268 lines
7.0 KiB
C
268 lines
7.0 KiB
C
/*
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* Dallas Semiconductor DS1682 Elapsed Time Recorder device driver
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*
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* Written by: Grant Likely <grant.likely@secretlab.ca>
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*
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* Copyright (C) 2007 Secret Lab Technologies Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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/*
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* The DS1682 elapsed timer recorder is a simple device that implements
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* one elapsed time counter, one event counter, an alarm signal and 10
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* bytes of general purpose EEPROM.
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*
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* This driver provides access to the DS1682 counters and user data via
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* the sysfs. The following attributes are added to the device node:
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* elapsed_time (u32): Total elapsed event time in ms resolution
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* alarm_time (u32): When elapsed time exceeds the value in alarm_time,
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* then the alarm pin is asserted.
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* event_count (u16): number of times the event pin has gone low.
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* eeprom (u8[10]): general purpose EEPROM
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*
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* Counter registers and user data are both read/write unless the device
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* has been write protected. This driver does not support turning off write
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* protection. Once write protection is turned on, it is impossible to
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* turn it off again, so I have left the feature out of this driver to avoid
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* accidental enabling, but it is trivial to add write protect support.
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*
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/string.h>
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#include <linux/list.h>
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#include <linux/sysfs.h>
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#include <linux/ctype.h>
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#include <linux/hwmon-sysfs.h>
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/* Device registers */
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#define DS1682_REG_CONFIG 0x00
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#define DS1682_REG_ALARM 0x01
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#define DS1682_REG_ELAPSED 0x05
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#define DS1682_REG_EVT_CNTR 0x09
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#define DS1682_REG_EEPROM 0x0b
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#define DS1682_REG_RESET 0x1d
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#define DS1682_REG_WRITE_DISABLE 0x1e
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#define DS1682_REG_WRITE_MEM_DISABLE 0x1f
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#define DS1682_EEPROM_SIZE 10
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/*
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* Generic counter attributes
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*/
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static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
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struct i2c_client *client = to_i2c_client(dev);
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__le32 val = 0;
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int rc;
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dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name);
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/* Read the register */
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rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr,
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(u8 *) & val);
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if (rc < 0)
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return -EIO;
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/* Special case: the 32 bit regs are time values with 1/4s
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* resolution, scale them up to milliseconds */
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if (sattr->nr == 4)
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return sprintf(buf, "%llu\n",
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((unsigned long long)le32_to_cpu(val)) * 250);
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/* Format the output string and return # of bytes */
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return sprintf(buf, "%li\n", (long)le32_to_cpu(val));
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}
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static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
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struct i2c_client *client = to_i2c_client(dev);
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char *endp;
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u64 val;
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__le32 val_le;
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int rc;
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dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name);
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/* Decode input */
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val = simple_strtoull(buf, &endp, 0);
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if (buf == endp) {
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dev_dbg(dev, "input string not a number\n");
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return -EINVAL;
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}
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/* Special case: the 32 bit regs are time values with 1/4s
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* resolution, scale input down to quarter-seconds */
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if (sattr->nr == 4)
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do_div(val, 250);
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/* write out the value */
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val_le = cpu_to_le32(val);
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rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr,
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(u8 *) & val_le);
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if (rc < 0) {
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dev_err(dev, "register write failed; reg=0x%x, size=%i\n",
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sattr->index, sattr->nr);
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return -EIO;
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}
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return count;
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}
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/*
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* Simple register attributes
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*/
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static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show,
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ds1682_store, 4, DS1682_REG_ELAPSED);
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static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show,
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ds1682_store, 4, DS1682_REG_ALARM);
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static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show,
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ds1682_store, 2, DS1682_REG_EVT_CNTR);
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static const struct attribute_group ds1682_group = {
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.attrs = (struct attribute *[]) {
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&sensor_dev_attr_elapsed_time.dev_attr.attr,
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&sensor_dev_attr_alarm_time.dev_attr.attr,
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&sensor_dev_attr_event_count.dev_attr.attr,
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NULL,
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},
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};
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/*
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* User data attribute
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*/
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static ssize_t ds1682_eeprom_read(struct kobject *kobj, struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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struct i2c_client *client = kobj_to_i2c_client(kobj);
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int rc;
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dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n",
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buf, off, count);
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if (off >= DS1682_EEPROM_SIZE)
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return 0;
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if (off + count > DS1682_EEPROM_SIZE)
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count = DS1682_EEPROM_SIZE - off;
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rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off,
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count, buf);
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if (rc < 0)
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return -EIO;
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return count;
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}
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static ssize_t ds1682_eeprom_write(struct kobject *kobj, struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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struct i2c_client *client = kobj_to_i2c_client(kobj);
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dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n",
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buf, off, count);
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if (off >= DS1682_EEPROM_SIZE)
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return -ENOSPC;
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if (off + count > DS1682_EEPROM_SIZE)
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count = DS1682_EEPROM_SIZE - off;
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/* Write out to the device */
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if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off,
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count, buf) < 0)
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return -EIO;
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return count;
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}
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static struct bin_attribute ds1682_eeprom_attr = {
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.attr = {
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.name = "eeprom",
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.mode = S_IRUGO | S_IWUSR,
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},
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.size = DS1682_EEPROM_SIZE,
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.read = ds1682_eeprom_read,
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.write = ds1682_eeprom_write,
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};
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/*
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* Called when a ds1682 device is matched with this driver
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*/
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static int ds1682_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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int rc;
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_I2C_BLOCK)) {
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dev_err(&client->dev, "i2c bus does not support the ds1682\n");
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rc = -ENODEV;
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goto exit;
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}
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rc = sysfs_create_group(&client->dev.kobj, &ds1682_group);
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if (rc)
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goto exit;
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rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
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if (rc)
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goto exit_bin_attr;
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return 0;
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exit_bin_attr:
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sysfs_remove_group(&client->dev.kobj, &ds1682_group);
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exit:
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return rc;
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}
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static int ds1682_remove(struct i2c_client *client)
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{
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sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr);
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sysfs_remove_group(&client->dev.kobj, &ds1682_group);
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return 0;
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}
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static const struct i2c_device_id ds1682_id[] = {
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{ "ds1682", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ds1682_id);
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static struct i2c_driver ds1682_driver = {
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.driver = {
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.name = "ds1682",
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},
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.probe = ds1682_probe,
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.remove = ds1682_remove,
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.id_table = ds1682_id,
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};
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static int __init ds1682_init(void)
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{
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return i2c_add_driver(&ds1682_driver);
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}
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static void __exit ds1682_exit(void)
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{
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i2c_del_driver(&ds1682_driver);
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}
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MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
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MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver");
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MODULE_LICENSE("GPL");
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module_init(ds1682_init);
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module_exit(ds1682_exit);
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