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
197
198
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Maxim Integrated MAX5481-MAX5484 digital potentiometer driver
* Copyright 2016 Rockwell Collins
*
* Datasheet:
* https://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf
*/
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/spi/spi.h>
/* write wiper reg */
#define MAX5481_WRITE_WIPER (0 << 4)
/* copy wiper reg to NV reg */
#define MAX5481_COPY_AB_TO_NV (2 << 4)
/* copy NV reg to wiper reg */
#define MAX5481_COPY_NV_TO_AB (3 << 4)
#define MAX5481_MAX_POS 1023
enum max5481_variant {
max5481,
max5482,
max5483,
max5484,
};
struct max5481_cfg {
int kohms;
};
static const struct max5481_cfg max5481_cfg[] = {
[max5481] = { .kohms = 10, },
[max5482] = { .kohms = 50, },
[max5483] = { .kohms = 10, },
[max5484] = { .kohms = 50, },
};
struct max5481_data {
struct spi_device *spi;
const struct max5481_cfg *cfg;
u8 msg[3] ____cacheline_aligned;
};
#define MAX5481_CHANNEL { \
.type = IIO_RESISTANCE, \
.indexed = 1, \
.output = 1, \
.channel = 0, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec max5481_channels[] = {
MAX5481_CHANNEL,
};
static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val)
{
struct spi_device *spi = data->spi;
data->msg[0] = cmd;
switch (cmd) {
case MAX5481_WRITE_WIPER:
data->msg[1] = val >> 2;
data->msg[2] = (val & 0x3) << 6;
return spi_write(spi, data->msg, 3);
case MAX5481_COPY_AB_TO_NV:
case MAX5481_COPY_NV_TO_AB:
return spi_write(spi, data->msg, 1);
default:
return -EIO;
}
}
static int max5481_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct max5481_data *data = iio_priv(indio_dev);
if (mask != IIO_CHAN_INFO_SCALE)
return -EINVAL;
*val = 1000 * data->cfg->kohms;
*val2 = MAX5481_MAX_POS;
return IIO_VAL_FRACTIONAL;
}
static int max5481_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct max5481_data *data = iio_priv(indio_dev);
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
if (val < 0 || val > MAX5481_MAX_POS)
return -EINVAL;
return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val);
}
static const struct iio_info max5481_info = {
.read_raw = max5481_read_raw,
.write_raw = max5481_write_raw,
};
static const struct of_device_id max5481_match[] = {
{ .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] },
{ .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] },
{ .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] },
{ .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] },
{ }
};
MODULE_DEVICE_TABLE(of, max5481_match);
static int max5481_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct max5481_data *data;
const struct spi_device_id *id = spi_get_device_id(spi);
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
dev_set_drvdata(&spi->dev, indio_dev);
data = iio_priv(indio_dev);
data->spi = spi;
data->cfg = device_get_match_data(&spi->dev);
if (!data->cfg)
data->cfg = &max5481_cfg[id->driver_data];
indio_dev->name = id->name;
indio_dev->modes = INDIO_DIRECT_MODE;
/* variant specific configuration */
indio_dev->info = &max5481_info;
indio_dev->channels = max5481_channels;
indio_dev->num_channels = ARRAY_SIZE(max5481_channels);
/* restore wiper from NV */
ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, 0);
if (ret < 0)
return ret;
return iio_device_register(indio_dev);
}
static int max5481_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
struct max5481_data *data = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
/* save wiper reg to NV reg */
return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0);
}
static const struct spi_device_id max5481_id_table[] = {
{ "max5481", max5481 },
{ "max5482", max5482 },
{ "max5483", max5483 },
{ "max5484", max5484 },
{ }
};
MODULE_DEVICE_TABLE(spi, max5481_id_table);
static struct spi_driver max5481_driver = {
.driver = {
.name = "max5481",
.of_match_table = max5481_match,
},
.probe = max5481_probe,
.remove = max5481_remove,
.id_table = max5481_id_table,
};
module_spi_driver(max5481_driver);
MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>");
MODULE_DESCRIPTION("max5481 SPI driver");
MODULE_LICENSE("GPL v2");
|
