drivers/misc/ds1682.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
   4  *
   5  * Written by: Grant Likely <grant.likely@secretlab.ca>
   6  *
   7  * Copyright (C) 2007 Secret Lab Technologies Ltd.
   8  */
   9
  10 /*
  11  * The DS1682 elapsed timer recorder is a simple device that implements
  12  * one elapsed time counter, one event counter, an alarm signal and 10
  13  * bytes of general purpose EEPROM.
  14  *
  15  * This driver provides access to the DS1682 counters and user data via
  16  * the sysfs.  The following attributes are added to the device node:
  17  *     elapsed_time (u32): Total elapsed event time in ms resolution
  18  *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
  19  *                       then the alarm pin is asserted.
  20  *     event_count (u16): number of times the event pin has gone low.
  21  *     eeprom (u8[10]): general purpose EEPROM
  22  *
  23  * Counter registers and user data are both read/write unless the device
  24  * has been write protected.  This driver does not support turning off write
  25  * protection.  Once write protection is turned on, it is impossible to
  26  * turn it off again, so I have left the feature out of this driver to avoid
  27  * accidental enabling, but it is trivial to add write protect support.
  28  *
  29  */
  30
  31 #include <linux/module.h>
  32 #include <linux/i2c.h>
  33 #include <linux/string.h>
  34 #include <linux/list.h>
  35 #include <linux/sysfs.h>
  36 #include <linux/ctype.h>
  37 #include <linux/hwmon-sysfs.h>
  38
  39 /* Device registers */
  40 #define DS1682_REG_CONFIG               0x00
  41 #define DS1682_REG_ALARM                0x01
  42 #define DS1682_REG_ELAPSED              0x05
  43 #define DS1682_REG_EVT_CNTR             0x09
  44 #define DS1682_REG_EEPROM               0x0b
  45 #define DS1682_REG_RESET                0x1d
  46 #define DS1682_REG_WRITE_DISABLE        0x1e
  47 #define DS1682_REG_WRITE_MEM_DISABLE    0x1f
  48
  49 #define DS1682_EEPROM_SIZE              10
  50
  51 /*
  52  * Generic counter attributes
  53  */
  54 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
  55                            char *buf)
  56 {
  57         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
  58         struct i2c_client *client = to_i2c_client(dev);
  59         unsigned long long val, check;
  60         __le32 val_le = 0;
  61         int rc;
  62
  63         dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
  64
  65         /* Read the register */
  66         rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
  67                                            (u8 *)&val_le);
  68         if (rc < 0)
  69                 return -EIO;
  70
  71         val = le32_to_cpu(val_le);
  72
  73         if (sattr->index == DS1682_REG_ELAPSED) {
  74                 int retries = 5;
  75
  76                 /* Detect and retry when a tick occurs mid-read */
  77                 do {
  78                         rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
  79                                                            sattr->nr,
  80                                                            (u8 *)&val_le);
  81                         if (rc < 0 || retries <= 0)
  82                                 return -EIO;
  83
  84                         check = val;
  85                         val = le32_to_cpu(val_le);
  86                         retries--;
  87                 } while (val != check && val != (check + 1));
  88         }
  89
  90         /* Format the output string and return # of bytes
  91          * Special case: the 32 bit regs are time values with 1/4s
  92          * resolution, scale them up to milliseconds
  93          */
  94         return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
  95 }
  96
  97 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
  98                             const char *buf, size_t count)
  99 {
 100         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
 101         struct i2c_client *client = to_i2c_client(dev);
 102         u64 val;
 103         __le32 val_le;
 104         int rc;
 105
 106         dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
 107
 108         /* Decode input */
 109         rc = kstrtoull(buf, 0, &val);
 110         if (rc < 0) {
 111                 dev_dbg(dev, "input string not a number\n");
 112                 return -EINVAL;
 113         }
 114
 115         /* Special case: the 32 bit regs are time values with 1/4s
 116          * resolution, scale input down to quarter-seconds */
 117         if (sattr->nr == 4)
 118                 do_div(val, 250);
 119
 120         /* write out the value */
 121         val_le = cpu_to_le32(val);
 122         rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
 123                                             (u8 *) & val_le);
 124         if (rc < 0) {
 125                 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
 126                         sattr->index, sattr->nr);
 127                 return -EIO;
 128         }
 129
 130         return count;
 131 }
 132
 133 /*
 134  * Simple register attributes
 135  */
 136 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
 137                             ds1682_store, 4, DS1682_REG_ELAPSED);
 138 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
 139                             ds1682_store, 4, DS1682_REG_ALARM);
 140 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
 141                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
 142
 143 static const struct attribute_group ds1682_group = {
 144         .attrs = (struct attribute *[]) {
 145                 &sensor_dev_attr_elapsed_time.dev_attr.attr,
 146                 &sensor_dev_attr_alarm_time.dev_attr.attr,
 147                 &sensor_dev_attr_event_count.dev_attr.attr,
 148                 NULL,
 149         },
 150 };
 151
 152 /*
 153  * User data attribute
 154  */
 155 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
 156                                   struct bin_attribute *attr,
 157                                   char *buf, loff_t off, size_t count)
 158 {
 159         struct i2c_client *client = kobj_to_i2c_client(kobj);
 160         int rc;
 161
 162         dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
 163                 buf, off, count);
 164
 165         rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
 166                                            count, buf);
 167         if (rc < 0)
 168                 return -EIO;
 169
 170         return count;
 171 }
 172
 173 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
 174                                    struct bin_attribute *attr,
 175                                    char *buf, loff_t off, size_t count)
 176 {
 177         struct i2c_client *client = kobj_to_i2c_client(kobj);
 178
 179         dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
 180                 buf, off, count);
 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 const 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 const struct of_device_id ds1682_of_match[] = {
 245         { .compatible = "dallas,ds1682", },
 246         {}
 247 };
 248 MODULE_DEVICE_TABLE(of, ds1682_of_match);
 249
 250 static struct i2c_driver ds1682_driver = {
 251         .driver = {
 252                 .name = "ds1682",
 253                 .of_match_table = ds1682_of_match,
 254         },
 255         .probe = ds1682_probe,
 256         .remove = ds1682_remove,
 257         .id_table = ds1682_id,
 258 };
 259
 260 module_i2c_driver(ds1682_driver);
 261
 262 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 263 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
 264 MODULE_LICENSE("GPL");