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
|
/*
* ltc2485.c - Driver for Linear Technology LTC2485 ADC
*
* Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf
*/
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */
#define LTC2485_CONFIG_DEFAULT 0
struct ltc2485_data {
struct i2c_client *client;
ktime_t time_prev; /* last conversion */
};
static void ltc2485_wait_conv(struct ltc2485_data *data)
{
const unsigned int conv_time = 147; /* conversion time ms */
unsigned int time_elapsed;
/* delay if conversion time not passed since last read or write */
time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev);
if (time_elapsed < conv_time)
msleep(conv_time - time_elapsed);
}
static int ltc2485_read(struct ltc2485_data *data, int *val)
{
struct i2c_client *client = data->client;
__be32 buf = 0;
int ret;
ltc2485_wait_conv(data);
ret = i2c_master_recv(client, (char *)&buf, 4);
if (ret < 0) {
dev_err(&client->dev, "i2c_master_recv failed\n");
return ret;
}
data->time_prev = ktime_get();
*val = sign_extend32(be32_to_cpu(buf) >> 6, 24);
return ret;
}
static int ltc2485_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct ltc2485_data *data = iio_priv(indio_dev);
int ret;
if (mask == IIO_CHAN_INFO_RAW) {
ret = ltc2485_read(data, val);
if (ret < 0)
return ret;
return IIO_VAL_INT;
} else if (mask == IIO_CHAN_INFO_SCALE) {
*val = 5000; /* on board vref millivolts */
*val2 = 25; /* 25 (24 + sign) data bits */
return IIO_VAL_FRACTIONAL_LOG2;
} else {
return -EINVAL;
}
}
static const struct iio_chan_spec ltc2485_channel[] = {
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)
},
};
static const struct iio_info ltc2485_info = {
.read_raw = ltc2485_read_raw,
};
static int ltc2485_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct ltc2485_data *data;
int ret;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
I2C_FUNC_SMBUS_WRITE_BYTE))
return -EOPNOTSUPP;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
data->client = client;
indio_dev->dev.parent = &client->dev;
indio_dev->name = id->name;
indio_dev->info = <c2485_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ltc2485_channel;
indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel);
ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT);
if (ret < 0)
return ret;
data->time_prev = ktime_get();
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id ltc2485_id[] = {
{ "ltc2485", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2485_id);
static struct i2c_driver ltc2485_driver = {
.driver = {
.name = "ltc2485",
},
.probe = ltc2485_probe,
.id_table = ltc2485_id,
};
module_i2c_driver(ltc2485_driver);
MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>");
MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver");
MODULE_LICENSE("GPL v2");
|
