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
|
// 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/bitmap.h>
#include <linux/dev_printk.h>
#include <linux/device/devres.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/input.h>
#include <linux/minmax.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/types.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;
DECLARE_BITMAP(values, 32);
unsigned int size;
int err;
size = min(gpios->ndescs, 32U);
err = gpiod_get_array_value_cansleep(size, gpios->desc, gpios->info, values);
if (err) {
dev_err(decoder->dev, "Error reading GPIO: %d\n", err);
return err;
}
return bitmap_read(values, 0, size);
}
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))
return dev_err_probe(dev, PTR_ERR(decoder->input_gpios),
"unable to acquire input gpios\n");
if (decoder->input_gpios->ndescs < 2)
return dev_err_probe(dev, -EINVAL, "not enough gpios found\n");
if (decoder->input_gpios->ndescs > 31)
return dev_err_probe(dev, -EINVAL, "too many gpios found\n");
if (device_property_read_u32(dev, "decoder-max-value", &max))
max = BIT(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)
return dev_err_probe(dev, err, "failed to set up polling\n");
err = input_register_device(input);
if (err)
return dev_err_probe(dev, err, "failed to register input device\n");
return 0;
}
static const struct of_device_id gpio_decoder_of_match[] = {
{ .compatible = "gpio-decoder", },
{ }
};
MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
static struct platform_driver gpio_decoder_driver = {
.probe = gpio_decoder_probe,
.driver = {
.name = "gpio-decoder",
.of_match_table = 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");
|
