
218	if (rc)
219		goto exit_bin_attr;
220
221	return 0;
222
223 exit_bin_attr:
224	sysfs_remove_group(&client->dev.kobj, &ds1682_group);
225 exit:
226	return rc;
227}
228
229static int ds1682_remove(struct i2c_client *client)
230{
231	sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
232	sysfs_remove_group(&client->dev.kobj, &ds1682_group);
233	return 0;
234}
235
236static const struct i2c_device_id ds1682_id[] = {
237	{ "ds1682", 0 },
238	{ }
239};
240MODULE_DEVICE_TABLE(i2c, ds1682_id);
241
242static struct i2c_driver ds1682_driver = {
243	.driver = {
244		.name = "ds1682",
245	},
246	.probe = ds1682_probe,
247	.remove = ds1682_remove,
248	.id_table = ds1682_id,
249};
250
251module_i2c_driver(ds1682_driver);
252
253MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
254MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
255MODULE_LICENSE("GPL");
256