/**************************************************************************** * drivers/sensors/scd30.c * Driver for the Sensirion SCD30 CO₂, temperature and humidity sensor * * Copyright (C) 2019 Haltian Ltd. All rights reserved. * Author: Jussi Kivilinna * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(CONFIG_SENSORS_SCD30) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #ifdef CONFIG_SCD30_DEBUG # define scd30_dbg(x, ...) _info(x, ##__VA_ARGS__) #else # define scd30_dbg(x, ...) sninfo(x, ##__VA_ARGS__) #endif #ifndef CONFIG_SCD30_I2C_FREQUENCY # define CONFIG_SCD30_I2C_FREQUENCY 100000 #endif #define SCD30_I2C_RETRIES 3 /* SCD30 command words */ #define SCD30_CMD_START_MEASUREMENT 0x0010 #define SCD30_CMD_STOP_MEASUREMENT 0x0104 #define SCD30_CMD_SET_INTERVAL 0x4600 #define SCD30_CMD_GET_DATA_READY 0x0202 #define SCD30_CMD_READ_MEASUREMENT 0x0300 #define SCD30_CMD_SET_ASC 0x5306 #define SCD30_CMD_SET_FRC 0x5204 #define SCD30_CMD_SET_TEMP_OFFSET 0x5403 #define SCD30_CMD_SET_ALT_COMPENSATION 0x5102 #define SCD30_CMD_SOFT_RESET 0xd304 #define SCD30_DEFAULT_MEASUREMENT_INTERVAL 2 /* seconds */ #define SCD30_DEFAULT_PRESSURE_COMPENSATION 0 #define SCD30_DEFAULT_ALTITUDE_COMPENSATION 0 #define SCD30_DEFAULT_TEMPERATURE_OFFSET 0 /**************************************************************************** * Private ****************************************************************************/ struct scd30_dev_s { #ifdef CONFIG_SCD30_I2C FAR struct i2c_master_s *i2c; /* I2C interface */ uint8_t addr; /* I2C address */ #endif bool valid; /* If cached readings are valid */ bool started; /* If continuous measurement is enabled */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS bool unlinked; /* True, driver has been unlinked */ #endif struct timespec last_update; /* Last time when sensor was read */ float co2; /* Cached CO₂ (PPM) */ float temperature; /* Cached temperature (°C) */ float humidity; /* Cached humidity (RH%) */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS int16_t crefs; /* Number of open references */ #endif sem_t devsem; uint16_t pressure_comp; /* Pressure compensation in mbar (non-zero * value overrides altitude compensation). */ uint16_t altitude_comp; /* Altitude compensation in meters */ uint16_t interval; /* Background measurement interval in * seconds (2 to 1800). */ uint16_t temperature_offset; /* Temperature offset in 0.01 Kelvin. */ }; struct scd30_word_s { uint8_t data[2]; uint8_t crc; }; /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /* IO Helpers */ #ifdef CONFIG_SCD30_I2C static int scd30_do_transfer(FAR struct i2c_master_s *i2c, FAR struct i2c_msg_s *msgv, size_t nmsg); #endif static int scd30_write_cmd(FAR struct scd30_dev_s *priv, uint16_t cmd, FAR struct scd30_word_s *params, unsigned int num_params); static int scd30_read_words(FAR struct scd30_dev_s *priv, FAR struct scd30_word_s *words, unsigned int num_words); /* Data conversion */ static uint8_t scd30_crc_word(uint16_t word); static void scd30_set_command_param(FAR struct scd30_word_s *param, uint16_t value); static int scd30_check_data_crc(FAR const struct scd30_word_s *words, unsigned int num_words); static uint16_t scd30_data_word_to_uint16(FAR const struct scd30_word_s *word); static float scd30_data_words_to_float(FAR const struct scd30_word_s words[2]); /* Driver features */ static int scd30_read_values(FAR struct scd30_dev_s *priv, FAR float *temp, FAR float *rh, FAR float *co2, bool wait); static int scd30_configure(FAR struct scd30_dev_s *priv, bool start); /* Character driver methods */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int scd30_open(FAR struct file *filep); static int scd30_close(FAR struct file *filep); #endif static ssize_t scd30_read(FAR struct file *filep, FAR char *buffer, size_t buflen); static ssize_t scd30_write(FAR struct file *filep, FAR const char *buffer, size_t buflen); static int scd30_ioctl(FAR struct file *filep, int cmd, unsigned long arg); #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int scd30_unlink(FAR struct inode *inode); #endif /**************************************************************************** * Private Data ****************************************************************************/ static const struct file_operations g_scd30fops = { #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS scd30_open, /* open */ scd30_close, /* close */ #else NULL, /* open */ NULL, /* close */ #endif scd30_read, /* read */ scd30_write, /* write */ NULL, /* seek */ scd30_ioctl, /* ioctl */ NULL /* poll */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS , scd30_unlink /* unlink */ #endif }; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: scd30_do_transfer ****************************************************************************/ #ifdef CONFIG_SCD30_I2C static int scd30_do_transfer(FAR struct i2c_master_s *i2c, FAR struct i2c_msg_s *msgv, size_t nmsg) { int ret = -EIO; int retries; for (retries = 0; retries < SCD30_I2C_RETRIES; retries++) { ret = I2C_TRANSFER(i2c, msgv, nmsg); if (ret >= 0) { return 0; } else { /* Some error. Try to reset I2C bus and keep trying. */ #ifdef CONFIG_I2C_RESET if (retries == SCD30_I2C_RETRIES - 1) { break; } ret = I2C_RESET(i2c); if (ret < 0) { scd30_dbg("I2C_RESET failed: %d\n", ret); return ret; } #endif } } scd30_dbg("xfer failed: %d\n", ret); return ret; } #endif /**************************************************************************** * Name: scd30_write_cmd ****************************************************************************/ static int scd30_write_cmd(FAR struct scd30_dev_s *priv, uint16_t cmd, FAR struct scd30_word_s *params, unsigned int num_params) { #ifdef CONFIG_SCD30_I2C struct i2c_msg_s msg[2]; uint8_t cmd_buf[2]; int ret; cmd_buf[0] = cmd >> 8; cmd_buf[1] = cmd >> 0; msg[0].frequency = CONFIG_SCD30_I2C_FREQUENCY; msg[0].addr = priv->addr; msg[0].flags = 0; msg[0].buffer = cmd_buf; msg[0].length = 2; if (num_params) { msg[1].frequency = CONFIG_SCD30_I2C_FREQUENCY; msg[1].addr = priv->addr; msg[1].flags = I2C_M_NOSTART; msg[1].buffer = (FAR uint8_t *)params; msg[1].length = num_params * sizeof(*params); } ret = scd30_do_transfer(priv->i2c, msg, (num_params) ? 2 : 1); scd30_dbg("cmd: 0x%04X num_params: %d ret: %d\n", cmd, num_params, ret); return (ret >= 0) ? OK : ret; #else /* UART mode not implemented yet. */ return -ENODEV; #endif } /**************************************************************************** * Name: scd30_read_words ****************************************************************************/ static int scd30_read_words(FAR struct scd30_dev_s *priv, FAR struct scd30_word_s *words, unsigned int num_words) { #ifdef CONFIG_SCD30_I2C struct i2c_msg_s msg[1]; int ret; msg[0].frequency = CONFIG_SCD30_I2C_FREQUENCY; msg[0].addr = priv->addr; msg[0].flags = I2C_M_READ; msg[0].buffer = (FAR uint8_t *)words; msg[0].length = num_words * sizeof(*words); ret = scd30_do_transfer(priv->i2c, msg, 1); scd30_dbg("num_words: %d ret: %d\n", num_words, ret); return (ret >= 0) ? OK : ret; #else /* UART mode not implemented yet. */ return -ENODEV; #endif } /**************************************************************************** * Name: scd30_crc_word ****************************************************************************/ static uint8_t scd30_crc_word(uint16_t word) { static const uint8_t crc_table[16] = { 0x00, 0x31, 0x62, 0x53, 0xc4, 0xf5, 0xa6, 0x97, 0xb9, 0x88, 0xdb, 0xea, 0x7d, 0x4c, 0x1f, 0x2e }; uint8_t crc = 0xff; crc ^= word >> 8; crc = (crc << 4) ^ crc_table[crc >> 4]; crc = (crc << 4) ^ crc_table[crc >> 4]; crc ^= word >> 0; crc = (crc << 4) ^ crc_table[crc >> 4]; crc = (crc << 4) ^ crc_table[crc >> 4]; return crc; } /**************************************************************************** * Name: scd30_set_command_param ****************************************************************************/ static void scd30_set_command_param(FAR struct scd30_word_s *param, uint16_t value) { param->data[0] = value >> 8; param->data[1] = value >> 0; param->crc = scd30_crc_word(value); } /**************************************************************************** * Name: scd30_data_words_to_float ****************************************************************************/ static float scd30_data_words_to_float(FAR const struct scd30_word_s words[2]) { uint8_t data[4]; float value; data[3] = words[0].data[0]; data[2] = words[0].data[1]; data[1] = words[1].data[0]; data[0] = words[1].data[1]; memcpy(&value, data, 4); return value; } /**************************************************************************** * Name: scd30_data_word_to_uint16 ****************************************************************************/ static uint16_t scd30_data_word_to_uint16(FAR const struct scd30_word_s *word) { return (word[0].data[0] << 8) | (word[0].data[1]); } /**************************************************************************** * Name: scd30_crc_word ****************************************************************************/ static int scd30_check_data_crc(FAR const struct scd30_word_s *words, unsigned int num_words) { while (num_words) { if (scd30_crc_word(scd30_data_word_to_uint16(words)) != words->crc) { return -1; } num_words--; words++; } return 0; } /**************************************************************************** * Name: scd30_softreset * * Description: * Reset the SCD30 sensor. This takes less than 2000 ms. * ****************************************************************************/ static int scd30_softreset(FAR struct scd30_dev_s *priv) { int ret; ret = scd30_write_cmd(priv, SCD30_CMD_SOFT_RESET, NULL, 0); if (ret < 0) { return ret; } return 0; } /**************************************************************************** * Name: has_time_passed * * Description: * Return true if curr >= start + secs_since_start * ****************************************************************************/ static bool has_time_passed(struct timespec curr, struct timespec start, unsigned int secs_since_start) { if ((long)((start.tv_sec + secs_since_start) - curr.tv_sec) == 0) { return start.tv_nsec <= curr.tv_nsec; } return (long)((start.tv_sec + secs_since_start) - curr.tv_sec) <= 0; } /**************************************************************************** * Name: scd30_read_values ****************************************************************************/ static int scd30_read_values(FAR struct scd30_dev_s *priv, FAR float *temp, FAR float *rh, FAR float *co2, bool wait) { struct scd30_word_s data[6]; struct timespec ts; int ret; clock_gettime(CLOCK_REALTIME, &ts); if (wait || !priv->valid || has_time_passed(ts, priv->last_update, SCD30_DEFAULT_MEASUREMENT_INTERVAL)) { while (1) { /* Wait data to be ready. */ ret = scd30_write_cmd(priv, SCD30_CMD_GET_DATA_READY, NULL, 0); if (ret < 0) { scd30_dbg("ERROR: scd30_write_cmd failed: %d\n", ret); return ret; } ret = scd30_read_words(priv, data, 1); if (ret < 0) { scd30_dbg("ERROR: scd30_read_words failed: %d\n", ret); return ret; } if (scd30_check_data_crc(data, 1) < 0) { scd30_dbg("ERROR: scd30_read_words crc failed\n"); ret = -EIO; return ret; } if (scd30_data_word_to_uint16(data) != 0x0001) { if (!wait) { scd30_dbg("ERROR: data not ready\n"); ret = -EAGAIN; return ret; } ret = nxsig_usleep(500 * 1000); if (ret == -EINTR) { return ret; } } else { break; } } /* Read the raw data */ ret = scd30_write_cmd(priv, SCD30_CMD_READ_MEASUREMENT, NULL, 0); if (ret < 0) { scd30_dbg("ERROR: scd30_write_cmd failed: %d\n", ret); return ret; } ret = scd30_read_words(priv, data, 6); if (ret < 0) { scd30_dbg("ERROR: scd30_read_words failed: %d\n", ret); return ret; } if (scd30_check_data_crc(data, 6) < 0) { scd30_dbg("ERROR: scd30_read_words crc failed\n"); ret = -EIO; return ret; } add_sensor_randomness(((data[0].crc ^ data[1].crc) << 0) ^ ((data[2].crc ^ data[3].crc) << 8) ^ ((data[4].crc ^ data[5].crc) << 16)); priv->co2 = scd30_data_words_to_float(data + 0); priv->temperature = scd30_data_words_to_float(data + 2); priv->humidity = scd30_data_words_to_float(data + 4); priv->last_update = ts; priv->valid = true; } *temp = priv->temperature; *rh = priv->humidity; *co2 = priv->co2; return OK; } /**************************************************************************** * Name: scd30_configure ****************************************************************************/ static int scd30_configure(FAR struct scd30_dev_s *priv, bool start) { struct scd30_word_s param; int ret; /* Set measurement interval. */ scd30_set_command_param(¶m, priv->interval); scd30_write_cmd(priv, SCD30_CMD_SET_INTERVAL, ¶m, 1); /* Set altitude compensation. */ scd30_set_command_param(¶m, priv->altitude_comp); scd30_write_cmd(priv, SCD30_CMD_SET_ALT_COMPENSATION, ¶m, 1); /* Set temperature offset. */ scd30_set_command_param(¶m, priv->temperature_offset); scd30_write_cmd(priv, SCD30_CMD_SET_TEMP_OFFSET, ¶m, 1); if (!start) { /* Stop measurements. */ ret = scd30_write_cmd(priv, SCD30_CMD_STOP_MEASUREMENT, ¶m, 1); if (ret >= 0) { priv->started = false; } } else { /* Start measurements (and set pressure compensation). */ scd30_set_command_param(¶m, priv->pressure_comp); ret = scd30_write_cmd(priv, SCD30_CMD_START_MEASUREMENT, ¶m, 1); if (ret >= 0) { priv->started = true; } } return ret; } /**************************************************************************** * Name: scd30_open * * Description: * This function is called whenever the SCD30x device is opened. * ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int scd30_open(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct scd30_dev_s *priv = inode->i_private; int ret = OK; /* Get exclusive access */ nxsem_wait_uninterruptible(&priv->devsem); /* Increment the count of open references on the driver */ priv->crefs++; DEBUGASSERT(priv->crefs > 0); if (priv->crefs == 1) { ret = scd30_configure(priv, true); } if (ret < 0) { priv->crefs--; } nxsem_post(&priv->devsem); return ret; } #endif /**************************************************************************** * Name: scd30_close * * Description: * This routine is called when the SCD30 device is closed. * ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int scd30_close(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct scd30_dev_s *priv = inode->i_private; /* Get exclusive access */ nxsem_wait_uninterruptible(&priv->devsem); /* Decrement the count of open references on the driver */ DEBUGASSERT(priv->crefs > 0); priv->crefs--; /* If the count has decremented to zero and the driver has been unlinked, * then free memory now. */ if (priv->crefs <= 0 && priv->unlinked) { nxsem_destroy(&priv->devsem); kmm_free(priv); return OK; } nxsem_post(&priv->devsem); return OK; } #endif /**************************************************************************** * Name: scd30_read ****************************************************************************/ static ssize_t scd30_read(FAR struct file *filep, FAR char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR struct scd30_dev_s *priv = inode->i_private; ssize_t length = 0; float temp; float rh; float co2; unsigned int temp100; unsigned int rh100; unsigned int co2_100; int ret; /* Get exclusive access */ nxsem_wait_uninterruptible(&priv->devsem); #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS if (priv->unlinked) { /* Do not allow operations on unlinked sensors. This allows * sensor use on hot swappable I2C bus. */ nxsem_post(&priv->devsem); return -ENODEV; } #endif if (!priv->started) { return -ENODATA; } ret = scd30_read_values(priv, &temp, &rh, &co2, !(filep->f_oflags & O_NONBLOCK)); if (ret < 0) { scd30_dbg("cannot read data: %d\n", ret); } else { /* This interface is mainly intended for easy debugging in nsh. */ temp100 = abs(temp * 100); rh100 = abs(rh * 100); co2_100 = abs(co2 * 100); length = snprintf(buffer, buflen, "%s%u.%02u %s%u.%02u %s%u.%02u\n", co2 < 0 ? "-" : "", co2_100 / 100, co2_100 % 100, temp < 0 ? "-" : "", temp100 / 100, temp100 % 100, rh < 0 ? "-" : "", rh100 / 100, rh100 % 100); if (length > buflen) { length = buflen; } } nxsem_post(&priv->devsem); return length; } /**************************************************************************** * Name: scd30_write ****************************************************************************/ static ssize_t scd30_write(FAR struct file *filep, FAR const char *buffer, size_t buflen) { return -ENOSYS; } /**************************************************************************** * Name: scd30_ioctl ****************************************************************************/ static int scd30_ioctl(FAR struct file *filep, int cmd, unsigned long arg) { FAR struct inode *inode = filep->f_inode; FAR struct scd30_dev_s *priv = inode->i_private; struct scd30_word_s param; int ret; /* Get exclusive access */ nxsem_wait_uninterruptible(&priv->devsem); #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS if (priv->unlinked) { /* Do not allow operations on unlinked sensors. This allows * sensor use on hot swappable I2C bus. */ nxsem_post(&priv->devsem); return -ENODEV; } #endif switch (cmd) { /* Soft reset the SCD30, Arg: None */ case SNIOC_RESET: { priv->interval = SCD30_DEFAULT_MEASUREMENT_INTERVAL; priv->pressure_comp = SCD30_DEFAULT_PRESSURE_COMPENSATION; priv->altitude_comp = SCD30_DEFAULT_ALTITUDE_COMPENSATION; priv->temperature_offset = SCD30_DEFAULT_TEMPERATURE_OFFSET; ret = scd30_softreset(priv); scd30_dbg("softreset ret: %d\n", ret); scd30_configure(priv, priv->started); } break; /* Start background measurement, Arg: None */ case SNIOC_START: { /* Start measurements (and set pressure compensation). */ scd30_set_command_param(¶m, priv->pressure_comp); ret = scd30_write_cmd(priv, SCD30_CMD_START_MEASUREMENT, ¶m, 1); if (ret >= 0) { priv->started = true; } } break; /* Stop background measurement, Arg: None */ case SNIOC_STOP: { /* Stop measurements. */ ret = scd30_write_cmd(priv, SCD30_CMD_STOP_MEASUREMENT, NULL, 0); if (ret >= 0) { priv->started = false; } } break; /* Set background measurement interval, Arg: uint16_t */ case SNIOC_SET_INTERVAL: { if (arg < 2 && arg > 1800) { ret = -EINVAL; break; } priv->interval = arg; scd30_set_command_param(¶m, priv->interval); ret = scd30_write_cmd(priv, SCD30_CMD_SET_INTERVAL, ¶m, 1); } break; /* Set temperature offset value, Arg: uint16_t */ case SNIOC_SET_TEMP_OFFSET: { if (arg < 0 && arg > UINT16_MAX) { ret = -EINVAL; break; } priv->temperature_offset = arg; scd30_set_command_param(¶m, priv->temperature_offset); ret = scd30_write_cmd(priv, SCD30_CMD_SET_TEMP_OFFSET, ¶m, 1); } break; /* Set pressure compensation value, Arg: uint16_t */ case SNIOC_SET_PRESSURE_COMP: { if (arg != 0 && arg < 700 && arg > 1200) { ret = -EINVAL; break; } priv->pressure_comp = arg; if (priv->started) { scd30_set_command_param(¶m, priv->pressure_comp); ret = scd30_write_cmd(priv, SCD30_CMD_START_MEASUREMENT, ¶m, 1); } else { ret = 0; } } break; /* Set altitude compensation value, Arg: uint16_t */ case SNIOC_SET_ALTITUDE_COMP: { if (arg < 0 && arg > UINT16_MAX) { ret = -EINVAL; break; } priv->altitude_comp = arg; scd30_set_command_param(¶m, priv->altitude_comp); ret = scd30_write_cmd(priv, SCD30_CMD_SET_ALT_COMPENSATION, ¶m, 1); } break; /* Set Forced Recalibration value (FRC), Arg: uint16_t */ case SNIOC_SET_FRC: { if (arg < 0 && arg > UINT16_MAX) { ret = -EINVAL; break; } scd30_set_command_param(¶m, arg); ret = scd30_write_cmd(priv, SCD30_CMD_SET_FRC, ¶m, 1); } break; /* (De-)Activate Automatic Self-Calibration (ASC), Arg: bool */ case SNIOC_ENABLE_ASC: { if (arg != !!arg) /* 0 or 1 */ { ret = -EINVAL; break; } scd30_set_command_param(¶m, arg); ret = scd30_write_cmd(priv, SCD30_CMD_SET_ASC, ¶m, 1); } break; /* Read sensor data, Arg: struct scd30_conv_data_s *data */ case SNIOC_READ_CONVERT_DATA: { float temp; float rh; float co2; ret = scd30_read_values(priv, &temp, &rh, &co2, false); if (ret < 0) { scd30_dbg("cannot read data: %d\n", ret); } else { FAR struct scd30_conv_data_s *data = (FAR struct scd30_conv_data_s *)arg; data->temperature = temp; data->humidity = rh; data->co2 = co2; } } break; default: scd30_dbg("Unrecognized cmd: %d\n", cmd); ret = -ENOTTY; break; } nxsem_post(&priv->devsem); return ret; } /**************************************************************************** * Name: scd30_unlink ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int scd30_unlink(FAR struct inode *inode) { FAR struct scd30_dev_s *priv; DEBUGASSERT(inode != NULL && inode->i_private != NULL); priv = (FAR struct scd30_dev_s *)inode->i_private; /* Get exclusive access */ nxsem_wait_uninterruptible(&priv->devsem); /* Are there open references to the driver data structure? */ if (priv->crefs <= 0) { nxsem_destroy(&priv->devsem); kmm_free(priv); return OK; } /* No... just mark the driver as unlinked and free the resources when * the last client closes their reference to the driver. */ priv->unlinked = true; nxsem_post(&priv->devsem); return OK; } #endif /**************************************************************************** * Public Functions ****************************************************************************/ #ifdef CONFIG_SCD30_I2C /**************************************************************************** * Name: scd30_register_i2c * * Description: * Register the SCD30 character device as 'devpath' * * Input Parameters: * devpath - The full path to the driver to register. E.g., "/dev/co2_0" * i2c - An instance of the I2C interface to use to communicate with * the SCD30 * addr - The I2C address of the SCD30. The I2C address of SCD30 is * always 0x61. * * Returned Value: * Zero (OK) on success; a negated errno value on failure. * ****************************************************************************/ int scd30_register_i2c(FAR const char *devpath, FAR struct i2c_master_s *i2c, uint8_t addr) { FAR struct scd30_dev_s *priv; int ret; DEBUGASSERT(i2c != NULL); DEBUGASSERT(addr == CONFIG_SCD30_ADDR); DEBUGASSERT(scd30_crc_word(0xbeef) == 0x92); /* Initialize the device structure */ priv = (FAR struct scd30_dev_s *)kmm_zalloc(sizeof(struct scd30_dev_s)); if (priv == NULL) { scd30_dbg("ERROR: Failed to allocate instance\n"); return -ENOMEM; } priv->i2c = i2c; priv->addr = addr; priv->started = false; priv->interval = SCD30_DEFAULT_MEASUREMENT_INTERVAL; priv->pressure_comp = SCD30_DEFAULT_PRESSURE_COMPENSATION; priv->altitude_comp = SCD30_DEFAULT_ALTITUDE_COMPENSATION; priv->temperature_offset = SCD30_DEFAULT_TEMPERATURE_OFFSET; nxsem_init(&priv->devsem, 0, 1); /* Register the character driver */ ret = register_driver(devpath, &g_scd30fops, 0666, priv); if (ret < 0) { scd30_dbg("ERROR: Failed to register driver: %d\n", ret); kmm_free(priv); } return ret; } #endif /* CONFIG_SCD30_I2C */ #endif /* CONFIG_SENSORS_SCD30 */