388 lines
12 KiB
C
388 lines
12 KiB
C
/****************************************************************************
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* drivers/sensors/mcp9844.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 <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/mcp9844.h>
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#include <nuttx/random.h>
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#if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_MCP9844)
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/****************************************************************************
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* Pre-process Definitions
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****************************************************************************/
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#ifndef CONFIG_MCP9844_I2C_FREQUENCY
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# define CONFIG_MCP9844_I2C_FREQUENCY 400000
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#endif
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct mcp9844_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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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/* I2C helper functions */
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static int mcp9844_read_u16(FAR struct mcp9844_dev_s *priv,
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uint8_t const regaddr, FAR uint16_t *value);
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static int mcp9844_write_u16(FAR struct mcp9844_dev_s *priv,
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uint8_t const regaddr,
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uint16_t const regval);
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/* Character driver methods */
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static ssize_t mcp9844_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t mcp9844_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static int mcp9844_ioctl(FAR struct file *filep, int cmd,
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unsigned long arg);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_mcp9844_fops =
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{
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NULL, /* open */
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NULL, /* close */
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mcp9844_read, /* read */
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mcp9844_write, /* write */
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NULL, /* seek */
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mcp9844_ioctl, /* ioctl */
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mcp9844_read_u16
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*
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* Description:
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* Read a 16 bit valie from the MCP9844 at the address regaddr.
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*
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****************************************************************************/
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static int mcp9844_read_u16(FAR struct mcp9844_dev_s *priv,
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uint8_t const regaddr, FAR uint16_t *value)
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{
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struct i2c_config_s config;
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uint8_t buffer[2];
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int ret = -1;
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/* Set up the I2C configuration */
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config.frequency = CONFIG_MCP9844_I2C_FREQUENCY;
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config.address = priv->addr;
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config.addrlen = 7;
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/* Write the register address */
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ret = i2c_write(priv->i2c, &config, ®addr, 1);
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if (ret < 0)
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{
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snerr ("i2c_write failed: %d\n", ret);
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return ret;
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}
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/* Restart and read 16-bits from the register */
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ret = i2c_read(priv->i2c, &config, buffer, 2);
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if (ret < 0)
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{
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snerr ("i2c_read failed: %d\n", ret);
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return ret;
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}
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/* Copy the content of the buffer to the location of the uint16_t pointer */
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*value = (((uint16_t)(buffer[0])) << 8) + ((uint16_t)(buffer[1]));
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sninfo("addr: %02x value: %08x ret: %d\n", regaddr, *value, ret);
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return OK;
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}
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/****************************************************************************
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* Name: mcp9844_write_u16
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*
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* Description:
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* Write to a 16-bit register of the MCP9844.
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*
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****************************************************************************/
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static int mcp9844_write_u16(FAR struct mcp9844_dev_s *priv,
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uint8_t const regaddr, uint16_t const regval)
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{
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struct i2c_config_s config;
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sninfo("addr: %02x value: %08x\n", regaddr, regval);
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/* Set up a 3 byte message to send */
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uint8_t const BUFFER_SIZE = 3;
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uint8_t buffer[BUFFER_SIZE];
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buffer[0] = regaddr;
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buffer[1] = (uint8_t)(regval >> 8);
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buffer[2] = (uint8_t)(regval);
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/* Set up the I2C configuration */
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config.frequency = CONFIG_MCP9844_I2C_FREQUENCY;
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config.address = priv->addr;
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config.addrlen = 7;
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/* Write the register address followed by the data (no RESTART) */
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return i2c_write(priv->i2c, &config, buffer, BUFFER_SIZE);
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}
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/****************************************************************************
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* Name: mcp9844_read
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****************************************************************************/
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static ssize_t mcp9844_read(FAR struct file *filep, FAR 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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* Name: mcp9844_write
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****************************************************************************/
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static ssize_t mcp9844_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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* Name: lm75_ioctl
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****************************************************************************/
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static int mcp9844_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct mcp9844_dev_s *priv = inode->i_private;
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int ret = OK;
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switch (cmd)
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{
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/* Read from the ambient temperature register. Arg: uint16_t* pointer */
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case SNIOC_READTEMP:
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{
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FAR struct mcp9844_temp_arg_s *temp_result =
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(FAR struct mcp9844_temp_arg_s *)((uintptr_t)arg);
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DEBUGASSERT(temp_result != NULL);
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/* Read the ambient temperature value from the device */
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uint16_t raw_temperature = 0;
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ret = mcp9844_read_u16(priv, MCP9844_TEMP_REG, &raw_temperature);
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/* Convert from the proprietary sensor temperature data
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* representation to a more user-friendly version.
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*/
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if (ret == OK)
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{
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/* Feed sensor data to entropy pool */
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add_sensor_randomness(raw_temperature);
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/* BIT15 - 13 contain information if preset temperature values
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* have been exceeded or undercut. BIT12 is now not any longer
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* needed since we do have the sign information retrieved.
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* We do not need them for the temperature so those bits
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* need to be masked out.
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*/
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raw_temperature &= 0x0fff; /* 0x0fff = 0b 0000 1111 1111 1111 */
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/* The post comma temperature value is encoded in BIT3 to
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* BIT0
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*/
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temp_result->temp_post_comma =
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(uint8_t)(raw_temperature & 0x000f);
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/* The pre comma temperature value is encoded in BIT11 to
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* BIT4
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*/
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temp_result->temp_pre_comma = (int8_t)(raw_temperature >> 4);
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}
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else
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{
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snerr("ERROR: ioctl::SNIOC_READTEMP - mcp9844_read_u16 failed"
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" - no temperature retrieved\n");
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}
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}
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break;
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case SNIOC_SETRESOLUTION:
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{
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ret = mcp9844_write_u16(priv, MCP9844_RESO_REG, (uint16_t)(arg));
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if (ret != OK)
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{
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snerr("ERROR: ioctl::SNIOC_SETRESOLUTION - mcp9844_write_u16"
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"failed - no resolution set\n");
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}
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}
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break;
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case SNIOC_SHUTDOWN:
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{
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uint16_t config_reg;
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/* Perform a read-modify-write cycle on the config register */
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ret = mcp9844_read_u16(priv, MCP9844_CONF_REG, &config_reg);
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if (ret == OK)
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{
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config_reg |= MCP9844_CONF_REG_SHDN;
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ret = mcp9844_write_u16(priv, MCP9844_CONF_REG, config_reg);
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if (ret != OK)
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{
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snerr("ERROR: ioctl::SNIOC_SHUTDOWN - "
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"mcp9844_write_u16 failed\n");
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}
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}
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else
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{
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snerr("ERROR: ioctl::SNIOC_SHUTDOWN - "
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"mcp9844_read_u16 failed\n");
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}
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}
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break;
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case SNIOC_POWERUP:
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{
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uint16_t config_reg;
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/* Perform a read-modify-write cycle on the config register */
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ret = mcp9844_read_u16(priv, MCP9844_CONF_REG, &config_reg);
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if (ret == OK)
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{
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config_reg &= ~MCP9844_CONF_REG_SHDN;
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ret = mcp9844_write_u16(priv, MCP9844_CONF_REG, config_reg);
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if (ret != OK)
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{
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snerr("ERROR: ioctl::SNIOC_POWERUP - "
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"mcp9844_write_u16 failed\n");
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}
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}
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else
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{
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snerr("ERROR: ioctl::SNIOC_POWERUP - "
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"mcp9844_read_u16 failed\n");
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}
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}
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break;
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default:
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snerr("ERROR: Unrecognized cmd: %d\n", cmd);
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ret = -ENOTTY;
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break;
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}
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return ret;
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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: mcp9844_register
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*
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* Description:
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* Register the MCP9844 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/temp0"
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* i2c - An instance of the I2C interface to use to communicate with
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* MCP9844
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* addr - The I2C address of the MCP9844.
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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 mcp9844_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
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uint8_t addr)
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{
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/* Sanity check */
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DEBUGASSERT(i2c != NULL);
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/* Initialize the MCP9844 device structure */
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FAR struct mcp9844_dev_s *priv =
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(FAR struct mcp9844_dev_s *)kmm_malloc(sizeof(struct mcp9844_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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/* Register the character driver */
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int ret = register_driver(devpath, &g_mcp9844_fops, 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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return ret;
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}
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#endif /* CONFIG_I2C && CONFIG_LM75_I2C */
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