iio: chemical: scd30: add serial interface driver (d4553d6e) · Commits · github.com / kvm-riscv / linux

MAINTAINERS

+1 −0

Original line number	Diff line number	Diff line
		@@ -15357,6 +15357,7 @@ S: Maintained
		F: drivers/iio/chemical/scd30.h
		F: drivers/iio/chemical/scd30_core.c
		F: drivers/iio/chemical/scd30_i2c.c
		F: drivers/iio/chemical/scd30_serial.c

		SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER
		M: Tomasz Duszynski <tduszyns@gmail.com>

drivers/iio/chemical/Kconfig

+11 −0

Original line number	Diff line number	Diff line
		@@ -107,6 +107,17 @@ config SCD30_I2C
		To compile this driver as a module, choose M here: the module will
		be called scd30_i2c.

		config SCD30_SERIAL
		tristate "SCD30 carbon dioxide sensor serial driver"
		depends on SCD30_CORE && SERIAL_DEV_BUS
		select CRC16
		help
		Say Y here to build support for the Sensirion SCD30 serial interface
		driver.

		To compile this driver as a module, choose M here: the module will
		be called scd30_serial.

		config SENSIRION_SGP30
		tristate "Sensirion SGPxx gas sensors"
		depends on I2C

drivers/iio/chemical/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,7 @@ obj-$(CONFIG_IAQCORE) += ams-iaq-core.o
		obj-$(CONFIG_PMS7003) += pms7003.o
		obj-$(CONFIG_SCD30_CORE) += scd30_core.o
		obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o
		obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
		obj-$(CONFIG_SENSIRION_SGP30) += sgp30.o
		obj-$(CONFIG_SPS30) += sps30.o
		obj-$(CONFIG_VZ89X) += vz89x.o

drivers/iio/chemical/scd30_serial.c

0 → 100644

+263 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/*
		* Sensirion SCD30 carbon dioxide sensor serial driver
		*
		* Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
		*/
		#include <linux/crc16.h>
		#include <linux/device.h>
		#include <linux/errno.h>
		#include <linux/iio/iio.h>
		#include <linux/jiffies.h>
		#include <linux/mod_devicetable.h>
		#include <linux/module.h>
		#include <linux/property.h>
		#include <linux/serdev.h>
		#include <linux/string.h>
		#include <linux/types.h>
		#include <asm/unaligned.h>

		#include "scd30.h"

		#define SCD30_SERDEV_ADDR 0x61
		#define SCD30_SERDEV_WRITE 0x06
		#define SCD30_SERDEV_READ 0x03
		#define SCD30_SERDEV_MAX_BUF_SIZE 17
		#define SCD30_SERDEV_RX_HEADER_SIZE 3
		#define SCD30_SERDEV_CRC_SIZE 2
		#define SCD30_SERDEV_TIMEOUT msecs_to_jiffies(200)

		struct scd30_serdev_priv {
		struct completion meas_ready;
		char *buf;
		int num_expected;
		int num;
		};

		static u16 scd30_serdev_cmd_lookup_tbl[] = {
		[CMD_START_MEAS] = 0x0036,
		[CMD_STOP_MEAS] = 0x0037,
		[CMD_MEAS_INTERVAL] = 0x0025,
		[CMD_MEAS_READY] = 0x0027,
		[CMD_READ_MEAS] = 0x0028,
		[CMD_ASC] = 0x003a,
		[CMD_FRC] = 0x0039,
		[CMD_TEMP_OFFSET] = 0x003b,
		[CMD_FW_VERSION] = 0x0020,
		[CMD_RESET] = 0x0034,
		};

		static u16 scd30_serdev_calc_crc(const char *buf, int size)
		{
		return crc16(0xffff, buf, size);
		}

		static int scd30_serdev_xfer(struct scd30_state state, char txbuf, int txsize,
		char *rxbuf, int rxsize)
		{
		struct serdev_device *serdev = to_serdev_device(state->dev);
		struct scd30_serdev_priv *priv = state->priv;
		int ret;

		priv->buf = rxbuf;
		priv->num_expected = rxsize;
		priv->num = 0;

		ret = serdev_device_write(serdev, txbuf, txsize, SCD30_SERDEV_TIMEOUT);
		if (ret < 0)
		return ret;
		if (ret != txsize)
		return -EIO;

		ret = wait_for_completion_interruptible_timeout(&priv->meas_ready, SCD30_SERDEV_TIMEOUT);
		if (ret < 0)
		return ret;
		if (!ret)
		return -ETIMEDOUT;

		return 0;
		}

		static int scd30_serdev_command(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
		void *response, int size)
		{
		/*
		* Communication over serial line is based on modbus protocol (or rather
		* its variation called modbus over serial to be precise). Upon
		* receiving a request device should reply with response.
		*
		* Frame below represents a request message. Each field takes
		* exactly one byte.
		*
		* +------+------+-----+-----+-------+-------+-----+-----+
		* \| dev \| op \| reg \| reg \| byte1 \| byte0 \| crc \| crc \|
		* \| addr \| code \| msb \| lsb \| \| \| lsb \| msb \|
		* +------+------+-----+-----+-------+-------+-----+-----+
		*
		* The message device replies with depends on the 'op code' field from
		* the request. In case it was set to SCD30_SERDEV_WRITE sensor should
		* reply with unchanged request. Otherwise 'op code' was set to
		* SCD30_SERDEV_READ and response looks like the one below. As with
		* request, each field takes one byte.
		*
		* +------+------+--------+-------+-----+-------+-----+-----+
		* \| dev \| op \| num of \| byte0 \| ... \| byteN \| crc \| crc \|
		* \| addr \| code \| bytes \| \| \| \| lsb \| msb \|
		* +------+------+--------+-------+-----+-------+-----+-----+
		*/
		char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
		rxbuf[SCD30_SERDEV_MAX_BUF_SIZE];
		int ret, rxsize, txsize = 2;
		char *rsp = response;
		u16 crc;

		put_unaligned_be16(scd30_serdev_cmd_lookup_tbl[cmd], txbuf + txsize);
		txsize += 2;

		if (rsp) {
		txbuf[1] = SCD30_SERDEV_READ;
		if (cmd == CMD_READ_MEAS)
		/* number of u16 words to read */
		put_unaligned_be16(size / 2, txbuf + txsize);
		else
		put_unaligned_be16(0x0001, txbuf + txsize);
		txsize += 2;
		crc = scd30_serdev_calc_crc(txbuf, txsize);
		put_unaligned_le16(crc, txbuf + txsize);
		txsize += 2;
		rxsize = SCD30_SERDEV_RX_HEADER_SIZE + size + SCD30_SERDEV_CRC_SIZE;
		} else {
		if ((cmd == CMD_STOP_MEAS) \|\| (cmd == CMD_RESET))
		arg = 0x0001;

		txbuf[1] = SCD30_SERDEV_WRITE;
		put_unaligned_be16(arg, txbuf + txsize);
		txsize += 2;
		crc = scd30_serdev_calc_crc(txbuf, txsize);
		put_unaligned_le16(crc, txbuf + txsize);
		txsize += 2;
		rxsize = txsize;
		}

		ret = scd30_serdev_xfer(state, txbuf, txsize, rxbuf, rxsize);
		if (ret)
		return ret;

		switch (txbuf[1]) {
		case SCD30_SERDEV_WRITE:
		if (memcmp(txbuf, rxbuf, txsize)) {
		dev_err(state->dev, "wrong message received\n");
		return -EIO;
		}
		break;
		case SCD30_SERDEV_READ:
		if (rxbuf[2] != (rxsize - SCD30_SERDEV_RX_HEADER_SIZE - SCD30_SERDEV_CRC_SIZE)) {
		dev_err(state->dev, "received data size does not match header\n");
		return -EIO;
		}

		rxsize -= SCD30_SERDEV_CRC_SIZE;
		crc = get_unaligned_le16(rxbuf + rxsize);
		if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
		dev_err(state->dev, "data integrity check failed\n");
		return -EIO;
		}

		rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
		memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
		break;
		default:
		dev_err(state->dev, "received unknown op code\n");
		return -EIO;
		}

		return 0;
		}

		static int scd30_serdev_receive_buf(struct serdev_device *serdev,
		const unsigned char *buf, size_t size)
		{
		struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev);
		struct scd30_serdev_priv *priv;
		struct scd30_state *state;
		int num;

		if (!indio_dev)
		return 0;

		state = iio_priv(indio_dev);
		priv = state->priv;

		/* just in case sensor puts some unexpected bytes on the bus */
		if (!priv->buf)
		return 0;

		if (priv->num + size >= priv->num_expected)
		num = priv->num_expected - priv->num;
		else
		num = size;

		memcpy(priv->buf + priv->num, buf, num);
		priv->num += num;

		if (priv->num == priv->num_expected) {
		priv->buf = NULL;
		complete(&priv->meas_ready);
		}

		return num;
		}

		static const struct serdev_device_ops scd30_serdev_ops = {
		.receive_buf = scd30_serdev_receive_buf,
		.write_wakeup = serdev_device_write_wakeup,
		};

		static int scd30_serdev_probe(struct serdev_device *serdev)
		{
		struct device *dev = &serdev->dev;
		struct scd30_serdev_priv *priv;
		int irq, ret;

		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
		if (!priv)
		return -ENOMEM;

		init_completion(&priv->meas_ready);
		serdev_device_set_client_ops(serdev, &scd30_serdev_ops);

		ret = devm_serdev_device_open(dev, serdev);
		if (ret)
		return ret;

		serdev_device_set_baudrate(serdev, 19200);
		serdev_device_set_flow_control(serdev, false);

		ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
		if (ret)
		return ret;

		irq = fwnode_irq_get(dev_fwnode(dev), 0);

		return scd30_probe(dev, irq, KBUILD_MODNAME, priv, scd30_serdev_command);
		}

		static const struct of_device_id scd30_serdev_of_match[] = {
		{ .compatible = "sensirion,scd30" },
		{ }
		};
		MODULE_DEVICE_TABLE(of, scd30_serdev_of_match);

		static struct serdev_device_driver scd30_serdev_driver = {
		.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = scd30_serdev_of_match,
		.pm = &scd30_pm_ops,
		},
		.probe = scd30_serdev_probe,
		};
		module_serdev_device_driver(scd30_serdev_driver);

		MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
		MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor serial driver");
		MODULE_LICENSE("GPL v2");