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([61.108.38.194]) by smtp.googlemail.com with ESMTPSA id 41be03b00d2f7-b02a2d3abffsm114028a12.48.2025.04.08.19.44.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Apr 2025 19:45:01 -0700 (PDT) From: Gyeyoung Baek To: jic23@kernel.org Cc: Gyeyoung Baek , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org Subject: [PATCH v3 3/4] iio: chemical: add support for winsen MHZ19B CO2 sensor Date: Wed, 9 Apr 2025 11:43:10 +0900 Message-Id: <20250409024311.19466-5-gye976@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250409024311.19466-1-gye976@gmail.com> References: <20250409024311.19466-1-gye976@gmail.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add support for winsen MHZ19B CO2 sensor. Datasheet: https://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh-z19b-co2-ver1_0.pdf Signed-off-by: Gyeyoung Baek --- drivers/iio/chemical/Kconfig | 10 + drivers/iio/chemical/Makefile | 1 + drivers/iio/chemical/mhz19b.c | 347 ++++++++++++++++++++++++++++++++++ 3 files changed, 358 insertions(+) create mode 100644 drivers/iio/chemical/mhz19b.c diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig index 330fe0af946f..641bf9b35915 100644 --- a/drivers/iio/chemical/Kconfig +++ b/drivers/iio/chemical/Kconfig @@ -237,4 +237,14 @@ config VZ89X Sensortech MiCS VZ89X VOC (Volatile Organic Compounds) sensors +config WINSEN_MHZ19B + tristate "Winsen MHZ19B CO2 sensor" + depends on SERIAL_DEV_BUS + help + Say Y here to build Serdev interface support for the Winsen + MHZ19B CO2 sensor. + + To compile this driver as a module, choose M here: the module will + be called mhz19b. + endmenu diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile index 4866db06bdc9..deed437dd396 100644 --- a/drivers/iio/chemical/Makefile +++ b/drivers/iio/chemical/Makefile @@ -27,3 +27,4 @@ obj-$(CONFIG_SPS30) += sps30.o obj-$(CONFIG_SPS30_I2C) += sps30_i2c.o obj-$(CONFIG_SPS30_SERIAL) += sps30_serial.o obj-$(CONFIG_VZ89X) += vz89x.o +obj-$(CONFIG_WINSEN_MHZ19B) += mhz19b.o diff --git a/drivers/iio/chemical/mhz19b.c b/drivers/iio/chemical/mhz19b.c new file mode 100644 index 000000000000..d9a16e022b36 --- /dev/null +++ b/drivers/iio/chemical/mhz19b.c @@ -0,0 +1,347 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * mh-z19b co2 sensor driver + * + * Copyright (c) 2025 Gyeyoung Baek + * + * Datasheet: + * https://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh-z19b-co2-ver1_0.pdf + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct mhz19b_state { + struct serdev_device *serdev; + struct regulator *vin; + + /* + * serdev receive buffer. + * When data is received from the MH-Z19B, + * the 'mhz19b_receive_buf' callback function is called and fills this buffer. + */ + char buf[9]; + int buf_idx; + + /* must wait the 'buf' is filled with 9 bytes.*/ + struct completion buf_ready; +}; + +/* + * commands have following format: + * + * +------+------+-----+------+------+------+------+------+-------+ + * | 0xFF | 0x01 | cmd | arg0 | arg1 | 0x00 | 0x00 | 0x00 | cksum | + * +------+------+-----+------+------+------+------+------+-------+ + */ +#define MHZ19B_CMD_SIZE 9 + +#define MHZ19B_ABC_LOGIC_CMD 0x79 +#define MHZ19B_READ_CO2_CMD 0x86 +#define MHZ19B_SPAN_POINT_CMD 0x88 +#define MHZ19B_ZERO_POINT_CMD 0x87 + +#define MHZ19B_ABC_LOGIC_OFF_CKSUM 0x86 +#define MHZ19B_ABC_LOGIC_ON_CKSUM 0xE6 +#define MHZ19B_READ_CO2_CKSUM 0x79 +#define MHZ19B_ZERO_POINT_CKSUM 0x78 + +/* ABC logic in MHZ19B means auto calibration. */ + +#define MHZ19B_SERDEV_TIMEOUT msecs_to_jiffies(100) + +static uint8_t mhz19b_get_checksum(uint8_t *packet) +{ + uint8_t i, checksum = 0; + + for (i = 1; i < 8; i++) + checksum += packet[i]; + + checksum = 0xff - checksum; + checksum += 1; + + return checksum; +} + +static int mhz19b_serdev_cmd(struct iio_dev *indio_dev, + int cmd, void *arg) +{ + struct mhz19b_state *st = iio_priv(indio_dev); + struct serdev_device *serdev = st->serdev; + struct device *dev = &indio_dev->dev; + int ret; + + /* + * cmd_buf[3,4] : arg0,1 + * cmd_buf[8] : checksum + */ + uint8_t cmd_buf[MHZ19B_CMD_SIZE] = { + 0xFF, 0x01, cmd, + }; + + switch (cmd) { + case MHZ19B_ABC_LOGIC_CMD: { + bool enable = *((bool *)arg); + + if (enable) { + cmd_buf[3] = 0xA0; + cmd_buf[8] = MHZ19B_ABC_LOGIC_ON_CKSUM; + } else { + cmd_buf[3] = 0; + cmd_buf[8] = MHZ19B_ABC_LOGIC_OFF_CKSUM; + } + break; + } case MHZ19B_READ_CO2_CMD: { + cmd_buf[8] = MHZ19B_READ_CO2_CKSUM; + break; + } case MHZ19B_SPAN_POINT_CMD: { + uint16_t ppm = *((uint16_t *)arg); + + put_unaligned_be16(ppm, &cmd_buf[3]); + cmd_buf[MHZ19B_CMD_SIZE - 1] = mhz19b_get_checksum(cmd_buf); + break; + } case MHZ19B_ZERO_POINT_CMD: { + cmd_buf[8] = MHZ19B_ZERO_POINT_CKSUM; + break; + } default: + break; + } + + /* write buf to uart ctrl syncronously */ + ret = serdev_device_write(serdev, cmd_buf, MHZ19B_CMD_SIZE, 0); + if (ret != MHZ19B_CMD_SIZE) { + dev_err(dev, "write err, %d bytes written", ret); + return -EINVAL; + } + + switch (cmd) { + case MHZ19B_READ_CO2_CMD: + ret = wait_for_completion_interruptible_timeout(&st->buf_ready, + MHZ19B_SERDEV_TIMEOUT); + if (ret < 0) + return ret; + if (!ret) + return -ETIMEDOUT; + + ret = mhz19b_get_checksum(st->buf); + if (st->buf[MHZ19B_CMD_SIZE - 1] != mhz19b_get_checksum(st->buf)) { + dev_err(dev, "checksum err"); + return -EINVAL; + } + + ret = get_unaligned_be16(&st->buf[2]); + return ret; + default: + /* no response commands. */ + return 0; + } +} + +static int mhz19b_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + int ret = mhz19b_serdev_cmd(indio_dev, MHZ19B_READ_CO2_CMD, NULL); + + if (ret < 0) + return ret; + + *val = ret; + return IIO_VAL_INT; +} + +/* + * MHZ19B only supports writing configuration values. + * + * echo 0 > calibration_auto_enable : ABC logic off + * echo 1 > calibration_auto_enable : ABC logic on + * + * echo 0 > calibration_forced_value : zero point calibration + * (make sure the sensor had been worked under 400ppm for over 20 minutes.) + * echo [1000 1 5000] > calibration_forced_value : span point calibration + * (make sure the sensor had been worked under a certain level co2 for over 20 minutes.) + */ +static ssize_t calibration_auto_enable_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + bool enable; + int ret = kstrtobool(buf, &enable); + + if (ret) + return ret; + + ret = mhz19b_serdev_cmd(indio_dev, MHZ19B_ABC_LOGIC_CMD, &enable); + if (ret < 0) + return ret; + + return len; +} +static IIO_DEVICE_ATTR_WO(calibration_auto_enable, 0); + +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); + uint16_t ppm; + int cmd, ret; + + ret = kstrtou16(buf, 10, &ppm); + if (ret) + return ret; + + /* at least 1000ppm */ + if (ppm) { + if (ppm < 1000 || ppm > 5000) { + dev_dbg(&indio_dev->dev, + "span point ppm should be 1000~5000"); + return -EINVAL; + } + + cmd = MHZ19B_SPAN_POINT_CMD; + } else { + cmd = MHZ19B_ZERO_POINT_CMD; + } + + ret = mhz19b_serdev_cmd(indio_dev, cmd, &ppm); + if (ret < 0) + return ret; + + return len; +} +static IIO_DEVICE_ATTR_WO(calibration_forced_value, 0); + +static struct attribute *mhz19b_attrs[] = { + &iio_dev_attr_calibration_auto_enable.dev_attr.attr, + &iio_dev_attr_calibration_forced_value.dev_attr.attr, + NULL +}; + +static const struct attribute_group mhz19b_attr_group = { + .attrs = mhz19b_attrs, +}; + +static const struct iio_info mhz19b_info = { + .attrs = &mhz19b_attr_group, + .read_raw = mhz19b_read_raw, +}; + +static const struct iio_chan_spec mhz19b_channels[] = { + { + .type = IIO_CONCENTRATION, + .channel2 = IIO_MOD_CO2, + .modified = 1, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + }, +}; + +static size_t mhz19b_receive_buf(struct serdev_device *serdev, + const u8 *data, size_t len) +{ + struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev); + struct mhz19b_state *st = iio_priv(indio_dev); + + for (int i = 0; i < len; i++) + st->buf[st->buf_idx++] = data[i]; + + if (st->buf_idx == MHZ19B_CMD_SIZE) { + st->buf_idx = 0; + complete(&st->buf_ready); + } + + return len; +} + +static const struct serdev_device_ops mhz19b_ops = { + .receive_buf = mhz19b_receive_buf, + .write_wakeup = serdev_device_write_wakeup, +}; + +static int mhz19b_probe(struct serdev_device *serdev) +{ + int ret; + struct device *dev = &serdev->dev; + struct iio_dev *indio_dev; + struct mhz19b_state *st; + + serdev_device_set_client_ops(serdev, &mhz19b_ops); + + ret = devm_serdev_device_open(dev, serdev); + if (ret) + return ret; + + ret = serdev_device_set_baudrate(serdev, 9600); + if (ret < 0) + return ret; + + serdev_device_set_flow_control(serdev, false); + + ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE); + if (ret < 0) + return ret; + + indio_dev = devm_iio_device_alloc(dev, sizeof(struct mhz19b_state)); + if (!indio_dev) + return ret; + dev_set_drvdata(dev, indio_dev); + + st = iio_priv(indio_dev); + st->serdev = serdev; + + init_completion(&st->buf_ready); + + st->vin = devm_regulator_get(dev, "vin"); + if (IS_ERR(st->vin)) + return PTR_ERR(st->vin); + + ret = regulator_enable(st->vin); + if (ret) + return ret; + + indio_dev->name = "mh-z19b"; + indio_dev->channels = mhz19b_channels; + indio_dev->num_channels = ARRAY_SIZE(mhz19b_channels); + indio_dev->info = &mhz19b_info; + + return devm_iio_device_register(dev, indio_dev); +} + +static void mhz19b_remove(struct serdev_device *serdev) +{ + struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev); + struct mhz19b_state *st = iio_priv(indio_dev); + + regulator_disable(st->vin); +} + +static const struct of_device_id mhz19b_of_match[] = { + { .compatible = "winsen,mhz19b", }, + { } +}; +MODULE_DEVICE_TABLE(of, mhz19b_of_match); + +static struct serdev_device_driver mhz19b_driver = { + .driver = { + .name = "mhz19b", + .of_match_table = mhz19b_of_match, + }, + .probe = mhz19b_probe, + .remove = mhz19b_remove, +}; +module_serdev_device_driver(mhz19b_driver); + +MODULE_AUTHOR("Gyeyoung Baek"); +MODULE_DESCRIPTION("MH-Z19B CO2 sensor driver using serdev interface"); +MODULE_LICENSE("GPL"); -- 2.34.1