/*
* Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
*
*
*
*
* 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_attri
