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linux/drivers/hwmon/ltc4245.c
Ira W. Snyder 5950ec8d3e hwmon: (ltc4245) Expose all GPIO pins as analog voltages 
Add support for exposing all GPIO pins as analog voltages. Though this is
not an ideal use of the chip, some hardware engineers may decide that the
LTC4245 meets their design requirements when studying the datasheet.

The GPIO pins are sampled in round-robin fashion, meaning that a slow
reader will see stale data. A userspace application can detect this,
because it will get -EAGAIN when reading from a sysfs file which contains
stale data.

Users can choose to use this feature on a per-chip basis by using either
platform data or the OF device tree (where applicable).

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2010-08-14 21:08:49 +02:00

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/*
* Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
*
* Copyright (C) 2008 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.
*
* This driver is based on the ds1621 and ina209 drivers.
*
* Datasheet:
* http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
*/
#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/i2c/ltc4245.h>
/* Here are names of the chip's registers (a.k.a. commands) */
enum ltc4245_cmd {
LTC4245_STATUS = 0x00, /* readonly */
LTC4245_ALERT = 0x01,
LTC4245_CONTROL = 0x02,
LTC4245_ON = 0x03,
LTC4245_FAULT1 = 0x04,
LTC4245_FAULT2 = 0x05,
LTC4245_GPIO = 0x06,
LTC4245_ADCADR = 0x07,
LTC4245_12VIN = 0x10,
LTC4245_12VSENSE = 0x11,
LTC4245_12VOUT = 0x12,
LTC4245_5VIN = 0x13,
LTC4245_5VSENSE = 0x14,
LTC4245_5VOUT = 0x15,
LTC4245_3VIN = 0x16,
LTC4245_3VSENSE = 0x17,
LTC4245_3VOUT = 0x18,
LTC4245_VEEIN = 0x19,
LTC4245_VEESENSE = 0x1a,
LTC4245_VEEOUT = 0x1b,
LTC4245_GPIOADC = 0x1c,
};
struct ltc4245_data {
struct device *hwmon_dev;
struct mutex update_lock;
bool valid;
unsigned long last_updated; /* in jiffies */
/* Control registers */
u8 cregs[0x08];
/* Voltage registers */
u8 vregs[0x0d];
/* GPIO ADC registers */
bool use_extra_gpios;
int gpios[3];
};
/*
* Update the readings from the GPIO pins. If the driver has been configured to
* sample all GPIO's as analog voltages, a round-robin sampling method is used.
* Otherwise, only the configured GPIO pin is sampled.
*
* LOCKING: must hold data->update_lock
*/
static void ltc4245_update_gpios(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct ltc4245_data *data = i2c_get_clientdata(client);
u8 gpio_curr, gpio_next, gpio_reg;
int i;
/* no extra gpio support, we're basically done */
if (!data->use_extra_gpios) {
data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
return;
}
/*
* If the last reading was too long ago, then we mark all old GPIO
* readings as stale by setting them to -EAGAIN
*/
if (time_after(jiffies, data->last_updated + 5 * HZ)) {
dev_dbg(&client->dev, "Marking GPIOs invalid\n");
for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
data->gpios[i] = -EAGAIN;
}
/*
* Get the current GPIO pin
*
* The datasheet calls these GPIO[1-3], but we'll calculate the zero
* based array index instead, and call them GPIO[0-2]. This is much
* easier to think about.
*/
gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
if (gpio_curr > 0)
gpio_curr -= 1;
/* Read the GPIO voltage from the GPIOADC register */
data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
/* Find the next GPIO pin to read */
gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
/*
* Calculate the correct setting for the GPIO register so it will
* sample the next GPIO pin
*/
gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
/* Update the GPIO register */
i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
/* Update saved data */
data->cregs[LTC4245_GPIO] = gpio_reg;
}
static struct ltc4245_data *ltc4245_update_device(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct ltc4245_data *data = i2c_get_clientdata(client);
s32 val;
int i;
mutex_lock(&data->update_lock);
if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
dev_dbg(&client->dev, "Starting ltc4245 update\n");
/* Read control registers -- 0x00 to 0x07 */
for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
val = i2c_smbus_read_byte_data(client, i);
if (unlikely(val < 0))
data->cregs[i] = 0;
else
data->cregs[i] = val;
}
/* Read voltage registers -- 0x10 to 0x1c */
for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
val = i2c_smbus_read_byte_data(client, i+0x10);
if (unlikely(val < 0))
data->vregs[i] = 0;
else
data->vregs[i] = val;
}
/* Update GPIO readings */
ltc4245_update_gpios(dev);
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 ltc4245_get_voltage(struct device *dev, u8 reg)
{
struct ltc4245_data *data = ltc4245_update_device(dev);
const u8 regval = data->vregs[reg - 0x10];
u32 voltage = 0;
switch (reg) {
case LTC4245_12VIN:
case LTC4245_12VOUT:
voltage = regval * 55;
break;
case LTC4245_5VIN:
case LTC4245_5VOUT:
voltage = regval * 22;
break;
case LTC4245_3VIN:
case LTC4245_3VOUT:
voltage = regval * 15;
break;
case LTC4245_VEEIN:
case LTC4245_VEEOUT:
voltage = regval * -55;
break;
case LTC4245_GPIOADC:
voltage = regval * 10;
break;
default:
/* If we get here, the developer messed up */
WARN_ON_ONCE(1);
break;
}
return voltage;
}
/* Return the current in the given sense register in milliAmperes */
static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
{
struct ltc4245_data *data = ltc4245_update_device(dev);
const u8 regval = data->vregs[reg - 0x10];
unsigned int voltage;
unsigned int curr;
/* 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.
*/
switch (reg) {
case LTC4245_12VSENSE:
voltage = regval * 250; /* voltage in uV */
curr = voltage / 50; /* sense resistor 50 mOhm */
break;
case LTC4245_5VSENSE:
voltage = regval * 125; /* voltage in uV */
curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
break;
case LTC4245_3VSENSE:
voltage = regval * 125; /* voltage in uV */
curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
break;
case LTC4245_VEESENSE:
voltage = regval * 250; /* voltage in uV */
curr = voltage / 100; /* sense resistor 100 mOhm */
break;
default:
/* If we get here, the developer messed up */
WARN_ON_ONCE(1);
curr = 0;
break;
}
return curr;
}
static ssize_t ltc4245_show_voltage(struct device *dev,
struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
const int voltage = ltc4245_get_voltage(dev, attr->index);
return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
}
static ssize_t ltc4245_show_current(struct device *dev,
struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
const unsigned int curr = ltc4245_get_current(dev, attr->index);
return snprintf(buf, PAGE_SIZE, "%u\n", curr);
}
static ssize_t ltc4245_show_power(struct device *dev,
struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
const unsigned int curr = ltc4245_get_current(dev, attr->index);
const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);
/* 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 ltc4245_show_alarm(struct device *dev,
struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
struct ltc4245_data *data = ltc4245_update_device(dev);
const u8 reg = data->cregs[attr->index];
const u32 mask = attr->nr;
return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
}
static ssize_t ltc4245_show_gpio(struct device *dev,
struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ltc4245_data *data = ltc4245_update_device(dev);
int val = data->gpios[attr->index];
/* handle stale GPIO's */
if (val < 0)
return val;
/* Convert to millivolts and print */
return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
}
/* 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 LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
ltc4245_show_voltage, NULL, ltc4245_cmd_idx)
#define LTC4245_CURRENT(name, ltc4245_cmd_idx) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
ltc4245_show_current, NULL, ltc4245_cmd_idx)
#define LTC4245_POWER(name, ltc4245_cmd_idx) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
ltc4245_show_power, NULL, ltc4245_cmd_idx)
#define LTC4245_ALARM(name, mask, reg) \
static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
ltc4245_show_alarm, NULL, (mask), reg)
#define LTC4245_GPIO_VOLTAGE(name, gpio_num) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
ltc4245_show_gpio, NULL, gpio_num)
/* Construct a sensor_device_attribute structure for each register */
/* Input voltages */
LTC4245_VOLTAGE(in1_input, LTC4245_12VIN);
LTC4245_VOLTAGE(in2_input, LTC4245_5VIN);
LTC4245_VOLTAGE(in3_input, LTC4245_3VIN);
LTC4245_VOLTAGE(in4_input, LTC4245_VEEIN);
/* Input undervoltage alarms */
LTC4245_ALARM(in1_min_alarm, (1 << 0), LTC4245_FAULT1);
LTC4245_ALARM(in2_min_alarm, (1 << 1), LTC4245_FAULT1);
LTC4245_ALARM(in3_min_alarm, (1 << 2), LTC4245_FAULT1);
LTC4245_ALARM(in4_min_alarm, (1 << 3), LTC4245_FAULT1);
/* Currents (via sense resistor) */
LTC4245_CURRENT(curr1_input, LTC4245_12VSENSE);
LTC4245_CURRENT(curr2_input, LTC4245_5VSENSE);
LTC4245_CURRENT(curr3_input, LTC4245_3VSENSE);
LTC4245_CURRENT(curr4_input, LTC4245_VEESENSE);
/* Overcurrent alarms */
LTC4245_ALARM(curr1_max_alarm, (1 << 4), LTC4245_FAULT1);
LTC4245_ALARM(curr2_max_alarm, (1 << 5), LTC4245_FAULT1);
LTC4245_ALARM(curr3_max_alarm, (1 << 6), LTC4245_FAULT1);
LTC4245_ALARM(curr4_max_alarm, (1 << 7), LTC4245_FAULT1);
/* Output voltages */
LTC4245_VOLTAGE(in5_input, LTC4245_12VOUT);
LTC4245_VOLTAGE(in6_input, LTC4245_5VOUT);
LTC4245_VOLTAGE(in7_input, LTC4245_3VOUT);
LTC4245_VOLTAGE(in8_input, LTC4245_VEEOUT);
/* Power Bad alarms */
LTC4245_ALARM(in5_min_alarm, (1 << 0), LTC4245_FAULT2);
LTC4245_ALARM(in6_min_alarm, (1 << 1), LTC4245_FAULT2);
LTC4245_ALARM(in7_min_alarm, (1 << 2), LTC4245_FAULT2);
LTC4245_ALARM(in8_min_alarm, (1 << 3), LTC4245_FAULT2);
/* GPIO voltages */
LTC4245_GPIO_VOLTAGE(in9_input, 0);
LTC4245_GPIO_VOLTAGE(in10_input, 1);
LTC4245_GPIO_VOLTAGE(in11_input, 2);
/* Power Consumption (virtual) */
LTC4245_POWER(power1_input, LTC4245_12VSENSE);
LTC4245_POWER(power2_input, LTC4245_5VSENSE);
LTC4245_POWER(power3_input, LTC4245_3VSENSE);
LTC4245_POWER(power4_input, LTC4245_VEESENSE);
/* Finally, construct an array of pointers to members of the above objects,
* as required for sysfs_create_group()
*/
static struct attribute *ltc4245_std_attributes[] = {
&sensor_dev_attr_in1_input.dev_attr.attr,
&sensor_dev_attr_in2_input.dev_attr.attr,
&sensor_dev_attr_in3_input.dev_attr.attr,
&sensor_dev_attr_in4_input.dev_attr.attr,
&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
&sensor_dev_attr_in3_min_alarm.dev_attr.attr,
&sensor_dev_attr_in4_min_alarm.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
&sensor_dev_attr_curr2_input.dev_attr.attr,
&sensor_dev_attr_curr3_input.dev_attr.attr,
&sensor_dev_attr_curr4_input.dev_attr.attr,
&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
&sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
&sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
&sensor_dev_attr_curr4_max_alarm.dev_attr.attr,
&sensor_dev_attr_in5_input.dev_attr.attr,
&sensor_dev_attr_in6_input.dev_attr.attr,
&sensor_dev_attr_in7_input.dev_attr.attr,
&sensor_dev_attr_in8_input.dev_attr.attr,
&sensor_dev_attr_in5_min_alarm.dev_attr.attr,
&sensor_dev_attr_in6_min_alarm.dev_attr.attr,
&sensor_dev_attr_in7_min_alarm.dev_attr.attr,
&sensor_dev_attr_in8_min_alarm.dev_attr.attr,
&sensor_dev_attr_in9_input.dev_attr.attr,
&sensor_dev_attr_power1_input.dev_attr.attr,
&sensor_dev_attr_power2_input.dev_attr.attr,
&sensor_dev_attr_power3_input.dev_attr.attr,
&sensor_dev_attr_power4_input.dev_attr.attr,
NULL,
};
static struct attribute *ltc4245_gpio_attributes[] = {
&sensor_dev_attr_in10_input.dev_attr.attr,
&sensor_dev_attr_in11_input.dev_attr.attr,
NULL,
};
static const struct attribute_group ltc4245_std_group = {
.attrs = ltc4245_std_attributes,
};
static const struct attribute_group ltc4245_gpio_group = {
.attrs = ltc4245_gpio_attributes,
};
static int ltc4245_sysfs_create_groups(struct i2c_client *client)
{
struct ltc4245_data *data = i2c_get_clientdata(client);
struct device *dev = &client->dev;
int ret;
/* register the standard sysfs attributes */
ret = sysfs_create_group(&dev->kobj, &ltc4245_std_group);
if (ret) {
dev_err(dev, "unable to register standard attributes\n");
return ret;
}
/* if we're using the extra gpio support, register it's attributes */
if (data->use_extra_gpios) {
ret = sysfs_create_group(&dev->kobj, &ltc4245_gpio_group);
if (ret) {
dev_err(dev, "unable to register gpio attributes\n");
sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
return ret;
}
}
return 0;
}
static void ltc4245_sysfs_remove_groups(struct i2c_client *client)
{
struct ltc4245_data *data = i2c_get_clientdata(client);
struct device *dev = &client->dev;
if (data->use_extra_gpios)
sysfs_remove_group(&dev->kobj, &ltc4245_gpio_group);
sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
}
static bool ltc4245_use_extra_gpios(struct i2c_client *client)
{
struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
#ifdef CONFIG_OF
struct device_node *np = client->dev.of_node;
#endif
/* prefer platform data */
if (pdata)
return pdata->use_extra_gpios;
#ifdef CONFIG_OF
/* fallback on OF */
if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
return true;
#endif
return false;
}
static int ltc4245_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct i2c_adapter *adapter = client->adapter;
struct ltc4245_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);
data->use_extra_gpios = ltc4245_use_extra_gpios(client);
/* Initialize the LTC4245 chip */
i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
/* Register sysfs hooks */
ret = ltc4245_sysfs_create_groups(client);
if (ret)
goto out_sysfs_create_groups;
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:
ltc4245_sysfs_remove_groups(client);
out_sysfs_create_groups:
kfree(data);
out_kzalloc:
return ret;
}
static int ltc4245_remove(struct i2c_client *client)
{
struct ltc4245_data *data = i2c_get_clientdata(client);
hwmon_device_unregister(data->hwmon_dev);
ltc4245_sysfs_remove_groups(client);
kfree(data);
return 0;
}
static const struct i2c_device_id ltc4245_id[] = {
{ "ltc4245", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc4245_id);
/* This is the driver that will be inserted */
static struct i2c_driver ltc4245_driver = {
.driver = {
.name = "ltc4245",
},
.probe = ltc4245_probe,
.remove = ltc4245_remove,
.id_table = ltc4245_id,
};
static int __init ltc4245_init(void)
{
return i2c_add_driver(&ltc4245_driver);
}
static void __exit ltc4245_exit(void)
{
i2c_del_driver(&ltc4245_driver);
}
MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
MODULE_DESCRIPTION("LTC4245 driver");
MODULE_LICENSE("GPL");
module_init(ltc4245_init);
module_exit(ltc4245_exit);
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