Add scd30 driver

Author: jadonk

drivers/iio/chemical/Kconfig

@@ -82,6 +82,39 @@ config PMS7003
 	  To compile this driver as a module, choose M here: the module will
 	  be called pms7003.
 
+config SCD30_CORE
+	tristate "SCD30 carbon dioxide sensor driver"
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say Y here to build support for the Sensirion SCD30 sensor with carbon
+	  dioxide, relative humidity and temperature sensing capabilities.
+
+	  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 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

@@ -12,6 +12,9 @@ obj-$(CONFIG_CCS811)		+= ccs811.o
 obj-$(CONFIG_HM3301)		+= hm3301.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-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o

drivers/iio/chemical/scd30.h

@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SCD30_H
+#define _SCD30_H
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+
+struct scd30_state;
+
+enum scd30_cmd {
+	/* start continuous measurement with pressure compensation */
+	CMD_START_MEAS,
+	/* stop continuous measurement */
+	CMD_STOP_MEAS,
+	/* set/get measurement interval */
+	CMD_MEAS_INTERVAL,
+	/* check whether new measurement is ready */
+	CMD_MEAS_READY,
+	/* get measurement */
+	CMD_READ_MEAS,
+	/* turn on/off automatic self calibration */
+	CMD_ASC,
+	/* set/get forced recalibration value */
+	CMD_FRC,
+	/* set/get temperature offset */
+	CMD_TEMP_OFFSET,
+	/* get firmware version */
+	CMD_FW_VERSION,
+	/* reset sensor */
+	CMD_RESET,
+	/*
+	 * Command for altitude compensation was omitted intentionally because
+	 * the same can be achieved by means of CMD_START_MEAS which takes
+	 * pressure above the sea level as an argument.
+	 */
+};
+
+#define SCD30_MEAS_COUNT 3
+
+typedef int (*scd30_command_t)(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
+			       void *response, int size);
+
+struct scd30_state {
+	/* serialize access to the device */
+	struct mutex lock;
+	struct device *dev;
+	struct regulator *vdd;
+	struct completion meas_ready;
+	/*
+	 * priv pointer is solely for serdev driver private data. We keep it
+	 * here because driver_data inside dev has been already used for iio and
+	 * struct serdev_device doesn't have one.
+	 */
+	void *priv;
+	int irq;
+	/*
+	 * no way to retrieve current ambient pressure compensation value from
+	 * the sensor so keep one around
+	 */
+	u16 pressure_comp;
+	u16 meas_interval;
+	int meas[SCD30_MEAS_COUNT];
+
+	scd30_command_t command;
+};
+
+int scd30_suspend(struct device *dev);
+int scd30_resume(struct device *dev);
+
+static __maybe_unused SIMPLE_DEV_PM_OPS(scd30_pm_ops, scd30_suspend, scd30_resume);
+
+int scd30_probe(struct device *dev, int irq, const char *name, void *priv, scd30_command_t command);
+
+#endif