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081e4c478a
Permissions (Part 2) Description: In kernel builds, any unprivileged process running on the NuttX device can open /dev/efuse and attempt to read/write fuse content. Reading the fuses may provide valuable information to an attacker controlling the user process. The write operation, in extreme cases where the fuse blocks are not locked, may brick the device. DISCLAIMER: I tried to be strict with the settings, better to relax them later if it's needed. This is part of https://github.com/apache/nuttx/issues/19410 See https://github.com/apache/nuttx/issues/19410 Compiles ok. Signed-off-by: Catalin Visinescu <catalin_visinescu@yahoo.com>
319 lines
9.4 KiB
C
319 lines
9.4 KiB
C
/****************************************************************************
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* drivers/sensors/max31855.c
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*
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* SPDX-License-Identifier: Apache-2.0
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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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/* WARNING for developers:
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*
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* This driver uses the legacy style of writing sensor drivers for NuttX. The
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* project has since decided to adopt a new sensor framework in order to
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* have a consistent API and feature-set.
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*
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* Sensors which use the uORB framework are typically suffixed "_uorb". You
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* can also visit the documentation about the new sensor framework to learn
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* more.
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*/
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#warning "This is a deprecated legacy sensor driver."
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/* Character driver for the Maxim MAX31855 Thermocouple-to-Digital Converter
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*
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* NOTE: Some Maxim MAX31855 chips have an issue it report value 25% lower
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* of real temperature, for more info read this thread:
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* http://www.eevblog.com/forum/projects/max31855-temperature-error/
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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 <inttypes.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 <nuttx/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/spi/spi.h>
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#include <nuttx/sensors/max31855.h>
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#include <nuttx/random.h>
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#if defined(CONFIG_SPI) && defined(CONFIG_SENSORS_MAX31855)
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define MAX31855_FAULT (1 << 16)
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#define MAX31855_SHORT_VCC (1 << 2)
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#define MAX31855_SHORT_GND (1 << 1)
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#define MAX31855_OPEN_CIRCUIT (1 << 0)
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#define MAX31855_TEMP_COUPLE 0xffffc000
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#define MAX31855_TEMP_JUNCTION 0xfff0
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct max31855_dev_s
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{
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FAR struct spi_dev_s *spi; /* Saved SPI driver instance */
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int16_t temp;
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uint16_t devid; /* Select minor device number */
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static void max31855_lock(FAR struct spi_dev_s *spi);
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static void max31855_unlock(FAR struct spi_dev_s *spi);
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/* Character driver methods */
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static ssize_t max31855_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t max31855_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_max31855fops =
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{
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NULL, /* open */
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NULL, /* close */
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max31855_read, /* read */
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max31855_write, /* write */
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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: max31855_lock
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*
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* Description:
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* Lock and configure the SPI bus.
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*
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****************************************************************************/
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static void max31855_lock(FAR struct spi_dev_s *spi)
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{
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SPI_LOCK(spi, true);
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SPI_SETMODE(spi, SPIDEV_MODE0);
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SPI_SETBITS(spi, 8);
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SPI_HWFEATURES(spi, 0);
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SPI_SETFREQUENCY(spi, 400000);
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}
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/****************************************************************************
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* Name: max31855_unlock
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*
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* Description:
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* Unlock the SPI bus.
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*
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****************************************************************************/
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static void max31855_unlock(FAR struct spi_dev_s *spi)
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{
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SPI_LOCK(spi, false);
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}
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/****************************************************************************
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* Name: max31855_read
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****************************************************************************/
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static ssize_t max31855_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct max31855_dev_s *priv = inode->i_private;
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FAR uint16_t *temp = (FAR uint16_t *) buffer;
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int ret = 2;
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int32_t regmsb;
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int32_t regval;
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/* Check for issues */
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if (!buffer)
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{
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snerr("ERROR: Buffer is null\n");
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return -EINVAL;
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}
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if (buflen != 2)
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{
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snerr("ERROR: You can't read something other than 16 bits "
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"(2 bytes)\n");
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return -EINVAL;
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}
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/* Enable MAX31855's chip select */
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max31855_lock(priv->spi);
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SPI_SELECT(priv->spi, SPIDEV_TEMPERATURE(priv->devid), true);
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/* Read temperature */
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SPI_RECVBLOCK(priv->spi, ®msb, 4);
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/* Disable MAX31855's chip select */
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SPI_SELECT(priv->spi, SPIDEV_TEMPERATURE(priv->devid), false);
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max31855_unlock(priv->spi);
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/* Detect any errors during SPI transmission */
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if (!(regmsb) || regmsb == -1)
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{
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snerr("ERROR: Data transmission failed on device %d:\n", priv->devid);
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snerr(" One or more MAX31855 pins are not properly connected!\n\n");
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return -EINVAL;
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}
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regval = (regmsb & 0xff000000) >> 24;
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regval |= (regmsb & 0xff0000) >> 8;
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regval |= (regmsb & 0xff00) << 8;
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regval |= (regmsb & 0xff) << 24;
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sninfo("Read from MAX31855 = 0x%08" PRIX32 "\n", regval);
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/* Feed sensor data to entropy pool */
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add_sensor_randomness(regval);
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/* If negative, fix signal bits */
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if (regval & 0x80000000)
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{
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*temp = 0xc000 | (regval >> 18);
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}
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else
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{
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*temp = (regval >> 18);
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}
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/* Detect any fault */
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if (regval & MAX31855_FAULT)
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{
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snerr("ERROR: A fault was detected by MAX31855:\n");
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if (regval & MAX31855_SHORT_VCC)
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{
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snerr(" The thermocouple input is shorted to VCC!\n");
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}
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if (regval & MAX31855_SHORT_GND)
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{
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snerr(" The thermocouple input is shorted to GND!\n");
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}
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if (regval & MAX31855_OPEN_CIRCUIT)
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{
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snerr(" The thermocouple input is not connected!\n");
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}
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return -EINVAL;
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}
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/* Return two bytes, the temperature is fixed point Q12.2, then divide by 4
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* in your application in other to get real temperature in Celsius degrees.
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*/
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return ret;
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}
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/****************************************************************************
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* Name: max31855_write
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****************************************************************************/
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static ssize_t max31855_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: max31855_register
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*
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* Description:
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* This function will register the max31855 driver as /dev/tempN
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* where N is the minor device number
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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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* spi - An instance of the SPI interface to use to communicate with
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* MAX31855
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* devid - Minor device number. E.g., 0, 1, 2, etc.
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*
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* Returned Value:
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* Zero is returned on success. Otherwise, a negated errno value is
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* returned to indicate the nature of the failure.
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*
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****************************************************************************/
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int max31855_register(FAR const char *devpath, FAR struct spi_dev_s *spi,
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uint16_t devid)
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{
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FAR struct max31855_dev_s *priv;
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int ret;
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/* Sanity check */
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DEBUGASSERT(spi != NULL);
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/* Initialize the MAX31855 device structure */
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priv = (FAR struct max31855_dev_s *)
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kmm_malloc(sizeof(struct max31855_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->spi = spi;
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priv->temp = 0;
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priv->devid = devid;
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/* Register the character driver */
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ret = register_driver(devpath, &g_max31855fops, 0600, 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_SPI && CONFIG_SENSORS_MAX31855 */
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