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/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  */
  57 static 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         unsigned long long val, check;
  63         __le32 val_le = 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_le);
  71         if (rc < 0)
  72                 return -EIO;
  73
  74         val = le32_to_cpu(val_le);
  75
  76         if (sattr->index == DS1682_REG_ELAPSED) {
  77                 int retries = 5;
  78
  79                 /* Detect and retry when a tick occurs mid-read */
  80                 do {
  81                         rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
  82                                                            sattr->nr,
  83                                                            (u8 *)&val_le);
  84                         if (rc < 0 || retries <= 0)
  85                                 return -EIO;
  86
  87                         check = val;
  88                         val = le32_to_cpu(val_le);
  89                         retries--;
  90                 } while (val != check && val != (check + 1));
  91         }
  92
  93         /* Format the output string and return # of bytes
  94          * Special case: the 32 bit regs are time values with 1/4s
  95          * resolution, scale them up to milliseconds
  96          */
  97         return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
  98 }
  99
 100 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
 101                             const char *buf, size_t count)
 102 {
 103         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
 104         struct i2c_client *client = to_i2c_client(dev);
 105         u64 val;
 106         __le32 val_le;
 107         int rc;
 108
 109         dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
 110
 111         /* Decode input */
 112         rc = kstrtoull(buf, 0, &val);
 113         if (rc < 0) {
 114                 dev_dbg(dev, "input string not a number\n");
 115                 return -EINVAL;
 116         }
 117
 118         /* Special case: the 32 bit regs are time values with 1/4s
 119          * resolution, scale input down to quarter-seconds */
 120         if (sattr->nr == 4)
 121                 do_div(val, 250);
 122
 123         /* write out the value */
 124         val_le = cpu_to_le32(val);
 125         rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
 126                                             (u8 *) & val_le);
 127         if (rc < 0) {
 128                 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
 129                         sattr->index, sattr->nr);
 130                 return -EIO;
 131         }
 132
 133         return count;
 134 }
 135
 136 /*
 137  * Simple register attributes
 138  */
 139 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
 140                             ds1682_store, 4, DS1682_REG_ELAPSED);
 141 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
 142                             ds1682_store, 4, DS1682_REG_ALARM);
 143 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
 144                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
 145
 146 static const struct attribute_group ds1682_group = {
 147         .attrs = (struct attribute *[]) {
 148                 &sensor_dev_attr_elapsed_time.dev_attr.attr,
 149                 &sensor_dev_attr_alarm_time.dev_attr.attr,
 150                 &sensor_dev_attr_event_count.dev_attr.attr,
 151                 NULL,
 152         },
 153 };
 154
 155 /*
 156  * User data attribute
 157  */
 158 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
 159                                   struct bin_attribute *attr,
 160                                   char *buf, loff_t off, size_t count)
 161 {
 162         struct i2c_client *client = kobj_to_i2c_client(kobj);
 163         int rc;
 164
 165         dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
 166                 buf, off, count);
 167
 168         rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
 169                                            count, buf);
 170         if (rc < 0)
 171                 return -EIO;
 172
 173         return count;
 174 }
 175
 176 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
 177                                    struct bin_attribute *attr,
 178                                    char *buf, loff_t off, size_t count)
 179 {
 180         struct i2c_client *client = kobj_to_i2c_client(kobj);
 181
 182         dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
 183                 buf, off, count);
 184
 185         /* Write out to the device */
 186         if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
 187                                            count, buf) < 0)
 188                 return -EIO;
 189
 190         return count;
 191 }
 192
 193 static const struct bin_attribute ds1682_eeprom_attr = {
 194         .attr = {
 195                 .name = "eeprom",
 196                 .mode = S_IRUGO | S_IWUSR,
 197         },
 198         .size = DS1682_EEPROM_SIZE,
 199         .read = ds1682_eeprom_read,
 200         .write = ds1682_eeprom_write,
 201 };
 202
 203 /*
 204  * Called when a ds1682 device is matched with this driver
 205  */
 206 static int ds1682_probe(struct i2c_client *client,
 207                         const struct i2c_device_id *id)
 208 {
 209         int rc;
 210
 211         if (!i2c_check_functionality(client->adapter,
 212                                      I2C_FUNC_SMBUS_I2C_BLOCK)) {
 213                 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
 214                 rc = -ENODEV;
 215                 goto exit;
 216         }
 217
 218         rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
 219         if (rc)
 220                 goto exit;
 221
 222         rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
 223         if (rc)
 224                 goto exit_bin_attr;
 225
 226         return 0;
 227
 228  exit_bin_attr:
 229         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
 230  exit:
 231         return rc;
 232 }
 233
 234 static int ds1682_remove(struct i2c_client *client)
 235 {
 236         sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
 237         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
 238         return 0;
 239 }
 240
 241 static const struct i2c_device_id ds1682_id[] = {
 242         { "ds1682", 0 },
 243         { }
 244 };
 245 MODULE_DEVICE_TABLE(i2c, ds1682_id);
 246
 247 static const struct of_device_id ds1682_of_match[] = {
 248         { .compatible = "dallas,ds1682", },
 249         {}
 250 };
 251 MODULE_DEVICE_TABLE(of, ds1682_of_match);
 252
 253 static struct i2c_driver ds1682_driver = {
 254         .driver = {
 255                 .name = "ds1682",
 256                 .of_match_table = ds1682_of_match,
 257         },
 258         .probe = ds1682_probe,
 259         .remove = ds1682_remove,
 260         .id_table = ds1682_id,
 261 };
 262
 263 module_i2c_driver(ds1682_driver);
 264
 265 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 266 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
 267 MODULE_LICENSE("GPL");