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140 lines
3.5 KiB
140 lines
3.5 KiB
/* |
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* Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/ |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License as |
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* published by the Free Software Foundation version 2. |
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* |
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any |
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* kind, whether express or implied; without even the implied warranty |
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* A generic driver to read multiple gpio lines and translate the |
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* encoded numeric value into an input event. |
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*/ |
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#include <linux/device.h> |
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#include <linux/gpio/consumer.h> |
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#include <linux/input.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/platform_device.h> |
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struct gpio_decoder { |
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struct gpio_descs *input_gpios; |
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struct device *dev; |
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u32 axis; |
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u32 last_stable; |
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}; |
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static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder) |
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{ |
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struct gpio_descs *gpios = decoder->input_gpios; |
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unsigned int ret = 0; |
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int i, val; |
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for (i = 0; i < gpios->ndescs; i++) { |
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val = gpiod_get_value_cansleep(gpios->desc[i]); |
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if (val < 0) { |
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dev_err(decoder->dev, |
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"Error reading gpio %d: %d\n", |
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desc_to_gpio(gpios->desc[i]), val); |
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return val; |
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} |
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val = !!val; |
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ret = (ret << 1) | val; |
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} |
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return ret; |
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} |
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static void gpio_decoder_poll_gpios(struct input_dev *input) |
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{ |
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struct gpio_decoder *decoder = input_get_drvdata(input); |
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int state; |
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state = gpio_decoder_get_gpios_state(decoder); |
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if (state >= 0 && state != decoder->last_stable) { |
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input_report_abs(input, decoder->axis, state); |
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input_sync(input); |
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decoder->last_stable = state; |
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} |
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} |
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static int gpio_decoder_probe(struct platform_device *pdev) |
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{ |
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struct device *dev = &pdev->dev; |
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struct gpio_decoder *decoder; |
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struct input_dev *input; |
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u32 max; |
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int err; |
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decoder = devm_kzalloc(dev, sizeof(*decoder), GFP_KERNEL); |
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if (!decoder) |
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return -ENOMEM; |
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decoder->dev = dev; |
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device_property_read_u32(dev, "linux,axis", &decoder->axis); |
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decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN); |
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if (IS_ERR(decoder->input_gpios)) { |
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dev_err(dev, "unable to acquire input gpios\n"); |
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return PTR_ERR(decoder->input_gpios); |
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} |
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if (decoder->input_gpios->ndescs < 2) { |
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dev_err(dev, "not enough gpios found\n"); |
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return -EINVAL; |
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} |
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if (device_property_read_u32(dev, "decoder-max-value", &max)) |
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max = (1U << decoder->input_gpios->ndescs) - 1; |
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input = devm_input_allocate_device(dev); |
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if (!input) |
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return -ENOMEM; |
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input_set_drvdata(input, decoder); |
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input->name = pdev->name; |
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input->id.bustype = BUS_HOST; |
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input_set_abs_params(input, decoder->axis, 0, max, 0, 0); |
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err = input_setup_polling(input, gpio_decoder_poll_gpios); |
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if (err) { |
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dev_err(dev, "failed to set up polling\n"); |
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return err; |
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} |
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err = input_register_device(input); |
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if (err) { |
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dev_err(dev, "failed to register input device\n"); |
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return err; |
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} |
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return 0; |
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} |
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#ifdef CONFIG_OF |
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static const struct of_device_id gpio_decoder_of_match[] = { |
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{ .compatible = "gpio-decoder", }, |
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{ }, |
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}; |
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MODULE_DEVICE_TABLE(of, gpio_decoder_of_match); |
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#endif |
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static struct platform_driver gpio_decoder_driver = { |
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.probe = gpio_decoder_probe, |
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.driver = { |
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.name = "gpio-decoder", |
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.of_match_table = of_match_ptr(gpio_decoder_of_match), |
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} |
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}; |
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module_platform_driver(gpio_decoder_driver); |
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MODULE_DESCRIPTION("GPIO decoder input driver"); |
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MODULE_AUTHOR("Vignesh R <[email protected]>"); |
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MODULE_LICENSE("GPL v2");
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