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/*
* Driver for Linear Technology LTC4151 High Voltage I2C Current
* and Voltage Monitor
*
* Copyright (C) 2011 AppearTV AS
*
* Derived from:
*
* Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
* Swap Controller
* Copyright (C) 2010 Ericsson AB.
*
* Datasheet: http://www.linear.com/docs/Datasheet/4151fc.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/of.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 LTC4151_SENSE_H 0x00
#define LTC4151_SENSE_L 0x01
#define LTC4151_VIN_H 0x02
#define LTC4151_VIN_L 0x03
#define LTC4151_ADIN_H 0x04
#define LTC4151_ADIN_L 0x05
struct ltc4151_data {
struct i2c_client *client;
struct mutex update_lock;
bool valid;
unsigned long last_updated; /* in jiffies */
unsigned int shunt; /* in micro ohms */
/* Registers */
u8 regs[6];
};
static struct ltc4151_data *ltc4151_update_device(struct device *dev)
{
struct ltc4151_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
struct ltc4151_data *ret = data;
mutex_lock(&data->update_lock);
/*
* The chip's A/D updates 6 times per second
* (Conversion Rate 6 - 9 Hz)
*/
if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
int i;
dev_dbg(&client->dev, "Starting ltc4151 update\n");
/* Read all registers */
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);
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 */
static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
{
u32 val;
val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
switch (reg) {
case LTC4151_ADIN_H:
/* 500uV resolution. Convert to mV. */
val = val * 500 / 1000;
break;
case LTC4151_SENSE_H:
/*
* 20uV resolution. Convert to current as measured with
* a given sense resistor, in mA.
*/
val = val * 20 * 1000 / data->shunt;
break;
case LTC4151_VIN_H:
/* 25 mV per increment */
val = val * 25;
break;
default:
/* If we get here, the developer messed up */
WARN_ON_ONCE(1);
val = 0;
break;
}
return val;
}
static ssize_t ltc4151_value_show(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ltc4151_data *data = ltc4151_update_device(dev);
int value;
if (IS_ERR(data))
return PTR_ERR(data);
value = ltc4151_get_value(data, attr->index);
return snprintf(buf, PAGE_SIZE, "%d\n", value);
}
/*
* Input voltages.
*/
static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H);
static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H);
/* Currents (via sense resistor) */
static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H);
/*
* Finally, construct an array of pointers to members of the above objects,
* as required for sysfs_create_group()
*/
static struct attribute *ltc4151_attrs[] = {
&sensor_dev_attr_in1_input.dev_attr.attr,
&sensor_dev_attr_in2_input.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(ltc4151);
static int ltc4151_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct i2c_adapter *adapter = client->adapter;
struct device *dev = &client->dev;
struct ltc4151_data *data;
struct device *hwmon_dev;
u32 shunt;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
return -ENODEV;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
if (of_property_read_u32(client->dev.of_node,
"shunt-resistor-micro-ohms", &shunt))
shunt = 1000; /* 1 mOhm if not set via DT */
if (shunt == 0)
return -EINVAL;
data->shunt = shunt;
data->client = client;
mutex_init(&data->update_lock);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
data,
ltc4151_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id ltc4151_id[] = {
{ "ltc4151", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc4151_id);
static const struct of_device_id ltc4151_match[] = {
{ .compatible = "lltc,ltc4151" },
{},
};
MODULE_DEVICE_TABLE(of, ltc4151_match);
/* This is the driver that will be inserted */
static struct i2c_driver ltc4151_driver = {
.driver = {
.name = "ltc4151",
.of_match_table = of_match_ptr(ltc4151_match),
},
.probe = ltc4151_probe,
.id_table = ltc4151_id,
};
module_i2c_driver(ltc4151_driver);
MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
MODULE_DESCRIPTION("LTC4151 driver");
MODULE_LICENSE("GPL");
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