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  */
  58 static 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
  84 static 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  */
 124 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
 125                             ds1682_store, 4, DS1682_REG_ELAPSED);
 126 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
 127                             ds1682_store, 4, DS1682_REG_ALARM);
 128 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
 129                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
 130
 131 static 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  */
 143 static 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
 167 static 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
 190 static 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                         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
 231 static 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
 238 static const struct i2c_device_id ds1682_id[] = {
 239         { "ds1682", 0 },
 240         { }
 241 };
 242 MODULE_DEVICE_TABLE(i2c, ds1682_id);
 243
 244 static 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
 253 module_i2c_driver(ds1682_driver);
 254
 255 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 256 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
 257 MODULE_LICENSE("GPL");