> Add basic support for the Aosong AM2315 relative humidity > and ambient temperature sensor. > Includes support for raw readings and ACPI detection. comments below > Datasheet: > http://www.aosong.com/asp_bin/Products/en/AM2315.pdf > > Signed-off-by: Tiberiu Breana <tiberiu.a.breana@xxxxxxxxx> > --- > drivers/iio/humidity/Kconfig | 10 ++ > drivers/iio/humidity/Makefile | 1 + > drivers/iio/humidity/am2315.c | 212 ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 223 insertions(+) > create mode 100644 drivers/iio/humidity/am2315.c > > diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig > index 866dda1..738a86d 100644 > --- a/drivers/iio/humidity/Kconfig > +++ b/drivers/iio/humidity/Kconfig > @@ -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 > diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile > index c9f089a..4a73442 100644 > --- a/drivers/iio/humidity/Makefile > +++ b/drivers/iio/humidity/Makefile > @@ -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 > diff --git a/drivers/iio/humidity/am2315.c b/drivers/iio/humidity/am2315.c > new file mode 100644 > index 0000000..c374078 > --- /dev/null > +++ b/drivers/iio/humidity/am2315.c > @@ -0,0 +1,212 @@ > +/** > + * 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 0 > +#define AM2315_TEMP_OFFSET 2 > + > +#define AM2315_DRIVER_NAME "am2315" > + > +struct am2315_data { > + struct i2c_client *client; not needed as is, but I suggest to add a mutex below > +}; > + > +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. */ drop inline the comment is not very precise: this SENDS the chip address and the register value, then RECEIVES a BYTE (or maybe not) > +static inline void am2315_ping(struct i2c_client *client) > +{ > + i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB); > +} > + > +static int am2315_read_data(struct i2c_client *client, u8 *rx_buf) > +{ > + 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 }; > + u16 crc; > + you need a mutex around here > + /* First wake up the device. */ > + am2315_ping(client); > + > + ret = i2c_master_send(client, tx_buf, sizeof(tx_buf)); > + if (ret < 0) { > + dev_err(&client->dev, "failed to send read request\n"); > + return ret; > + } > + /* Wait 2-3 ms, then read back the data sent by the device. */ > + usleep_range(2000, 3000); > + > + ret = i2c_master_recv(client, rx_buf, sizeof(rx_buf)); this seems very wrong; sizeof(rx_buf) is the size of a pointer > + if (ret < 0) { > + dev_err(&client->dev, "failed to read sensor data\n"); > + return ret; > + } > + /* > + * 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(&client->dev, "failed to verify sensor data\n"); > + return -EIO; > + } > + > + 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; > + u8 rx_buf[8]; > + u8 offset; > + struct am2315_data *data = iio_priv(indio_dev); > + struct i2c_client *client = data->client; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + offset = (chan->type == IIO_HUMIDITYRELATIVE) ? > + AM2315_HUM_OFFSET : AM2315_TEMP_OFFSET; > + /* Do a bulk data read, then pick out what we need. */ > + ret = am2315_read_data(client, rx_buf); > + if (ret < 0) > + return ret; > + /* > + * rx_buf format: > + * <function code> <number of registers read> > + * <humidity MSB> <humidity LSB> <temp MSB> <temp LSB> > + * <CRC LSB> <CRC MSB> > + */ > + *val = (rx_buf[offset + 2] << 8) | rx_buf[offset + 3]; the + 2 could go into AM2315_HUM_OFFSET and AM2315_TEMP_OFFSET, resp. a packed struct with the fields would be even nicer > + 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); > + > + 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); could use devm_, but probably not due to subsequent patch > +} > + > +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@xxxxxxxxx>"); > +MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature"); > +MODULE_LICENSE("GPL v2"); > -- Peter Meerwald-Stadler +43-664-2444418 (mobile) -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
