1
2
3
4
5
6
7
8
9
10
11
12
13#include <linux/acpi.h>
14#include <linux/delay.h>
15#include <linux/i2c.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/iio/buffer.h>
19#include <linux/iio/iio.h>
20#include <linux/iio/sysfs.h>
21#include <linux/iio/trigger_consumer.h>
22#include <linux/iio/triggered_buffer.h>
23
24#define AM2315_REG_HUM_MSB 0x00
25#define AM2315_REG_HUM_LSB 0x01
26#define AM2315_REG_TEMP_MSB 0x02
27#define AM2315_REG_TEMP_LSB 0x03
28
29#define AM2315_FUNCTION_READ 0x03
30#define AM2315_HUM_OFFSET 2
31#define AM2315_TEMP_OFFSET 4
32#define AM2315_ALL_CHANNEL_MASK GENMASK(1, 0)
33
34#define AM2315_DRIVER_NAME "am2315"
35
36struct am2315_data {
37 struct i2c_client *client;
38 struct mutex lock;
39 s16 buffer[8];
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
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
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
107 u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 };
108
109
110
111
112
113
114 u8 rx_buf[8];
115 u16 crc;
116
117
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
127 usleep_range(2000, 3000);
128
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
137
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->buffer[0] = sensor_data.hum_data;
174 data->buffer[1] = sensor_data.temp_data;
175 } else {
176 i = 0;
177 for_each_set_bit(bit, indio_dev->active_scan_mask,
178 indio_dev->masklength) {
179 data->buffer[i] = (bit ? sensor_data.temp_data :
180 sensor_data.hum_data);
181 i++;
182 }
183 }
184 mutex_unlock(&data->lock);
185
186 iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
187 pf->timestamp);
188err:
189 iio_trigger_notify_done(indio_dev->trig);
190 return IRQ_HANDLED;
191}
192
193static int am2315_read_raw(struct iio_dev *indio_dev,
194 struct iio_chan_spec const *chan,
195 int *val, int *val2, long mask)
196{
197 int ret;
198 struct am2315_sensor_data sensor_data;
199 struct am2315_data *data = iio_priv(indio_dev);
200
201 switch (mask) {
202 case IIO_CHAN_INFO_RAW:
203 ret = am2315_read_data(data, &sensor_data);
204 if (ret < 0)
205 return ret;
206 *val = (chan->type == IIO_HUMIDITYRELATIVE) ?
207 sensor_data.hum_data : sensor_data.temp_data;
208 return IIO_VAL_INT;
209 case IIO_CHAN_INFO_SCALE:
210 *val = 100;
211 return IIO_VAL_INT;
212 }
213
214 return -EINVAL;
215}
216
217static const struct iio_info am2315_info = {
218 .read_raw = am2315_read_raw,
219};
220
221static int am2315_probe(struct i2c_client *client,
222 const struct i2c_device_id *id)
223{
224 int ret;
225 struct iio_dev *indio_dev;
226 struct am2315_data *data;
227
228 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
229 if (!indio_dev) {
230 dev_err(&client->dev, "iio allocation failed!\n");
231 return -ENOMEM;
232 }
233
234 data = iio_priv(indio_dev);
235 data->client = client;
236 i2c_set_clientdata(client, indio_dev);
237 mutex_init(&data->lock);
238
239 indio_dev->dev.parent = &client->dev;
240 indio_dev->info = &am2315_info;
241 indio_dev->name = AM2315_DRIVER_NAME;
242 indio_dev->modes = INDIO_DIRECT_MODE;
243 indio_dev->channels = am2315_channels;
244 indio_dev->num_channels = ARRAY_SIZE(am2315_channels);
245
246 ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
247 am2315_trigger_handler, NULL);
248 if (ret < 0) {
249 dev_err(&client->dev, "iio triggered buffer setup failed\n");
250 return ret;
251 }
252
253 ret = iio_device_register(indio_dev);
254 if (ret < 0)
255 goto err_buffer_cleanup;
256
257 return 0;
258
259err_buffer_cleanup:
260 iio_triggered_buffer_cleanup(indio_dev);
261 return ret;
262}
263
264static int am2315_remove(struct i2c_client *client)
265{
266 struct iio_dev *indio_dev = i2c_get_clientdata(client);
267
268 iio_device_unregister(indio_dev);
269 iio_triggered_buffer_cleanup(indio_dev);
270
271 return 0;
272}
273
274static const struct i2c_device_id am2315_i2c_id[] = {
275 {"am2315", 0},
276 {}
277};
278MODULE_DEVICE_TABLE(i2c, am2315_i2c_id);
279
280static const struct acpi_device_id am2315_acpi_id[] = {
281 {"AOS2315", 0},
282 {}
283};
284
285MODULE_DEVICE_TABLE(acpi, am2315_acpi_id);
286
287static struct i2c_driver am2315_driver = {
288 .driver = {
289 .name = "am2315",
290 .acpi_match_table = ACPI_PTR(am2315_acpi_id),
291 },
292 .probe = am2315_probe,
293 .remove = am2315_remove,
294 .id_table = am2315_i2c_id,
295};
296
297module_i2c_driver(am2315_driver);
298
299MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
300MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature");
301MODULE_LICENSE("GPL v2");
302
