drivers/misc/ds1682.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
0004  *
0005  * Written by: Grant Likely <grant.likely@secretlab.ca>
0006  *
0007  * Copyright (C) 2007 Secret Lab Technologies Ltd.
0008  */
0009
0010 /*
0011  * The DS1682 elapsed timer recorder is a simple device that implements
0012  * one elapsed time counter, one event counter, an alarm signal and 10
0013  * bytes of general purpose EEPROM.
0014  *
0015  * This driver provides access to the DS1682 counters and user data via
0016  * the sysfs.  The following attributes are added to the device node:
0017  *     elapsed_time (u32): Total elapsed event time in ms resolution
0018  *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
0019  *                       then the alarm pin is asserted.
0020  *     event_count (u16): number of times the event pin has gone low.
0021  *     eeprom (u8[10]): general purpose EEPROM
0022  *
0023  * Counter registers and user data are both read/write unless the device
0024  * has been write protected.  This driver does not support turning off write
0025  * protection.  Once write protection is turned on, it is impossible to
0026  * turn it off again, so I have left the feature out of this driver to avoid
0027  * accidental enabling, but it is trivial to add write protect support.
0028  *
0029  */
0030
0031 #include <linux/module.h>
0032 #include <linux/i2c.h>
0033 #include <linux/string.h>
0034 #include <linux/list.h>
0035 #include <linux/sysfs.h>
0036 #include <linux/ctype.h>
0037 #include <linux/hwmon-sysfs.h>
0038
0039 /* Device registers */
0040 #define DS1682_REG_CONFIG       0x00
0041 #define DS1682_REG_ALARM        0x01
0042 #define DS1682_REG_ELAPSED      0x05
0043 #define DS1682_REG_EVT_CNTR     0x09
0044 #define DS1682_REG_EEPROM       0x0b
0045 #define DS1682_REG_RESET        0x1d
0046 #define DS1682_REG_WRITE_DISABLE    0x1e
0047 #define DS1682_REG_WRITE_MEM_DISABLE    0x1f
0048
0049 #define DS1682_EEPROM_SIZE      10
0050
0051 /*
0052  * Generic counter attributes
0053  */
0054 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
0055                char *buf)
0056 {
0057     struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
0058     struct i2c_client *client = to_i2c_client(dev);
0059     unsigned long long val, check;
0060     __le32 val_le = 0;
0061     int rc;
0062
0063     dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
0064
0065     /* Read the register */
0066     rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
0067                        (u8 *)&val_le);
0068     if (rc < 0)
0069         return -EIO;
0070
0071     val = le32_to_cpu(val_le);
0072
0073     if (sattr->index == DS1682_REG_ELAPSED) {
0074         int retries = 5;
0075
0076         /* Detect and retry when a tick occurs mid-read */
0077         do {
0078             rc = i2c_smbus_read_i2c_block_data(client, sattr->index,
0079                                sattr->nr,
0080                                (u8 *)&val_le);
0081             if (rc < 0 || retries <= 0)
0082                 return -EIO;
0083
0084             check = val;
0085             val = le32_to_cpu(val_le);
0086             retries--;
0087         } while (val != check && val != (check + 1));
0088     }
0089
0090     /* Format the output string and return # of bytes
0091      * Special case: the 32 bit regs are time values with 1/4s
0092      * resolution, scale them up to milliseconds
0093      */
0094     return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);
0095 }
0096
0097 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
0098                 const char *buf, size_t count)
0099 {
0100     struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
0101     struct i2c_client *client = to_i2c_client(dev);
0102     u64 val;
0103     __le32 val_le;
0104     int rc;
0105
0106     dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
0107
0108     /* Decode input */
0109     rc = kstrtoull(buf, 0, &val);
0110     if (rc < 0) {
0111         dev_dbg(dev, "input string not a number\n");
0112         return -EINVAL;
0113     }
0114
0115     /* Special case: the 32 bit regs are time values with 1/4s
0116      * resolution, scale input down to quarter-seconds */
0117     if (sattr->nr == 4)
0118         do_div(val, 250);
0119
0120     /* write out the value */
0121     val_le = cpu_to_le32(val);
0122     rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
0123                         (u8 *) & val_le);
0124     if (rc < 0) {
0125         dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
0126             sattr->index, sattr->nr);
0127         return -EIO;
0128     }
0129
0130     return count;
0131 }
0132
0133 /*
0134  * Simple register attributes
0135  */
0136 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
0137                 ds1682_store, 4, DS1682_REG_ELAPSED);
0138 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
0139                 ds1682_store, 4, DS1682_REG_ALARM);
0140 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
0141                 ds1682_store, 2, DS1682_REG_EVT_CNTR);
0142
0143 static const struct attribute_group ds1682_group = {
0144     .attrs = (struct attribute *[]) {
0145         &sensor_dev_attr_elapsed_time.dev_attr.attr,
0146         &sensor_dev_attr_alarm_time.dev_attr.attr,
0147         &sensor_dev_attr_event_count.dev_attr.attr,
0148         NULL,
0149     },
0150 };
0151
0152 /*
0153  * User data attribute
0154  */
0155 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
0156                   struct bin_attribute *attr,
0157                   char *buf, loff_t off, size_t count)
0158 {
0159     struct i2c_client *client = kobj_to_i2c_client(kobj);
0160     int rc;
0161
0162     dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
0163         buf, off, count);
0164
0165     rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
0166                        count, buf);
0167     if (rc < 0)
0168         return -EIO;
0169
0170     return count;
0171 }
0172
0173 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
0174                    struct bin_attribute *attr,
0175                    char *buf, loff_t off, size_t count)
0176 {
0177     struct i2c_client *client = kobj_to_i2c_client(kobj);
0178
0179     dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
0180         buf, off, count);
0181
0182     /* Write out to the device */
0183     if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
0184                        count, buf) < 0)
0185         return -EIO;
0186
0187     return count;
0188 }
0189
0190 static const struct bin_attribute ds1682_eeprom_attr = {
0191     .attr = {
0192         .name = "eeprom",
0193         .mode = S_IRUGO | S_IWUSR,
0194     },
0195     .size = DS1682_EEPROM_SIZE,
0196     .read = ds1682_eeprom_read,
0197     .write = ds1682_eeprom_write,
0198 };
0199
0200 /*
0201  * Called when a ds1682 device is matched with this driver
0202  */
0203 static int ds1682_probe(struct i2c_client *client,
0204             const struct i2c_device_id *id)
0205 {
0206     int rc;
0207
0208     if (!i2c_check_functionality(client->adapter,
0209                      I2C_FUNC_SMBUS_I2C_BLOCK)) {
0210         dev_err(&client->dev, "i2c bus does not support the ds1682\n");
0211         rc = -ENODEV;
0212         goto exit;
0213     }
0214
0215     rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
0216     if (rc)
0217         goto exit;
0218
0219     rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
0220     if (rc)
0221         goto exit_bin_attr;
0222
0223     return 0;
0224
0225  exit_bin_attr:
0226     sysfs_remove_group(&client->dev.kobj, &ds1682_group);
0227  exit:
0228     return rc;
0229 }
0230
0231 static int ds1682_remove(struct i2c_client *client)
0232 {
0233     sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
0234     sysfs_remove_group(&client->dev.kobj, &ds1682_group);
0235     return 0;
0236 }
0237
0238 static const struct i2c_device_id ds1682_id[] = {
0239     { "ds1682", 0 },
0240     { }
0241 };
0242 MODULE_DEVICE_TABLE(i2c, ds1682_id);
0243
0244 static const struct of_device_id ds1682_of_match[] = {
0245     { .compatible = "dallas,ds1682", },
0246     {}
0247 };
0248 MODULE_DEVICE_TABLE(of, ds1682_of_match);
0249
0250 static struct i2c_driver ds1682_driver = {
0251     .driver = {
0252         .name = "ds1682",
0253         .of_match_table = ds1682_of_match,
0254     },
0255     .probe = ds1682_probe,
0256     .remove = ds1682_remove,
0257     .id_table = ds1682_id,
0258 };
0259
0260 module_i2c_driver(ds1682_driver);
0261
0262 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
0263 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
0264 MODULE_LICENSE("GPL");