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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
*
* A generic driver to read multiple gpio lines and translate the
* encoded numeric value into an input event.
*/
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
struct gpio_decoder {
struct gpio_descs *input_gpios;
struct device *dev;
u32 axis;
u32 last_stable;
};
static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder)
{
struct gpio_descs *gpios = decoder->input_gpios;
unsigned int ret = 0;
int i, val;
for (i = 0; i < gpios->ndescs; i++) {
val = gpiod_get_value_cansleep(gpios->desc[i]);
if (val < 0) {
dev_err(decoder->dev,
"Error reading gpio %d: %d\n",
desc_to_gpio(gpios->desc[i]), val);
return val;
}
val = !!val;
ret = (ret << 1) | val;
}
return ret;
}
static void gpio_decoder_poll_gpios(struct input_dev *input)
{
struct gpio_decoder *decoder = input_get_drvdata(input);
int state;
state = gpio_decoder_get_gpios_state(decoder);
if (state >= 0 && state != decoder->last_stable) {
input_report_abs(input, decoder->axis, state);
input_sync(input);
decoder->last_stable = state;
}
}
static int gpio_decoder_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct gpio_decoder *decoder;
struct input_dev *input;
u32 max;
int err;
decoder = devm_kzalloc(dev, sizeof(*decoder), GFP_KERNEL);
if (!decoder)
return -ENOMEM;
decoder->dev = dev;
device_property_read_u32(dev, "linux,axis", &decoder->axis);
decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
if (IS_ERR(decoder->input_gpios)) {
dev_err(dev, "unable to acquire input gpios\n");
return PTR_ERR(decoder->input_gpios);
}
if (decoder->input_gpios->ndescs < 2) {
dev_err(dev, "not enough gpios found\n");
return -EINVAL;
}
if (device_property_read_u32(dev, "decoder-max-value", &max))
max = (1U << decoder->input_gpios->ndescs) - 1;
input = devm_input_allocate_device(dev);
if (!input)
return -ENOMEM;
input_set_drvdata(input, decoder);
input->name = pdev->name;
input->id.bustype = BUS_HOST;
input_set_abs_params(input, decoder->axis, 0, max, 0, 0);
err = input_setup_polling(input, gpio_decoder_poll_gpios);
if (err) {
dev_err(dev, "failed to set up polling\n");
return err;
}
err = input_register_device(input);
if (err) {
dev_err(dev, "failed to register input device\n");
return err;
}
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id gpio_decoder_of_match[] = {
{ .compatible = "gpio-decoder", },
{ },
};
MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
#endif
static struct platform_driver gpio_decoder_driver = {
.probe = gpio_decoder_probe,
.driver = {
.name = "gpio-decoder",
.of_match_table = of_match_ptr(gpio_decoder_of_match),
}
};
module_platform_driver(gpio_decoder_driver);
MODULE_DESCRIPTION("GPIO decoder input driver");
MODULE_AUTHOR("Vignesh R <vigneshr@ti.com>");
MODULE_LICENSE("GPL v2");
|
