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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver4 *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 implements12 * one elapsed time counter, one event counter, an alarm signal and 1013 * bytes of general purpose EEPROM.14 *15 * This driver provides access to the DS1682 counters and user data via16 * the sysfs. The following attributes are added to the device node:17 * elapsed_time (u32): Total elapsed event time in ms resolution18 * 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 EEPROM22 *23 * Counter registers and user data are both read/write unless the device24 * has been write protected. This driver does not support turning off write25 * protection. Once write protection is turned on, it is impossible to26 * turn it off again, so I have left the feature out of this driver to avoid27 * 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 0x0042#define DS1682_REG_ALARM 0x0143#define DS1682_REG_ELAPSED 0x0544#define DS1682_REG_EVT_CNTR 0x0945#define DS1682_REG_EEPROM 0x0b46#define DS1682_REG_RESET 0x1d47#define DS1682_REG_WRITE_DISABLE 0x1e48#define DS1682_REG_WRITE_MEM_DISABLE 0x1f49 50#define DS1682_EEPROM_SIZE 1051 52/*53 * Generic counter attributes54 */55static 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 bytes92 * Special case: the 32 bit regs are time values with 1/4s93 * resolution, scale them up to milliseconds94 */95 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val);96}97 98static 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 1/4s117 * 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 attributes136 */137static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,138 ds1682_store, 4, DS1682_REG_ELAPSED);139static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,140 ds1682_store, 4, DS1682_REG_ALARM);141static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,142 ds1682_store, 2, DS1682_REG_EVT_CNTR);143 144static 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 attribute155 */156static 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 174static 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 191static 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 201static 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 212static 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 driver225 */226static 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 267static 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 273static const struct i2c_device_id ds1682_id[] = {274 { "ds1682" },275 { }276};277MODULE_DEVICE_TABLE(i2c, ds1682_id);278 279static const struct of_device_id ds1682_of_match[] = {280 { .compatible = "dallas,ds1682", },281 {}282};283MODULE_DEVICE_TABLE(of, ds1682_of_match);284 285static 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 295module_i2c_driver(ds1682_driver);296 297MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");298MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");299MODULE_LICENSE("GPL");300