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         __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
  83 static 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         char *endp;
  89         u64 val;
  90         __le32 val_le;
  91         int rc;
  92
  93         dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
  94
  95         /* Decode input */
  96         val = simple_strtoull(buf, &endp, 0);
  97         if (buf == endp) {
  98                 dev_dbg(dev, "input string not a number\n");
  99                 return -EINVAL;
 100         }
 101
 102         /* Special case: the 32 bit regs are time values with 1/4s
 103          * resolution, scale input down to quarter-seconds */
 104         if (sattr->nr == 4)
 105                 do_div(val, 250);
 106
 107         /* write out the value */
 108         val_le = cpu_to_le32(val);
 109         rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
 110                                             (u8 *) & val_le);
 111         if (rc < 0) {
 112                 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
 113                         sattr->index, sattr->nr);
 114                 return -EIO;
 115         }
 116
 117         return count;
 118 }
 119
 120 /*
 121  * Simple register attributes
 122  */
 123 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
 124                             ds1682_store, 4, DS1682_REG_ELAPSED);
 125 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
 126                             ds1682_store, 4, DS1682_REG_ALARM);
 127 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
 128                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
 129
 130 static const struct attribute_group ds1682_group = {
 131         .attrs = (struct attribute *[]) {
 132                 &sensor_dev_attr_elapsed_time.dev_attr.attr,
 133                 &sensor_dev_attr_alarm_time.dev_attr.attr,
 134                 &sensor_dev_attr_event_count.dev_attr.attr,
 135                 NULL,
 136         },
 137 };
 138
 139 /*
 140  * User data attribute
 141  */
 142 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
 143                                   struct bin_attribute *attr,
 144                                   char *buf, loff_t off, size_t count)
 145 {
 146         struct i2c_client *client = kobj_to_i2c_client(kobj);
 147         int rc;
 148
 149         dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
 150                 buf, off, count);
 151
 152         if (off >= DS1682_EEPROM_SIZE)
 153                 return 0;
 154
 155         if (off + count > DS1682_EEPROM_SIZE)
 156                 count = DS1682_EEPROM_SIZE - off;
 157
 158         rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
 159                                            count, buf);
 160         if (rc < 0)
 161                 return -EIO;
 162
 163         return count;
 164 }
 165
 166 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
 167                                    struct bin_attribute *attr,
 168                                    char *buf, loff_t off, size_t count)
 169 {
 170         struct i2c_client *client = kobj_to_i2c_client(kobj);
 171
 172         dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
 173                 buf, off, count);
 174
 175         if (off >= DS1682_EEPROM_SIZE)
 176                 return -ENOSPC;
 177
 178         if (off + count > DS1682_EEPROM_SIZE)
 179                 count = DS1682_EEPROM_SIZE - off;
 180
 181         /* Write out to the device */
 182         if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
 183                                            count, buf) < 0)
 184                 return -EIO;
 185
 186         return count;
 187 }
 188
 189 static struct bin_attribute ds1682_eeprom_attr = {
 190         .attr = {
 191                 .name = "eeprom",
 192                 .mode = S_IRUGO | S_IWUSR,
 193         },
 194         .size = DS1682_EEPROM_SIZE,
 195         .read = ds1682_eeprom_read,
 196         .write = ds1682_eeprom_write,
 197 };
 198
 199 /*
 200  * Called when a ds1682 device is matched with this driver
 201  */
 202 static int ds1682_probe(struct i2c_client *client,
 203                         const struct i2c_device_id *id)
 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
 230 static int 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         return 0;
 235 }
 236
 237 static const struct i2c_device_id ds1682_id[] = {
 238         { "ds1682", 0 },
 239         { }
 240 };
 241 MODULE_DEVICE_TABLE(i2c, ds1682_id);
 242
 243 static struct i2c_driver ds1682_driver = {
 244         .driver = {
 245                 .name = "ds1682",
 246         },
 247         .probe = ds1682_probe,
 248         .remove = ds1682_remove,
 249         .id_table = ds1682_id,
 250 };
 251
 252 module_i2c_driver(ds1682_driver);
 253
 254 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 255 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
 256 MODULE_LICENSE("GPL");