diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/misc/ds1682.c | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/misc/ds1682.c b/drivers/misc/ds1682.c new file mode 100644 index 000000000..98a921ea9 --- /dev/null +++ b/drivers/misc/ds1682.c @@ -0,0 +1,267 @@ +/* + * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver + * + * Written by: Grant Likely <grant.likely@secretlab.ca> + * + * Copyright (C) 2007 Secret Lab Technologies Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +/* + * 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/sysfs.h> +#include <linux/ctype.h> +#include <linux/hwmon-sysfs.h> + +/* Device registers */ +#define DS1682_REG_CONFIG 0x00 +#define DS1682_REG_ALARM 0x01 +#define DS1682_REG_ELAPSED 0x05 +#define DS1682_REG_EVT_CNTR 0x09 +#define DS1682_REG_EEPROM 0x0b +#define DS1682_REG_RESET 0x1d +#define DS1682_REG_WRITE_DISABLE 0x1e +#define DS1682_REG_WRITE_MEM_DISABLE 0x1f + +#define DS1682_EEPROM_SIZE 10 + +/* + * Generic counter attributes + */ +static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); + struct i2c_client *client = to_i2c_client(dev); + unsigned long long val, check; + __le32 val_le = 0; + int rc; + + dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name); + + /* Read the register */ + rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr, + (u8 *)&val_le); + if (rc < 0) + return -EIO; + + val = le32_to_cpu(val_le); + + if (sattr->index == DS1682_REG_ELAPSED) { + int retries = 5; + + /* Detect and retry when a tick occurs mid-read */ + do { + rc = i2c_smbus_read_i2c_block_data(client, sattr->index, + sattr->nr, + (u8 *)&val_le); + if (rc < 0 || retries <= 0) + return -EIO; + + check = val; + val = le32_to_cpu(val_le); + retries--; + } while (val != check && val != (check + 1)); + } + + /* Format the output string and return # of bytes + * Special case: the 32 bit regs are time values with 1/4s + * resolution, scale them up to milliseconds + */ + return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val); +} + +static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); + struct i2c_client *client = to_i2c_client(dev); + u64 val; + __le32 val_le; + int rc; + + dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); + + /* Decode input */ + rc = kstrtoull(buf, 0, &val); + if (rc < 0) { + dev_dbg(dev, "input string not a number\n"); + return -EINVAL; + } + + /* Special case: the 32 bit regs are time values with 1/4s + * resolution, scale input down to quarter-seconds */ + if (sattr->nr == 4) + do_div(val, 250); + + /* write out the value */ + val_le = cpu_to_le32(val); + rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, + (u8 *) & val_le); + if (rc < 0) { + dev_err(dev, "register write failed; reg=0x%x, size=%i\n", + sattr->index, sattr->nr); + return -EIO; + } + + return 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 = { + .attrs = (struct attribute *[]) { + &sensor_dev_attr_elapsed_time.dev_attr.attr, + &sensor_dev_attr_alarm_time.dev_attr.attr, + &sensor_dev_attr_event_count.dev_attr.attr, + NULL, + }, +}; + +/* + * 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) +{ + struct i2c_client *client = kobj_to_i2c_client(kobj); + int rc; + + dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", + buf, off, count); + + rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, + count, buf); + if (rc < 0) + return -EIO; + + return 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) +{ + struct i2c_client *client = kobj_to_i2c_client(kobj); + + dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", + buf, off, count); + + /* Write out to the device */ + if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, + count, buf) < 0) + return -EIO; + + return count; +} + +static const struct bin_attribute ds1682_eeprom_attr = { + .attr = { + .name = "eeprom", + .mode = S_IRUGO | S_IWUSR, + }, + .size = DS1682_EEPROM_SIZE, + .read = ds1682_eeprom_read, + .write = ds1682_eeprom_write, +}; + +/* + * Called when a ds1682 device is matched with this driver + */ +static int ds1682_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + int rc; + + if (!i2c_check_functionality(client->adapter, + I2C_FUNC_SMBUS_I2C_BLOCK)) { + dev_err(&client->dev, "i2c bus does not support the ds1682\n"); + rc = -ENODEV; + goto exit; + } + + rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); + if (rc) + goto exit; + + rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); + if (rc) + goto exit_bin_attr; + + return 0; + + exit_bin_attr: + sysfs_remove_group(&client->dev.kobj, &ds1682_group); + exit: + return rc; +} + +static int ds1682_remove(struct i2c_client *client) +{ + sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); + sysfs_remove_group(&client->dev.kobj, &ds1682_group); + return 0; +} + +static const struct i2c_device_id ds1682_id[] = { + { "ds1682", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ds1682_id); + +static const struct of_device_id ds1682_of_match[] = { + { .compatible = "dallas,ds1682", }, + {} +}; +MODULE_DEVICE_TABLE(of, ds1682_of_match); + +static struct i2c_driver ds1682_driver = { + .driver = { + .name = "ds1682", + .of_match_table = ds1682_of_match, + }, + .probe = ds1682_probe, + .remove = ds1682_remove, + .id_table = ds1682_id, +}; + +module_i2c_driver(ds1682_driver); + +MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); +MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); +MODULE_LICENSE("GPL"); |