summaryrefslogtreecommitdiff
path: root/drivers/iio/chemical/sps30_serial.c
blob: 3f311d50087cb10e23e0ccc83bc16cd3a05b8884 (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
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SPS30 particulate matter sensor serial driver
 *
 * Copyright (c) 2021 Tomasz Duszynski <tomasz.duszynski@octakon.com>
 */
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/iio/iio.h>
#include <linux/minmax.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/serdev.h>
#include <linux/types.h>

#include "sps30.h"

#define SPS30_SERIAL_DEV_NAME "sps30"

#define SPS30_SERIAL_SOF_EOF 0x7e
#define SPS30_SERIAL_TIMEOUT msecs_to_jiffies(20)
#define SPS30_SERIAL_MAX_BUF_SIZE 263
#define SPS30_SERIAL_ESCAPE_CHAR 0x7d

#define SPS30_SERIAL_FRAME_MIN_SIZE 7
#define SPS30_SERIAL_FRAME_ADR_OFFSET 1
#define SPS30_SERIAL_FRAME_CMD_OFFSET 2
#define SPS30_SERIAL_FRAME_MOSI_LEN_OFFSET 3
#define SPS30_SERIAL_FRAME_MISO_STATE_OFFSET 3
#define SPS30_SERIAL_FRAME_MISO_LEN_OFFSET 4
#define SPS30_SERIAL_FRAME_MISO_DATA_OFFSET 5

#define SPS30_SERIAL_START_MEAS 0x00
#define SPS30_SERIAL_STOP_MEAS 0x01
#define SPS30_SERIAL_READ_MEAS 0x03
#define SPS30_SERIAL_RESET 0xd3
#define SPS30_SERIAL_CLEAN_FAN 0x56
#define SPS30_SERIAL_PERIOD 0x80
#define SPS30_SERIAL_DEV_INFO 0xd0
#define SPS30_SERIAL_READ_VERSION 0xd1

struct sps30_serial_priv {
	struct completion new_frame;
	unsigned char buf[SPS30_SERIAL_MAX_BUF_SIZE];
	size_t num;
	bool escaped;
	bool done;
};

static int sps30_serial_xfer(struct sps30_state *state, const unsigned char *buf, size_t size)
{
	struct serdev_device *serdev = to_serdev_device(state->dev);
	struct sps30_serial_priv *priv = state->priv;
	int ret;

	priv->num = 0;
	priv->escaped = false;
	priv->done = false;

	ret = serdev_device_write(serdev, buf, size, SPS30_SERIAL_TIMEOUT);
	if (ret < 0)
		return ret;
	if (ret != size)
		return -EIO;

	ret = wait_for_completion_interruptible_timeout(&priv->new_frame, SPS30_SERIAL_TIMEOUT);
	if (ret < 0)
		return ret;
	if (!ret)
		return -ETIMEDOUT;

	return 0;
}

static const struct {
	unsigned char byte;
	unsigned char byte2;
} sps30_serial_bytes[] = {
	{ 0x11, 0x31 },
	{ 0x13, 0x33 },
	{ 0x7e, 0x5e },
	{ 0x7d, 0x5d },
};

static int sps30_serial_put_byte(unsigned char *buf, unsigned char byte)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(sps30_serial_bytes); i++) {
		if (sps30_serial_bytes[i].byte != byte)
			continue;

		buf[0] = SPS30_SERIAL_ESCAPE_CHAR;
		buf[1] = sps30_serial_bytes[i].byte2;

		return 2;
	}

	buf[0] = byte;

	return 1;
}

static char sps30_serial_get_byte(bool escaped, unsigned char byte2)
{
	int i;

	if (!escaped)
		return byte2;

	for (i = 0; i < ARRAY_SIZE(sps30_serial_bytes); i++) {
		if (sps30_serial_bytes[i].byte2 != byte2)
			continue;

		return sps30_serial_bytes[i].byte;
	}

	return 0;
}

static unsigned char sps30_serial_calc_chksum(const unsigned char *buf, size_t num)
{
	unsigned int chksum = 0;
	size_t i;

	for (i = 0; i < num; i++)
		chksum += buf[i];

	return ~chksum;
}

static int sps30_serial_prep_frame(unsigned char *buf, unsigned char cmd,
				   const unsigned char *arg, size_t arg_size)
{
	unsigned char chksum;
	int num = 0;
	size_t i;

	buf[num++] = SPS30_SERIAL_SOF_EOF;
	buf[num++] = 0;
	num += sps30_serial_put_byte(buf + num, cmd);
	num += sps30_serial_put_byte(buf + num, arg_size);

	for (i = 0; i < arg_size; i++)
		num += sps30_serial_put_byte(buf + num, arg[i]);

	/* SOF isn't checksummed */
	chksum = sps30_serial_calc_chksum(buf + 1, num - 1);
	num += sps30_serial_put_byte(buf + num, chksum);
	buf[num++] = SPS30_SERIAL_SOF_EOF;

	return num;
}

static bool sps30_serial_frame_valid(struct sps30_state *state, const unsigned char *buf)
{
	struct sps30_serial_priv *priv = state->priv;
	unsigned char chksum;

	if ((priv->num < SPS30_SERIAL_FRAME_MIN_SIZE) ||
	    (priv->num != SPS30_SERIAL_FRAME_MIN_SIZE +
	     priv->buf[SPS30_SERIAL_FRAME_MISO_LEN_OFFSET])) {
		dev_err(state->dev, "frame has invalid number of bytes\n");
		return false;
	}

	if ((priv->buf[SPS30_SERIAL_FRAME_ADR_OFFSET] != buf[SPS30_SERIAL_FRAME_ADR_OFFSET]) ||
	    (priv->buf[SPS30_SERIAL_FRAME_CMD_OFFSET] != buf[SPS30_SERIAL_FRAME_CMD_OFFSET])) {
		dev_err(state->dev, "frame has wrong ADR and CMD bytes\n");
		return false;
	}

	if (priv->buf[SPS30_SERIAL_FRAME_MISO_STATE_OFFSET]) {
		dev_err(state->dev, "frame with non-zero state received (0x%02x)\n",
			priv->buf[SPS30_SERIAL_FRAME_MISO_STATE_OFFSET]);
		return false;
	}

	/* SOF, checksum and EOF are not checksummed */
	chksum = sps30_serial_calc_chksum(priv->buf + 1, priv->num - 3);
	if (priv->buf[priv->num - 2] != chksum) {
		dev_err(state->dev, "frame integrity check failed\n");
		return false;
	}

	return true;
}

static int sps30_serial_command(struct sps30_state *state, unsigned char cmd,
				const void *arg, size_t arg_size, void *rsp, size_t rsp_size)
{
	struct sps30_serial_priv *priv = state->priv;
	unsigned char buf[SPS30_SERIAL_MAX_BUF_SIZE];
	int ret, size;

	size = sps30_serial_prep_frame(buf, cmd, arg, arg_size);
	ret = sps30_serial_xfer(state, buf, size);
	if (ret)
		return ret;

	if (!sps30_serial_frame_valid(state, buf))
		return -EIO;

	if (rsp) {
		rsp_size = min_t(size_t, priv->buf[SPS30_SERIAL_FRAME_MISO_LEN_OFFSET], rsp_size);
		memcpy(rsp, &priv->buf[SPS30_SERIAL_FRAME_MISO_DATA_OFFSET], rsp_size);
	}

	return rsp_size;
}

static int sps30_serial_receive_buf(struct serdev_device *serdev,
				    const unsigned char *buf, size_t size)
{
	struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev);
	struct sps30_serial_priv *priv;
	struct sps30_state *state;
	unsigned char byte;
	size_t i;

	if (!indio_dev)
		return 0;

	state = iio_priv(indio_dev);
	priv = state->priv;

	/* just in case device put some unexpected data on the bus */
	if (priv->done)
		return size;

	/* wait for the start of frame */
	if (!priv->num && size && buf[0] != SPS30_SERIAL_SOF_EOF)
		return 1;

	if (priv->num + size >= ARRAY_SIZE(priv->buf))
		size = ARRAY_SIZE(priv->buf) - priv->num;

	for (i = 0; i < size; i++) {
		byte = buf[i];
		/* remove stuffed bytes on-the-fly */
		if (byte == SPS30_SERIAL_ESCAPE_CHAR) {
			priv->escaped = true;
			continue;
		}

		byte = sps30_serial_get_byte(priv->escaped, byte);
		if (priv->escaped && !byte)
			dev_warn(state->dev, "unrecognized escaped char (0x%02x)\n", byte);

		priv->buf[priv->num++] = byte;

		/* EOF received */
		if (!priv->escaped && byte == SPS30_SERIAL_SOF_EOF) {
			if (priv->num < SPS30_SERIAL_FRAME_MIN_SIZE)
				continue;

			priv->done = true;
			complete(&priv->new_frame);
			i++;
			break;
		}

		priv->escaped = false;
	}

	return i;
}

static const struct serdev_device_ops sps30_serial_device_ops = {
	.receive_buf = sps30_serial_receive_buf,
	.write_wakeup = serdev_device_write_wakeup,
};

static int sps30_serial_start_meas(struct sps30_state *state)
{
	/* request BE IEEE754 formatted data */
	unsigned char buf[] = { 0x01, 0x03 };

	return sps30_serial_command(state, SPS30_SERIAL_START_MEAS, buf, sizeof(buf), NULL, 0);
}

static int sps30_serial_stop_meas(struct sps30_state *state)
{
	return sps30_serial_command(state, SPS30_SERIAL_STOP_MEAS, NULL, 0, NULL, 0);
}

static int sps30_serial_reset(struct sps30_state *state)
{
	int ret;

	ret = sps30_serial_command(state, SPS30_SERIAL_RESET, NULL, 0, NULL, 0);
	msleep(500);

	return ret;
}

static int sps30_serial_read_meas(struct sps30_state *state, __be32 *meas, size_t num)
{
	int ret;

	/* measurements are ready within a second */
	if (msleep_interruptible(1000))
		return -EINTR;

	ret = sps30_serial_command(state, SPS30_SERIAL_READ_MEAS, NULL, 0, meas, num * sizeof(num));
	if (ret < 0)
		return ret;
	/* if measurements aren't ready sensor returns empty frame */
	if (ret == SPS30_SERIAL_FRAME_MIN_SIZE)
		return -ETIMEDOUT;
	if (ret != num * sizeof(*meas))
		return -EIO;

	return 0;
}

static int sps30_serial_clean_fan(struct sps30_state *state)
{
	return sps30_serial_command(state, SPS30_SERIAL_CLEAN_FAN, NULL, 0, NULL, 0);
}

static int sps30_serial_read_cleaning_period(struct sps30_state *state, __be32 *period)
{
	unsigned char buf[] = { 0x00 };
	int ret;

	ret = sps30_serial_command(state, SPS30_SERIAL_PERIOD, buf, sizeof(buf),
				   period, sizeof(*period));
	if (ret < 0)
		return ret;
	if (ret != sizeof(*period))
		return -EIO;

	return 0;
}

static int sps30_serial_write_cleaning_period(struct sps30_state *state, __be32 period)
{
	unsigned char buf[5] = { 0x00 };

	memcpy(buf + 1, &period, sizeof(period));

	return sps30_serial_command(state, SPS30_SERIAL_PERIOD, buf, sizeof(buf), NULL, 0);
}

static int sps30_serial_show_info(struct sps30_state *state)
{
	/*
	 * tell device do return serial number and add extra nul byte just in case
	 * serial number isn't a valid string
	 */
	unsigned char buf[32 + 1] = { 0x03 };
	struct device *dev = state->dev;
	int ret;

	ret = sps30_serial_command(state, SPS30_SERIAL_DEV_INFO, buf, 1, buf, sizeof(buf) - 1);
	if (ret < 0)
		return ret;
	if (ret != sizeof(buf) - 1)
		return -EIO;

	dev_info(dev, "serial number: %s\n", buf);

	ret = sps30_serial_command(state, SPS30_SERIAL_READ_VERSION, NULL, 0, buf, sizeof(buf) - 1);
	if (ret < 0)
		return ret;
	if (ret < 2)
		return -EIO;

	dev_info(dev, "fw version: %u.%u\n", buf[0], buf[1]);

	return 0;
}

static const struct sps30_ops sps30_serial_ops = {
	.start_meas = sps30_serial_start_meas,
	.stop_meas = sps30_serial_stop_meas,
	.read_meas = sps30_serial_read_meas,
	.reset = sps30_serial_reset,
	.clean_fan = sps30_serial_clean_fan,
	.read_cleaning_period = sps30_serial_read_cleaning_period,
	.write_cleaning_period = sps30_serial_write_cleaning_period,
	.show_info = sps30_serial_show_info,
};

static int sps30_serial_probe(struct serdev_device *serdev)
{
	struct device *dev = &serdev->dev;
	struct sps30_serial_priv *priv;
	int ret;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	init_completion(&priv->new_frame);
	serdev_device_set_client_ops(serdev, &sps30_serial_device_ops);

	ret = devm_serdev_device_open(dev, serdev);
	if (ret)
		return ret;

	serdev_device_set_baudrate(serdev, 115200);
	serdev_device_set_flow_control(serdev, false);

	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
	if (ret)
		return ret;

	return sps30_probe(dev, SPS30_SERIAL_DEV_NAME, priv, &sps30_serial_ops);
}

static const struct of_device_id sps30_serial_of_match[] = {
	{ .compatible = "sensirion,sps30" },
	{ }
};
MODULE_DEVICE_TABLE(of, sps30_serial_of_match);

static struct serdev_device_driver sps30_serial_driver = {
	.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = sps30_serial_of_match,
	},
	.probe = sps30_serial_probe,
};
module_serdev_device_driver(sps30_serial_driver);

MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor serial driver");
MODULE_LICENSE("GPL v2");