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cd8d9777 MR |
1 | /* |
2 | * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors | |
3 | * | |
4 | * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <linux/module.h> | |
19 | #include <linux/mutex.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/i2c.h> | |
22 | ||
23 | #include <linux/iio/iio.h> | |
24 | #include <linux/iio/sysfs.h> | |
25 | ||
26 | #define VZ89X_REG_MEASUREMENT 0x09 | |
27 | #define VZ89X_REG_MEASUREMENT_SIZE 6 | |
28 | ||
29 | #define VZ89X_VOC_CO2_IDX 0 | |
30 | #define VZ89X_VOC_SHORT_IDX 1 | |
31 | #define VZ89X_VOC_TVOC_IDX 2 | |
32 | #define VZ89X_VOC_RESISTANCE_IDX 3 | |
33 | ||
34 | struct vz89x_data { | |
35 | struct i2c_client *client; | |
36 | struct mutex lock; | |
37 | unsigned long last_update; | |
38 | ||
39 | u8 buffer[VZ89X_REG_MEASUREMENT_SIZE]; | |
40 | }; | |
41 | ||
42 | static const struct iio_chan_spec vz89x_channels[] = { | |
43 | { | |
44 | .type = IIO_CONCENTRATION, | |
45 | .channel2 = IIO_MOD_CO2, | |
46 | .modified = 1, | |
47 | .info_mask_separate = | |
48 | BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW), | |
49 | .address = VZ89X_VOC_CO2_IDX, | |
50 | }, | |
51 | { | |
52 | .type = IIO_CONCENTRATION, | |
53 | .channel2 = IIO_MOD_VOC, | |
54 | .modified = 1, | |
55 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), | |
56 | .address = VZ89X_VOC_SHORT_IDX, | |
57 | .extend_name = "short", | |
58 | }, | |
59 | { | |
60 | .type = IIO_CONCENTRATION, | |
61 | .channel2 = IIO_MOD_VOC, | |
62 | .modified = 1, | |
63 | .info_mask_separate = | |
64 | BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW), | |
65 | .address = VZ89X_VOC_TVOC_IDX, | |
66 | }, | |
67 | { | |
68 | .type = IIO_RESISTANCE, | |
69 | .info_mask_separate = | |
70 | BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), | |
71 | .address = VZ89X_VOC_RESISTANCE_IDX, | |
72 | }, | |
73 | }; | |
74 | ||
75 | static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689"); | |
76 | static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223"); | |
77 | ||
78 | static struct attribute *vz89x_attributes[] = { | |
79 | &iio_const_attr_in_concentration_co2_scale.dev_attr.attr, | |
80 | &iio_const_attr_in_concentration_voc_scale.dev_attr.attr, | |
81 | NULL, | |
82 | }; | |
83 | ||
84 | static const struct attribute_group vz89x_attrs_group = { | |
85 | .attrs = vz89x_attributes, | |
86 | }; | |
87 | ||
bf23cee6 MR |
88 | /* |
89 | * Chipset sometime updates in the middle of a reading causing it to reset the | |
90 | * data pointer, and causing invalid reading of previous data. | |
91 | * We can check for this by reading MSB of the resistance reading that is | |
92 | * always zero, and by also confirming the VOC_short isn't zero. | |
93 | */ | |
94 | ||
95 | static int vz89x_measurement_is_valid(struct vz89x_data *data) | |
96 | { | |
97 | if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0) | |
98 | return 1; | |
99 | ||
100 | return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0); | |
101 | } | |
102 | ||
cd8d9777 MR |
103 | static int vz89x_get_measurement(struct vz89x_data *data) |
104 | { | |
105 | int ret; | |
106 | int i; | |
107 | ||
108 | /* sensor can only be polled once a second max per datasheet */ | |
109 | if (!time_after(jiffies, data->last_update + HZ)) | |
110 | return 0; | |
111 | ||
112 | ret = i2c_smbus_write_word_data(data->client, | |
113 | VZ89X_REG_MEASUREMENT, 0); | |
114 | if (ret < 0) | |
115 | return ret; | |
116 | ||
117 | for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) { | |
118 | ret = i2c_smbus_read_byte(data->client); | |
119 | if (ret < 0) | |
120 | return ret; | |
121 | data->buffer[i] = ret; | |
122 | } | |
123 | ||
bf23cee6 MR |
124 | ret = vz89x_measurement_is_valid(data); |
125 | if (ret) | |
126 | return -EAGAIN; | |
127 | ||
cd8d9777 MR |
128 | data->last_update = jiffies; |
129 | ||
130 | return 0; | |
131 | } | |
132 | ||
133 | static int vz89x_get_resistance_reading(struct vz89x_data *data) | |
134 | { | |
bf23cee6 | 135 | u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX]; |
cd8d9777 | 136 | |
bf23cee6 | 137 | return buf[0] | (buf[1] << 8); |
cd8d9777 MR |
138 | } |
139 | ||
140 | static int vz89x_read_raw(struct iio_dev *indio_dev, | |
141 | struct iio_chan_spec const *chan, int *val, | |
142 | int *val2, long mask) | |
143 | { | |
144 | struct vz89x_data *data = iio_priv(indio_dev); | |
145 | int ret = -EINVAL; | |
146 | ||
147 | switch (mask) { | |
148 | case IIO_CHAN_INFO_RAW: | |
149 | mutex_lock(&data->lock); | |
150 | ret = vz89x_get_measurement(data); | |
151 | mutex_unlock(&data->lock); | |
152 | ||
153 | if (ret) | |
154 | return ret; | |
155 | ||
156 | switch (chan->address) { | |
157 | case VZ89X_VOC_CO2_IDX: | |
158 | case VZ89X_VOC_SHORT_IDX: | |
159 | case VZ89X_VOC_TVOC_IDX: | |
160 | *val = data->buffer[chan->address]; | |
161 | return IIO_VAL_INT; | |
162 | case VZ89X_VOC_RESISTANCE_IDX: | |
163 | *val = vz89x_get_resistance_reading(data); | |
164 | return IIO_VAL_INT; | |
165 | default: | |
166 | return -EINVAL; | |
167 | } | |
168 | break; | |
169 | case IIO_CHAN_INFO_SCALE: | |
170 | switch (chan->type) { | |
171 | case IIO_RESISTANCE: | |
172 | *val = 10; | |
173 | return IIO_VAL_INT; | |
174 | default: | |
175 | return -EINVAL; | |
176 | } | |
177 | break; | |
178 | case IIO_CHAN_INFO_OFFSET: | |
179 | switch (chan->address) { | |
180 | case VZ89X_VOC_CO2_IDX: | |
181 | *val = 44; | |
182 | *val2 = 250000; | |
183 | return IIO_VAL_INT_PLUS_MICRO; | |
184 | case VZ89X_VOC_TVOC_IDX: | |
185 | *val = -13; | |
186 | return IIO_VAL_INT; | |
187 | default: | |
188 | return -EINVAL; | |
189 | } | |
190 | } | |
191 | ||
192 | return ret; | |
193 | } | |
194 | ||
195 | static const struct iio_info vz89x_info = { | |
196 | .attrs = &vz89x_attrs_group, | |
197 | .read_raw = vz89x_read_raw, | |
198 | .driver_module = THIS_MODULE, | |
199 | }; | |
200 | ||
201 | static int vz89x_probe(struct i2c_client *client, | |
202 | const struct i2c_device_id *id) | |
203 | { | |
204 | struct iio_dev *indio_dev; | |
205 | struct vz89x_data *data; | |
206 | ||
207 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA | | |
208 | I2C_FUNC_SMBUS_BYTE)) | |
209 | return -ENODEV; | |
210 | ||
211 | indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); | |
212 | if (!indio_dev) | |
213 | return -ENOMEM; | |
214 | ||
215 | data = iio_priv(indio_dev); | |
216 | i2c_set_clientdata(client, indio_dev); | |
217 | data->client = client; | |
218 | data->last_update = jiffies - HZ; | |
219 | mutex_init(&data->lock); | |
220 | ||
221 | indio_dev->dev.parent = &client->dev; | |
222 | indio_dev->info = &vz89x_info, | |
223 | indio_dev->name = dev_name(&client->dev); | |
224 | indio_dev->modes = INDIO_DIRECT_MODE; | |
225 | ||
226 | indio_dev->channels = vz89x_channels; | |
227 | indio_dev->num_channels = ARRAY_SIZE(vz89x_channels); | |
228 | ||
229 | return devm_iio_device_register(&client->dev, indio_dev); | |
230 | } | |
231 | ||
232 | static const struct i2c_device_id vz89x_id[] = { | |
233 | { "vz89x", 0 }, | |
234 | { } | |
235 | }; | |
236 | MODULE_DEVICE_TABLE(i2c, vz89x_id); | |
237 | ||
238 | static const struct of_device_id vz89x_dt_ids[] = { | |
239 | { .compatible = "sgx,vz89x" }, | |
240 | { } | |
241 | }; | |
242 | MODULE_DEVICE_TABLE(of, vz89x_dt_ids); | |
243 | ||
244 | static struct i2c_driver vz89x_driver = { | |
245 | .driver = { | |
246 | .name = "vz89x", | |
247 | .of_match_table = of_match_ptr(vz89x_dt_ids), | |
248 | }, | |
249 | .probe = vz89x_probe, | |
250 | .id_table = vz89x_id, | |
251 | }; | |
252 | module_i2c_driver(vz89x_driver); | |
253 | ||
254 | MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>"); | |
255 | MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors"); | |
256 | MODULE_LICENSE("GPL v2"); |