| // 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; |
| /* Ensure timestamp is naturally aligned */ |
| struct { |
| s16 chans[2]; |
| s64 timestamp __aligned(8); |
| } scan; |
| }; |
| |
| 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->scan.chans[0] = sensor_data.hum_data; |
| data->scan.chans[1] = sensor_data.temp_data; |
| } else { |
| i = 0; |
| for_each_set_bit(bit, indio_dev->active_scan_mask, |
| indio_dev->masklength) { |
| data->scan.chans[i] = (bit ? sensor_data.temp_data : |
| sensor_data.hum_data); |
| i++; |
| } |
| } |
| mutex_unlock(&data->lock); |
| |
| iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, |
| 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->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); |
| |
| 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"); |