120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/*
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* Copyright (c) 2021 Leica Geosystems AG
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT lm75
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#include <device.h>
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#include <devicetree.h>
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#include <drivers/i2c.h>
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#include <drivers/sensor.h>
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#include <logging/log.h>
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LOG_MODULE_REGISTER(LM75, CONFIG_SENSOR_LOG_LEVEL);
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#define LM75_REG_TEMP 0x00
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#define LM75_REG_CONFIG 0x01
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#define LM75_REG_T_HYST 0x02
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#define LM75_REG_T_OS 0x03
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struct lm75_data {
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int16_t temp; /*temp in 0.1°C*/
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};
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struct lm75_config {
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const struct device *i2c_dev;
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uint8_t i2c_addr;
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};
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static inline int lm75_reg_read(struct lm75_config *cfg, uint8_t reg,
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uint8_t *buf, uint32_t size)
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{
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return i2c_burst_read(cfg->i2c_dev, cfg->i2c_addr, reg, buf, size);
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}
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static inline int lm75_fetch_temp(struct lm75_config *cfg, struct lm75_data *data)
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{
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int ret;
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uint8_t temp_read[2];
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int16_t temp;
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ret = lm75_reg_read(cfg, LM75_REG_TEMP, temp_read, sizeof(temp_read));
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if (ret) {
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LOG_ERR("Could not fetch temperature [%d]", ret);
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return -EIO;
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}
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/* temp is in two's complement.
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* bit 7 in the lower part corresponds to 0.5
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*/
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temp = temp_read[0] << 8 | temp_read[1];
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/* shift right by 7, multiply by 10 to get 0.1° and divide by 2 to get °C */
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data->temp = (temp / 128) * 10 / 2;
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return 0;
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}
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static int lm75_sample_fetch(const struct device *dev,
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enum sensor_channel chan)
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{
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struct lm75_data *data = (struct lm75_data *)dev->data;
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struct lm75_config *cfg = (struct lm75_config *)dev->config;
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switch (chan) {
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case SENSOR_CHAN_ALL:
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case SENSOR_CHAN_AMBIENT_TEMP:
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return lm75_fetch_temp(cfg, data);
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default:
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return -ENOTSUP;
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}
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}
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static int lm75_channel_get(const struct device *dev,
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enum sensor_channel chan,
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struct sensor_value *val)
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{
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struct lm75_data *data = (struct lm75_data *)dev->data;
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switch (chan) {
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case SENSOR_CHAN_AMBIENT_TEMP:
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val->val1 = data->temp / 10;
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val->val2 = (data->temp - val->val1 * 10) * 100000U;
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return 0;
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default:
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return -ENOTSUP;
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}
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}
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static const struct sensor_driver_api lm75_driver_api = {
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.sample_fetch = lm75_sample_fetch,
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.channel_get = lm75_channel_get,
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};
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int lm75_init(const struct device *dev)
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{
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struct lm75_config *cfg = (struct lm75_config *)dev->config;
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if (device_is_ready(cfg->i2c_dev)) {
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return 0;
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}
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LOG_ERR("I2C dev not ready");
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return -ENODEV;
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}
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#define LM75_INST(inst) \
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static struct lm75_data lm75_data_##inst; \
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static const struct lm75_config lm75_config_##inst = { \
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.i2c_dev = DEVICE_DT_GET(DT_INST_BUS(inst)), \
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.i2c_addr = DT_INST_REG_ADDR(inst), \
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}; \
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DEVICE_DT_INST_DEFINE(inst, lm75_init, NULL, &lm75_data_##inst, \
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&lm75_config_##inst, POST_KERNEL, \
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CONFIG_SENSOR_INIT_PRIORITY, &lm75_driver_api);
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DT_INST_FOREACH_STATUS_OKAY(LM75_INST)
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