iio: chemical: scd30: add I2C interface driver (e510190e) · Commits · github.com / kvm-riscv / linux

MAINTAINERS

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		@@ -15356,6 +15356,7 @@ M: Tomasz Duszynski <tomasz.duszynski@octakon.com>
		S: Maintained
		F: drivers/iio/chemical/scd30.h
		F: drivers/iio/chemical/scd30_core.c
		F: drivers/iio/chemical/scd30_i2c.c

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

drivers/iio/chemical/Kconfig

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		@@ -96,6 +96,17 @@ config SCD30_CORE
		To compile this driver as a module, choose M here: the module will
		be called scd30_core.

		config SCD30_I2C
		tristate "SCD30 carbon dioxide sensor I2C driver"
		depends on SCD30_CORE && I2C
		select CRC8
		help
		Say Y here to build support for the Sensirion SCD30 I2C interface
		driver.

		To compile this driver as a module, choose M here: the module will
		be called scd30_i2c.

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

drivers/iio/chemical/Makefile

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		@@ -13,6 +13,7 @@ obj-$(CONFIG_CCS811) += ccs811.o
		obj-$(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_SENSIRION_SGP30) += sgp30.o
		obj-$(CONFIG_SPS30) += sps30.o
		obj-$(CONFIG_VZ89X) += vz89x.o

drivers/iio/chemical/scd30_i2c.c

0 → 100644

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		// SPDX-License-Identifier: GPL-2.0
		/*
		* Sensirion SCD30 carbon dioxide sensor i2c driver
		*
		* Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
		*
		* I2C slave address: 0x61
		*/
		#include <linux/crc8.h>
		#include <linux/device.h>
		#include <linux/errno.h>
		#include <linux/i2c.h>
		#include <linux/mod_devicetable.h>
		#include <linux/module.h>
		#include <linux/types.h>
		#include <asm/unaligned.h>

		#include "scd30.h"

		#define SCD30_I2C_MAX_BUF_SIZE 18
		#define SCD30_I2C_CRC8_POLYNOMIAL 0x31

		static u16 scd30_i2c_cmd_lookup_tbl[] = {
		[CMD_START_MEAS] = 0x0010,
		[CMD_STOP_MEAS] = 0x0104,
		[CMD_MEAS_INTERVAL] = 0x4600,
		[CMD_MEAS_READY] = 0x0202,
		[CMD_READ_MEAS] = 0x0300,
		[CMD_ASC] = 0x5306,
		[CMD_FRC] = 0x5204,
		[CMD_TEMP_OFFSET] = 0x5403,
		[CMD_FW_VERSION] = 0xd100,
		[CMD_RESET] = 0xd304,
		};

		DECLARE_CRC8_TABLE(scd30_i2c_crc8_tbl);

		static int scd30_i2c_xfer(struct scd30_state state, char txbuf, int txsize,
		char *rxbuf, int rxsize)
		{
		struct i2c_client *client = to_i2c_client(state->dev);
		int ret;

		/*
		* repeated start is not supported hence instead of sending two i2c
		* messages in a row we send one by one
		*/
		ret = i2c_master_send(client, txbuf, txsize);
		if (ret < 0)
		return ret;
		if (ret != txsize)
		return -EIO;

		if (!rxbuf)
		return 0;

		ret = i2c_master_recv(client, rxbuf, rxsize);
		if (ret < 0)
		return ret;
		if (ret != rxsize)
		return -EIO;

		return 0;
		}

		static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
		void *response, int size)
		{
		char buf[SCD30_I2C_MAX_BUF_SIZE];
		char *rsp = response;
		int i, ret;
		char crc;

		put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);
		i = 2;

		if (rsp) {
		/* each two bytes are followed by a crc8 */
		size += size / 2;
		} else {
		put_unaligned_be16(arg, buf + i);
		crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
		i += 2;
		buf[i] = crc;
		i += 1;

		/* commands below don't take an argument */
		if ((cmd == CMD_STOP_MEAS) \|\| (cmd == CMD_RESET))
		i -= 3;
		}

		ret = scd30_i2c_xfer(state, buf, i, buf, size);
		if (ret)
		return ret;

		/* validate received data and strip off crc bytes */
		for (i = 0; i < size; i += 3) {
		crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
		if (crc != buf[i + 2]) {
		dev_err(state->dev, "data integrity check failed\n");
		return -EIO;
		}

		*rsp++ = buf[i];
		*rsp++ = buf[i + 1];
		}

		return 0;
		}

		static int scd30_i2c_probe(struct i2c_client *client)
		{
		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
		return -EOPNOTSUPP;

		crc8_populate_msb(scd30_i2c_crc8_tbl, SCD30_I2C_CRC8_POLYNOMIAL);

		return scd30_probe(&client->dev, client->irq, client->name, NULL, scd30_i2c_command);
		}

		static const struct of_device_id scd30_i2c_of_match[] = {
		{ .compatible = "sensirion,scd30" },
		{ }
		};
		MODULE_DEVICE_TABLE(of, scd30_i2c_of_match);

		static struct i2c_driver scd30_i2c_driver = {
		.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = scd30_i2c_of_match,
		.pm = &scd30_pm_ops,
		},
		.probe_new = scd30_i2c_probe,
		};
		module_i2c_driver(scd30_i2c_driver);

		MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
		MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor i2c driver");
		MODULE_LICENSE("GPL v2");