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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 | /* * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/ * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation version 2. * * This program is distributed "as is" WITHOUT ANY WARRANTY of any * kind, whether express or implied; without even the implied warranty * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * 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"); |