1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * atlas-ezo-sensor.c - Support for Atlas Scientific EZO sensors
4  *
5  * Copyright (C) 2020 Konsulko Group
6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7  */
8 
9 #include <linux/init.h>
10 #include <linux/delay.h>
11 #include <linux/mod_devicetable.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
14 #include <linux/property.h>
15 #include <linux/err.h>
16 #include <linux/i2c.h>
17 
18 #include <linux/iio/iio.h>
19 
20 #define ATLAS_EZO_DRV_NAME		"atlas-ezo-sensor"
21 #define ATLAS_INT_TIME_IN_MS		950
22 #define ATLAS_INT_HUM_TIME_IN_MS	350
23 
24 enum {
25 	ATLAS_CO2_EZO,
26 	ATLAS_O2_EZO,
27 	ATLAS_HUM_EZO,
28 };
29 
30 struct atlas_ezo_device {
31 	const struct iio_chan_spec *channels;
32 	int num_channels;
33 	int delay;
34 };
35 
36 struct atlas_ezo_data {
37 	struct i2c_client *client;
38 	const struct atlas_ezo_device *chip;
39 
40 	/* lock to avoid multiple concurrent read calls */
41 	struct mutex lock;
42 
43 	u8 buffer[8];
44 };
45 
46 #define ATLAS_CONCENTRATION_CHANNEL(_modifier) \
47 	{ \
48 		.type = IIO_CONCENTRATION, \
49 		.modified = 1,\
50 		.channel2 = _modifier, \
51 		.info_mask_separate = \
52 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), \
53 		.scan_index = 0, \
54 		.scan_type =  { \
55 			.sign = 'u', \
56 			.realbits = 32, \
57 			.storagebits = 32, \
58 			.endianness = IIO_CPU, \
59 		}, \
60 	}
61 
62 static const struct iio_chan_spec atlas_co2_ezo_channels[] = {
63 	ATLAS_CONCENTRATION_CHANNEL(IIO_MOD_CO2),
64 };
65 
66 static const struct iio_chan_spec atlas_o2_ezo_channels[] = {
67 	ATLAS_CONCENTRATION_CHANNEL(IIO_MOD_O2),
68 };
69 
70 static const struct iio_chan_spec atlas_hum_ezo_channels[] = {
71 	{
72 		.type = IIO_HUMIDITYRELATIVE,
73 		.info_mask_separate =
74 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
75 		.scan_index = 0,
76 		.scan_type =  {
77 			.sign = 'u',
78 			.realbits = 32,
79 			.storagebits = 32,
80 			.endianness = IIO_CPU,
81 		},
82 	},
83 };
84 
85 static struct atlas_ezo_device atlas_ezo_devices[] = {
86 	[ATLAS_CO2_EZO] = {
87 		.channels = atlas_co2_ezo_channels,
88 		.num_channels = 1,
89 		.delay = ATLAS_INT_TIME_IN_MS,
90 	},
91 	[ATLAS_O2_EZO] = {
92 		.channels = atlas_o2_ezo_channels,
93 		.num_channels = 1,
94 		.delay = ATLAS_INT_TIME_IN_MS,
95 	},
96 	[ATLAS_HUM_EZO] = {
97 		.channels = atlas_hum_ezo_channels,
98 		.num_channels = 1,
99 		.delay = ATLAS_INT_HUM_TIME_IN_MS,
100 	},
101 };
102 
103 static void atlas_ezo_sanitize(char *buf)
104 {
105 	char *ptr = strchr(buf, '.');
106 
107 	if (!ptr)
108 		return;
109 
110 	memmove(ptr, ptr + 1, strlen(ptr));
111 }
112 
113 static int atlas_ezo_read_raw(struct iio_dev *indio_dev,
114 			  struct iio_chan_spec const *chan,
115 			  int *val, int *val2, long mask)
116 {
117 	struct atlas_ezo_data *data = iio_priv(indio_dev);
118 	struct i2c_client *client = data->client;
119 
120 	if (chan->type != IIO_CONCENTRATION)
121 		return -EINVAL;
122 
123 	switch (mask) {
124 	case IIO_CHAN_INFO_RAW: {
125 		int ret;
126 		long tmp;
127 
128 		mutex_lock(&data->lock);
129 
130 		tmp = i2c_smbus_write_byte(client, 'R');
131 
132 		if (tmp < 0) {
133 			mutex_unlock(&data->lock);
134 			return tmp;
135 		}
136 
137 		msleep(data->chip->delay);
138 
139 		tmp = i2c_master_recv(client, data->buffer, sizeof(data->buffer));
140 
141 		if (tmp < 0 || data->buffer[0] != 1) {
142 			mutex_unlock(&data->lock);
143 			return -EBUSY;
144 		}
145 
146 		/* removing floating point for fixed number representation */
147 		atlas_ezo_sanitize(data->buffer + 2);
148 
149 		ret = kstrtol(data->buffer + 1, 10, &tmp);
150 
151 		*val = tmp;
152 
153 		mutex_unlock(&data->lock);
154 
155 		return ret ? ret : IIO_VAL_INT;
156 	}
157 	case IIO_CHAN_INFO_SCALE:
158 		switch (chan->type) {
159 		case IIO_HUMIDITYRELATIVE:
160 			*val = 10;
161 			return IIO_VAL_INT;
162 		case IIO_CONCENTRATION:
163 			break;
164 		default:
165 			return -EINVAL;
166 		}
167 
168 		/* IIO_CONCENTRATION modifiers */
169 		switch (chan->channel2) {
170 		case IIO_MOD_CO2:
171 			*val = 0;
172 			*val2 = 100; /* 0.0001 */
173 			return IIO_VAL_INT_PLUS_MICRO;
174 		case IIO_MOD_O2:
175 			*val = 100;
176 			return IIO_VAL_INT;
177 		}
178 		return -EINVAL;
179 	}
180 
181 	return 0;
182 }
183 
184 static const struct iio_info atlas_info = {
185 	.read_raw = atlas_ezo_read_raw,
186 };
187 
188 static const struct i2c_device_id atlas_ezo_id[] = {
189 	{ "atlas-co2-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_CO2_EZO] },
190 	{ "atlas-o2-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_O2_EZO] },
191 	{ "atlas-hum-ezo", (kernel_ulong_t)&atlas_ezo_devices[ATLAS_HUM_EZO] },
192 	{}
193 };
194 MODULE_DEVICE_TABLE(i2c, atlas_ezo_id);
195 
196 static const struct of_device_id atlas_ezo_dt_ids[] = {
197 	{ .compatible = "atlas,co2-ezo", .data = &atlas_ezo_devices[ATLAS_CO2_EZO], },
198 	{ .compatible = "atlas,o2-ezo", .data = &atlas_ezo_devices[ATLAS_O2_EZO], },
199 	{ .compatible = "atlas,hum-ezo", .data = &atlas_ezo_devices[ATLAS_HUM_EZO], },
200 	{}
201 };
202 MODULE_DEVICE_TABLE(of, atlas_ezo_dt_ids);
203 
204 static int atlas_ezo_probe(struct i2c_client *client)
205 {
206 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
207 	const struct atlas_ezo_device *chip;
208 	struct atlas_ezo_data *data;
209 	struct iio_dev *indio_dev;
210 
211 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
212 	if (!indio_dev)
213 		return -ENOMEM;
214 
215 	if (dev_fwnode(&client->dev))
216 		chip = device_get_match_data(&client->dev);
217 	else
218 		chip = (const struct atlas_ezo_device *)id->driver_data;
219 	if (!chip)
220 		return -EINVAL;
221 
222 	indio_dev->info = &atlas_info;
223 	indio_dev->name = ATLAS_EZO_DRV_NAME;
224 	indio_dev->channels = chip->channels;
225 	indio_dev->num_channels = chip->num_channels;
226 	indio_dev->modes = INDIO_DIRECT_MODE;
227 
228 	data = iio_priv(indio_dev);
229 	data->client = client;
230 	data->chip = chip;
231 	mutex_init(&data->lock);
232 
233 	return devm_iio_device_register(&client->dev, indio_dev);
234 };
235 
236 static struct i2c_driver atlas_ezo_driver = {
237 	.driver = {
238 		.name	= ATLAS_EZO_DRV_NAME,
239 		.of_match_table	= atlas_ezo_dt_ids,
240 	},
241 	.probe		= atlas_ezo_probe,
242 	.id_table	= atlas_ezo_id,
243 };
244 module_i2c_driver(atlas_ezo_driver);
245 
246 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
247 MODULE_DESCRIPTION("Atlas Scientific EZO sensors");
248 MODULE_LICENSE("GPL");
249