hwmon: Driver for Linear Technologies LTC4260

LTC4260 is a Positive Voltage Hot Swap Controller.
The driver currently only supports voltage monitoring, not voltage control.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2014-01-11 00:17:05 -08:00
parent 79ffe8594f
commit 69e1ded651
4 changed files with 269 additions and 0 deletions

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Kernel driver ltc4260
=====================
Supported chips:
* Linear Technology LTC4260
Prefix: 'ltc4260'
Addresses scanned: -
Datasheet:
http://cds.linear.com/docs/en/datasheet/4260fc.pdf
Author: Guenter Roeck <linux@roeck-us.net>
Description
-----------
The LTC4260 Hot Swap controller allows a board to be safely inserted
and removed from a live backplane.
Usage Notes
-----------
This driver does not probe for LTC4260 devices, since there is no register
which can be safely used to identify the chip. You will have to instantiate
the devices explicitly.
Example: the following will load the driver for an LTC4260 at address 0x10
on I2C bus #1:
$ modprobe ltc4260
$ echo ltc4260 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
Sysfs entries
-------------
Voltage readings provided by this driver are reported as obtained from the ADC
registers. If a set of voltage divider resistors is installed, calculate the
real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
value of the divider resistor against the measured voltage and R2 is the value
of the divider resistor against Ground.
Current reading provided by this driver is reported as obtained from the ADC
Current Sense register. The reported value assumes that a 1 mOhm sense resistor
is installed. If a different sense resistor is installed, calculate the real
current by dividing the reported value by the sense resistor value in mOhm.
in1_input SOURCE voltage (mV)
in1_min_alarm Undervoltage alarm
in1_max_alarm Overvoltage alarm
in2_input ADIN voltage (mV)
in2_alarm Power bad alarm
curr1_input SENSE current (mA)
curr1_alarm SENSE overcurrent alarm

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@ -821,6 +821,18 @@ config SENSORS_LTC4245
This driver can also be built as a module. If so, the module will
be called ltc4245.
config SENSORS_LTC4260
tristate "Linear Technology LTC4260"
depends on I2C
select REGMAP_I2C
default n
help
If you say yes here you get support for Linear Technology LTC4261
Positive Voltage Hot Swap Controller I2C interface.
This driver can also be built as a module. If so, the module will
be called ltc4260.
config SENSORS_LTC4261
tristate "Linear Technology LTC4261"
depends on I2C

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@ -99,6 +99,7 @@ obj-$(CONFIG_SENSORS_LTC4151) += ltc4151.o
obj-$(CONFIG_SENSORS_LTC4215) += ltc4215.o
obj-$(CONFIG_SENSORS_LTC4222) += ltc4222.o
obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o
obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o
obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o
obj-$(CONFIG_SENSORS_MAX1111) += max1111.o
obj-$(CONFIG_SENSORS_MAX16065) += max16065.o

200
drivers/hwmon/ltc4260.c Normal file
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/*
* 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 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, &ltc4260_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");