linux/drivers/misc/ds1682.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
 *
 * Written by: Grant Likely <[email protected]>
 *
 * Copyright (C) 2007 Secret Lab Technologies Ltd.
 */

/*
 * The DS1682 elapsed timer recorder is a simple device that implements
 * one elapsed time counter, one event counter, an alarm signal and 10
 * bytes of general purpose EEPROM.
 *
 * This driver provides access to the DS1682 counters and user data via
 * the sysfs.  The following attributes are added to the device node:
 *     elapsed_time (u32): Total elapsed event time in ms resolution
 *     alarm_time (u32): When elapsed time exceeds the value in alarm_time,
 *                       then the alarm pin is asserted.
 *     event_count (u16): number of times the event pin has gone low.
 *     eeprom (u8[10]): general purpose EEPROM
 *
 * Counter registers and user data are both read/write unless the device
 * has been write protected.  This driver does not support turning off write
 * protection.  Once write protection is turned on, it is impossible to
 * turn it off again, so I have left the feature out of this driver to avoid
 * accidental enabling, but it is trivial to add write protect support.
 *
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/nvmem-provider.h>
#include <linux/sysfs.h>
#include <linux/ctype.h>
#include <linux/hwmon-sysfs.h>

/* Device registers */
#define DS1682_REG_CONFIG …
#define DS1682_REG_ALARM …
#define DS1682_REG_ELAPSED …
#define DS1682_REG_EVT_CNTR …
#define DS1682_REG_EEPROM …
#define DS1682_REG_RESET …
#define DS1682_REG_WRITE_DISABLE …
#define DS1682_REG_WRITE_MEM_DISABLE …

#define DS1682_EEPROM_SIZE …

/*
 * Generic counter attributes
 */
static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
			   char *buf)
{ … }

static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
			    const char *buf, size_t count)
{ … }

/*
 * Simple register attributes
 */
static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
			    ds1682_store, 4, DS1682_REG_ELAPSED);
static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
			    ds1682_store, 4, DS1682_REG_ALARM);
static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
			    ds1682_store, 2, DS1682_REG_EVT_CNTR);

static const struct attribute_group ds1682_group = …;

/*
 * User data attribute
 */
static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj,
				  struct bin_attribute *attr,
				  char *buf, loff_t off, size_t count)
{ … }

static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj,
				   struct bin_attribute *attr,
				   char *buf, loff_t off, size_t count)
{ … }

static const struct bin_attribute ds1682_eeprom_attr = …;

static int ds1682_nvmem_read(void *priv, unsigned int offset, void *val,
			     size_t bytes)
{ … }

static int ds1682_nvmem_write(void *priv, unsigned int offset, void *val,
			      size_t bytes)
{ … }

/*
 * Called when a ds1682 device is matched with this driver
 */
static int ds1682_probe(struct i2c_client *client)
{ … }

static void ds1682_remove(struct i2c_client *client)
{ … }

static const struct i2c_device_id ds1682_id[] = …;
MODULE_DEVICE_TABLE(i2c, ds1682_id);

static const struct of_device_id ds1682_of_match[] = …;
MODULE_DEVICE_TABLE(of, ds1682_of_match);

static struct i2c_driver ds1682_driver = …;

module_i2c_driver(…) …;

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;