1 /*
2 * Copyright (c) 2024 Benedikt Schmidt <benediktibk@gmail.com>
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #define DT_DRV_COMPAT onnn_nct75
8
9 #include <zephyr/drivers/i2c.h>
10 #include <zephyr/drivers/sensor.h>
11 #include <zephyr/logging/log.h>
12 #include <zephyr/sys/byteorder.h>
13 #include <zephyr/sys/util.h>
14
15 LOG_MODULE_REGISTER(NCT75, CONFIG_SENSOR_LOG_LEVEL);
16
17 #define NCT75REGISTER_STOREDTEMPERATUREVALUE 0x00
18 #define NCT75REGISTER_CONFIGURATION 0x01
19 #define NCT75REGISTER_ONESHOT 0x04
20
21 #define NCT75_CONFIGURATION_ONESHOTMODE_POS 5
22
23 #define NCT75_TEMPERATURE_CONVERSION_TIME_US 48500
24 #define NCT75_TEMPERATURE_CONVERSION_WAIT_TIME_US (NCT75_TEMPERATURE_CONVERSION_TIME_US + 1000)
25
26 struct nct75_config {
27 struct i2c_dt_spec i2c;
28 };
29
30 struct nct75_data {
31 /* temperature in 1e-6 °C */
32 int64_t value;
33 };
34
nct75_sample_fetch(const struct device * dev,enum sensor_channel chan)35 static int nct75_sample_fetch(const struct device *dev, enum sensor_channel chan)
36 {
37 const struct nct75_config *config = dev->config;
38 struct nct75_data *data = dev->data;
39 int result;
40 uint8_t write_buffer = 0;
41 uint16_t read_buffer;
42 int16_t raw_value;
43
44 __ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
45
46 result = i2c_reg_write_byte_dt(&config->i2c, NCT75REGISTER_ONESHOT, 0);
47 if (result != 0) {
48 LOG_ERR("%s: unable to trigger temperature one shot measurement", dev->name);
49 return result;
50 }
51
52 k_sleep(K_USEC(NCT75_TEMPERATURE_CONVERSION_WAIT_TIME_US));
53
54 write_buffer = NCT75REGISTER_STOREDTEMPERATUREVALUE;
55 result = i2c_write_read_dt(&config->i2c, &write_buffer, sizeof(write_buffer), &read_buffer,
56 sizeof(read_buffer));
57 if (result != 0) {
58 LOG_ERR("%s: unable to read temperature", dev->name);
59 return result;
60 }
61
62 raw_value = arithmetic_shift_right(sys_be16_to_cpu(read_buffer), 4);
63 data->value = (raw_value * 1000 * 1000) * 100 / 0x640;
64
65 return 0;
66 }
67
nct75_channel_get(const struct device * dev,enum sensor_channel chan,struct sensor_value * val)68 static int nct75_channel_get(const struct device *dev, enum sensor_channel chan,
69 struct sensor_value *val)
70 {
71 struct nct75_data *data = dev->data;
72
73 if (chan != SENSOR_CHAN_AMBIENT_TEMP) {
74 LOG_ERR("%s: requesting unsupported channel %i", dev->name, chan);
75 return -ENOTSUP;
76 }
77
78 val->val1 = data->value / (1000 * 1000);
79 val->val2 = data->value - val->val1 * 1000 * 1000;
80 return 0;
81 }
82
83 static DEVICE_API(sensor, nct75_api) = {
84 .sample_fetch = nct75_sample_fetch,
85 .channel_get = nct75_channel_get,
86 };
87
nct75_init(const struct device * dev)88 static int nct75_init(const struct device *dev)
89 {
90 const struct nct75_config *config = dev->config;
91 uint8_t configuration_register_value = BIT(NCT75_CONFIGURATION_ONESHOTMODE_POS);
92 int result;
93
94 if (!i2c_is_ready_dt(&config->i2c)) {
95 LOG_ERR("I2C device not ready");
96 return -ENODEV;
97 }
98
99 result = i2c_reg_write_byte_dt(&config->i2c, NCT75REGISTER_CONFIGURATION,
100 configuration_register_value);
101 if (result != 0) {
102 LOG_ERR("%s: unable to configure temperature sensor", dev->name);
103 return result;
104 }
105
106 return 0;
107 }
108
109 #define NCT75_INIT(inst) \
110 static const struct nct75_config nct75_##inst##_config = { \
111 .i2c = I2C_DT_SPEC_INST_GET(inst), \
112 }; \
113 \
114 static struct nct75_data nct75_##inst##_data; \
115 \
116 SENSOR_DEVICE_DT_INST_DEFINE(inst, nct75_init, NULL, &nct75_##inst##_data, \
117 &nct75_##inst##_config, POST_KERNEL, \
118 CONFIG_SENSOR_INIT_PRIORITY, &nct75_api);
119
120 DT_INST_FOREACH_STATUS_OKAY(NCT75_INIT);
121
