1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
4 *
5 * Copyright (C) 2015-2018
6 * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7 */
8
9#include <linux/module.h>
10#include <linux/mutex.h>
11#include <linux/init.h>
12#include <linux/i2c.h>
13#include <linux/mod_devicetable.h>
14
15#include <linux/iio/iio.h>
16#include <linux/iio/sysfs.h>
17
18#define VZ89X_REG_MEASUREMENT		0x09
19#define VZ89X_REG_MEASUREMENT_RD_SIZE	6
20#define VZ89X_REG_MEASUREMENT_WR_SIZE	3
21
22#define VZ89X_VOC_CO2_IDX		0
23#define VZ89X_VOC_SHORT_IDX		1
24#define VZ89X_VOC_TVOC_IDX		2
25#define VZ89X_VOC_RESISTANCE_IDX	3
26
27#define VZ89TE_REG_MEASUREMENT		0x0c
28#define VZ89TE_REG_MEASUREMENT_RD_SIZE	7
29#define VZ89TE_REG_MEASUREMENT_WR_SIZE	6
30
31#define VZ89TE_VOC_TVOC_IDX		0
32#define VZ89TE_VOC_CO2_IDX		1
33#define VZ89TE_VOC_RESISTANCE_IDX	2
34
35enum {
36	VZ89X,
37	VZ89TE,
38};
39
40struct vz89x_chip_data;
41
42struct vz89x_data {
43	struct i2c_client *client;
44	const struct vz89x_chip_data *chip;
45	struct mutex lock;
46	int (*xfer)(struct vz89x_data *data, u8 cmd);
47
48	bool is_valid;
49	unsigned long last_update;
50	u8 buffer[VZ89TE_REG_MEASUREMENT_RD_SIZE];
51};
52
53struct vz89x_chip_data {
54	bool (*valid)(struct vz89x_data *data);
55	const struct iio_chan_spec *channels;
56	u8 num_channels;
57
58	u8 cmd;
59	u8 read_size;
60	u8 write_size;
61};
62
63static const struct iio_chan_spec vz89x_channels[] = {
64	{
65		.type = IIO_CONCENTRATION,
66		.channel2 = IIO_MOD_CO2,
67		.modified = 1,
68		.info_mask_separate =
69			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
70		.address = VZ89X_VOC_CO2_IDX,
71	},
72	{
73		.type = IIO_CONCENTRATION,
74		.channel2 = IIO_MOD_VOC,
75		.modified = 1,
76		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
77		.address = VZ89X_VOC_SHORT_IDX,
78		.extend_name = "short",
79	},
80	{
81		.type = IIO_CONCENTRATION,
82		.channel2 = IIO_MOD_VOC,
83		.modified = 1,
84		.info_mask_separate =
85			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
86		.address = VZ89X_VOC_TVOC_IDX,
87	},
88	{
89		.type = IIO_RESISTANCE,
90		.info_mask_separate =
91			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
92		.address = VZ89X_VOC_RESISTANCE_IDX,
93		.scan_index = -1,
94		.scan_type = {
95			.endianness = IIO_LE,
96		},
97	},
98};
99
100static const struct iio_chan_spec vz89te_channels[] = {
101	{
102		.type = IIO_CONCENTRATION,
103		.channel2 = IIO_MOD_VOC,
104		.modified = 1,
105		.info_mask_separate =
106			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
107		.address = VZ89TE_VOC_TVOC_IDX,
108	},
109
110	{
111		.type = IIO_CONCENTRATION,
112		.channel2 = IIO_MOD_CO2,
113		.modified = 1,
114		.info_mask_separate =
115			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
116		.address = VZ89TE_VOC_CO2_IDX,
117	},
118	{
119		.type = IIO_RESISTANCE,
120		.info_mask_separate =
121			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
122		.address = VZ89TE_VOC_RESISTANCE_IDX,
123		.scan_index = -1,
124		.scan_type = {
125			.endianness = IIO_BE,
126		},
127	},
128};
129
130static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
131static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");
132
133static struct attribute *vz89x_attributes[] = {
134	&iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
135	&iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
136	NULL,
137};
138
139static const struct attribute_group vz89x_attrs_group = {
140	.attrs = vz89x_attributes,
141};
142
143/*
144 * Chipset sometime updates in the middle of a reading causing it to reset the
145 * data pointer, and causing invalid reading of previous data.
146 * We can check for this by reading MSB of the resistance reading that is
147 * always zero, and by also confirming the VOC_short isn't zero.
148 */
149
150static bool vz89x_measurement_is_valid(struct vz89x_data *data)
151{
152	if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
153		return true;
154
155	return !!(data->buffer[data->chip->read_size - 1] > 0);
156}
157
158/* VZ89TE device has a modified CRC-8 two complement check */
159static bool vz89te_measurement_is_valid(struct vz89x_data *data)
160{
161	u8 crc = 0;
162	int i, sum = 0;
163
164	for (i = 0; i < (data->chip->read_size - 1); i++) {
165		sum = crc + data->buffer[i];
166		crc = sum;
167		crc += sum / 256;
168	}
169
170	return !((0xff - crc) == data->buffer[data->chip->read_size - 1]);
171}
172
173static int vz89x_i2c_xfer(struct vz89x_data *data, u8 cmd)
174{
175	const struct vz89x_chip_data *chip = data->chip;
176	struct i2c_client *client = data->client;
177	struct i2c_msg msg[2];
178	int ret;
179	u8 buf[6] = { cmd, 0, 0, 0, 0, 0xf3 };
180
181	msg[0].addr = client->addr;
182	msg[0].flags = client->flags;
183	msg[0].len = chip->write_size;
184	msg[0].buf  = (char *) &buf;
185
186	msg[1].addr = client->addr;
187	msg[1].flags = client->flags | I2C_M_RD;
188	msg[1].len = chip->read_size;
189	msg[1].buf = (char *) &data->buffer;
190
191	ret = i2c_transfer(client->adapter, msg, 2);
192
193	return (ret == 2) ? 0 : ret;
194}
195
196static int vz89x_smbus_xfer(struct vz89x_data *data, u8 cmd)
197{
198	struct i2c_client *client = data->client;
199	int ret;
200	int i;
201
202	ret = i2c_smbus_write_word_data(client, cmd, 0);
203	if (ret < 0)
204		return ret;
205
206	for (i = 0; i < data->chip->read_size; i++) {
207		ret = i2c_smbus_read_byte(client);
208		if (ret < 0)
209			return ret;
210		data->buffer[i] = ret;
211	}
212
213	return 0;
214}
215
216static int vz89x_get_measurement(struct vz89x_data *data)
217{
218	const struct vz89x_chip_data *chip = data->chip;
219	int ret;
220
221	/* sensor can only be polled once a second max per datasheet */
222	if (!time_after(jiffies, data->last_update + HZ))
223		return data->is_valid ? 0 : -EAGAIN;
224
225	data->is_valid = false;
226	data->last_update = jiffies;
227
228	ret = data->xfer(data, chip->cmd);
229	if (ret < 0)
230		return ret;
231
232	ret = chip->valid(data);
233	if (ret)
234		return -EAGAIN;
235
236	data->is_valid = true;
237
238	return 0;
239}
240
241static int vz89x_get_resistance_reading(struct vz89x_data *data,
242					struct iio_chan_spec const *chan,
243					int *val)
244{
245	u8 *tmp = &data->buffer[chan->address];
246
247	switch (chan->scan_type.endianness) {
248	case IIO_LE:
249		*val = le32_to_cpup((__le32 *) tmp) & GENMASK(23, 0);
250		break;
251	case IIO_BE:
252		*val = be32_to_cpup((__be32 *) tmp) >> 8;
253		break;
254	default:
255		return -EINVAL;
256	}
257
258	return 0;
259}
260
261static int vz89x_read_raw(struct iio_dev *indio_dev,
262			  struct iio_chan_spec const *chan, int *val,
263			  int *val2, long mask)
264{
265	struct vz89x_data *data = iio_priv(indio_dev);
266	int ret = -EINVAL;
267
268	switch (mask) {
269	case IIO_CHAN_INFO_RAW:
270		mutex_lock(&data->lock);
271		ret = vz89x_get_measurement(data);
272		mutex_unlock(&data->lock);
273
274		if (ret)
275			return ret;
276
277		switch (chan->type) {
278		case IIO_CONCENTRATION:
279			*val = data->buffer[chan->address];
280			return IIO_VAL_INT;
281		case IIO_RESISTANCE:
282			ret = vz89x_get_resistance_reading(data, chan, val);
283			if (!ret)
284				return IIO_VAL_INT;
285			break;
286		default:
287			return -EINVAL;
288		}
289		break;
290	case IIO_CHAN_INFO_SCALE:
291		switch (chan->type) {
292		case IIO_RESISTANCE:
293			*val = 10;
294			return IIO_VAL_INT;
295		default:
296			return -EINVAL;
297		}
298		break;
299	case IIO_CHAN_INFO_OFFSET:
300		switch (chan->channel2) {
301		case IIO_MOD_CO2:
302			*val = 44;
303			*val2 = 250000;
304			return IIO_VAL_INT_PLUS_MICRO;
305		case IIO_MOD_VOC:
306			*val = -13;
307			return IIO_VAL_INT;
308		default:
309			return -EINVAL;
310		}
311	}
312
313	return ret;
314}
315
316static const struct iio_info vz89x_info = {
317	.attrs		= &vz89x_attrs_group,
318	.read_raw	= vz89x_read_raw,
319};
320
321static const struct vz89x_chip_data vz89x_chips[] = {
322	{
323		.valid = vz89x_measurement_is_valid,
324
325		.cmd = VZ89X_REG_MEASUREMENT,
326		.read_size = VZ89X_REG_MEASUREMENT_RD_SIZE,
327		.write_size = VZ89X_REG_MEASUREMENT_WR_SIZE,
328
329		.channels = vz89x_channels,
330		.num_channels = ARRAY_SIZE(vz89x_channels),
331	},
332	{
333		.valid = vz89te_measurement_is_valid,
334
335		.cmd = VZ89TE_REG_MEASUREMENT,
336		.read_size = VZ89TE_REG_MEASUREMENT_RD_SIZE,
337		.write_size = VZ89TE_REG_MEASUREMENT_WR_SIZE,
338
339		.channels = vz89te_channels,
340		.num_channels = ARRAY_SIZE(vz89te_channels),
341	},
342};
343
344static const struct of_device_id vz89x_dt_ids[] = {
345	{ .compatible = "sgx,vz89x", .data = (void *) VZ89X },
346	{ .compatible = "sgx,vz89te", .data = (void *) VZ89TE },
347	{ }
348};
349MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
350
351static int vz89x_probe(struct i2c_client *client)
352{
353	const struct i2c_device_id *id = i2c_client_get_device_id(client);
354	struct device *dev = &client->dev;
355	struct iio_dev *indio_dev;
356	struct vz89x_data *data;
357	int chip_id;
358
359	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
360	if (!indio_dev)
361		return -ENOMEM;
362	data = iio_priv(indio_dev);
363
364	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
365		data->xfer = vz89x_i2c_xfer;
366	else if (i2c_check_functionality(client->adapter,
367				I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
368		data->xfer = vz89x_smbus_xfer;
369	else
370		return -EOPNOTSUPP;
371
372	if (!dev_fwnode(dev))
373		chip_id = id->driver_data;
374	else
375		chip_id = (unsigned long)device_get_match_data(dev);
376
377	i2c_set_clientdata(client, indio_dev);
378	data->client = client;
379	data->chip = &vz89x_chips[chip_id];
380	data->last_update = jiffies - HZ;
381	mutex_init(&data->lock);
382
383	indio_dev->info = &vz89x_info;
384	indio_dev->name = dev_name(dev);
385	indio_dev->modes = INDIO_DIRECT_MODE;
386
387	indio_dev->channels = data->chip->channels;
388	indio_dev->num_channels = data->chip->num_channels;
389
390	return devm_iio_device_register(dev, indio_dev);
391}
392
393static const struct i2c_device_id vz89x_id[] = {
394	{ "vz89x", VZ89X },
395	{ "vz89te", VZ89TE },
396	{ }
397};
398MODULE_DEVICE_TABLE(i2c, vz89x_id);
399
400static struct i2c_driver vz89x_driver = {
401	.driver = {
402		.name	= "vz89x",
403		.of_match_table = vz89x_dt_ids,
404	},
405	.probe = vz89x_probe,
406	.id_table = vz89x_id,
407};
408module_i2c_driver(vz89x_driver);
409
410MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
411MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
412MODULE_LICENSE("GPL v2");
413