/*
* Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
*
* Copyright (C) 2010 Ericsson AB.
*
* Derived from:
*
* Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
* Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
*
* Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.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>
/* chip registers */
#define LTC4261_STATUS 0x00 /* readonly */
#define LTC4261_FAULT 0x01
#define LTC4261_ALERT 0x02
#define LTC4261_CONTROL 0x03
#define LTC4261_SENSE_H 0x04
#define LTC4261_SENSE_L 0x05
#define LTC4261_ADIN2_H 0x06
#define LTC4261_ADIN2_L 0x07
#define LTC4261_ADIN_H 0x08
#define LTC4261_ADIN_L 0x09
/*
* Fault register bits
*/
#define FAULT_OV (1<<0)
#define FAULT_UV (1<<1)
#define FAULT_OC (1<<2)
struct ltc4261_data {
struct i2c_client *client;
struct mutex update_lock;
bool valid;
unsigned long last_updated; /* in jiffies */
/* Registers */
u8 regs[10];
};
static struct ltc4261_data *ltc4261_update_device(struct device *dev)
{
struct ltc4261_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
struct ltc4261_data *ret = data;
mutex_lock(&data->update_lock);
if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
int i;
/* Read registers -- 0x00 to 0x09 */
for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
int val;
val = i2c_smbus_read_byte_data(client, i);
if (unlikely(val < 0)) {
dev_dbg(dev,
"Failed to read ADC value: error %d\n",
val);
ret = ERR_PTR(val);
data->valid = 0;
goto abort;
}
data->regs[i] = val;
}
data->last_updated = jiffies;
data->valid = 1;
}
abort:
mutex_unlock(&data->update_lock);
return ret;
}
/* Return the voltage from the given register in mV or mA */
static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
{
u32 val;
val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
switch (reg) {
case LTC4261_ADIN_H:
case LTC4261_ADIN2_H:
/* 2.5mV resolution. Convert to mV. */
val = val * 25 / 10;
break;
case LTC4261_SENSE_H:
/*
* 62.5uV 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 * 625 / 10;
break;
default:
/* If we get here, the developer messed up */
WARN_ON_ONCE(1);
val = 0;
break;
}
return val;
}
static ssize_t ltc4261_show_value(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ltc4261_data *data = ltc4261_update_device(dev);
int value;
if (IS_ERR(data))
return PTR_ERR(data);
value = ltc4261_get_value(data, attr->index);
return snprintf(buf, PAGE_SIZE, "%d\n", value);
}
static ssize_t ltc4261_show_bool(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ltc4261_data *data = ltc4261_update_device(dev);
u8 fault;
if (IS_ERR(data))
return PTR_ERR(data);
fault = data->regs[LTC4261_FAULT] & attr->index;
if (fault) /* Clear reported faults in chip register */
i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);
return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
}
/*
* Input voltages.
*/
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4261_show_value, NULL,
LTC4261_ADIN_H);
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4261_show_value, NULL,
LTC4261_ADIN2_H);
/*
* Voltage alarms. The chip has only one set of voltage alarm status bits,
* triggered by input voltage alarms. In many designs, those alarms are
* associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
* to the OV pin. ADIN2 is, however, not available on all chip variants.
* To ensure that the alarm condition is reported to the user, report it
* with both voltage sensors.
*/
static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4261_show_bool, NULL,
FAULT_UV);
static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL,
FAULT_OV);
static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4261_show_bool, NULL,
FAULT_UV);
static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc4261_show_bool, NULL,
FAULT_OV);
/* Currents (via sense resistor) */
static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4261_show_value, NULL,
LTC4261_SENSE_H);
/* Overcurrent alarm */
static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL,
FAULT_OC);
static struct attribute *ltc4261_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_min_alarm.dev_attr.attr,
&sensor_dev_attr_in2_max_alarm.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(ltc4261);
static int ltc4261_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct i2c_adapter *adapter = client->adapter;
struct device *dev = &client->dev;
struct ltc4261_data *data;
struct device *hwmon_dev;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
return -ENODEV;
if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
dev_err(dev, "Failed to read status register\n");
return -ENODEV;
}
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
mutex_init(&data->update_lock);
/* Clear faults */
i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
data,
ltc4261_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id ltc4261_id[] = {
{"ltc4261", 0},
{}
};
MODULE_DEVICE_TABLE(i2c, ltc4261_id);
/* This is the driver that will be inserted */
static struct i2c_driver ltc4261_driver = {
.driver = {
.name = "ltc4261",
},
.probe = ltc4261_probe,
.id_table = ltc4261_id,
};
module_i2c_driver(ltc4261_driver);
MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("LTC4261 driver");
MODULE_LICENSE("GPL");
