322 lines
10 KiB
C
322 lines
10 KiB
C
/****************************************************************************
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* drivers/sensors/ltc4151.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <fixedmath.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/i2c/i2c_master.h>
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#include <nuttx/sensors/ltc4151.h>
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#if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_LTC4151)
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef CONFIG_LTC4151_I2C_FREQUENCY
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# define CONFIG_LTC4151_I2C_FREQUENCY 400000
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#endif
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#define I2C_NOSTARTSTOP_MSGS 2
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#define I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX 0
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#define I2C_NOSTARTSTOP_DATA_MSG_INDEX 1
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/****************************************************************************
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* Private
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****************************************************************************/
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struct ltc4151_dev_s
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{
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FAR struct i2c_master_s *i2c; /* I2C interface */
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uint8_t addr; /* I2C address */
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float shunt_resistor_value; /* [ohm] */
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/* I2C Helpers */
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static int ltc4151_read16(FAR struct ltc4151_dev_s *priv,
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uint8_t regaddr,
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FAR uint16_t *regvalue);
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static int ltc4151_readpower(FAR struct ltc4151_dev_s *priv,
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FAR struct ltc4151_s *buffer);
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/* Character driver methods */
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static ssize_t ltc4151_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t ltc4151_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_ltc4151fops =
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{
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NULL, /* open */
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NULL, /* close */
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ltc4151_read, /* read */
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ltc4151_write, /* write */
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NULL, /* seek */
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NULL, /* ioctl */
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NULL /* poll */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, NULL /* unlink */
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#endif
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static int ltc4151_read_reg(FAR struct ltc4151_dev_s *priv,
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uint8_t start_register_address,
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FAR uint8_t *register_value, uint8_t data_length)
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{
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struct i2c_msg_s msg[I2C_NOSTARTSTOP_MSGS];
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int ret;
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].frequency =
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CONFIG_LTC4151_I2C_FREQUENCY;
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].addr = priv->addr;
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].flags = 0;
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].buffer = &start_register_address;
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].length = 1;
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msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].addr =
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msg[I2C_NOSTARTSTOP_ADDRESS_MSG_INDEX].addr;
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msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].flags = I2C_M_READ;
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msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].buffer = register_value;
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msg[I2C_NOSTARTSTOP_DATA_MSG_INDEX].length = data_length;
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ret = I2C_TRANSFER(priv->i2c, msg, I2C_NOSTARTSTOP_MSGS);
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sninfo("start_register_address: "
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"0x%02X data_length: %d register_value: 0x%02x (0x%04x) ret: %d\n",
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start_register_address, data_length, *register_value,
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*((FAR uint16_t *)register_value), ret);
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return ret;
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}
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static int ltc4151_read16(FAR struct ltc4151_dev_s *priv, uint8_t regaddr,
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FAR uint16_t *regvalue)
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{
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int ret = ltc4151_read_reg(priv, regaddr, (FAR uint8_t *)regvalue,
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sizeof(*regvalue));
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/* Bytes are 8bit_msb.4bit_0.4bit_lsb = 16bit */
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*regvalue = ((*regvalue & LTC4151_VALUE_MSB_MASK) << 4) |
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((*regvalue & LTC4151_VALUE_LSB_MASK) >> 8);
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return ret;
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}
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/****************************************************************************
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* Name: ltc4151_readpower
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*
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* Description:
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* Read the current and voltage register with special scaling
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*
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****************************************************************************/
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static int ltc4151_readpower(FAR struct ltc4151_dev_s *priv,
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FAR struct ltc4151_s *buffer)
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{
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float float_current;
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float float_voltage;
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uint16_t current_reg;
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uint16_t volt_reg;
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int ret;
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/* Read the raw temperature data (b16_t) */
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ret = ltc4151_read16(priv, LTC4151_CURR_REG, ¤t_reg);
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if (ret < 0)
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{
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snerr("ERROR: ltc4151_read16 failed: %d\n", ret);
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return ret;
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}
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ret = ltc4151_read16(priv, LTC4151_VOLT_REG, &volt_reg);
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if (ret < 0)
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{
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snerr("ERROR: ltc4151_read16 failed: %d\n", ret);
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return ret;
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}
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/* Current is passed as delta voltage, to get the current divide it by the
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* used resistors resistance.
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*
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* float_current = register in 20 micro volt, shunt in ohm -> result in
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* milliampere
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*/
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float_current = (((float)current_reg) * 20.0 /
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(1000.0 * priv->shunt_resistor_value));
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buffer->current = ftob16(float_current);
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sninfo("current_reg=0x%04x float_current=%d\n",
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current_reg, (int)float_current);
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/* fload_voltage = register in 25 micro volt -> result in volt */
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float_voltage = ((float)volt_reg) * 25.0 / 1000.0;
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buffer->voltage = ftob16(float_voltage);
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sninfo("volt_reg=0x%04x float_voltage=%d\n",
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volt_reg, (int)float_voltage);
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return OK;
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}
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/****************************************************************************
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* Name: ltc4151_read
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****************************************************************************/
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static ssize_t ltc4151_read(FAR struct file *filep,
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FAR char *buffer, size_t buflen)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct ltc4151_dev_s *priv = inode->i_private;
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FAR struct ltc4151_s *ptr;
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ssize_t nsamples;
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int i;
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int ret;
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/* How many samples were requested to get? */
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nsamples = buflen / sizeof(struct ltc4151_s);
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ptr = (FAR struct ltc4151_s *)buffer;
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sninfo("buflen: %d nsamples: %d\n", buflen, nsamples);
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/* Get the requested number of samples */
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for (i = 0; i < nsamples; i++)
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{
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struct ltc4151_s pwr;
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/* Read the next struct ltc4151_s power value */
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ret = ltc4151_readpower(priv, &pwr);
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if (ret < 0)
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{
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snerr("ERROR: ltc4151_readtemp failed: %d\n", ret);
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return (ssize_t)ret;
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}
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/* Save the temperature value in the user buffer */
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*ptr++ = pwr;
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}
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return nsamples * sizeof(struct ltc4151_s);
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}
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/****************************************************************************
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* Name: ltc4151_write
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****************************************************************************/
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static ssize_t ltc4151_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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return -ENOSYS;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ltc4151_register
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*
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* Description:
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* Register the LTC4151 character device as 'devpath'
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*
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* Input Parameters:
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* devpath - The full path to the driver to register. E.g., "/dev/pwrmntr0"
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* i2c - An instance of the I2C interface to use to communicate with
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* LTC4151
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* addr - The I2C address of the LTC4151. The base I2C address of the
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* LTC4151 is 0x6f. Bits 0-3 can be controlled to get 10 unique
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* addresses from 0x66 through 0x6f.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int ltc4151_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
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uint8_t addr, float shunt_resistor_value)
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{
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FAR struct ltc4151_dev_s *priv;
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int ret;
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/* Sanity check */
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DEBUGASSERT(i2c != NULL);
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DEBUGASSERT(addr == CONFIG_LTC4151_ADDR0 || addr == CONFIG_LTC4151_ADDR1 ||
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addr == CONFIG_LTC4151_ADDR2 || addr == CONFIG_LTC4151_ADDR3 ||
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addr == CONFIG_LTC4151_ADDR4 || addr == CONFIG_LTC4151_ADDR5 ||
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addr == CONFIG_LTC4151_ADDR6 || addr == CONFIG_LTC4151_ADDR7 ||
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addr == CONFIG_LTC4151_ADDR8 || addr == CONFIG_LTC4151_ADDR9);
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/* Initialize the ltc4151 device structure */
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priv = (FAR struct ltc4151_dev_s *)
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kmm_malloc(sizeof(struct ltc4151_dev_s));
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if (priv == NULL)
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{
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snerr("ERROR: Failed to allocate instance\n");
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return -ENOMEM;
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}
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priv->i2c = i2c;
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priv->addr = addr;
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priv->shunt_resistor_value = shunt_resistor_value;
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/* Register the character driver */
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ret = register_driver(devpath, &g_ltc4151fops, 0666, priv);
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if (ret < 0)
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{
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snerr("ERROR: Failed to register driver: %d\n", ret);
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kmm_free(priv);
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}
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sninfo("ltc4151 (addr=0x%02x) registered at %s\n", priv->addr, devpath);
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return ret;
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}
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#endif /* CONFIG_I2C && CONFIG_SENSORS_LTC4151 */
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