1366a3270STiberiu Breana /** 2366a3270STiberiu Breana * Aosong AM2315 relative humidity and temperature 3366a3270STiberiu Breana * 4366a3270STiberiu Breana * Copyright (c) 2016, Intel Corporation. 5366a3270STiberiu Breana * 6366a3270STiberiu Breana * This file is subject to the terms and conditions of version 2 of 7366a3270STiberiu Breana * the GNU General Public License. See the file COPYING in the main 8366a3270STiberiu Breana * directory of this archive for more details. 9366a3270STiberiu Breana * 10366a3270STiberiu Breana * 7-bit I2C address: 0x5C. 11366a3270STiberiu Breana */ 12366a3270STiberiu Breana 13366a3270STiberiu Breana #include <linux/acpi.h> 14366a3270STiberiu Breana #include <linux/delay.h> 15366a3270STiberiu Breana #include <linux/i2c.h> 16366a3270STiberiu Breana #include <linux/kernel.h> 17366a3270STiberiu Breana #include <linux/module.h> 18366a3270STiberiu Breana #include <linux/iio/iio.h> 19366a3270STiberiu Breana #include <linux/iio/sysfs.h> 20366a3270STiberiu Breana 21366a3270STiberiu Breana #define AM2315_REG_HUM_MSB 0x00 22366a3270STiberiu Breana #define AM2315_REG_HUM_LSB 0x01 23366a3270STiberiu Breana #define AM2315_REG_TEMP_MSB 0x02 24366a3270STiberiu Breana #define AM2315_REG_TEMP_LSB 0x03 25366a3270STiberiu Breana 26366a3270STiberiu Breana #define AM2315_FUNCTION_READ 0x03 27366a3270STiberiu Breana #define AM2315_HUM_OFFSET 2 28366a3270STiberiu Breana #define AM2315_TEMP_OFFSET 4 29366a3270STiberiu Breana 30366a3270STiberiu Breana #define AM2315_DRIVER_NAME "am2315" 31366a3270STiberiu Breana 32366a3270STiberiu Breana struct am2315_data { 33366a3270STiberiu Breana struct i2c_client *client; 34366a3270STiberiu Breana struct mutex lock; 35366a3270STiberiu Breana }; 36366a3270STiberiu Breana 37366a3270STiberiu Breana struct am2315_sensor_data { 38366a3270STiberiu Breana s16 hum_data; 39366a3270STiberiu Breana s16 temp_data; 40366a3270STiberiu Breana }; 41366a3270STiberiu Breana 42366a3270STiberiu Breana static const struct iio_chan_spec am2315_channels[] = { 43366a3270STiberiu Breana { 44366a3270STiberiu Breana .type = IIO_HUMIDITYRELATIVE, 45366a3270STiberiu Breana .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 46366a3270STiberiu Breana BIT(IIO_CHAN_INFO_SCALE) 47366a3270STiberiu Breana }, 48366a3270STiberiu Breana { 49366a3270STiberiu Breana .type = IIO_TEMP, 50366a3270STiberiu Breana .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 51366a3270STiberiu Breana BIT(IIO_CHAN_INFO_SCALE) 52366a3270STiberiu Breana }, 53366a3270STiberiu Breana }; 54366a3270STiberiu Breana 55366a3270STiberiu Breana /* CRC calculation algorithm, as specified in the datasheet (page 13). */ 56366a3270STiberiu Breana static u16 am2315_crc(u8 *data, u8 nr_bytes) 57366a3270STiberiu Breana { 58366a3270STiberiu Breana int i; 59366a3270STiberiu Breana u16 crc = 0xffff; 60366a3270STiberiu Breana 61366a3270STiberiu Breana while (nr_bytes--) { 62366a3270STiberiu Breana crc ^= *data++; 63366a3270STiberiu Breana for (i = 0; i < 8; i++) { 64366a3270STiberiu Breana if (crc & 0x01) { 65366a3270STiberiu Breana crc >>= 1; 66366a3270STiberiu Breana crc ^= 0xA001; 67366a3270STiberiu Breana } else { 68366a3270STiberiu Breana crc >>= 1; 69366a3270STiberiu Breana } 70366a3270STiberiu Breana } 71366a3270STiberiu Breana } 72366a3270STiberiu Breana 73366a3270STiberiu Breana return crc; 74366a3270STiberiu Breana } 75366a3270STiberiu Breana 76366a3270STiberiu Breana /* Simple function that sends a few bytes to the device to wake it up. */ 77366a3270STiberiu Breana static void am2315_ping(struct i2c_client *client) 78366a3270STiberiu Breana { 79366a3270STiberiu Breana i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB); 80366a3270STiberiu Breana } 81366a3270STiberiu Breana 82366a3270STiberiu Breana static int am2315_read_data(struct am2315_data *data, 83366a3270STiberiu Breana struct am2315_sensor_data *sensor_data) 84366a3270STiberiu Breana { 85366a3270STiberiu Breana int ret; 86366a3270STiberiu Breana /* tx_buf format: <function code> <start addr> <nr of regs to read> */ 87366a3270STiberiu Breana u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 }; 88366a3270STiberiu Breana /* 89366a3270STiberiu Breana * rx_buf format: 90366a3270STiberiu Breana * <function code> <number of registers read> 91366a3270STiberiu Breana * <humidity MSB> <humidity LSB> <temp MSB> <temp LSB> 92366a3270STiberiu Breana * <CRC LSB> <CRC MSB> 93366a3270STiberiu Breana */ 94366a3270STiberiu Breana u8 rx_buf[8]; 95366a3270STiberiu Breana u16 crc; 96366a3270STiberiu Breana 97366a3270STiberiu Breana /* First wake up the device. */ 98366a3270STiberiu Breana am2315_ping(data->client); 99366a3270STiberiu Breana 100366a3270STiberiu Breana mutex_lock(&data->lock); 101366a3270STiberiu Breana ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf)); 102366a3270STiberiu Breana if (ret < 0) { 103366a3270STiberiu Breana dev_err(&data->client->dev, "failed to send read request\n"); 104366a3270STiberiu Breana goto exit_unlock; 105366a3270STiberiu Breana } 106366a3270STiberiu Breana /* Wait 2-3 ms, then read back the data sent by the device. */ 107366a3270STiberiu Breana usleep_range(2000, 3000); 108366a3270STiberiu Breana /* Do a bulk data read, then pick out what we need. */ 109366a3270STiberiu Breana ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf)); 110366a3270STiberiu Breana if (ret < 0) { 111366a3270STiberiu Breana dev_err(&data->client->dev, "failed to read sensor data\n"); 112366a3270STiberiu Breana goto exit_unlock; 113366a3270STiberiu Breana } 114366a3270STiberiu Breana mutex_unlock(&data->lock); 115366a3270STiberiu Breana /* 116366a3270STiberiu Breana * Do a CRC check on the data and compare it to the value 117366a3270STiberiu Breana * calculated by the device. 118366a3270STiberiu Breana */ 119366a3270STiberiu Breana crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2); 120366a3270STiberiu Breana if ((crc & 0xff) != rx_buf[6] || (crc >> 8) != rx_buf[7]) { 121366a3270STiberiu Breana dev_err(&data->client->dev, "failed to verify sensor data\n"); 122366a3270STiberiu Breana return -EIO; 123366a3270STiberiu Breana } 124366a3270STiberiu Breana 125366a3270STiberiu Breana sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) | 126366a3270STiberiu Breana rx_buf[AM2315_HUM_OFFSET + 1]; 127366a3270STiberiu Breana sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) | 128366a3270STiberiu Breana rx_buf[AM2315_TEMP_OFFSET + 1]; 129366a3270STiberiu Breana 130366a3270STiberiu Breana return ret; 131366a3270STiberiu Breana 132366a3270STiberiu Breana exit_unlock: 133366a3270STiberiu Breana mutex_unlock(&data->lock); 134366a3270STiberiu Breana return ret; 135366a3270STiberiu Breana } 136366a3270STiberiu Breana 137366a3270STiberiu Breana static int am2315_read_raw(struct iio_dev *indio_dev, 138366a3270STiberiu Breana struct iio_chan_spec const *chan, 139366a3270STiberiu Breana int *val, int *val2, long mask) 140366a3270STiberiu Breana { 141366a3270STiberiu Breana int ret; 142366a3270STiberiu Breana struct am2315_sensor_data sensor_data; 143366a3270STiberiu Breana struct am2315_data *data = iio_priv(indio_dev); 144366a3270STiberiu Breana 145366a3270STiberiu Breana switch (mask) { 146366a3270STiberiu Breana case IIO_CHAN_INFO_RAW: 147366a3270STiberiu Breana ret = am2315_read_data(data, &sensor_data); 148366a3270STiberiu Breana if (ret < 0) 149366a3270STiberiu Breana return ret; 150366a3270STiberiu Breana *val = (chan->type == IIO_HUMIDITYRELATIVE) ? 151366a3270STiberiu Breana sensor_data.hum_data : sensor_data.temp_data; 152366a3270STiberiu Breana return IIO_VAL_INT; 153366a3270STiberiu Breana case IIO_CHAN_INFO_SCALE: 154366a3270STiberiu Breana *val = 100; 155366a3270STiberiu Breana return IIO_VAL_INT; 156366a3270STiberiu Breana } 157366a3270STiberiu Breana 158366a3270STiberiu Breana return -EINVAL; 159366a3270STiberiu Breana } 160366a3270STiberiu Breana 161366a3270STiberiu Breana static const struct iio_info am2315_info = { 162366a3270STiberiu Breana .driver_module = THIS_MODULE, 163366a3270STiberiu Breana .read_raw = am2315_read_raw, 164366a3270STiberiu Breana }; 165366a3270STiberiu Breana 166366a3270STiberiu Breana static int am2315_probe(struct i2c_client *client, 167366a3270STiberiu Breana const struct i2c_device_id *id) 168366a3270STiberiu Breana { 169366a3270STiberiu Breana struct iio_dev *indio_dev; 170366a3270STiberiu Breana struct am2315_data *data; 171366a3270STiberiu Breana 172366a3270STiberiu Breana indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 173366a3270STiberiu Breana if (!indio_dev) { 174366a3270STiberiu Breana dev_err(&client->dev, "iio allocation failed!\n"); 175366a3270STiberiu Breana return -ENOMEM; 176366a3270STiberiu Breana } 177366a3270STiberiu Breana 178366a3270STiberiu Breana data = iio_priv(indio_dev); 179366a3270STiberiu Breana data->client = client; 180366a3270STiberiu Breana i2c_set_clientdata(client, indio_dev); 181366a3270STiberiu Breana mutex_init(&data->lock); 182366a3270STiberiu Breana 183366a3270STiberiu Breana indio_dev->dev.parent = &client->dev; 184366a3270STiberiu Breana indio_dev->info = &am2315_info; 185366a3270STiberiu Breana indio_dev->name = AM2315_DRIVER_NAME; 186366a3270STiberiu Breana indio_dev->modes = INDIO_DIRECT_MODE; 187366a3270STiberiu Breana indio_dev->channels = am2315_channels; 188366a3270STiberiu Breana indio_dev->num_channels = ARRAY_SIZE(am2315_channels); 189366a3270STiberiu Breana 190366a3270STiberiu Breana return iio_device_register(indio_dev); 191366a3270STiberiu Breana } 192366a3270STiberiu Breana 193366a3270STiberiu Breana static int am2315_remove(struct i2c_client *client) 194366a3270STiberiu Breana { 195366a3270STiberiu Breana struct iio_dev *indio_dev = i2c_get_clientdata(client); 196366a3270STiberiu Breana 197366a3270STiberiu Breana iio_device_unregister(indio_dev); 198366a3270STiberiu Breana 199366a3270STiberiu Breana return 0; 200366a3270STiberiu Breana } 201366a3270STiberiu Breana 202366a3270STiberiu Breana static const struct i2c_device_id am2315_i2c_id[] = { 203366a3270STiberiu Breana {"am2315", 0}, 204366a3270STiberiu Breana {} 205366a3270STiberiu Breana }; 206366a3270STiberiu Breana 207366a3270STiberiu Breana static const struct acpi_device_id am2315_acpi_id[] = { 208366a3270STiberiu Breana {"AOS2315", 0}, 209366a3270STiberiu Breana {} 210366a3270STiberiu Breana }; 211366a3270STiberiu Breana 212366a3270STiberiu Breana MODULE_DEVICE_TABLE(acpi, am2315_acpi_id); 213366a3270STiberiu Breana 214366a3270STiberiu Breana static struct i2c_driver am2315_driver = { 215366a3270STiberiu Breana .driver = { 216366a3270STiberiu Breana .name = "am2315", 217366a3270STiberiu Breana .acpi_match_table = ACPI_PTR(am2315_acpi_id), 218366a3270STiberiu Breana }, 219366a3270STiberiu Breana .probe = am2315_probe, 220366a3270STiberiu Breana .remove = am2315_remove, 221366a3270STiberiu Breana .id_table = am2315_i2c_id, 222366a3270STiberiu Breana }; 223366a3270STiberiu Breana 224366a3270STiberiu Breana module_i2c_driver(am2315_driver); 225366a3270STiberiu Breana 226366a3270STiberiu Breana MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); 227366a3270STiberiu Breana MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature"); 228366a3270STiberiu Breana MODULE_LICENSE("GPL v2"); 229