328 lines
8.3 KiB
C
328 lines
8.3 KiB
C
/*
|
|
* Driver for Linear Technology LTC4215 I2C Hot Swap Controller
|
|
*
|
|
* Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>
|
|
*
|
|
* 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; version 2 of the License.
|
|
*
|
|
* Datasheet:
|
|
* http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
|
|
*/
|
|
|
|
#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>
|
|
|
|
/* Here are names of the chip's registers (a.k.a. commands) */
|
|
enum ltc4215_cmd {
|
|
LTC4215_CONTROL = 0x00, /* rw */
|
|
LTC4215_ALERT = 0x01, /* rw */
|
|
LTC4215_STATUS = 0x02, /* ro */
|
|
LTC4215_FAULT = 0x03, /* rw */
|
|
LTC4215_SENSE = 0x04, /* rw */
|
|
LTC4215_SOURCE = 0x05, /* rw */
|
|
LTC4215_ADIN = 0x06, /* rw */
|
|
};
|
|
|
|
struct ltc4215_data {
|
|
struct device *hwmon_dev;
|
|
|
|
struct mutex update_lock;
|
|
bool valid;
|
|
unsigned long last_updated; /* in jiffies */
|
|
|
|
/* Registers */
|
|
u8 regs[7];
|
|
};
|
|
|
|
static struct ltc4215_data *ltc4215_update_device(struct device *dev)
|
|
{
|
|
struct i2c_client *client = to_i2c_client(dev);
|
|
struct ltc4215_data *data = i2c_get_clientdata(client);
|
|
s32 val;
|
|
int i;
|
|
|
|
mutex_lock(&data->update_lock);
|
|
|
|
/* The chip's A/D updates 10 times per second */
|
|
if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
|
|
|
|
dev_dbg(&client->dev, "Starting ltc4215 update\n");
|
|
|
|
/* Read all registers */
|
|
for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
|
|
val = i2c_smbus_read_byte_data(client, i);
|
|
if (unlikely(val < 0))
|
|
data->regs[i] = 0;
|
|
else
|
|
data->regs[i] = val;
|
|
}
|
|
|
|
data->last_updated = jiffies;
|
|
data->valid = 1;
|
|
}
|
|
|
|
mutex_unlock(&data->update_lock);
|
|
|
|
return data;
|
|
}
|
|
|
|
/* Return the voltage from the given register in millivolts */
|
|
static int ltc4215_get_voltage(struct device *dev, u8 reg)
|
|
{
|
|
struct ltc4215_data *data = ltc4215_update_device(dev);
|
|
const u8 regval = data->regs[reg];
|
|
u32 voltage = 0;
|
|
|
|
switch (reg) {
|
|
case LTC4215_SENSE:
|
|
/* 151 uV per increment */
|
|
voltage = regval * 151 / 1000;
|
|
break;
|
|
case LTC4215_SOURCE:
|
|
/* 60.5 mV per increment */
|
|
voltage = regval * 605 / 10;
|
|
break;
|
|
case LTC4215_ADIN:
|
|
/* The ADIN input is divided by 12.5, and has 4.82 mV
|
|
* per increment, so we have the additional multiply */
|
|
voltage = regval * 482 * 125 / 1000;
|
|
break;
|
|
default:
|
|
/* If we get here, the developer messed up */
|
|
WARN_ON_ONCE(1);
|
|
break;
|
|
}
|
|
|
|
return voltage;
|
|
}
|
|
|
|
/* Return the current from the sense resistor in mA */
|
|
static unsigned int ltc4215_get_current(struct device *dev)
|
|
{
|
|
struct ltc4215_data *data = ltc4215_update_device(dev);
|
|
|
|
/* The strange looking conversions that follow are fixed-point
|
|
* math, since we cannot do floating point in the kernel.
|
|
*
|
|
* Step 1: convert sense register to microVolts
|
|
* Step 2: convert voltage to milliAmperes
|
|
*
|
|
* If you play around with the V=IR equation, you come up with
|
|
* the following: X uV / Y mOhm == Z mA
|
|
*
|
|
* With the resistors that are fractions of a milliOhm, we multiply
|
|
* the voltage and resistance by 10, to shift the decimal point.
|
|
* Now we can use the normal division operator again.
|
|
*/
|
|
|
|
/* Calculate voltage in microVolts (151 uV per increment) */
|
|
const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;
|
|
|
|
/* Calculate current in milliAmperes (4 milliOhm sense resistor) */
|
|
const unsigned int curr = voltage / 4;
|
|
|
|
return curr;
|
|
}
|
|
|
|
static ssize_t ltc4215_show_voltage(struct device *dev,
|
|
struct device_attribute *da,
|
|
char *buf)
|
|
{
|
|
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
|
|
const int voltage = ltc4215_get_voltage(dev, attr->index);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
|
|
}
|
|
|
|
static ssize_t ltc4215_show_current(struct device *dev,
|
|
struct device_attribute *da,
|
|
char *buf)
|
|
{
|
|
const unsigned int curr = ltc4215_get_current(dev);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%u\n", curr);
|
|
}
|
|
|
|
static ssize_t ltc4215_show_power(struct device *dev,
|
|
struct device_attribute *da,
|
|
char *buf)
|
|
{
|
|
const unsigned int curr = ltc4215_get_current(dev);
|
|
const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);
|
|
|
|
/* current in mA * voltage in mV == power in uW */
|
|
const unsigned int power = abs(output_voltage * curr);
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%u\n", power);
|
|
}
|
|
|
|
static ssize_t ltc4215_show_alarm(struct device *dev,
|
|
struct device_attribute *da,
|
|
char *buf)
|
|
{
|
|
struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
|
|
struct ltc4215_data *data = ltc4215_update_device(dev);
|
|
const u8 reg = data->regs[attr->index];
|
|
const u32 mask = attr->nr;
|
|
|
|
return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
|
|
}
|
|
|
|
/* These macros are used below in constructing device attribute objects
|
|
* for use with sysfs_create_group() to make a sysfs device file
|
|
* for each register.
|
|
*/
|
|
|
|
#define LTC4215_VOLTAGE(name, ltc4215_cmd_idx) \
|
|
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
|
|
ltc4215_show_voltage, NULL, ltc4215_cmd_idx)
|
|
|
|
#define LTC4215_CURRENT(name) \
|
|
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
|
|
ltc4215_show_current, NULL, 0);
|
|
|
|
#define LTC4215_POWER(name) \
|
|
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
|
|
ltc4215_show_power, NULL, 0);
|
|
|
|
#define LTC4215_ALARM(name, mask, reg) \
|
|
static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
|
|
ltc4215_show_alarm, NULL, (mask), reg)
|
|
|
|
/* Construct a sensor_device_attribute structure for each register */
|
|
|
|
/* Current */
|
|
LTC4215_CURRENT(curr1_input);
|
|
LTC4215_ALARM(curr1_max_alarm, (1 << 2), LTC4215_STATUS);
|
|
|
|
/* Power (virtual) */
|
|
LTC4215_POWER(power1_input);
|
|
|
|
/* Input Voltage */
|
|
LTC4215_VOLTAGE(in1_input, LTC4215_ADIN);
|
|
LTC4215_ALARM(in1_max_alarm, (1 << 0), LTC4215_STATUS);
|
|
LTC4215_ALARM(in1_min_alarm, (1 << 1), LTC4215_STATUS);
|
|
|
|
/* Output Voltage */
|
|
LTC4215_VOLTAGE(in2_input, LTC4215_SOURCE);
|
|
LTC4215_ALARM(in2_min_alarm, (1 << 3), LTC4215_STATUS);
|
|
|
|
/* Finally, construct an array of pointers to members of the above objects,
|
|
* as required for sysfs_create_group()
|
|
*/
|
|
static struct attribute *ltc4215_attributes[] = {
|
|
&sensor_dev_attr_curr1_input.dev_attr.attr,
|
|
&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
|
|
|
|
&sensor_dev_attr_power1_input.dev_attr.attr,
|
|
|
|
&sensor_dev_attr_in1_input.dev_attr.attr,
|
|
&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
|
|
&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
|
|
|
|
&sensor_dev_attr_in2_input.dev_attr.attr,
|
|
&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
|
|
|
|
NULL,
|
|
};
|
|
|
|
static const struct attribute_group ltc4215_group = {
|
|
.attrs = ltc4215_attributes,
|
|
};
|
|
|
|
static int ltc4215_probe(struct i2c_client *client,
|
|
const struct i2c_device_id *id)
|
|
{
|
|
struct i2c_adapter *adapter = client->adapter;
|
|
struct ltc4215_data *data;
|
|
int ret;
|
|
|
|
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
|
|
return -ENODEV;
|
|
|
|
data = kzalloc(sizeof(*data), GFP_KERNEL);
|
|
if (!data) {
|
|
ret = -ENOMEM;
|
|
goto out_kzalloc;
|
|
}
|
|
|
|
i2c_set_clientdata(client, data);
|
|
mutex_init(&data->update_lock);
|
|
|
|
/* Initialize the LTC4215 chip */
|
|
i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);
|
|
|
|
/* Register sysfs hooks */
|
|
ret = sysfs_create_group(&client->dev.kobj, <c4215_group);
|
|
if (ret)
|
|
goto out_sysfs_create_group;
|
|
|
|
data->hwmon_dev = hwmon_device_register(&client->dev);
|
|
if (IS_ERR(data->hwmon_dev)) {
|
|
ret = PTR_ERR(data->hwmon_dev);
|
|
goto out_hwmon_device_register;
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_hwmon_device_register:
|
|
sysfs_remove_group(&client->dev.kobj, <c4215_group);
|
|
out_sysfs_create_group:
|
|
kfree(data);
|
|
out_kzalloc:
|
|
return ret;
|
|
}
|
|
|
|
static int ltc4215_remove(struct i2c_client *client)
|
|
{
|
|
struct ltc4215_data *data = i2c_get_clientdata(client);
|
|
|
|
hwmon_device_unregister(data->hwmon_dev);
|
|
sysfs_remove_group(&client->dev.kobj, <c4215_group);
|
|
|
|
kfree(data);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct i2c_device_id ltc4215_id[] = {
|
|
{ "ltc4215", 0 },
|
|
{ }
|
|
};
|
|
MODULE_DEVICE_TABLE(i2c, ltc4215_id);
|
|
|
|
/* This is the driver that will be inserted */
|
|
static struct i2c_driver ltc4215_driver = {
|
|
.driver = {
|
|
.name = "ltc4215",
|
|
},
|
|
.probe = ltc4215_probe,
|
|
.remove = ltc4215_remove,
|
|
.id_table = ltc4215_id,
|
|
};
|
|
|
|
static int __init ltc4215_init(void)
|
|
{
|
|
return i2c_add_driver(<c4215_driver);
|
|
}
|
|
|
|
static void __exit ltc4215_exit(void)
|
|
{
|
|
i2c_del_driver(<c4215_driver);
|
|
}
|
|
|
|
MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
|
|
MODULE_DESCRIPTION("LTC4215 driver");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_init(ltc4215_init);
|
|
module_exit(ltc4215_exit);
|