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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Aosong AM2315 relative humidity and temperature4 *5 * Copyright (c) 2016, Intel Corporation.6 *7 * 7-bit I2C address: 0x5C.8 */9 10#include <linux/delay.h>11#include <linux/i2c.h>12#include <linux/kernel.h>13#include <linux/module.h>14#include <linux/iio/buffer.h>15#include <linux/iio/iio.h>16#include <linux/iio/sysfs.h>17#include <linux/iio/trigger_consumer.h>18#include <linux/iio/triggered_buffer.h>19 20#define AM2315_REG_HUM_MSB 0x0021#define AM2315_REG_HUM_LSB 0x0122#define AM2315_REG_TEMP_MSB 0x0223#define AM2315_REG_TEMP_LSB 0x0324 25#define AM2315_FUNCTION_READ 0x0326#define AM2315_HUM_OFFSET 227#define AM2315_TEMP_OFFSET 428#define AM2315_ALL_CHANNEL_MASK GENMASK(1, 0)29 30#define AM2315_DRIVER_NAME "am2315"31 32struct am2315_data {33 struct i2c_client *client;34 struct mutex lock;35 /* Ensure timestamp is naturally aligned */36 struct {37 s16 chans[2];38 s64 timestamp __aligned(8);39 } scan;40};41 42struct am2315_sensor_data {43 s16 hum_data;44 s16 temp_data;45};46 47static const struct iio_chan_spec am2315_channels[] = {48 {49 .type = IIO_HUMIDITYRELATIVE,50 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |51 BIT(IIO_CHAN_INFO_SCALE),52 .scan_index = 0,53 .scan_type = {54 .sign = 's',55 .realbits = 16,56 .storagebits = 16,57 .endianness = IIO_CPU,58 },59 },60 {61 .type = IIO_TEMP,62 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |63 BIT(IIO_CHAN_INFO_SCALE),64 .scan_index = 1,65 .scan_type = {66 .sign = 's',67 .realbits = 16,68 .storagebits = 16,69 .endianness = IIO_CPU,70 },71 },72 IIO_CHAN_SOFT_TIMESTAMP(2),73};74 75/* CRC calculation algorithm, as specified in the datasheet (page 13). */76static u16 am2315_crc(u8 *data, u8 nr_bytes)77{78 int i;79 u16 crc = 0xffff;80 81 while (nr_bytes--) {82 crc ^= *data++;83 for (i = 0; i < 8; i++) {84 if (crc & 0x01) {85 crc >>= 1;86 crc ^= 0xA001;87 } else {88 crc >>= 1;89 }90 }91 }92 93 return crc;94}95 96/* Simple function that sends a few bytes to the device to wake it up. */97static void am2315_ping(struct i2c_client *client)98{99 i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB);100}101 102static int am2315_read_data(struct am2315_data *data,103 struct am2315_sensor_data *sensor_data)104{105 int ret;106 /* tx_buf format: <function code> <start addr> <nr of regs to read> */107 u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 };108 /*109 * rx_buf format:110 * <function code> <number of registers read>111 * <humidity MSB> <humidity LSB> <temp MSB> <temp LSB>112 * <CRC LSB> <CRC MSB>113 */114 u8 rx_buf[8];115 u16 crc;116 117 /* First wake up the device. */118 am2315_ping(data->client);119 120 mutex_lock(&data->lock);121 ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf));122 if (ret < 0) {123 dev_err(&data->client->dev, "failed to send read request\n");124 goto exit_unlock;125 }126 /* Wait 2-3 ms, then read back the data sent by the device. */127 usleep_range(2000, 3000);128 /* Do a bulk data read, then pick out what we need. */129 ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf));130 if (ret < 0) {131 dev_err(&data->client->dev, "failed to read sensor data\n");132 goto exit_unlock;133 }134 mutex_unlock(&data->lock);135 /*136 * Do a CRC check on the data and compare it to the value137 * calculated by the device.138 */139 crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2);140 if ((crc & 0xff) != rx_buf[6] || (crc >> 8) != rx_buf[7]) {141 dev_err(&data->client->dev, "failed to verify sensor data\n");142 return -EIO;143 }144 145 sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) |146 rx_buf[AM2315_HUM_OFFSET + 1];147 sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) |148 rx_buf[AM2315_TEMP_OFFSET + 1];149 150 return ret;151 152exit_unlock:153 mutex_unlock(&data->lock);154 return ret;155}156 157static irqreturn_t am2315_trigger_handler(int irq, void *p)158{159 int i;160 int ret;161 int bit;162 struct iio_poll_func *pf = p;163 struct iio_dev *indio_dev = pf->indio_dev;164 struct am2315_data *data = iio_priv(indio_dev);165 struct am2315_sensor_data sensor_data;166 167 ret = am2315_read_data(data, &sensor_data);168 if (ret < 0)169 goto err;170 171 mutex_lock(&data->lock);172 if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) {173 data->scan.chans[0] = sensor_data.hum_data;174 data->scan.chans[1] = sensor_data.temp_data;175 } else {176 i = 0;177 iio_for_each_active_channel(indio_dev, bit) {178 data->scan.chans[i] = (bit ? sensor_data.temp_data :179 sensor_data.hum_data);180 i++;181 }182 }183 mutex_unlock(&data->lock);184 185 iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,186 pf->timestamp);187err:188 iio_trigger_notify_done(indio_dev->trig);189 return IRQ_HANDLED;190}191 192static int am2315_read_raw(struct iio_dev *indio_dev,193 struct iio_chan_spec const *chan,194 int *val, int *val2, long mask)195{196 int ret;197 struct am2315_sensor_data sensor_data;198 struct am2315_data *data = iio_priv(indio_dev);199 200 switch (mask) {201 case IIO_CHAN_INFO_RAW:202 ret = am2315_read_data(data, &sensor_data);203 if (ret < 0)204 return ret;205 *val = (chan->type == IIO_HUMIDITYRELATIVE) ?206 sensor_data.hum_data : sensor_data.temp_data;207 return IIO_VAL_INT;208 case IIO_CHAN_INFO_SCALE:209 *val = 100;210 return IIO_VAL_INT;211 }212 213 return -EINVAL;214}215 216static const struct iio_info am2315_info = {217 .read_raw = am2315_read_raw,218};219 220static int am2315_probe(struct i2c_client *client)221{222 int ret;223 struct iio_dev *indio_dev;224 struct am2315_data *data;225 226 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));227 if (!indio_dev) {228 dev_err(&client->dev, "iio allocation failed!\n");229 return -ENOMEM;230 }231 232 data = iio_priv(indio_dev);233 data->client = client;234 i2c_set_clientdata(client, indio_dev);235 mutex_init(&data->lock);236 237 indio_dev->info = &am2315_info;238 indio_dev->name = AM2315_DRIVER_NAME;239 indio_dev->modes = INDIO_DIRECT_MODE;240 indio_dev->channels = am2315_channels;241 indio_dev->num_channels = ARRAY_SIZE(am2315_channels);242 243 ret = devm_iio_triggered_buffer_setup(&client->dev,244 indio_dev, iio_pollfunc_store_time,245 am2315_trigger_handler, NULL);246 if (ret < 0) {247 dev_err(&client->dev, "iio triggered buffer setup failed\n");248 return ret;249 }250 251 return devm_iio_device_register(&client->dev, indio_dev);252}253 254static const struct i2c_device_id am2315_i2c_id[] = {255 { "am2315" },256 {}257};258MODULE_DEVICE_TABLE(i2c, am2315_i2c_id);259 260static struct i2c_driver am2315_driver = {261 .driver = {262 .name = "am2315",263 },264 .probe = am2315_probe,265 .id_table = am2315_i2c_id,266};267 268module_i2c_driver(am2315_driver);269 270MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");271MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature");272MODULE_LICENSE("GPL v2");273