linux/drivers/iio/humidity/am2315.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Aosong AM2315 relative humidity and temperature
*
* Copyright (c) 2016, Intel Corporation.
*
* 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/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.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_ALL_CHANNEL_MASK GENMASK(1, 0)
#define AM2315_DRIVER_NAME "am2315"
struct am2315_data {
struct i2c_client *client;
struct mutex lock;
s16 buffer[8]; /* 2x16-bit channels + 2x16 padding + 4x16 timestamp */
};
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),
.scan_index = 0,
.scan_type = {
.sign = 's',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_CPU,
},
},
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.scan_index = 1,
.scan_type = {
.sign = 's',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_CPU,
},
},
IIO_CHAN_SOFT_TIMESTAMP(2),
};
/* 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 irqreturn_t am2315_trigger_handler(int irq, void *p)
{
int i;
int ret;
int bit;
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct am2315_data *data = iio_priv(indio_dev);
struct am2315_sensor_data sensor_data;
ret = am2315_read_data(data, &sensor_data);
if (ret < 0)
goto err;
mutex_lock(&data->lock);
if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) {
data->buffer[0] = sensor_data.hum_data;
data->buffer[1] = sensor_data.temp_data;
} else {
i = 0;
for_each_set_bit(bit, indio_dev->active_scan_mask,
indio_dev->masklength) {
data->buffer[i] = (bit ? sensor_data.temp_data :
sensor_data.hum_data);
i++;
}
}
mutex_unlock(&data->lock);
iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
pf->timestamp);
err:
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
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 = {
.read_raw = am2315_read_raw,
};
static int am2315_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int ret;
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->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);
ret = devm_iio_triggered_buffer_setup(&client->dev,
indio_dev, iio_pollfunc_store_time,
am2315_trigger_handler, NULL);
if (ret < 0) {
dev_err(&client->dev, "iio triggered buffer setup failed\n");
return ret;
}
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id am2315_i2c_id[] = {
{"am2315", 0},
{}
};
MODULE_DEVICE_TABLE(i2c, am2315_i2c_id);
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,
.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");