iio: humidity: Add support for AM2315 (366a3270) · Commits · e / devices / android_kernel_teracube_2e

drivers/iio/humidity/Kconfig

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Original line number	Diff line number	Diff line
		@@ -3,6 +3,16 @@
		#
		menu "Humidity sensors"

		config AM2315
		tristate "Aosong AM2315 relative humidity and temperature sensor"
		depends on I2C
		help
		If you say yes here you get support for the Aosong AM2315
		relative humidity and ambient temperature sensor.

		This driver can also be built as a module. If so, the module will
		be called am2315.

		config DHT11
		tristate "DHT11 (and compatible sensors) driver"
		depends on GPIOLIB \|\| COMPILE_TEST

drivers/iio/humidity/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,7 @@
		# Makefile for IIO humidity sensor drivers
		#

		obj-$(CONFIG_AM2315) += am2315.o
		obj-$(CONFIG_DHT11) += dht11.o
		obj-$(CONFIG_HDC100X) += hdc100x.o
		obj-$(CONFIG_HTU21) += htu21.o

drivers/iio/humidity/am2315.c

0 → 100644

+228 −0

Original line number	Diff line number	Diff line
		/**
		* Aosong AM2315 relative humidity and temperature
		*
		* Copyright (c) 2016, Intel Corporation.
		*
		* This file is subject to the terms and conditions of version 2 of
		* the GNU General Public License. See the file COPYING in the main
		* directory of this archive for more details.
		*
		* 7-bit I2C address: 0x5C.
		*/

		#include <linux/acpi.h>
		#include <linux/delay.h>
		#include <linux/i2c.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/iio/iio.h>
		#include <linux/iio/sysfs.h>

		#define AM2315_REG_HUM_MSB 0x00
		#define AM2315_REG_HUM_LSB 0x01
		#define AM2315_REG_TEMP_MSB 0x02
		#define AM2315_REG_TEMP_LSB 0x03

		#define AM2315_FUNCTION_READ 0x03
		#define AM2315_HUM_OFFSET 2
		#define AM2315_TEMP_OFFSET 4

		#define AM2315_DRIVER_NAME "am2315"

		struct am2315_data {
		struct i2c_client *client;
		struct mutex lock;
		};

		struct am2315_sensor_data {
		s16 hum_data;
		s16 temp_data;
		};

		static const struct iio_chan_spec am2315_channels[] = {
		{
		.type = IIO_HUMIDITYRELATIVE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
		BIT(IIO_CHAN_INFO_SCALE)
		},
		{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
		BIT(IIO_CHAN_INFO_SCALE)
		},
		};

		/* CRC calculation algorithm, as specified in the datasheet (page 13). */
		static u16 am2315_crc(u8 *data, u8 nr_bytes)
		{
		int i;
		u16 crc = 0xffff;

		while (nr_bytes--) {
		crc ^= *data++;
		for (i = 0; i < 8; i++) {
		if (crc & 0x01) {
		crc >>= 1;
		crc ^= 0xA001;
		} else {
		crc >>= 1;
		}
		}
		}

		return crc;
		}

		/* Simple function that sends a few bytes to the device to wake it up. */
		static void am2315_ping(struct i2c_client *client)
		{
		i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB);
		}

		static int am2315_read_data(struct am2315_data *data,
		struct am2315_sensor_data *sensor_data)
		{
		int ret;
		/* tx_buf format: <function code> <start addr> <nr of regs to read> */
		u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 };
		/*
		* rx_buf format:
		* <function code> <number of registers read>
		* <humidity MSB> <humidity LSB> <temp MSB> <temp LSB>
		* <CRC LSB> <CRC MSB>
		*/
		u8 rx_buf[8];
		u16 crc;

		/* First wake up the device. */
		am2315_ping(data->client);

		mutex_lock(&data->lock);
		ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf));
		if (ret < 0) {
		dev_err(&data->client->dev, "failed to send read request\n");
		goto exit_unlock;
		}
		/* Wait 2-3 ms, then read back the data sent by the device. */
		usleep_range(2000, 3000);
		/* Do a bulk data read, then pick out what we need. */
		ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf));
		if (ret < 0) {
		dev_err(&data->client->dev, "failed to read sensor data\n");
		goto exit_unlock;
		}
		mutex_unlock(&data->lock);
		/*
		* Do a CRC check on the data and compare it to the value
		* calculated by the device.
		*/
		crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2);
		if ((crc & 0xff) != rx_buf[6] \|\| (crc >> 8) != rx_buf[7]) {
		dev_err(&data->client->dev, "failed to verify sensor data\n");
		return -EIO;
		}

		sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) \|
		rx_buf[AM2315_HUM_OFFSET + 1];
		sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) \|
		rx_buf[AM2315_TEMP_OFFSET + 1];

		return ret;

		exit_unlock:
		mutex_unlock(&data->lock);
		return ret;
		}

		static int am2315_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val, int val2, long mask)
		{
		int ret;
		struct am2315_sensor_data sensor_data;
		struct am2315_data *data = iio_priv(indio_dev);

		switch (mask) {
		case IIO_CHAN_INFO_RAW:
		ret = am2315_read_data(data, &sensor_data);
		if (ret < 0)
		return ret;
		*val = (chan->type == IIO_HUMIDITYRELATIVE) ?
		sensor_data.hum_data : sensor_data.temp_data;
		return IIO_VAL_INT;
		case IIO_CHAN_INFO_SCALE:
		*val = 100;
		return IIO_VAL_INT;
		}

		return -EINVAL;
		}

		static const struct iio_info am2315_info = {
		.driver_module = THIS_MODULE,
		.read_raw = am2315_read_raw,
		};

		static int am2315_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
		{
		struct iio_dev *indio_dev;
		struct am2315_data *data;

		indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
		if (!indio_dev) {
		dev_err(&client->dev, "iio allocation failed!\n");
		return -ENOMEM;
		}

		data = iio_priv(indio_dev);
		data->client = client;
		i2c_set_clientdata(client, indio_dev);
		mutex_init(&data->lock);

		indio_dev->dev.parent = &client->dev;
		indio_dev->info = &am2315_info;
		indio_dev->name = AM2315_DRIVER_NAME;
		indio_dev->modes = INDIO_DIRECT_MODE;
		indio_dev->channels = am2315_channels;
		indio_dev->num_channels = ARRAY_SIZE(am2315_channels);

		return iio_device_register(indio_dev);
		}

		static int am2315_remove(struct i2c_client *client)
		{
		struct iio_dev *indio_dev = i2c_get_clientdata(client);

		iio_device_unregister(indio_dev);

		return 0;
		}

		static const struct i2c_device_id am2315_i2c_id[] = {
		{"am2315", 0},
		{}
		};

		static const struct acpi_device_id am2315_acpi_id[] = {
		{"AOS2315", 0},
		{}
		};

		MODULE_DEVICE_TABLE(acpi, am2315_acpi_id);

		static struct i2c_driver am2315_driver = {
		.driver = {
		.name = "am2315",
		.acpi_match_table = ACPI_PTR(am2315_acpi_id),
		},
		.probe = am2315_probe,
		.remove = am2315_remove,
		.id_table = am2315_i2c_id,
		};

		module_i2c_driver(am2315_driver);

		MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
		MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature");
		MODULE_LICENSE("GPL v2");