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
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IIO driver for Lite-On LTR390 ALS and UV sensor
* (7-bit I2C slave address 0x53)
*
* Based on the work of:
* Shreeya Patel and Shi Zhigang (LTRF216 Driver)
*
* Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
*
* Datasheet:
* https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
*
* TODO:
* - Support for configurable gain and resolution
* - Sensor suspend/resume support
* - Add support for reading the ALS
* - Interrupt support
*/
#include <linux/i2c.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#include <linux/iio/iio.h>
#include <asm/unaligned.h>
#define LTR390_MAIN_CTRL 0x00
#define LTR390_PART_ID 0x06
#define LTR390_UVS_DATA 0x10
#define LTR390_SW_RESET BIT(4)
#define LTR390_UVS_MODE BIT(3)
#define LTR390_SENSOR_ENABLE BIT(1)
#define LTR390_PART_NUMBER_ID 0xb
/*
* At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
* the sensor are equal to 1 UV Index [Datasheet Page#8].
*
* For the default resolution of 18-bit (integration time: 100ms) and default
* gain of 3x, the counts/uvi are calculated as follows:
* 2300 / ((3/18) * (100/400)) = 95.83
*/
#define LTR390_COUNTS_PER_UVI 96
/*
* Window Factor is needed when the device is under Window glass with coated
* tinted ink. This is to compensate for the light loss due to the lower
* transmission rate of the window glass and helps * in calculating lux.
*/
#define LTR390_WINDOW_FACTOR 1
struct ltr390_data {
struct regmap *regmap;
struct i2c_client *client;
/* Protects device from simulataneous reads */
struct mutex lock;
};
static const struct regmap_config ltr390_regmap_config = {
.name = "ltr390",
.reg_bits = 8,
.reg_stride = 1,
.val_bits = 8,
};
static int ltr390_register_read(struct ltr390_data *data, u8 register_address)
{
struct device *dev = &data->client->dev;
int ret;
u8 recieve_buffer[3];
guard(mutex)(&data->lock);
ret = regmap_bulk_read(data->regmap, register_address, recieve_buffer,
sizeof(recieve_buffer));
if (ret) {
dev_err(dev, "failed to read measurement data");
return ret;
}
return get_unaligned_le24(recieve_buffer);
}
static int ltr390_read_raw(struct iio_dev *iio_device,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
int ret;
struct ltr390_data *data = iio_priv(iio_device);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = ltr390_register_read(data, LTR390_UVS_DATA);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = LTR390_WINDOW_FACTOR;
*val2 = LTR390_COUNTS_PER_UVI;
return IIO_VAL_FRACTIONAL;
default:
return -EINVAL;
}
}
static const struct iio_info ltr390_info = {
.read_raw = ltr390_read_raw,
};
static const struct iio_chan_spec ltr390_channel = {
.type = IIO_UVINDEX,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE)
};
static int ltr390_probe(struct i2c_client *client)
{
struct ltr390_data *data;
struct iio_dev *indio_dev;
struct device *dev;
int ret, part_number;
dev = &client->dev;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->regmap = devm_regmap_init_i2c(client, <r390_regmap_config);
if (IS_ERR(data->regmap))
return dev_err_probe(dev, PTR_ERR(data->regmap),
"regmap initialization failed\n");
data->client = client;
mutex_init(&data->lock);
indio_dev->info = <r390_info;
indio_dev->channels = <r390_channel;
indio_dev->num_channels = 1;
indio_dev->name = "ltr390";
ret = regmap_read(data->regmap, LTR390_PART_ID, &part_number);
if (ret)
return dev_err_probe(dev, ret,
"failed to get sensor's part id\n");
/* Lower 4 bits of `part_number` change with hardware revisions */
if (part_number >> 4 != LTR390_PART_NUMBER_ID)
dev_info(dev, "received invalid product id: 0x%x", part_number);
dev_dbg(dev, "LTR390, product id: 0x%x\n", part_number);
/* reset sensor, chip fails to respond to this, so ignore any errors */
regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_SW_RESET);
/* Wait for the registers to reset before proceeding */
usleep_range(1000, 2000);
ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL,
LTR390_SENSOR_ENABLE | LTR390_UVS_MODE);
if (ret)
return dev_err_probe(dev, ret, "failed to enable the sensor\n");
return devm_iio_device_register(dev, indio_dev);
}
static const struct i2c_device_id ltr390_id[] = {
{ "ltr390" },
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, ltr390_id);
static const struct of_device_id ltr390_of_table[] = {
{ .compatible = "liteon,ltr390" },
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, ltr390_of_table);
static struct i2c_driver ltr390_driver = {
.driver = {
.name = "ltr390",
.of_match_table = ltr390_of_table,
},
.probe = ltr390_probe,
.id_table = ltr390_id,
};
module_i2c_driver(ltr390_driver);
MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
MODULE_DESCRIPTION("Lite-On LTR390 ALS and UV sensor Driver");
MODULE_LICENSE("GPL");
|
