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/nvmem-provider.h>
  36 #include <linux/sysfs.h>
  37 #include <linux/ctype.h>
  38 #include <linux/hwmon-sysfs.h>
  39
  40 /* Device registers */
  41 #define DS1682_REG_CONFIG               0x00
  42 #define DS1682_REG_ALARM                0x01
  43 #define DS1682_REG_ELAPSED              0x05
  44 #define DS1682_REG_EVT_CNTR             0x09
  45 #define DS1682_REG_EEPROM               0x0b
  46 #define DS1682_REG_RESET                0x1d
  47 #define DS1682_REG_WRITE_DISABLE        0x1e
  48 #define DS1682_REG_WRITE_MEM_DISABLE    0x1f
  49
  50 #define DS1682_EEPROM_SIZE              10
  51
  52 /*
  53  * Generic counter attributes
  54  */
  55 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
  56                            char *buf)
  57 {
  58         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
  59         struct i2c_client *client = to_i2c_client(dev);
  60         unsigned long long val, check;
  61         __le32 val_le = 0;
  62         int rc;
  63
  64         dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
  65
  66         /* Read the register */
  67         rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
  68                                            (u8 *)&val_le);
  69         if (rc < 0)
  70                 return -EIO;
  71
  72         val = le32_to_cpu(val_le);
  73
  74         if (sattr->index == DS1682_REG_ELAPSED) {
  75                 int retries = 5;
  76
  77                 /* Detect and retry when a tick occurs mid-read */
  78                 do {
  79                         rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
  80                                                            sattr->nr,
  81                                                            (u8 *)&val_le);
  82                         if (rc < 0 || retries <= 0)
  83                                 return -EIO;
  84
  85                         check = val;
  86                         val = le32_to_cpu(val_le);
  87                         retries--;
  88                 } while (val != check && val != (check + 1));
  89         }
  90
  91         /* Format the output string and return # of bytes
  92          * Special case: the 32 bit regs are time values with 1/4s
  93          * resolution, scale them up to milliseconds
  94          */
  95         return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
  96 }
  97
  98 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
  99                             const char *buf, size_t count)
 100 {
 101         struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
 102         struct i2c_client *client = to_i2c_client(dev);
 103         u64 val;
 104         __le32 val_le;
 105         int rc;
 106
 107         dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
 108
 109         /* Decode input */
 110         rc = kstrtoull(buf, 0, &val);
 111         if (rc < 0) {
 112                 dev_dbg(dev, "input string not a number\n");
 113                 return -EINVAL;
 114         }
 115
 116         /* Special case: the 32 bit regs are time values with 1/4s
 117          * resolution, scale input down to quarter-seconds */
 118         if (sattr->nr == 4)
 119                 do_div(val, 250);
 120
 121         /* write out the value */
 122         val_le = cpu_to_le32(val);
 123         rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
 124                                             (u8 *) & val_le);
 125         if (rc < 0) {
 126                 dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
 127                         sattr->index, sattr->nr);
 128                 return -EIO;
 129         }
 130
 131         return count;
 132 }
 133
 134 /*
 135  * Simple register attributes
 136  */
 137 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
 138                             ds1682_store, 4, DS1682_REG_ELAPSED);
 139 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
 140                             ds1682_store, 4, DS1682_REG_ALARM);
 141 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
 142                             ds1682_store, 2, DS1682_REG_EVT_CNTR);
 143
 144 static const struct attribute_group ds1682_group = {
 145         .attrs = (struct attribute *[]) {
 146                 &sensor_dev_attr_elapsed_time.dev_attr.attr,
 147                 &sensor_dev_attr_alarm_time.dev_attr.attr,
 148                 &sensor_dev_attr_event_count.dev_attr.attr,
 149                 NULL,
 150         },
 151 };
 152
 153 /*
 154  * User data attribute
 155  */
 156 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
 157                                   struct bin_attribute *attr,
 158                                   char *buf, loff_t off, size_t count)
 159 {
 160         struct i2c_client *client = kobj_to_i2c_client(kobj);
 161         int rc;
 162
 163         dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
 164                 buf, off, count);
 165
 166         rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
 167                                            count, buf);
 168         if (rc < 0)
 169                 return -EIO;
 170
 171         return count;
 172 }
 173
 174 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
 175                                    struct bin_attribute *attr,
 176                                    char *buf, loff_t off, size_t count)
 177 {
 178         struct i2c_client *client = kobj_to_i2c_client(kobj);
 179
 180         dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
 181                 buf, off, count);
 182
 183         /* Write out to the device */
 184         if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
 185                                            count, buf) < 0)
 186                 return -EIO;
 187
 188         return count;
 189 }
 190
 191 static const struct bin_attribute ds1682_eeprom_attr = {
 192         .attr = {
 193                 .name = "eeprom",
 194                 .mode = S_IRUGO | S_IWUSR,
 195         },
 196         .size = DS1682_EEPROM_SIZE,
 197         .read = ds1682_eeprom_read,
 198         .write = ds1682_eeprom_write,
 199 };
 200
 201 static int ds1682_nvmem_read(void *priv, unsigned int offset, void *val,
 202                              size_t bytes)
 203 {
 204         struct i2c_client *client = priv;
 205         int ret;
 206
 207         ret = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + offset,
 208                                             bytes, val);
 209         return ret < 0 ? ret : 0;
 210 }
 211
 212 static int ds1682_nvmem_write(void *priv, unsigned int offset, void *val,
 213                               size_t bytes)
 214 {
 215         struct i2c_client *client = priv;
 216         int ret;
 217
 218         ret = i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + offset,
 219                                              bytes, val);
 220         return ret < 0 ? ret : 0;
 221 }
 222
 223 /*
 224  * Called when a ds1682 device is matched with this driver
 225  */
 226 static int ds1682_probe(struct i2c_client *client)
 227 {
 228         struct nvmem_config config = {
 229                 .dev = &client->dev,
 230                 .owner = THIS_MODULE,
 231                 .type = NVMEM_TYPE_EEPROM,
 232                 .reg_read = ds1682_nvmem_read,
 233                 .reg_write = ds1682_nvmem_write,
 234                 .size = DS1682_EEPROM_SIZE,
 235                 .priv = client,
 236         };
 237         struct nvmem_device *nvmem;
 238         int rc;
 239
 240         if (!i2c_check_functionality(client->adapter,
 241                                      I2C_FUNC_SMBUS_I2C_BLOCK)) {
 242                 dev_err(&client->dev, "i2c bus does not support the ds1682\n");
 243                 rc = -ENODEV;
 244                 goto exit;
 245         }
 246
 247         nvmem = devm_nvmem_register(&client->dev, &config);
 248         if (IS_ENABLED(CONFIG_NVMEM) && IS_ERR(nvmem))
 249                 return PTR_ERR(nvmem);
 250
 251         rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
 252         if (rc)
 253                 goto exit;
 254
 255         rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
 256         if (rc)
 257                 goto exit_bin_attr;
 258
 259         return 0;
 260
 261  exit_bin_attr:
 262         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
 263  exit:
 264         return rc;
 265 }
 266
 267 static void ds1682_remove(struct i2c_client *client)
 268 {
 269         sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
 270         sysfs_remove_group(&client->dev.kobj, &ds1682_group);
 271 }
 272
 273 static const struct i2c_device_id ds1682_id[] = {
 274         { "ds1682" },
 275         { }
 276 };
 277 MODULE_DEVICE_TABLE(i2c, ds1682_id);
 278
 279 static const struct of_device_id ds1682_of_match[] = {
 280         { .compatible = "dallas,ds1682", },
 281         {}
 282 };
 283 MODULE_DEVICE_TABLE(of, ds1682_of_match);
 284
 285 static struct i2c_driver ds1682_driver = {
 286         .driver = {
 287                 .name = "ds1682",
 288                 .of_match_table = ds1682_of_match,
 289         },
 290         .probe = ds1682_probe,
 291         .remove = ds1682_remove,
 292         .id_table = ds1682_id,
 293 };
 294
 295 module_i2c_driver(ds1682_driver);
 296
 297 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 298 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
 299 MODULE_LICENSE("GPL");