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274 lines
6.5 KiB
274 lines
6.5 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Aosong AM2315 relative humidity and temperature |
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* |
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* Copyright (c) 2016, Intel Corporation. |
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* |
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* 7-bit I2C address: 0x5C. |
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*/ |
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#include <linux/delay.h> |
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#include <linux/i2c.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/iio/buffer.h> |
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#include <linux/iio/iio.h> |
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#include <linux/iio/sysfs.h> |
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#include <linux/iio/trigger_consumer.h> |
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#include <linux/iio/triggered_buffer.h> |
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#define AM2315_REG_HUM_MSB 0x00 |
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#define AM2315_REG_HUM_LSB 0x01 |
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#define AM2315_REG_TEMP_MSB 0x02 |
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#define AM2315_REG_TEMP_LSB 0x03 |
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#define AM2315_FUNCTION_READ 0x03 |
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#define AM2315_HUM_OFFSET 2 |
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#define AM2315_TEMP_OFFSET 4 |
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#define AM2315_ALL_CHANNEL_MASK GENMASK(1, 0) |
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#define AM2315_DRIVER_NAME "am2315" |
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struct am2315_data { |
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struct i2c_client *client; |
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struct mutex lock; |
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/* Ensure timestamp is naturally aligned */ |
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struct { |
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s16 chans[2]; |
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s64 timestamp __aligned(8); |
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} scan; |
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}; |
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struct am2315_sensor_data { |
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s16 hum_data; |
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s16 temp_data; |
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}; |
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static const struct iio_chan_spec am2315_channels[] = { |
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{ |
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.type = IIO_HUMIDITYRELATIVE, |
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
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BIT(IIO_CHAN_INFO_SCALE), |
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.scan_index = 0, |
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.scan_type = { |
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.sign = 's', |
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.realbits = 16, |
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.storagebits = 16, |
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.endianness = IIO_CPU, |
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}, |
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}, |
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{ |
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.type = IIO_TEMP, |
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
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BIT(IIO_CHAN_INFO_SCALE), |
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.scan_index = 1, |
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.scan_type = { |
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.sign = 's', |
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.realbits = 16, |
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.storagebits = 16, |
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.endianness = IIO_CPU, |
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}, |
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}, |
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IIO_CHAN_SOFT_TIMESTAMP(2), |
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}; |
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/* CRC calculation algorithm, as specified in the datasheet (page 13). */ |
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static u16 am2315_crc(u8 *data, u8 nr_bytes) |
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{ |
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int i; |
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u16 crc = 0xffff; |
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while (nr_bytes--) { |
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crc ^= *data++; |
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for (i = 0; i < 8; i++) { |
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if (crc & 0x01) { |
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crc >>= 1; |
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crc ^= 0xA001; |
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} else { |
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crc >>= 1; |
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} |
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} |
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} |
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return crc; |
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} |
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/* Simple function that sends a few bytes to the device to wake it up. */ |
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static void am2315_ping(struct i2c_client *client) |
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{ |
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i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB); |
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} |
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static int am2315_read_data(struct am2315_data *data, |
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struct am2315_sensor_data *sensor_data) |
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{ |
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int ret; |
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/* tx_buf format: <function code> <start addr> <nr of regs to read> */ |
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u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 }; |
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/* |
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* rx_buf format: |
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* <function code> <number of registers read> |
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* <humidity MSB> <humidity LSB> <temp MSB> <temp LSB> |
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* <CRC LSB> <CRC MSB> |
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*/ |
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u8 rx_buf[8]; |
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u16 crc; |
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/* First wake up the device. */ |
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am2315_ping(data->client); |
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mutex_lock(&data->lock); |
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ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf)); |
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if (ret < 0) { |
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dev_err(&data->client->dev, "failed to send read request\n"); |
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goto exit_unlock; |
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} |
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/* Wait 2-3 ms, then read back the data sent by the device. */ |
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usleep_range(2000, 3000); |
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/* Do a bulk data read, then pick out what we need. */ |
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ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf)); |
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if (ret < 0) { |
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dev_err(&data->client->dev, "failed to read sensor data\n"); |
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goto exit_unlock; |
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} |
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mutex_unlock(&data->lock); |
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/* |
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* Do a CRC check on the data and compare it to the value |
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* calculated by the device. |
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*/ |
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crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2); |
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if ((crc & 0xff) != rx_buf[6] || (crc >> 8) != rx_buf[7]) { |
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dev_err(&data->client->dev, "failed to verify sensor data\n"); |
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return -EIO; |
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} |
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sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) | |
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rx_buf[AM2315_HUM_OFFSET + 1]; |
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sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) | |
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rx_buf[AM2315_TEMP_OFFSET + 1]; |
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return ret; |
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exit_unlock: |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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static irqreturn_t am2315_trigger_handler(int irq, void *p) |
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{ |
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int i; |
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int ret; |
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int bit; |
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struct iio_poll_func *pf = p; |
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struct iio_dev *indio_dev = pf->indio_dev; |
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struct am2315_data *data = iio_priv(indio_dev); |
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struct am2315_sensor_data sensor_data; |
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ret = am2315_read_data(data, &sensor_data); |
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if (ret < 0) |
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goto err; |
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mutex_lock(&data->lock); |
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if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) { |
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data->scan.chans[0] = sensor_data.hum_data; |
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data->scan.chans[1] = sensor_data.temp_data; |
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} else { |
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i = 0; |
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for_each_set_bit(bit, indio_dev->active_scan_mask, |
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indio_dev->masklength) { |
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data->scan.chans[i] = (bit ? sensor_data.temp_data : |
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sensor_data.hum_data); |
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i++; |
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} |
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} |
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mutex_unlock(&data->lock); |
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iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, |
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pf->timestamp); |
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err: |
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iio_trigger_notify_done(indio_dev->trig); |
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return IRQ_HANDLED; |
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} |
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static int am2315_read_raw(struct iio_dev *indio_dev, |
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struct iio_chan_spec const *chan, |
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int *val, int *val2, long mask) |
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{ |
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int ret; |
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struct am2315_sensor_data sensor_data; |
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struct am2315_data *data = iio_priv(indio_dev); |
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switch (mask) { |
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case IIO_CHAN_INFO_RAW: |
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ret = am2315_read_data(data, &sensor_data); |
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if (ret < 0) |
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return ret; |
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*val = (chan->type == IIO_HUMIDITYRELATIVE) ? |
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sensor_data.hum_data : sensor_data.temp_data; |
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return IIO_VAL_INT; |
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case IIO_CHAN_INFO_SCALE: |
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*val = 100; |
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return IIO_VAL_INT; |
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} |
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return -EINVAL; |
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} |
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static const struct iio_info am2315_info = { |
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.read_raw = am2315_read_raw, |
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}; |
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static int am2315_probe(struct i2c_client *client, |
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const struct i2c_device_id *id) |
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{ |
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int ret; |
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struct iio_dev *indio_dev; |
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struct am2315_data *data; |
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indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); |
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if (!indio_dev) { |
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dev_err(&client->dev, "iio allocation failed!\n"); |
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return -ENOMEM; |
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} |
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data = iio_priv(indio_dev); |
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data->client = client; |
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i2c_set_clientdata(client, indio_dev); |
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mutex_init(&data->lock); |
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indio_dev->info = &am2315_info; |
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indio_dev->name = AM2315_DRIVER_NAME; |
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indio_dev->modes = INDIO_DIRECT_MODE; |
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indio_dev->channels = am2315_channels; |
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indio_dev->num_channels = ARRAY_SIZE(am2315_channels); |
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ret = devm_iio_triggered_buffer_setup(&client->dev, |
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indio_dev, iio_pollfunc_store_time, |
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am2315_trigger_handler, NULL); |
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if (ret < 0) { |
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dev_err(&client->dev, "iio triggered buffer setup failed\n"); |
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return ret; |
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} |
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return devm_iio_device_register(&client->dev, indio_dev); |
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} |
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static const struct i2c_device_id am2315_i2c_id[] = { |
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{"am2315", 0}, |
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{} |
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}; |
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MODULE_DEVICE_TABLE(i2c, am2315_i2c_id); |
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static struct i2c_driver am2315_driver = { |
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.driver = { |
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.name = "am2315", |
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}, |
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.probe = am2315_probe, |
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.id_table = am2315_i2c_id, |
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}; |
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module_i2c_driver(am2315_driver); |
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MODULE_AUTHOR("Tiberiu Breana <[email protected]>"); |
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MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature"); |
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MODULE_LICENSE("GPL v2");
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