Root/drivers/misc/ds1682.c

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/init.h>
36#include <linux/i2c.h>
37#include <linux/string.h>
38#include <linux/list.h>
39#include <linux/sysfs.h>
40#include <linux/ctype.h>
41#include <linux/hwmon-sysfs.h>
42
43/* Device registers */
44#define DS1682_REG_CONFIG 0x00
45#define DS1682_REG_ALARM 0x01
46#define DS1682_REG_ELAPSED 0x05
47#define DS1682_REG_EVT_CNTR 0x09
48#define DS1682_REG_EEPROM 0x0b
49#define DS1682_REG_RESET 0x1d
50#define DS1682_REG_WRITE_DISABLE 0x1e
51#define DS1682_REG_WRITE_MEM_DISABLE 0x1f
52
53#define DS1682_EEPROM_SIZE 10
54
55/*
56 * Generic counter attributes
57 */
58static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
59               char *buf)
60{
61    struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
62    struct i2c_client *client = to_i2c_client(dev);
63    __le32 val = 0;
64    int rc;
65
66    dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
67
68    /* Read the register */
69    rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
70                       (u8 *) & val);
71    if (rc < 0)
72        return -EIO;
73
74    /* Special case: the 32 bit regs are time values with 1/4s
75     * resolution, scale them up to milliseconds */
76    if (sattr->nr == 4)
77        return sprintf(buf, "%llu\n",
78            ((unsigned long long)le32_to_cpu(val)) * 250);
79
80    /* Format the output string and return # of bytes */
81    return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
82}
83
84static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
85                const char *buf, size_t count)
86{
87    struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
88    struct i2c_client *client = to_i2c_client(dev);
89    char *endp;
90    u64 val;
91    __le32 val_le;
92    int rc;
93
94    dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
95
96    /* Decode input */
97    val = simple_strtoull(buf, &endp, 0);
98    if (buf == endp) {
99        dev_dbg(dev, "input string not a number\n");
100        return -EINVAL;
101    }
102
103    /* Special case: the 32 bit regs are time values with 1/4s
104     * resolution, scale input down to quarter-seconds */
105    if (sattr->nr == 4)
106        do_div(val, 250);
107
108    /* write out the value */
109    val_le = cpu_to_le32(val);
110    rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
111                        (u8 *) & val_le);
112    if (rc < 0) {
113        dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
114            sattr->index, sattr->nr);
115        return -EIO;
116    }
117
118    return count;
119}
120
121/*
122 * Simple register attributes
123 */
124static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
125                ds1682_store, 4, DS1682_REG_ELAPSED);
126static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
127                ds1682_store, 4, DS1682_REG_ALARM);
128static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
129                ds1682_store, 2, DS1682_REG_EVT_CNTR);
130
131static const struct attribute_group ds1682_group = {
132    .attrs = (struct attribute *[]) {
133        &sensor_dev_attr_elapsed_time.dev_attr.attr,
134        &sensor_dev_attr_alarm_time.dev_attr.attr,
135        &sensor_dev_attr_event_count.dev_attr.attr,
136        NULL,
137    },
138};
139
140/*
141 * User data attribute
142 */
143static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
144                  struct bin_attribute *attr,
145                  char *buf, loff_t off, size_t count)
146{
147    struct i2c_client *client = kobj_to_i2c_client(kobj);
148    int rc;
149
150    dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
151        buf, off, count);
152
153    if (off >= DS1682_EEPROM_SIZE)
154        return 0;
155
156    if (off + count > DS1682_EEPROM_SIZE)
157        count = DS1682_EEPROM_SIZE - off;
158
159    rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
160                       count, buf);
161    if (rc < 0)
162        return -EIO;
163
164    return count;
165}
166
167static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
168                   struct bin_attribute *attr,
169                   char *buf, loff_t off, size_t count)
170{
171    struct i2c_client *client = kobj_to_i2c_client(kobj);
172
173    dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
174        buf, off, count);
175
176    if (off >= DS1682_EEPROM_SIZE)
177        return -ENOSPC;
178
179    if (off + count > DS1682_EEPROM_SIZE)
180        count = DS1682_EEPROM_SIZE - off;
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 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            const struct i2c_device_id *id)
205{
206    int rc;
207
208    if (!i2c_check_functionality(client->adapter,
209                     I2C_FUNC_SMBUS_I2C_BLOCK)) {
210        dev_err(&client->dev, "i2c bus does not support the ds1682\n");
211        rc = -ENODEV;
212        goto exit;
213    }
214
215    rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
216    if (rc)
217        goto exit;
218
219    rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
220    if (rc)
221        goto exit_bin_attr;
222
223    return 0;
224
225 exit_bin_attr:
226    sysfs_remove_group(&client->dev.kobj, &ds1682_group);
227 exit:
228    return rc;
229}
230
231static int ds1682_remove(struct i2c_client *client)
232{
233    sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
234    sysfs_remove_group(&client->dev.kobj, &ds1682_group);
235    return 0;
236}
237
238static const struct i2c_device_id ds1682_id[] = {
239    { "ds1682", 0 },
240    { }
241};
242MODULE_DEVICE_TABLE(i2c, ds1682_id);
243
244static struct i2c_driver ds1682_driver = {
245    .driver = {
246        .name = "ds1682",
247    },
248    .probe = ds1682_probe,
249    .remove = ds1682_remove,
250    .id_table = ds1682_id,
251};
252
253module_i2c_driver(ds1682_driver);
254
255MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
256MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
257MODULE_LICENSE("GPL");
258

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