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/device.h> |
10 | #include <linux/gpio/consumer.h> |
11 | #include <linux/input.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/module.h> |
14 | #include <linux/of.h> |
15 | #include <linux/platform_device.h> |
16 | |
17 | struct gpio_decoder { |
18 | struct gpio_descs *input_gpios; |
19 | struct device *dev; |
20 | u32 axis; |
21 | u32 last_stable; |
22 | }; |
23 | |
24 | static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder) |
25 | { |
26 | struct gpio_descs *gpios = decoder->input_gpios; |
27 | unsigned int ret = 0; |
28 | int i, val; |
29 | |
30 | for (i = 0; i < gpios->ndescs; i++) { |
31 | val = gpiod_get_value_cansleep(desc: gpios->desc[i]); |
32 | if (val < 0) { |
33 | dev_err(decoder->dev, |
34 | "Error reading gpio %d: %d\n" , |
35 | desc_to_gpio(gpios->desc[i]), val); |
36 | return val; |
37 | } |
38 | |
39 | val = !!val; |
40 | ret = (ret << 1) | val; |
41 | } |
42 | |
43 | return ret; |
44 | } |
45 | |
46 | static void gpio_decoder_poll_gpios(struct input_dev *input) |
47 | { |
48 | struct gpio_decoder *decoder = input_get_drvdata(dev: input); |
49 | int state; |
50 | |
51 | state = gpio_decoder_get_gpios_state(decoder); |
52 | if (state >= 0 && state != decoder->last_stable) { |
53 | input_report_abs(dev: input, code: decoder->axis, value: state); |
54 | input_sync(dev: input); |
55 | decoder->last_stable = state; |
56 | } |
57 | } |
58 | |
59 | static int gpio_decoder_probe(struct platform_device *pdev) |
60 | { |
61 | struct device *dev = &pdev->dev; |
62 | struct gpio_decoder *decoder; |
63 | struct input_dev *input; |
64 | u32 max; |
65 | int err; |
66 | |
67 | decoder = devm_kzalloc(dev, size: sizeof(*decoder), GFP_KERNEL); |
68 | if (!decoder) |
69 | return -ENOMEM; |
70 | |
71 | decoder->dev = dev; |
72 | device_property_read_u32(dev, propname: "linux,axis" , val: &decoder->axis); |
73 | |
74 | decoder->input_gpios = devm_gpiod_get_array(dev, NULL, flags: GPIOD_IN); |
75 | if (IS_ERR(ptr: decoder->input_gpios)) { |
76 | dev_err(dev, "unable to acquire input gpios\n" ); |
77 | return PTR_ERR(ptr: decoder->input_gpios); |
78 | } |
79 | |
80 | if (decoder->input_gpios->ndescs < 2) { |
81 | dev_err(dev, "not enough gpios found\n" ); |
82 | return -EINVAL; |
83 | } |
84 | |
85 | if (device_property_read_u32(dev, propname: "decoder-max-value" , val: &max)) |
86 | max = (1U << decoder->input_gpios->ndescs) - 1; |
87 | |
88 | input = devm_input_allocate_device(dev); |
89 | if (!input) |
90 | return -ENOMEM; |
91 | |
92 | input_set_drvdata(dev: input, data: decoder); |
93 | |
94 | input->name = pdev->name; |
95 | input->id.bustype = BUS_HOST; |
96 | input_set_abs_params(dev: input, axis: decoder->axis, min: 0, max, fuzz: 0, flat: 0); |
97 | |
98 | err = input_setup_polling(dev: input, poll_fn: gpio_decoder_poll_gpios); |
99 | if (err) { |
100 | dev_err(dev, "failed to set up polling\n" ); |
101 | return err; |
102 | } |
103 | |
104 | err = input_register_device(input); |
105 | if (err) { |
106 | dev_err(dev, "failed to register input device\n" ); |
107 | return err; |
108 | } |
109 | |
110 | return 0; |
111 | } |
112 | |
113 | #ifdef CONFIG_OF |
114 | static const struct of_device_id gpio_decoder_of_match[] = { |
115 | { .compatible = "gpio-decoder" , }, |
116 | { }, |
117 | }; |
118 | MODULE_DEVICE_TABLE(of, gpio_decoder_of_match); |
119 | #endif |
120 | |
121 | static struct platform_driver gpio_decoder_driver = { |
122 | .probe = gpio_decoder_probe, |
123 | .driver = { |
124 | .name = "gpio-decoder" , |
125 | .of_match_table = of_match_ptr(gpio_decoder_of_match), |
126 | } |
127 | }; |
128 | module_platform_driver(gpio_decoder_driver); |
129 | |
130 | MODULE_DESCRIPTION("GPIO decoder input driver" ); |
131 | MODULE_AUTHOR("Vignesh R <vigneshr@ti.com>" ); |
132 | MODULE_LICENSE("GPL v2" ); |
133 | |