1 // SPDX-License-Identifier: GPL-2.0-only 2 /** 3 * Aosong AM2315 relative humidity and temperature 4 * 5 * Copyright (c) 2016, Intel Corporation. 6 * 7 * 7-bit I2C address: 0x5C. 8 */ 9 10 #include <linux/acpi.h> 11 #include <linux/delay.h> 12 #include <linux/i2c.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/iio/buffer.h> 16 #include <linux/iio/iio.h> 17 #include <linux/iio/sysfs.h> 18 #include <linux/iio/trigger_consumer.h> 19 #include <linux/iio/triggered_buffer.h> 20 21 #define AM2315_REG_HUM_MSB 0x00 22 #define AM2315_REG_HUM_LSB 0x01 23 #define AM2315_REG_TEMP_MSB 0x02 24 #define AM2315_REG_TEMP_LSB 0x03 25 26 #define AM2315_FUNCTION_READ 0x03 27 #define AM2315_HUM_OFFSET 2 28 #define AM2315_TEMP_OFFSET 4 29 #define AM2315_ALL_CHANNEL_MASK GENMASK(1, 0) 30 31 #define AM2315_DRIVER_NAME "am2315" 32 33 struct am2315_data { 34 struct i2c_client *client; 35 struct mutex lock; 36 s16 buffer[8]; /* 2x16-bit channels + 2x16 padding + 4x16 timestamp */ 37 }; 38 39 struct am2315_sensor_data { 40 s16 hum_data; 41 s16 temp_data; 42 }; 43 44 static const struct iio_chan_spec am2315_channels[] = { 45 { 46 .type = IIO_HUMIDITYRELATIVE, 47 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 48 BIT(IIO_CHAN_INFO_SCALE), 49 .scan_index = 0, 50 .scan_type = { 51 .sign = 's', 52 .realbits = 16, 53 .storagebits = 16, 54 .endianness = IIO_CPU, 55 }, 56 }, 57 { 58 .type = IIO_TEMP, 59 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 60 BIT(IIO_CHAN_INFO_SCALE), 61 .scan_index = 1, 62 .scan_type = { 63 .sign = 's', 64 .realbits = 16, 65 .storagebits = 16, 66 .endianness = IIO_CPU, 67 }, 68 }, 69 IIO_CHAN_SOFT_TIMESTAMP(2), 70 }; 71 72 /* CRC calculation algorithm, as specified in the datasheet (page 13). */ 73 static u16 am2315_crc(u8 *data, u8 nr_bytes) 74 { 75 int i; 76 u16 crc = 0xffff; 77 78 while (nr_bytes--) { 79 crc ^= *data++; 80 for (i = 0; i < 8; i++) { 81 if (crc & 0x01) { 82 crc >>= 1; 83 crc ^= 0xA001; 84 } else { 85 crc >>= 1; 86 } 87 } 88 } 89 90 return crc; 91 } 92 93 /* Simple function that sends a few bytes to the device to wake it up. */ 94 static void am2315_ping(struct i2c_client *client) 95 { 96 i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB); 97 } 98 99 static int am2315_read_data(struct am2315_data *data, 100 struct am2315_sensor_data *sensor_data) 101 { 102 int ret; 103 /* tx_buf format: <function code> <start addr> <nr of regs to read> */ 104 u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 }; 105 /* 106 * rx_buf format: 107 * <function code> <number of registers read> 108 * <humidity MSB> <humidity LSB> <temp MSB> <temp LSB> 109 * <CRC LSB> <CRC MSB> 110 */ 111 u8 rx_buf[8]; 112 u16 crc; 113 114 /* First wake up the device. */ 115 am2315_ping(data->client); 116 117 mutex_lock(&data->lock); 118 ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf)); 119 if (ret < 0) { 120 dev_err(&data->client->dev, "failed to send read request\n"); 121 goto exit_unlock; 122 } 123 /* Wait 2-3 ms, then read back the data sent by the device. */ 124 usleep_range(2000, 3000); 125 /* Do a bulk data read, then pick out what we need. */ 126 ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf)); 127 if (ret < 0) { 128 dev_err(&data->client->dev, "failed to read sensor data\n"); 129 goto exit_unlock; 130 } 131 mutex_unlock(&data->lock); 132 /* 133 * Do a CRC check on the data and compare it to the value 134 * calculated by the device. 135 */ 136 crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2); 137 if ((crc & 0xff) != rx_buf[6] || (crc >> 8) != rx_buf[7]) { 138 dev_err(&data->client->dev, "failed to verify sensor data\n"); 139 return -EIO; 140 } 141 142 sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) | 143 rx_buf[AM2315_HUM_OFFSET + 1]; 144 sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) | 145 rx_buf[AM2315_TEMP_OFFSET + 1]; 146 147 return ret; 148 149 exit_unlock: 150 mutex_unlock(&data->lock); 151 return ret; 152 } 153 154 static irqreturn_t am2315_trigger_handler(int irq, void *p) 155 { 156 int i; 157 int ret; 158 int bit; 159 struct iio_poll_func *pf = p; 160 struct iio_dev *indio_dev = pf->indio_dev; 161 struct am2315_data *data = iio_priv(indio_dev); 162 struct am2315_sensor_data sensor_data; 163 164 ret = am2315_read_data(data, &sensor_data); 165 if (ret < 0) 166 goto err; 167 168 mutex_lock(&data->lock); 169 if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) { 170 data->buffer[0] = sensor_data.hum_data; 171 data->buffer[1] = sensor_data.temp_data; 172 } else { 173 i = 0; 174 for_each_set_bit(bit, indio_dev->active_scan_mask, 175 indio_dev->masklength) { 176 data->buffer[i] = (bit ? sensor_data.temp_data : 177 sensor_data.hum_data); 178 i++; 179 } 180 } 181 mutex_unlock(&data->lock); 182 183 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, 184 pf->timestamp); 185 err: 186 iio_trigger_notify_done(indio_dev->trig); 187 return IRQ_HANDLED; 188 } 189 190 static int am2315_read_raw(struct iio_dev *indio_dev, 191 struct iio_chan_spec const *chan, 192 int *val, int *val2, long mask) 193 { 194 int ret; 195 struct am2315_sensor_data sensor_data; 196 struct am2315_data *data = iio_priv(indio_dev); 197 198 switch (mask) { 199 case IIO_CHAN_INFO_RAW: 200 ret = am2315_read_data(data, &sensor_data); 201 if (ret < 0) 202 return ret; 203 *val = (chan->type == IIO_HUMIDITYRELATIVE) ? 204 sensor_data.hum_data : sensor_data.temp_data; 205 return IIO_VAL_INT; 206 case IIO_CHAN_INFO_SCALE: 207 *val = 100; 208 return IIO_VAL_INT; 209 } 210 211 return -EINVAL; 212 } 213 214 static const struct iio_info am2315_info = { 215 .read_raw = am2315_read_raw, 216 }; 217 218 static int am2315_probe(struct i2c_client *client, 219 const struct i2c_device_id *id) 220 { 221 int ret; 222 struct iio_dev *indio_dev; 223 struct am2315_data *data; 224 225 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 226 if (!indio_dev) { 227 dev_err(&client->dev, "iio allocation failed!\n"); 228 return -ENOMEM; 229 } 230 231 data = iio_priv(indio_dev); 232 data->client = client; 233 i2c_set_clientdata(client, indio_dev); 234 mutex_init(&data->lock); 235 236 indio_dev->info = &am2315_info; 237 indio_dev->name = AM2315_DRIVER_NAME; 238 indio_dev->modes = INDIO_DIRECT_MODE; 239 indio_dev->channels = am2315_channels; 240 indio_dev->num_channels = ARRAY_SIZE(am2315_channels); 241 242 ret = devm_iio_triggered_buffer_setup(&client->dev, 243 indio_dev, iio_pollfunc_store_time, 244 am2315_trigger_handler, NULL); 245 if (ret < 0) { 246 dev_err(&client->dev, "iio triggered buffer setup failed\n"); 247 return ret; 248 } 249 250 return devm_iio_device_register(&client->dev, indio_dev); 251 } 252 253 static const struct i2c_device_id am2315_i2c_id[] = { 254 {"am2315", 0}, 255 {} 256 }; 257 MODULE_DEVICE_TABLE(i2c, am2315_i2c_id); 258 259 static const struct acpi_device_id am2315_acpi_id[] = { 260 {"AOS2315", 0}, 261 {} 262 }; 263 264 MODULE_DEVICE_TABLE(acpi, am2315_acpi_id); 265 266 static struct i2c_driver am2315_driver = { 267 .driver = { 268 .name = "am2315", 269 .acpi_match_table = ACPI_PTR(am2315_acpi_id), 270 }, 271 .probe = am2315_probe, 272 .id_table = am2315_i2c_id, 273 }; 274 275 module_i2c_driver(am2315_driver); 276 277 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); 278 MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature"); 279 MODULE_LICENSE("GPL v2"); 280