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nuttx/drivers/sensors/ltc4151.c

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/****************************************************************************
* drivers/sensors/ltc4151.c
* Character driver for the LTC 4151 Power Sensor
*
* Copyright (C) 2017 Giorgio Groß. All rights reserved.
* Author: Giorgio Groß <giorgio.gross@robodev.eu>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <fixedmath.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/i2c/i2c_master.h>
#include <nuttx/sensors/ltc4151.h>
#if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_LTC4151)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef CONFIG_LTC4151_I2C_FREQUENCY
# define CONFIG_LTC4151_I2C_FREQUENCY 400000
#endif
#define I2C_NOSTARTSTOP_MSGS 2
#define I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX 0
#define I2C_NOSTARTSTOP_DATA_MSG_INDEX 1
/****************************************************************************
* Private
****************************************************************************/
struct ltc4151_dev_s
{
FAR struct i2c_master_s *i2c; /* I2C interface */
uint8_t addr; /* I2C address */
float shunt_resistor_value; /* [ohm] */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* I2C Helpers */
static int ltc4151_read16(FAR struct ltc4151_dev_s *priv, uint8_t regaddr,
FAR uint16_t *regvalue);
static int ltc4151_readpower(FAR struct ltc4151_dev_s *priv,
FAR struct ltc4151_s *buffer);
/* Character driver methods */
static int ltc4151_open(FAR struct file *filep);
static int ltc4151_close(FAR struct file *filep);
static ssize_t ltc4151_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t ltc4151_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int ltc4151_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_ltc4151fops =
{
ltc4151_open,
ltc4151_close,
ltc4151_read,
ltc4151_write,
NULL,
ltc4151_ioctl,
NULL
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
static int ltc4151_read_reg(FAR struct ltc4151_dev_s *priv,
uint8_t start_register_address,
FAR uint8_t *register_value, uint8_t data_length)
{
struct i2c_msg_s msg[I2C_NOSTARTSTOP_MSGS];
int ret;
msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].frequency = CONFIG_LTC4151_I2C_FREQUENCY;
msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].addr = priv->addr;
msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].flags = 0;
msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].buffer = &start_register_address;
msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].length = 1;
msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].addr = msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].addr;
msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].flags = I2C_M_READ;
msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].buffer = register_value;
msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].length = data_length;
ret = I2C_TRANSFER(priv->i2c, msg, I2C_NOSTARTSTOP_MSGS);
sninfo("start_register_address: "
"0x%02X data_length: %d register_value: 0x%02x (0x%04x) ret: %d\n",
start_register_address, data_length, *register_value,
*((FAR uint16_t *)register_value), ret);
return ret;
}
static int ltc4151_read16(FAR struct ltc4151_dev_s *priv, uint8_t regaddr,
FAR uint16_t *regvalue)
{
int ret = ltc4151_read_reg(priv, regaddr, (FAR uint8_t *)regvalue,
sizeof(*regvalue));
/* Bytes are 8bit_msb.4bit_0.4bit_lsb = 16bit */
*regvalue = ((*regvalue & LTC4151_VALUE_MSB_MASK) << 4) |
((*regvalue & LTC4151_VALUE_LSB_MASK) >> 8);
return ret;
}
/****************************************************************************
* Name: ltc4151_readpower
*
* Description:
* Read the current and voltage register with special scaling
*
****************************************************************************/
static int ltc4151_readpower(FAR struct ltc4151_dev_s *priv,
FAR struct ltc4151_s *buffer)
{
float float_current;
float float_voltage;
uint16_t current_reg;
uint16_t volt_reg;
int ret;
/* Read the raw temperature data (b16_t) */
ret = ltc4151_read16(priv, LTC4151_CURR_REG, &current_reg);
if (ret < 0)
{
snerr("ERROR: ltc4151_read16 failed: %d\n", ret);
return ret;
}
ret = ltc4151_read16(priv, LTC4151_VOLT_REG, &volt_reg);
if (ret < 0)
{
snerr("ERROR: ltc4151_read16 failed: %d\n", ret);
return ret;
}
/* Current is passed as delta voltage, to get the current divide it by the
* used resistors resistance.
*
* float_current = register in 20 micro volt, shunt in ohm -> result in
* milliampere
*/
float_current = (((float)current_reg) * 20.0 /
(1000.0 * priv->shunt_resistor_value));
buffer->current = ftob16(float_current);
sninfo("current_reg=0x%04x float_current=%d\n",
current_reg, (int)float_current);
/* fload_voltage = register in 25 micro volt -> result in volt */
float_voltage = ((float)volt_reg) * 25.0 / 1000.0;
buffer->voltage = ftob16(float_voltage);
sninfo("volt_reg=0x%04x float_voltage=%d\n",
volt_reg, (int)float_voltage);
return OK;
}
/****************************************************************************
* Name: ltc4151_open
*
* Description:
* This function is called whenever the LTC4151 device is opened.
*
****************************************************************************/
static int ltc4151_open(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: ltc4151_close
*
* Description:
* This routine is called when the LTC4151 device is closed.
*
****************************************************************************/
static int ltc4151_close(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: ltc4151_read
****************************************************************************/
static ssize_t ltc4151_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct ltc4151_dev_s *priv = inode->i_private;
FAR struct ltc4151_s *ptr;
ssize_t nsamples;
int i;
int ret;
/* How many samples were requested to get? */
nsamples = buflen / sizeof(struct ltc4151_s);
ptr = (FAR struct ltc4151_s *)buffer;
sninfo("buflen: %d nsamples: %d\n", buflen, nsamples);
/* Get the requested number of samples */
for (i = 0; i < nsamples; i++)
{
struct ltc4151_s pwr;
/* Read the next struct ltc4151_s power value */
ret = ltc4151_readpower(priv, &pwr);
if (ret < 0)
{
snerr("ERROR: ltc4151_readtemp failed: %d\n", ret);
return (ssize_t)ret;
}
/* Save the temperature value in the user buffer */
*ptr++ = pwr;
}
return nsamples * sizeof(struct ltc4151_s);
}
/****************************************************************************
* Name: ltc4151_write
****************************************************************************/
static ssize_t ltc4151_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Name: ltc4151_ioctl
****************************************************************************/
static int ltc4151_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
return -ENOTTY;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: ltc4151_register
*
* Description:
* Register the LTC4151 character device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/pwrmntr0"
* i2c - An instance of the I2C interface to use to communicate with LTC4151
* addr - The I2C address of the LTC4151. The base I2C address of the LTC4151
* is 0x6f. Bits 0-3 can be controlled to get 10 unique addresses from 0x66
* through 0x6f.
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int ltc4151_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
uint8_t addr, float shunt_resistor_value)
{
FAR struct ltc4151_dev_s *priv;
int ret;
/* Sanity check */
DEBUGASSERT(i2c != NULL);
DEBUGASSERT(addr == CONFIG_LTC4151_ADDR0 || addr == CONFIG_LTC4151_ADDR1 ||
addr == CONFIG_LTC4151_ADDR2 || addr == CONFIG_LTC4151_ADDR3 ||
addr == CONFIG_LTC4151_ADDR4 || addr == CONFIG_LTC4151_ADDR5 ||
addr == CONFIG_LTC4151_ADDR6 || addr == CONFIG_LTC4151_ADDR7 ||
addr == CONFIG_LTC4151_ADDR8 || addr == CONFIG_LTC4151_ADDR9);
/* Initialize the ltc4151 device structure */
priv = (FAR struct ltc4151_dev_s *)kmm_malloc(sizeof(struct ltc4151_dev_s));
if (priv == NULL)
{
snerr("ERROR: Failed to allocate instance\n");
return -ENOMEM;
}
priv->i2c = i2c;
priv->addr = addr;
priv->shunt_resistor_value = shunt_resistor_value;
/* Register the character driver */
ret = register_driver(devpath, &g_ltc4151fops, 0666, priv);
if (ret < 0)
{
snerr("ERROR: Failed to register driver: %d\n", ret);
kmm_free(priv);
}
sninfo("ltc4151 (addr=0x%02x) registered at %s\n", priv->addr, devpath);
return ret;
}
#endif /* CONFIG_I2C && CONFIG_SENSORS_LTC4151 */
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