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incubator-nuttx/drivers/sensors/lm75.c

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/****************************************************************************
* drivers/sensors/lm75.c
* Character driver for the STMicro LM-75 Temperature Sensor
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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/fs/fs.h>
#include <nuttx/i2c.h>
#include <nuttx/sensors/lm75.h>
#if defined(CONFIG_I2C) && defined(CONFIG_I2C_LM75)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Centigrade to Fahrenheit conversion: F = 9*C/5 + 32 */
#define B16_9DIV5 (9 * 65536 / 5)
#define B16_32 (32 * 65536)
/* Debug for this file only */
#ifdef CONFIG_DEBUG_LM75
# define lm75dbg dbg
#else
# ifdef CONFIG_CPP_HAVE_VARARGS
# define lm75dbg(x...)
# else
# define lm75dbg (void)
# endif
#endif
/****************************************************************************
* Private
****************************************************************************/
struct lm75_dev_s
{
FAR struct i2c_dev_s *i2c; /* I2C interface */
uint8_t addr; /* I2C address */
bool fahrenheit; /* true: temperature will be reported in fahrenheit */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* I2C Helpers */
static int lm75_readb16(FAR struct lm75_dev_s *priv, uint8_t regaddr,
FAR b16_t *regvalue);
static int lm75_writeb16(FAR struct lm75_dev_s *priv, uint8_t regaddr,
b16_t regval);
static int lm75_readtemp(FAR struct lm75_dev_s *priv, FAR b16_t *temp);
static int lm75_readconf(FAR struct lm75_dev_s *priv, FAR uint8_t *conf);
static int lm75_writeconf(FAR struct lm75_dev_s *priv, uint8_t conf);
/* Character driver methods */
static int lm75_open(FAR struct file *filep);
static int lm75_close(FAR struct file *filep);
static ssize_t lm75_read(FAR struct file *, FAR char *, size_t);
static ssize_t lm75_write(FAR struct file *filep, FAR const char *buffer, size_t buflen);
static int lm75_ioctl(FAR struct file *filep,int cmd,unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_lm75fops =
{
lm75_open,
lm75_close,
lm75_read,
lm75_write,
0,
lm75_ioctl
#ifndef CONFIG_DISABLE_POLL
, 0
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: lm75_readb16
*
* Description:
* Read a 16-bit register (LM75_TEMP_REG, LM75_THYS_REG, or LM75_TOS_REG)
*
****************************************************************************/
static int lm75_readb16(FAR struct lm75_dev_s *priv, uint8_t regaddr,
FAR b16_t *regvalue)
{
uint8_t buffer[2];
int ret;
/* Write the register address */
I2C_SETADDRESS(priv->i2c, priv->addr, 7);
ret = I2C_WRITE(priv->i2c, &regaddr, 1);
if (ret < 0)
{
lm75dbg("I2C_WRITE failed: %d\n", ret);
return ret;
}
/* Restart and read 16-bits from the register (discarding 7) */
ret = I2C_READ(priv->i2c, buffer, 2);
if (ret < 0)
{
lm75dbg("I2C_READ failed: %d\n", ret);
return ret;
}
/* Data format is: TTTTTTTT Txxxxxxx where TTTTTTTTT is a nine-bit,
* signed temperature value with LSB = 0.5 degrees centigrade. So the
* raw data is b8_t
*/
*regvalue = b8tob16((b8_t)buffer[0] << 8 | (b8_t)buffer[1]);
lm75dbg("addr: %02x value: %08x ret: %d\n", regaddr, *regvalue, ret);
return OK;
}
/****************************************************************************
* Name: lm75_writeb16
*
* Description:
* Write to a 16-bit register (LM75_TEMP_REG, LM75_THYS_REG, or LM75_TOS_REG)
*
****************************************************************************/
static int lm75_writeb16(FAR struct lm75_dev_s *priv, uint8_t regaddr,
b16_t regval)
{
uint8_t buffer[3];
b8_t regb8;
lm75dbg("addr: %02x value: %08x\n", regaddr, regval);
/* Set up a 3 byte message to send */
buffer[0] = regaddr;
regb8 = b16tob8(regval);
buffer[1] = (uint8_t)(regb8 >> 8);
buffer[2] = (uint8_t)regb8;
/* Write the register address followed by the data (no RESTART) */
I2C_SETADDRESS(priv->i2c, priv->addr, 7);
return I2C_WRITE(priv->i2c, buffer, 3);
}
/****************************************************************************
* Name: lm75_readtemp
*
* Description:
* Read the temperature register with special scaling (LM75_TEMP_REG)
*
****************************************************************************/
static int lm75_readtemp(FAR struct lm75_dev_s *priv, FAR b16_t *temp)
{
b16_t temp16;
int ret;
/* Read the raw temperature data (b16_t) */
ret = lm75_readb16(priv, LM75_TEMP_REG, &temp16);
if (ret < 0)
{
lm75dbg("lm75_readb16 failed: %d\n", ret);
return ret;
}
lm75dbg("Centigrade: %08x\n", temp16);
/* Was fahrenheit requested? */
if (priv->fahrenheit)
{
/* Centigrade to Fahrenheit conversion: F = 9*C/5 + 32 */
temp16 = b16mulb16(temp16, B16_9DIV5) + B16_32;
lm75dbg("Fahrenheit: %08x\n", temp16);
}
*temp = temp16;
return OK;
}
/****************************************************************************
* Name: lm75_readconf
*
* Description:
* Read the 8-bit LM75 configuration register
*
****************************************************************************/
static int lm75_readconf(FAR struct lm75_dev_s *priv, FAR uint8_t *conf)
{
uint8_t buffer;
int ret;
/* Write the configuration register address */
I2C_SETADDRESS(priv->i2c, priv->addr, 7);
buffer = LM75_CONF_REG;
ret = I2C_WRITE(priv->i2c, &buffer, 1);
if (ret < 0)
{
lm75dbg("I2C_WRITE failed: %d\n", ret);
return ret;
}
/* Restart and read 8-bits from the register */
ret = I2C_READ(priv->i2c, conf, 1);
lm75dbg("conf: %02x ret: %d\n", *conf, ret);
return ret;
}
/****************************************************************************
* Name: lm75_writeconf
*
* Description:
* Write to a 8-bit LM75 configuration register.
*
****************************************************************************/
static int lm75_writeconf(FAR struct lm75_dev_s *priv, uint8_t conf)
{
uint8_t buffer[2];
lm75dbg("conf: %02x\n", conf);
/* Set up a 2 byte message to send */
buffer[0] = LM75_CONF_REG;
buffer[1] = conf;
/* Write the register address followed by the data (no RESTART) */
I2C_SETADDRESS(priv->i2c, priv->addr, 7);
return I2C_WRITE(priv->i2c, buffer, 2);
}
/****************************************************************************
* Name: lm75_open
*
* Description:
* This function is called whenever the LM-75 device is opened.
*
****************************************************************************/
static int lm75_open(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: lm75_close
*
* Description:
* This routine is called when the LM-75 device is closed.
*
****************************************************************************/
static int lm75_close(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: lm75_read
****************************************************************************/
static ssize_t lm75_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct lm75_dev_s *priv = inode->i_private;
FAR b16_t *ptr;
ssize_t nsamples;
int i;
int ret;
/* How many samples were requested to get? */
nsamples = buflen / sizeof(b16_t);
ptr = (FAR b16_t *)buffer;
lm75dbg("buflen: %d nsamples: %d\n", buflen, nsamples);
/* Get the requested number of samples */
for (i = 0; i < nsamples; i++)
{
b16_t temp;
/* Read the next b16_t temperature value */
ret = lm75_readtemp(priv, &temp);
if (ret < 0)
{
lm75dbg("lm75_readtemp failed: %d\n",ret);
return (ssize_t)ret;
}
/* Save the temperature value in the user buffer */
*ptr++ = temp;
}
return nsamples * sizeof(b16_t);
}
/****************************************************************************
* Name: lm75_write
****************************************************************************/
static ssize_t lm75_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Name: lm75_ioctl
****************************************************************************/
static int lm75_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct lm75_dev_s *priv = inode->i_private;
int ret = OK;
switch (cmd)
{
/* Read from the configuration register. Arg: uint8_t* pointer */
case SNIOC_READCONF:
{
FAR uint8_t *ptr = (FAR uint8_t *)((uintptr_t)arg);
ret = lm75_readconf(priv, ptr);
lm75dbg("conf: %02x ret: %d\n", *ptr, ret);
}
break;
/* Wrtie to the configuration register. Arg: uint8_t value */
case SNIOC_WRITECONF:
ret = lm75_writeconf(priv, (uint8_t)arg);
lm75dbg("conf: %02x ret: %d\n", *(uint8_t*)arg, ret);
break;
/* Shutdown the LM75, Arg: None */
case SNIOC_SHUTDOWN:
{
uint8_t conf;
ret = lm75_readconf(priv, &conf);
if (ret == OK)
{
ret = lm75_writeconf(priv, conf | LM75_CONF_SHUTDOWN);
}
lm75dbg("conf: %02x ret: %d\n", conf | LM75_CONF_SHUTDOWN, ret);
}
break;
/* Powerup the LM75, Arg: None */
case SNIOC_POWERUP:
{
uint8_t conf;
ret = lm75_readconf(priv, &conf);
if (ret == OK)
{
ret = lm75_writeconf(priv, conf & ~LM75_CONF_SHUTDOWN);
}
lm75dbg("conf: %02x ret: %d\n", conf & ~LM75_CONF_SHUTDOWN, ret);
}
break;
/* Report samples in Fahrenheit */
case SNIOC_FAHRENHEIT:
priv->fahrenheit = true;
lm75dbg("Fahrenheit\n");
break;
/* Report Samples in Centigrade */
case SNIOC_CENTIGRADE:
priv->fahrenheit = false;
lm75dbg("Centigrade\n");
break;
/* Read THYS temperature register. Arg: b16_t* pointer */
case SNIOC_READTHYS:
{
FAR b16_t *ptr = (FAR b16_t *)((uintptr_t)arg);
ret = lm75_readb16(priv, LM75_THYS_REG, ptr);
lm75dbg("THYS: %08x ret: %d\n", *ptr, ret);
}
break;
/* Write THYS temperature register. Arg: b16_t value */
case SNIOC_WRITETHYS:
ret = lm75_writeb16(priv, LM75_THYS_REG, (b16_t)arg);
lm75dbg("THYS: %08x ret: %d\n", (b16_t)arg, ret);
break;
/* Read TOS (Over-temp Shutdown Threshold) Register. Arg: b16_t* pointer */
case SNIOC_READTOS:
{
FAR b16_t *ptr = (FAR b16_t *)((uintptr_t)arg);
ret = lm75_readb16(priv, LM75_TOS_REG, ptr);
lm75dbg("TOS: %08x ret: %d\n", *ptr, ret);
}
break;
/* Write TOS (Over-temp Shutdown Threshold) Register. Arg: b16_t value */
case SNIOC_WRITRETOS:
ret = lm75_writeb16(priv, LM75_TOS_REG, (b16_t)arg);
lm75dbg("TOS: %08x ret: %d\n", (b16_t)arg, ret);
break;
default:
lm75dbg("Unrecognized cmd: %d\n", cmd);
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: lm75_register
*
* Description:
* Register the LM-75 character device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/temp0"
* i2c - An instance of the I2C interface to use to communicate with LM75
* addr - The I2C address of the LM-75. The base I2C address of the LM75
* is 0x48. Bits 0-3 can be controlled to get 8 unique addresses from 0x48
* through 0x4f.
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int lm75_register(FAR const char *devpath, FAR struct i2c_dev_s *i2c, uint8_t addr)
{
FAR struct lm75_dev_s *priv;
int ret;
/* Initialize the LM-75 device structure */
priv = (FAR struct lm75_dev_s *)malloc(sizeof(struct lm75_dev_s));
if (!priv)
{
lm75dbg("Failed to allocate instance\n");
return -ENOMEM;
}
priv->i2c = i2c;
priv->addr = addr;
priv->fahrenheit = false;
/* Register the character driver */
ret = register_driver(devpath, &g_lm75fops, 0666, priv);
if (ret < 0)
{
lm75dbg("Failed to register driver: %d\n", ret);
free(priv);
}
return ret;
}
#endif /* CONFIG_I2C && CONFIG_I2C_LM75 */
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