1 /*
2 * Copyright (c) 2020 Laird Connectivity
3 * Copyright (c) 2019 Electronut Labs
4 *
5 * SPDX-License-Identifier: Apache-2.0
6 */
7
8 #define DT_DRV_COMPAT silabs_si7055
9
10 #include <zephyr/drivers/sensor.h>
11 #include <zephyr/kernel.h>
12 #include <zephyr/device.h>
13 #include <zephyr/logging/log.h>
14 #include <zephyr/drivers/i2c.h>
15 #include "si7055.h"
16 #if CONFIG_SI7055_ENABLE_CHECKSUM
17 #include <zephyr/sys/crc.h>
18 #endif
19
20 LOG_MODULE_REGISTER(si7055, CONFIG_SENSOR_LOG_LEVEL);
21
22 struct si7055_data {
23 uint16_t temperature;
24 };
25
26 struct si7055_config {
27 struct i2c_dt_spec i2c;
28 };
29
30 /**
31 * @brief function to get temperature
32 *
33 * @return int 0 on success
34 * -EIO for I/O and checksum errors
35 */
si7055_get_temperature(const struct device * dev)36 static int si7055_get_temperature(const struct device *dev)
37 {
38 struct si7055_data *si_data = dev->data;
39 const struct si7055_config *config = dev->config;
40 int retval;
41 #if CONFIG_SI7055_ENABLE_CHECKSUM
42 uint8_t temp[SI7055_TEMPERATURE_READ_WITH_CHECKSUM_SIZE];
43 #else
44 uint8_t temp[SI7055_TEMPERATURE_READ_NO_CHECKSUM_SIZE];
45 #endif
46
47 retval = i2c_burst_read_dt(&config->i2c, SI7055_MEAS_TEMP_MASTER_MODE,
48 temp, sizeof(temp));
49
50 /* Refer to
51 * https://www.silabs.com/documents/public/data-sheets/Si7050-1-3-4-5-A20.pdf
52 */
53
54 if (retval == 0) {
55 #if CONFIG_SI7055_ENABLE_CHECKSUM
56 if (crc8(temp, SI7055_DATA_SIZE, SI7055_CRC_POLY,
57 SI7055_CRC_INIT, false) != temp[SI7055_DATA_SIZE]){
58 LOG_ERR("checksum failed.\n");
59 return(-EIO);
60 }
61 #endif
62 si_data->temperature = (temp[SI7055_TEMPERATURE_DATA_BYTE_0]
63 << 8) |
64 temp[SI7055_TEMPERATURE_DATA_BYTE_1];
65 } else {
66 LOG_ERR("read register err");
67 }
68
69 return retval;
70 }
71
72 /**
73 * @brief fetch a sample from the sensor
74 *
75 * @return 0
76 */
si7055_sample_fetch(const struct device * dev,enum sensor_channel chan)77 static int si7055_sample_fetch(const struct device *dev,
78 enum sensor_channel chan)
79 {
80 int retval;
81
82 retval = si7055_get_temperature(dev);
83
84 return retval;
85 }
86
87 /**
88 * @brief sensor value get
89 *
90 * @return -ENOTSUP for unsupported channels
91 */
si7055_channel_get(const struct device * dev,enum sensor_channel chan,struct sensor_value * val)92 static int si7055_channel_get(const struct device *dev,
93 enum sensor_channel chan,
94 struct sensor_value *val)
95 {
96 struct si7055_data *si_data = dev->data;
97
98 /* Refer to
99 * https://www.silabs.com/documents/public/data-sheets/Si7050-1-3-4-5-A20.pdf
100 */
101
102 if (chan == SENSOR_CHAN_AMBIENT_TEMP) {
103
104 int32_t temp_ucelcius = (((SI7055_CONV_FACTOR_1 *
105 (int32_t)si_data->temperature) /
106 (__UINT16_MAX__ + 1)) -
107 SI7055_CONV_FACTOR_2) *
108 SI7055_MULTIPLIER;
109
110 val->val1 = temp_ucelcius / SI7055_DIVIDER;
111 val->val2 = temp_ucelcius % SI7055_DIVIDER;
112
113 LOG_DBG("temperature = val1:%d, val2:%d",
114 val->val1, val->val2);
115
116 return 0;
117 } else {
118 return -ENOTSUP;
119 }
120 }
121
122 static DEVICE_API(sensor, si7055_api) = {
123 .sample_fetch = &si7055_sample_fetch,
124 .channel_get = &si7055_channel_get,
125 };
126
127 /**
128 * @brief initialize the sensor
129 *
130 * @return 0 for success
131 */
132
si7055_init(const struct device * dev)133 static int si7055_init(const struct device *dev)
134 {
135 const struct si7055_config *config = dev->config;
136
137 if (!device_is_ready(config->i2c.bus)) {
138 LOG_ERR("Bus device is not ready");
139 return -ENODEV;
140 }
141
142 LOG_DBG("si7055 init ok");
143
144 return 0;
145 }
146
147 #define SI7055_DEFINE(inst) \
148 static struct si7055_data si7055_data_##inst; \
149 \
150 static const struct si7055_config si7055_config_##inst = { \
151 .i2c = I2C_DT_SPEC_INST_GET(inst), \
152 }; \
153 \
154 SENSOR_DEVICE_DT_INST_DEFINE(inst, si7055_init, NULL, \
155 &si7055_data_##inst, &si7055_config_##inst, POST_KERNEL, \
156 CONFIG_SENSOR_INIT_PRIORITY, &si7055_api); \
157
158 DT_INST_FOREACH_STATUS_OKAY(SI7055_DEFINE)
159
