// 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/acpi.h>
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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 const struct acpi_device_id am2315_acpi_id[] = {
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{"AOS2315", 0},
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{}
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};
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MODULE_DEVICE_TABLE(acpi, am2315_acpi_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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.acpi_match_table = ACPI_PTR(am2315_acpi_id),
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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 <tiberiu.a.breana@intel.com>");
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MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature");
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MODULE_LICENSE("GPL v2");
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