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125 lines · 3.2 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
4 *
5 * A generic driver to read multiple gpio lines and translate the
6 * encoded numeric value into an input event.
7 */
8
9#include <linux/bitmap.h>
10#include <linux/dev_printk.h>
11#include <linux/device/devres.h>
12#include <linux/err.h>
13#include <linux/gpio/consumer.h>
14#include <linux/input.h>
15#include <linux/minmax.h>
16#include <linux/module.h>
17#include <linux/platform_device.h>
18#include <linux/property.h>
19#include <linux/types.h>
20
21struct gpio_decoder {
22 struct gpio_descs *input_gpios;
23 struct device *dev;
24 u32 axis;
25 u32 last_stable;
26};
27
28static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder)
29{
30 struct gpio_descs *gpios = decoder->input_gpios;
31 DECLARE_BITMAP(values, 32);
32 unsigned int size;
33 int err;
34
35 size = min(gpios->ndescs, 32U);
36 err = gpiod_get_array_value_cansleep(size, gpios->desc, gpios->info, values);
37 if (err) {
38 dev_err(decoder->dev, "Error reading GPIO: %d\n", err);
39 return err;
40 }
41
42 return bitmap_read(values, 0, size);
43}
44
45static void gpio_decoder_poll_gpios(struct input_dev *input)
46{
47 struct gpio_decoder *decoder = input_get_drvdata(input);
48 int state;
49
50 state = gpio_decoder_get_gpios_state(decoder);
51 if (state >= 0 && state != decoder->last_stable) {
52 input_report_abs(input, decoder->axis, state);
53 input_sync(input);
54 decoder->last_stable = state;
55 }
56}
57
58static int gpio_decoder_probe(struct platform_device *pdev)
59{
60 struct device *dev = &pdev->dev;
61 struct gpio_decoder *decoder;
62 struct input_dev *input;
63 u32 max;
64 int err;
65
66 decoder = devm_kzalloc(dev, sizeof(*decoder), GFP_KERNEL);
67 if (!decoder)
68 return -ENOMEM;
69
70 decoder->dev = dev;
71 device_property_read_u32(dev, "linux,axis", &decoder->axis);
72
73 decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
74 if (IS_ERR(decoder->input_gpios))
75 return dev_err_probe(dev, PTR_ERR(decoder->input_gpios),
76 "unable to acquire input gpios\n");
77
78 if (decoder->input_gpios->ndescs < 2)
79 return dev_err_probe(dev, -EINVAL, "not enough gpios found\n");
80
81 if (decoder->input_gpios->ndescs > 31)
82 return dev_err_probe(dev, -EINVAL, "too many gpios found\n");
83
84 if (device_property_read_u32(dev, "decoder-max-value", &max))
85 max = BIT(decoder->input_gpios->ndescs) - 1;
86
87 input = devm_input_allocate_device(dev);
88 if (!input)
89 return -ENOMEM;
90
91 input_set_drvdata(input, decoder);
92
93 input->name = pdev->name;
94 input->id.bustype = BUS_HOST;
95 input_set_abs_params(input, decoder->axis, 0, max, 0, 0);
96
97 err = input_setup_polling(input, gpio_decoder_poll_gpios);
98 if (err)
99 return dev_err_probe(dev, err, "failed to set up polling\n");
100
101 err = input_register_device(input);
102 if (err)
103 return dev_err_probe(dev, err, "failed to register input device\n");
104
105 return 0;
106}
107
108static const struct of_device_id gpio_decoder_of_match[] = {
109 { .compatible = "gpio-decoder", },
110 { }
111};
112MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
113
114static struct platform_driver gpio_decoder_driver = {
115 .probe = gpio_decoder_probe,
116 .driver = {
117 .name = "gpio-decoder",
118 .of_match_table = gpio_decoder_of_match,
119 }
120};
121module_platform_driver(gpio_decoder_driver);
122
123MODULE_DESCRIPTION("GPIO decoder input driver");
124MODULE_AUTHOR("Vignesh R <[email protected]>");
125MODULE_LICENSE("GPL v2");