/*
* Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
*
* Copyright (c) 2014 Guenter Roeck
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/regmap.h>
/* chip registers */
#define LTC4260_CONTROL 0x00
#define LTC4260_ALERT 0x01
#define LTC4260_STATUS 0x02
#define LTC4260_FAULT 0x03
#define LTC4260_SENSE 0x04
#define LTC4260_SOURCE 0x05
#define LTC4260_ADIN 0x06
/*
* Fault register bits
*/
#define FAULT_OV (1 << 0)
#define FAULT_UV (1 << 1)
#define FAULT_OC (1 << 2)
#define FAULT_POWER_BAD (1 << 3)
#define FAULT_FET_SHORT (1 << 5)
/* Return the voltage from the given register in mV or mA */
static int ltc4260_get_value(struct device *dev, u8 reg)
{
struct regmap *regmap = dev_get_drvdata(dev);
unsigned int val;
int ret;
ret = regmap_read(regmap, reg, &val);
if (ret < 0)
return ret;
switch (reg) {
case LTC4260_ADIN:
/* 10 mV resolution. Convert to mV. */
val = val * 10;
break;
case LTC4260_SOURCE:
/* 400 mV resolution. Convert to mV. */
val = val * 400;
break;
case LTC4260_SENSE:
/*
* 300 uV resolution. Convert to current as measured with
* an 1 mOhm sense resistor, in mA. If a different sense
* resistor is installed, calculate the actual current by
* dividing the reported current by the sense resistor value
* in mOhm.
*/
val = val * 300;
break;
default:
return -EINVAL;
}
return val;
}
static ssize_t ltc4260_show_value(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
int value;
value = ltc4260_get_value(dev, attr->index);
if (value < 0)
return value;
return snprintf(buf, PAGE_SIZE, "%d\n", value);
}
static ssize_t ltc4260_show_bool(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct regmap *regmap = dev_get_drvdata(dev);
unsigned int fault;
int ret;
ret = regmap_read(regmap, LTC4260_FAULT, &fault);
if (ret < 0)
return ret;
fault &= attr->index;
if (fault) /* Clear reported faults in chip register */
regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
}
/* Voltages */
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4260_show_value, NULL,
LTC4260_SOURCE);
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4260_show_value, NULL,
LTC4260_ADIN);
/*
* Voltage alarms
* UV/OV faults are associated with the input voltage, and the POWER BAD and
* FET SHORT faults are associated with the output voltage.
*/
static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4260_show_bool, NULL,
FAULT_UV);
static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
FAULT_OV);
static SENSOR_DEVICE_ATTR(in2_alarm, S_IRUGO, ltc4260_show_bool, NULL,
FAULT_POWER_BAD | FAULT_FET_SHORT);
/* Current (via sense resistor) */
static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4260_show_value, NULL,
LTC4260_SENSE);
/* Overcurrent alarm */
static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
FAULT_OC);
static struct attribute *ltc4260_attrs[] = {
&sensor_dev_attr_in1_input.dev_attr.attr,
&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
&sensor_dev_attr_in2_input.dev_attr.attr,
&sensor_dev_attr_in2_alarm.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(ltc4260);
static const struct regmap_config ltc4260_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = LTC4260_ADIN,
};
static int ltc4260_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct regmap *regmap;
regmap = devm_regmap_init_i2c(client, <c4260_regmap_config);
if (IS_ERR(regmap)) {
dev_err(dev, "failed to allocate register map\n");
return PTR_ERR(regmap);
}
/* Clear faults */
regmap_write(regmap, LTC4260_FAULT, 0x00);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
regmap,
ltc4260_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id ltc4260_id[] = {
{"ltc4260", 0},
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc4260_id);
static struct i2c_driver ltc4260_driver = {
.driver = {
.name = "ltc4260",
},
.probe = ltc4260_probe,
.id_table = ltc4260_id,
};
module_i2c_driver(ltc4260_driver);
MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("LTC4260 driver");
MODULE_LICENSE("GPL");
