700 lines
15 KiB
C
700 lines
15 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Sensirion SCD4X carbon dioxide sensor i2c driver
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*
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* Copyright (C) 2021 Protonic Holland
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* Author: Roan van Dijk <roan@protonic.nl>
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*
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* I2C slave address: 0x62
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*
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* Datasheets:
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* https://www.sensirion.com/file/datasheet_scd4x
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*/
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#include <asm/unaligned.h>
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#include <linux/crc8.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/i2c.h>
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#include <linux/iio/buffer.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/iio/trigger.h>
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#include <linux/iio/trigger_consumer.h>
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#include <linux/iio/triggered_buffer.h>
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#include <linux/iio/types.h>
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/types.h>
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#define SCD4X_CRC8_POLYNOMIAL 0x31
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#define SCD4X_TIMEOUT_ERR 1000
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#define SCD4X_READ_BUF_SIZE 9
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#define SCD4X_COMMAND_BUF_SIZE 2
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#define SCD4X_WRITE_BUF_SIZE 5
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#define SCD4X_FRC_MIN_PPM 0
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#define SCD4X_FRC_MAX_PPM 2000
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#define SCD4X_READY_MASK 0x01
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/*Commands SCD4X*/
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enum scd4x_cmd {
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CMD_START_MEAS = 0x21b1,
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CMD_READ_MEAS = 0xec05,
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CMD_STOP_MEAS = 0x3f86,
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CMD_SET_TEMP_OFFSET = 0x241d,
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CMD_GET_TEMP_OFFSET = 0x2318,
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CMD_FRC = 0x362f,
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CMD_SET_ASC = 0x2416,
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CMD_GET_ASC = 0x2313,
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CMD_GET_DATA_READY = 0xe4b8,
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};
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enum scd4x_channel_idx {
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SCD4X_CO2,
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SCD4X_TEMP,
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SCD4X_HR,
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};
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struct scd4x_state {
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struct i2c_client *client;
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/* maintain access to device, to prevent concurrent reads/writes */
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struct mutex lock;
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struct regulator *vdd;
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};
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DECLARE_CRC8_TABLE(scd4x_crc8_table);
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static int scd4x_i2c_xfer(struct scd4x_state *state, char *txbuf, int txsize,
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char *rxbuf, int rxsize)
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{
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struct i2c_client *client = state->client;
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int ret;
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ret = i2c_master_send(client, txbuf, txsize);
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if (ret < 0)
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return ret;
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if (ret != txsize)
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return -EIO;
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if (rxsize == 0)
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return 0;
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ret = i2c_master_recv(client, rxbuf, rxsize);
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if (ret < 0)
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return ret;
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if (ret != rxsize)
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return -EIO;
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return 0;
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}
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static int scd4x_send_command(struct scd4x_state *state, enum scd4x_cmd cmd)
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{
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char buf[SCD4X_COMMAND_BUF_SIZE];
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int ret;
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/*
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* Measurement needs to be stopped before sending commands.
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* Except stop and start command.
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*/
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if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {
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ret = scd4x_send_command(state, CMD_STOP_MEAS);
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if (ret)
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return ret;
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/* execution time for stopping measurement */
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msleep_interruptible(500);
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}
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put_unaligned_be16(cmd, buf);
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ret = scd4x_i2c_xfer(state, buf, 2, buf, 0);
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if (ret)
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return ret;
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if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {
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ret = scd4x_send_command(state, CMD_START_MEAS);
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if (ret)
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return ret;
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}
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return 0;
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}
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static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
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void *response, int response_sz)
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{
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struct i2c_client *client = state->client;
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char buf[SCD4X_READ_BUF_SIZE];
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char *rsp = response;
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int i, ret;
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char crc;
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/*
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* Measurement needs to be stopped before sending commands.
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* Except for reading measurement and data ready command.
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*/
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if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
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ret = scd4x_send_command(state, CMD_STOP_MEAS);
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if (ret)
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return ret;
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/* execution time for stopping measurement */
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msleep_interruptible(500);
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}
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/* CRC byte for every 2 bytes of data */
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response_sz += response_sz / 2;
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put_unaligned_be16(cmd, buf);
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ret = scd4x_i2c_xfer(state, buf, 2, buf, response_sz);
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if (ret)
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return ret;
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for (i = 0; i < response_sz; i += 3) {
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crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
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if (crc != buf[i + 2]) {
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dev_err(&client->dev, "CRC error\n");
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return -EIO;
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}
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*rsp++ = buf[i];
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*rsp++ = buf[i + 1];
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}
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/* start measurement */
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if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
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ret = scd4x_send_command(state, CMD_START_MEAS);
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if (ret)
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return ret;
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}
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return 0;
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}
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static int scd4x_write(struct scd4x_state *state, enum scd4x_cmd cmd, uint16_t arg)
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{
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char buf[SCD4X_WRITE_BUF_SIZE];
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int ret;
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char crc;
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put_unaligned_be16(cmd, buf);
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put_unaligned_be16(arg, buf + 2);
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crc = crc8(scd4x_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);
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buf[4] = crc;
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/* measurement needs to be stopped before sending commands */
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ret = scd4x_send_command(state, CMD_STOP_MEAS);
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if (ret)
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return ret;
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/* execution time */
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msleep_interruptible(500);
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ret = scd4x_i2c_xfer(state, buf, SCD4X_WRITE_BUF_SIZE, buf, 0);
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if (ret)
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return ret;
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/* start measurement, except for forced calibration command */
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if (cmd != CMD_FRC) {
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ret = scd4x_send_command(state, CMD_START_MEAS);
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if (ret)
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return ret;
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}
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return 0;
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}
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static int scd4x_write_and_fetch(struct scd4x_state *state, enum scd4x_cmd cmd,
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uint16_t arg, void *response, int response_sz)
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{
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struct i2c_client *client = state->client;
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char buf[SCD4X_READ_BUF_SIZE];
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char *rsp = response;
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int i, ret;
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char crc;
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ret = scd4x_write(state, CMD_FRC, arg);
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if (ret)
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goto err;
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/* execution time */
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msleep_interruptible(400);
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/* CRC byte for every 2 bytes of data */
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response_sz += response_sz / 2;
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ret = i2c_master_recv(client, buf, response_sz);
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if (ret < 0)
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goto err;
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if (ret != response_sz) {
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ret = -EIO;
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goto err;
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}
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for (i = 0; i < response_sz; i += 3) {
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crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
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if (crc != buf[i + 2]) {
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dev_err(&client->dev, "CRC error\n");
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ret = -EIO;
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goto err;
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}
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*rsp++ = buf[i];
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*rsp++ = buf[i + 1];
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}
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return scd4x_send_command(state, CMD_START_MEAS);
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err:
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/*
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* on error try to start the measurement,
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* puts sensor back into continuous measurement
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*/
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scd4x_send_command(state, CMD_START_MEAS);
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return ret;
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}
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static int scd4x_read_meas(struct scd4x_state *state, uint16_t *meas)
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{
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int i, ret;
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__be16 buf[3];
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ret = scd4x_read(state, CMD_READ_MEAS, buf, sizeof(buf));
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if (ret)
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return ret;
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for (i = 0; i < ARRAY_SIZE(buf); i++)
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meas[i] = be16_to_cpu(buf[i]);
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return 0;
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}
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static int scd4x_wait_meas_poll(struct scd4x_state *state)
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{
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struct i2c_client *client = state->client;
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int tries = 6;
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int ret;
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do {
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__be16 bval;
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uint16_t val;
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ret = scd4x_read(state, CMD_GET_DATA_READY, &bval, sizeof(bval));
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if (ret)
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return -EIO;
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val = be16_to_cpu(bval);
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/* new measurement available */
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if (val & 0x7FF)
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return 0;
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msleep_interruptible(1000);
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} while (--tries);
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/* try to start sensor on timeout */
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ret = scd4x_send_command(state, CMD_START_MEAS);
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if (ret)
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dev_err(&client->dev, "failed to start measurement: %d\n", ret);
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return -ETIMEDOUT;
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}
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static int scd4x_read_poll(struct scd4x_state *state, uint16_t *buf)
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{
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int ret;
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ret = scd4x_wait_meas_poll(state);
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if (ret)
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return ret;
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return scd4x_read_meas(state, buf);
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}
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static int scd4x_read_channel(struct scd4x_state *state, int chan)
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{
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int ret;
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uint16_t buf[3];
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ret = scd4x_read_poll(state, buf);
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if (ret)
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return ret;
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return buf[chan];
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}
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static int scd4x_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long mask)
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{
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struct scd4x_state *state = iio_priv(indio_dev);
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int ret;
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__be16 tmp;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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ret = iio_device_claim_direct_mode(indio_dev);
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if (ret)
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return ret;
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mutex_lock(&state->lock);
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ret = scd4x_read_channel(state, chan->address);
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mutex_unlock(&state->lock);
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iio_device_release_direct_mode(indio_dev);
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if (ret < 0)
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return ret;
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*val = ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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if (chan->type == IIO_CONCENTRATION) {
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*val = 0;
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*val2 = 100;
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return IIO_VAL_INT_PLUS_MICRO;
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} else if (chan->type == IIO_TEMP) {
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*val = 175000;
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*val2 = 65536;
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return IIO_VAL_FRACTIONAL;
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} else if (chan->type == IIO_HUMIDITYRELATIVE) {
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*val = 100000;
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*val2 = 65536;
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return IIO_VAL_FRACTIONAL;
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}
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return -EINVAL;
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case IIO_CHAN_INFO_OFFSET:
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*val = -16852;
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*val2 = 114286;
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return IIO_VAL_INT_PLUS_MICRO;
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case IIO_CHAN_INFO_CALIBBIAS:
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mutex_lock(&state->lock);
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ret = scd4x_read(state, CMD_GET_TEMP_OFFSET, &tmp, sizeof(tmp));
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mutex_unlock(&state->lock);
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if (ret)
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return ret;
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*val = be16_to_cpu(tmp);
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return IIO_VAL_INT;
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default:
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return -EINVAL;
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}
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}
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static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
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int val, int val2, long mask)
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{
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struct scd4x_state *state = iio_priv(indio_dev);
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int ret = 0;
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switch (mask) {
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case IIO_CHAN_INFO_CALIBBIAS:
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mutex_lock(&state->lock);
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ret = scd4x_write(state, CMD_SET_TEMP_OFFSET, val);
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mutex_unlock(&state->lock);
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return ret;
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default:
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return -EINVAL;
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}
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}
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static ssize_t calibration_auto_enable_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct scd4x_state *state = iio_priv(indio_dev);
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int ret;
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__be16 bval;
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u16 val;
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mutex_lock(&state->lock);
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ret = scd4x_read(state, CMD_GET_ASC, &bval, sizeof(bval));
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mutex_unlock(&state->lock);
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if (ret) {
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dev_err(dev, "failed to read automatic calibration");
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return ret;
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}
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val = (be16_to_cpu(bval) & SCD4X_READY_MASK) ? 1 : 0;
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return sysfs_emit(buf, "%d\n", val);
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}
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static ssize_t calibration_auto_enable_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t len)
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct scd4x_state *state = iio_priv(indio_dev);
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bool val;
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int ret;
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uint16_t value;
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ret = kstrtobool(buf, &val);
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if (ret)
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return ret;
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value = val;
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mutex_lock(&state->lock);
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ret = scd4x_write(state, CMD_SET_ASC, value);
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mutex_unlock(&state->lock);
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||
|
if (ret)
|
||
|
dev_err(dev, "failed to set automatic calibration");
|
||
|
|
||
|
return ret ?: len;
|
||
|
}
|
||
|
|
||
|
static ssize_t calibration_forced_value_store(struct device *dev,
|
||
|
struct device_attribute *attr,
|
||
|
const char *buf, size_t len)
|
||
|
{
|
||
|
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
|
||
|
struct scd4x_state *state = iio_priv(indio_dev);
|
||
|
uint16_t val, arg;
|
||
|
int ret;
|
||
|
|
||
|
ret = kstrtou16(buf, 0, &arg);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
if (arg < SCD4X_FRC_MIN_PPM || arg > SCD4X_FRC_MAX_PPM)
|
||
|
return -EINVAL;
|
||
|
|
||
|
mutex_lock(&state->lock);
|
||
|
ret = scd4x_write_and_fetch(state, CMD_FRC, arg, &val, sizeof(val));
|
||
|
mutex_unlock(&state->lock);
|
||
|
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
if (val == 0xff) {
|
||
|
dev_err(dev, "forced calibration has failed");
|
||
|
return -EINVAL;
|
||
|
}
|
||
|
|
||
|
return len;
|
||
|
}
|
||
|
|
||
|
static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
|
||
|
static IIO_DEVICE_ATTR_WO(calibration_forced_value, 0);
|
||
|
|
||
|
static IIO_CONST_ATTR(calibration_forced_value_available,
|
||
|
__stringify([SCD4X_FRC_MIN_PPM 1 SCD4X_FRC_MAX_PPM]));
|
||
|
|
||
|
static struct attribute *scd4x_attrs[] = {
|
||
|
&iio_dev_attr_calibration_auto_enable.dev_attr.attr,
|
||
|
&iio_dev_attr_calibration_forced_value.dev_attr.attr,
|
||
|
&iio_const_attr_calibration_forced_value_available.dev_attr.attr,
|
||
|
NULL
|
||
|
};
|
||
|
|
||
|
static const struct attribute_group scd4x_attr_group = {
|
||
|
.attrs = scd4x_attrs,
|
||
|
};
|
||
|
|
||
|
static const struct iio_info scd4x_info = {
|
||
|
.attrs = &scd4x_attr_group,
|
||
|
.read_raw = scd4x_read_raw,
|
||
|
.write_raw = scd4x_write_raw,
|
||
|
};
|
||
|
|
||
|
static const struct iio_chan_spec scd4x_channels[] = {
|
||
|
{
|
||
|
.type = IIO_CONCENTRATION,
|
||
|
.channel2 = IIO_MOD_CO2,
|
||
|
.modified = 1,
|
||
|
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
|
||
|
BIT(IIO_CHAN_INFO_SCALE),
|
||
|
.address = SCD4X_CO2,
|
||
|
.scan_index = SCD4X_CO2,
|
||
|
.scan_type = {
|
||
|
.sign = 'u',
|
||
|
.realbits = 16,
|
||
|
.storagebits = 16,
|
||
|
.endianness = IIO_BE,
|
||
|
},
|
||
|
},
|
||
|
{
|
||
|
.type = IIO_TEMP,
|
||
|
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
|
||
|
BIT(IIO_CHAN_INFO_SCALE) |
|
||
|
BIT(IIO_CHAN_INFO_OFFSET) |
|
||
|
BIT(IIO_CHAN_INFO_CALIBBIAS),
|
||
|
.address = SCD4X_TEMP,
|
||
|
.scan_index = SCD4X_TEMP,
|
||
|
.scan_type = {
|
||
|
.sign = 'u',
|
||
|
.realbits = 16,
|
||
|
.storagebits = 16,
|
||
|
.endianness = IIO_BE,
|
||
|
},
|
||
|
},
|
||
|
{
|
||
|
.type = IIO_HUMIDITYRELATIVE,
|
||
|
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
|
||
|
BIT(IIO_CHAN_INFO_SCALE),
|
||
|
.address = SCD4X_HR,
|
||
|
.scan_index = SCD4X_HR,
|
||
|
.scan_type = {
|
||
|
.sign = 'u',
|
||
|
.realbits = 16,
|
||
|
.storagebits = 16,
|
||
|
.endianness = IIO_BE,
|
||
|
},
|
||
|
},
|
||
|
};
|
||
|
|
||
|
static int scd4x_suspend(struct device *dev)
|
||
|
{
|
||
|
struct iio_dev *indio_dev = dev_get_drvdata(dev);
|
||
|
struct scd4x_state *state = iio_priv(indio_dev);
|
||
|
int ret;
|
||
|
|
||
|
ret = scd4x_send_command(state, CMD_STOP_MEAS);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
return regulator_disable(state->vdd);
|
||
|
}
|
||
|
|
||
|
static int scd4x_resume(struct device *dev)
|
||
|
{
|
||
|
struct iio_dev *indio_dev = dev_get_drvdata(dev);
|
||
|
struct scd4x_state *state = iio_priv(indio_dev);
|
||
|
int ret;
|
||
|
|
||
|
ret = regulator_enable(state->vdd);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
return scd4x_send_command(state, CMD_START_MEAS);
|
||
|
}
|
||
|
|
||
|
static DEFINE_SIMPLE_DEV_PM_OPS(scd4x_pm_ops, scd4x_suspend, scd4x_resume);
|
||
|
|
||
|
static void scd4x_stop_meas(void *state)
|
||
|
{
|
||
|
scd4x_send_command(state, CMD_STOP_MEAS);
|
||
|
}
|
||
|
|
||
|
static void scd4x_disable_regulator(void *data)
|
||
|
{
|
||
|
struct scd4x_state *state = data;
|
||
|
|
||
|
regulator_disable(state->vdd);
|
||
|
}
|
||
|
|
||
|
static irqreturn_t scd4x_trigger_handler(int irq, void *p)
|
||
|
{
|
||
|
struct iio_poll_func *pf = p;
|
||
|
struct iio_dev *indio_dev = pf->indio_dev;
|
||
|
struct scd4x_state *state = iio_priv(indio_dev);
|
||
|
struct {
|
||
|
uint16_t data[3];
|
||
|
int64_t ts __aligned(8);
|
||
|
} scan;
|
||
|
int ret;
|
||
|
|
||
|
memset(&scan, 0, sizeof(scan));
|
||
|
mutex_lock(&state->lock);
|
||
|
ret = scd4x_read_poll(state, scan.data);
|
||
|
mutex_unlock(&state->lock);
|
||
|
if (ret)
|
||
|
goto out;
|
||
|
|
||
|
iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
|
||
|
out:
|
||
|
iio_trigger_notify_done(indio_dev->trig);
|
||
|
return IRQ_HANDLED;
|
||
|
}
|
||
|
|
||
|
static int scd4x_probe(struct i2c_client *client, const struct i2c_device_id *id)
|
||
|
{
|
||
|
static const unsigned long scd4x_scan_masks[] = { 0x07, 0x00 };
|
||
|
struct device *dev = &client->dev;
|
||
|
struct iio_dev *indio_dev;
|
||
|
struct scd4x_state *state;
|
||
|
int ret;
|
||
|
|
||
|
indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
|
||
|
if (!indio_dev)
|
||
|
return -ENOMEM;
|
||
|
|
||
|
state = iio_priv(indio_dev);
|
||
|
mutex_init(&state->lock);
|
||
|
state->client = client;
|
||
|
crc8_populate_msb(scd4x_crc8_table, SCD4X_CRC8_POLYNOMIAL);
|
||
|
|
||
|
indio_dev->info = &scd4x_info;
|
||
|
indio_dev->name = client->name;
|
||
|
indio_dev->channels = scd4x_channels;
|
||
|
indio_dev->num_channels = ARRAY_SIZE(scd4x_channels);
|
||
|
indio_dev->modes = INDIO_DIRECT_MODE;
|
||
|
indio_dev->available_scan_masks = scd4x_scan_masks;
|
||
|
|
||
|
state->vdd = devm_regulator_get(dev, "vdd");
|
||
|
if (IS_ERR(state->vdd))
|
||
|
return dev_err_probe(dev, PTR_ERR(state->vdd), "failed to get regulator\n");
|
||
|
|
||
|
ret = regulator_enable(state->vdd);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
ret = devm_add_action_or_reset(dev, scd4x_disable_regulator, state);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
ret = scd4x_send_command(state, CMD_STOP_MEAS);
|
||
|
if (ret) {
|
||
|
dev_err(dev, "failed to stop measurement: %d\n", ret);
|
||
|
return ret;
|
||
|
}
|
||
|
|
||
|
/* execution time */
|
||
|
msleep_interruptible(500);
|
||
|
|
||
|
ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd4x_trigger_handler, NULL);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
ret = scd4x_send_command(state, CMD_START_MEAS);
|
||
|
if (ret) {
|
||
|
dev_err(dev, "failed to start measurement: %d\n", ret);
|
||
|
return ret;
|
||
|
}
|
||
|
|
||
|
ret = devm_add_action_or_reset(dev, scd4x_stop_meas, state);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
|
||
|
return devm_iio_device_register(dev, indio_dev);
|
||
|
}
|
||
|
|
||
|
static const struct of_device_id scd4x_dt_ids[] = {
|
||
|
{ .compatible = "sensirion,scd40" },
|
||
|
{ .compatible = "sensirion,scd41" },
|
||
|
{ }
|
||
|
};
|
||
|
MODULE_DEVICE_TABLE(of, scd4x_dt_ids);
|
||
|
|
||
|
static struct i2c_driver scd4x_i2c_driver = {
|
||
|
.driver = {
|
||
|
.name = KBUILD_MODNAME,
|
||
|
.of_match_table = scd4x_dt_ids,
|
||
|
.pm = pm_sleep_ptr(&scd4x_pm_ops),
|
||
|
},
|
||
|
.probe = scd4x_probe,
|
||
|
};
|
||
|
module_i2c_driver(scd4x_i2c_driver);
|
||
|
|
||
|
MODULE_AUTHOR("Roan van Dijk <roan@protonic.nl>");
|
||
|
MODULE_DESCRIPTION("Sensirion SCD4X carbon dioxide sensor core driver");
|
||
|
MODULE_LICENSE("GPL v2");
|