summaryrefslogtreecommitdiffstats
path: root/drivers/iio/humidity/am2315.c
blob: 11535911a5c697fa359aec0a4626f7a80b3d1e12 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
/**
 * Aosong AM2315 relative humidity and temperature
 *
 * Copyright (c) 2016, Intel Corporation.
 *
 * This file is subject to the terms and conditions of version 2 of
 * the GNU General Public License. See the file COPYING in the main
 * directory of this archive for more details.
 *
 * 7-bit I2C address: 0x5C.
 */

#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#define AM2315_REG_HUM_MSB			0x00
#define AM2315_REG_HUM_LSB			0x01
#define AM2315_REG_TEMP_MSB			0x02
#define AM2315_REG_TEMP_LSB			0x03

#define AM2315_FUNCTION_READ			0x03
#define AM2315_HUM_OFFSET			2
#define AM2315_TEMP_OFFSET			4
#define AM2315_ALL_CHANNEL_MASK			GENMASK(1, 0)

#define AM2315_DRIVER_NAME			"am2315"

struct am2315_data {
	struct i2c_client *client;
	struct mutex lock;
	s16 buffer[8]; /* 2x16-bit channels + 2x16 padding + 4x16 timestamp */
};

struct am2315_sensor_data {
	s16 hum_data;
	s16 temp_data;
};

static const struct iio_chan_spec am2315_channels[] = {
	{
		.type = IIO_HUMIDITYRELATIVE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 0,
		.scan_type = {
			.sign = 's',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_CPU,
		},
	},
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 1,
		.scan_type = {
			.sign = 's',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_CPU,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(2),
};

/* CRC calculation algorithm, as specified in the datasheet (page 13). */
static u16 am2315_crc(u8 *data, u8 nr_bytes)
{
	int i;
	u16 crc = 0xffff;

	while (nr_bytes--) {
		crc ^= *data++;
		for (i = 0; i < 8; i++) {
			if (crc & 0x01) {
				crc >>= 1;
				crc ^= 0xA001;
			} else {
				crc >>= 1;
			}
		}
	}

	return crc;
}

/* Simple function that sends a few bytes to the device to wake it up. */
static void am2315_ping(struct i2c_client *client)
{
	i2c_smbus_read_byte_data(client, AM2315_REG_HUM_MSB);
}

static int am2315_read_data(struct am2315_data *data,
			    struct am2315_sensor_data *sensor_data)
{
	int ret;
	/* tx_buf format: <function code> <start addr> <nr of regs to read> */
	u8 tx_buf[3] = { AM2315_FUNCTION_READ, AM2315_REG_HUM_MSB, 4 };
	/*
	 * rx_buf format:
	 * <function code> <number of registers read>
	 * <humidity MSB> <humidity LSB> <temp MSB> <temp LSB>
	 * <CRC LSB> <CRC MSB>
	 */
	u8 rx_buf[8];
	u16 crc;

	/* First wake up the device. */
	am2315_ping(data->client);

	mutex_lock(&data->lock);
	ret = i2c_master_send(data->client, tx_buf, sizeof(tx_buf));
	if (ret < 0) {
		dev_err(&data->client->dev, "failed to send read request\n");
		goto exit_unlock;
	}
	/* Wait 2-3 ms, then read back the data sent by the device. */
	usleep_range(2000, 3000);
	/* Do a bulk data read, then pick out what we need. */
	ret = i2c_master_recv(data->client, rx_buf, sizeof(rx_buf));
	if (ret < 0) {
		dev_err(&data->client->dev, "failed to read sensor data\n");
		goto exit_unlock;
	}
	mutex_unlock(&data->lock);
	/*
	 * Do a CRC check on the data and compare it to the value
	 * calculated by the device.
	 */
	crc = am2315_crc(rx_buf, sizeof(rx_buf) - 2);
	if ((crc & 0xff) != rx_buf[6] || (crc >> 8) != rx_buf[7]) {
		dev_err(&data->client->dev, "failed to verify sensor data\n");
		return -EIO;
	}

	sensor_data->hum_data = (rx_buf[AM2315_HUM_OFFSET] << 8) |
				 rx_buf[AM2315_HUM_OFFSET + 1];
	sensor_data->temp_data = (rx_buf[AM2315_TEMP_OFFSET] << 8) |
				  rx_buf[AM2315_TEMP_OFFSET + 1];

	return ret;

exit_unlock:
	mutex_unlock(&data->lock);
	return ret;
}

static irqreturn_t am2315_trigger_handler(int irq, void *p)
{
	int i;
	int ret;
	int bit;
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct am2315_data *data = iio_priv(indio_dev);
	struct am2315_sensor_data sensor_data;

	ret = am2315_read_data(data, &sensor_data);
	if (ret < 0)
		goto err;

	mutex_lock(&data->lock);
	if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) {
		data->buffer[0] = sensor_data.hum_data;
		data->buffer[1] = sensor_data.temp_data;
	} else {
		i = 0;
		for_each_set_bit(bit, indio_dev->active_scan_mask,
				 indio_dev->masklength) {
			data->buffer[i] = (bit ? sensor_data.temp_data :
						 sensor_data.hum_data);
			i++;
		}
	}
	mutex_unlock(&data->lock);

	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
					   pf->timestamp);
err:
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
}

static int am2315_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val, int *val2, long mask)
{
	int ret;
	struct am2315_sensor_data sensor_data;
	struct am2315_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = am2315_read_data(data, &sensor_data);
		if (ret < 0)
			return ret;
		*val = (chan->type == IIO_HUMIDITYRELATIVE) ?
				sensor_data.hum_data : sensor_data.temp_data;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = 100;
		return IIO_VAL_INT;
	}

	return -EINVAL;
}

static const struct iio_info am2315_info = {
	.driver_module		= THIS_MODULE,
	.read_raw		= am2315_read_raw,
};

static int am2315_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	int ret;
	struct iio_dev *indio_dev;
	struct am2315_data *data;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev) {
		dev_err(&client->dev, "iio allocation failed!\n");
		return -ENOMEM;
	}

	data = iio_priv(indio_dev);
	data->client = client;
	i2c_set_clientdata(client, indio_dev);
	mutex_init(&data->lock);

	indio_dev->dev.parent = &client->dev;
	indio_dev->info = &am2315_info;
	indio_dev->name = AM2315_DRIVER_NAME;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = am2315_channels;
	indio_dev->num_channels = ARRAY_SIZE(am2315_channels);

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
					 am2315_trigger_handler, NULL);
	if (ret < 0) {
		dev_err(&client->dev, "iio triggered buffer setup failed\n");
		return ret;
	}

	ret = iio_device_register(indio_dev);
	if (ret < 0)
		goto err_buffer_cleanup;

	return 0;

err_buffer_cleanup:
	iio_triggered_buffer_cleanup(indio_dev);
	return ret;
}

static int am2315_remove(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);

	return 0;
}

static const struct i2c_device_id am2315_i2c_id[] = {
	{"am2315", 0},
	{}
};

static const struct acpi_device_id am2315_acpi_id[] = {
	{"AOS2315", 0},
	{}
};

MODULE_DEVICE_TABLE(acpi, am2315_acpi_id);

static struct i2c_driver am2315_driver = {
	.driver = {
		.name = "am2315",
		.acpi_match_table = ACPI_PTR(am2315_acpi_id),
	},
	.probe =            am2315_probe,
	.remove =	    am2315_remove,
	.id_table =         am2315_i2c_id,
};

module_i2c_driver(am2315_driver);

MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
MODULE_DESCRIPTION("Aosong AM2315 relative humidity and temperature");
MODULE_LICENSE("GPL v2");
OpenPOWER on IntegriCloud