/*
   *  Driver for buttons on GPIO lines not capable of generating interrupts
   *
   *  Copyright (C) 2007-2010 Gabor Juhos <juhosg@openwrt.org>
   *  Copyright (C) 2010 Nuno Goncalves <nunojpg@gmail.com>
   *
   *  This file was based on: /drivers/input/misc/cobalt_btns.c
   *	Copyright (C) 2007 Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
   *
   *  also was based on: /drivers/input/keyboard/gpio_keys.c
   *	Copyright 2005 Phil Blundell
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2 as
   *  published by the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/input.h>
  #include <linux/input-polldev.h>
  #include <linux/ioport.h>
  #include <linux/platform_device.h>
  #include <linux/gpio.h>
  #include <linux/gpio/consumer.h>
  #include <linux/gpio_keys.h>
  #include <linux/property.h>
  
  #define DRV_NAME	"gpio-keys-polled"
  
  struct gpio_keys_button_data {
  	int last_state;
  	int count;
  	int threshold;
  	int can_sleep;
  };
  
  struct gpio_keys_polled_dev {
  	struct input_polled_dev *poll_dev;
  	struct device *dev;
  	const struct gpio_keys_platform_data *pdata;
  	unsigned long rel_axis_seen[BITS_TO_LONGS(REL_CNT)];
  	unsigned long abs_axis_seen[BITS_TO_LONGS(ABS_CNT)];
  	struct gpio_keys_button_data data[0];
  };
  
  static void gpio_keys_button_event(struct input_polled_dev *dev,
  				   struct gpio_keys_button *button,
  				   int state)
  {
  	struct gpio_keys_polled_dev *bdev = dev->private;
  	struct input_dev *input = dev->input;
  	unsigned int type = button->type ?: EV_KEY;
  
  	if (type == EV_REL) {
  		if (state) {
  			input_event(input, type, button->code, button->value);
  			__set_bit(button->code, bdev->rel_axis_seen);
  		}
  	} else if (type == EV_ABS) {
  		if (state) {
  			input_event(input, type, button->code, button->value);
  			__set_bit(button->code, bdev->abs_axis_seen);
  		}
  	} else {
  		input_event(input, type, button->code, state);
  		input_sync(input);
  	}
  }
  
  static void gpio_keys_polled_check_state(struct input_polled_dev *dev,
  					 struct gpio_keys_button *button,
  					 struct gpio_keys_button_data *bdata)
  {
  	int state;
  
  	if (bdata->can_sleep)
  		state = !!gpiod_get_value_cansleep(button->gpiod);
  	else
  		state = !!gpiod_get_value(button->gpiod);
  
  	gpio_keys_button_event(dev, button, state);
  
  	if (state != bdata->last_state) {
  		bdata->count = 0;
  		bdata->last_state = state;
  	}
  }
  
  static void gpio_keys_polled_poll(struct input_polled_dev *dev)
  {
  	struct gpio_keys_polled_dev *bdev = dev->private;
  	const struct gpio_keys_platform_data *pdata = bdev->pdata;
  	struct input_dev *input = dev->input;
  	int i;
  
  	memset(bdev->rel_axis_seen, 0, sizeof(bdev->rel_axis_seen));
  	memset(bdev->abs_axis_seen, 0, sizeof(bdev->abs_axis_seen));
  
  	for (i = 0; i < pdata->nbuttons; i++) {
  		struct gpio_keys_button_data *bdata = &bdev->data[i];
  
  		if (bdata->count < bdata->threshold) {
  			bdata->count++;
  			gpio_keys_button_event(dev, &pdata->buttons[i],
  					       bdata->last_state);
  		} else {
  			gpio_keys_polled_check_state(dev, &pdata->buttons[i],
  						     bdata);
  		}
  	}
  
  	for_each_set_bit(i, input->relbit, REL_CNT) {
  		if (!test_bit(i, bdev->rel_axis_seen))
  			input_event(input, EV_REL, i, 0);
  	}
  
  	for_each_set_bit(i, input->absbit, ABS_CNT) {
  		if (!test_bit(i, bdev->abs_axis_seen))
  			input_event(input, EV_ABS, i, 0);
  	}
  
  	input_sync(input);
  }
  
  static void gpio_keys_polled_open(struct input_polled_dev *dev)
  {
  	struct gpio_keys_polled_dev *bdev = dev->private;
  	const struct gpio_keys_platform_data *pdata = bdev->pdata;
  
  	if (pdata->enable)
  		pdata->enable(bdev->dev);
  }
  
  static void gpio_keys_polled_close(struct input_polled_dev *dev)
  {
  	struct gpio_keys_polled_dev *bdev = dev->private;
  	const struct gpio_keys_platform_data *pdata = bdev->pdata;
  
  	if (pdata->disable)
  		pdata->disable(bdev->dev);
  }
  
  static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct device *dev)
  {
  	struct gpio_keys_platform_data *pdata;
  	struct gpio_keys_button *button;
  	struct fwnode_handle *child;
  	int error;
  	int nbuttons;
  
  	nbuttons = device_get_child_node_count(dev);
  	if (nbuttons == 0)
  		return NULL;
  
  	pdata = devm_kzalloc(dev, sizeof(*pdata) + nbuttons * sizeof(*button),
  			     GFP_KERNEL);
  	if (!pdata)
  		return ERR_PTR(-ENOMEM);
  
  	pdata->buttons = (struct gpio_keys_button *)(pdata + 1);
  
  	pdata->rep = device_property_present(dev, "autorepeat");
  	device_property_read_u32(dev, "poll-interval", &pdata->poll_interval);
  
  	device_for_each_child_node(dev, child) {
  		struct gpio_desc *desc;
  
  		desc = devm_get_gpiod_from_child(dev, NULL, child);
  		if (IS_ERR(desc)) {
  			error = PTR_ERR(desc);
  			if (error != -EPROBE_DEFER)
  				dev_err(dev,
  					"Failed to get gpio flags, error: %d
  ",
  					error);
  			fwnode_handle_put(child);
  			return ERR_PTR(error);
  		}
  
  		button = &pdata->buttons[pdata->nbuttons++];
  		button->gpiod = desc;
  
  		if (fwnode_property_read_u32(child, "linux,code", &button->code)) {
  			dev_err(dev, "Button without keycode: %d
  ",
  				pdata->nbuttons - 1);
  			fwnode_handle_put(child);
  			return ERR_PTR(-EINVAL);
  		}
  
  		fwnode_property_read_string(child, "label", &button->desc);
  
  		if (fwnode_property_read_u32(child, "linux,input-type",
  					     &button->type))
  			button->type = EV_KEY;
  
  		if (fwnode_property_read_u32(child, "linux,input-value",
  					     (u32 *)&button->value))
  			button->value = 1;
  
  		button->wakeup =
  			fwnode_property_read_bool(child, "wakeup-source") ||
  			/* legacy name */
  			fwnode_property_read_bool(child, "gpio-key,wakeup");
  
  		if (fwnode_property_read_u32(child, "debounce-interval",
  					     &button->debounce_interval))
  			button->debounce_interval = 5;
  	}
  
  	if (pdata->nbuttons == 0)
  		return ERR_PTR(-EINVAL);
  
  	return pdata;
  }
  
  static void gpio_keys_polled_set_abs_params(struct input_dev *input,
  	const struct gpio_keys_platform_data *pdata, unsigned int code)
  {
  	int i, min = 0, max = 0;
  
  	for (i = 0; i < pdata->nbuttons; i++) {
  		struct gpio_keys_button *button = &pdata->buttons[i];
  
  		if (button->type != EV_ABS || button->code != code)
  			continue;
  
  		if (button->value < min)
  			min = button->value;
  		if (button->value > max)
  			max = button->value;
  	}
  	input_set_abs_params(input, code, min, max, 0, 0);
  }
  
  static const struct of_device_id gpio_keys_polled_of_match[] = {
  	{ .compatible = "gpio-keys-polled", },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, gpio_keys_polled_of_match);
  
  static int gpio_keys_polled_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	const struct gpio_keys_platform_data *pdata = dev_get_platdata(dev);
  	struct gpio_keys_polled_dev *bdev;
  	struct input_polled_dev *poll_dev;
  	struct input_dev *input;
  	size_t size;
  	int error;
  	int i;
  
  	if (!pdata) {
  		pdata = gpio_keys_polled_get_devtree_pdata(dev);
  		if (IS_ERR(pdata))
  			return PTR_ERR(pdata);
  		if (!pdata) {
  			dev_err(dev, "missing platform data
  ");
  			return -EINVAL;
  		}
  	}
  
  	if (!pdata->poll_interval) {
  		dev_err(dev, "missing poll_interval value
  ");
  		return -EINVAL;
  	}
  
  	size = sizeof(struct gpio_keys_polled_dev) +
  			pdata->nbuttons * sizeof(struct gpio_keys_button_data);
  	bdev = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
  	if (!bdev) {
  		dev_err(dev, "no memory for private data
  ");
  		return -ENOMEM;
  	}
  
  	poll_dev = devm_input_allocate_polled_device(&pdev->dev);
  	if (!poll_dev) {
  		dev_err(dev, "no memory for polled device
  ");
  		return -ENOMEM;
  	}
  
  	poll_dev->private = bdev;
  	poll_dev->poll = gpio_keys_polled_poll;
  	poll_dev->poll_interval = pdata->poll_interval;
  	poll_dev->open = gpio_keys_polled_open;
  	poll_dev->close = gpio_keys_polled_close;
  
  	input = poll_dev->input;
  
  	input->name = pdev->name;
  	input->phys = DRV_NAME"/input0";
  
  	input->id.bustype = BUS_HOST;
  	input->id.vendor = 0x0001;
  	input->id.product = 0x0001;
  	input->id.version = 0x0100;
  
  	__set_bit(EV_KEY, input->evbit);
  	if (pdata->rep)
  		__set_bit(EV_REP, input->evbit);
  
  	for (i = 0; i < pdata->nbuttons; i++) {
  		struct gpio_keys_button *button = &pdata->buttons[i];
  		struct gpio_keys_button_data *bdata = &bdev->data[i];
  		unsigned int type = button->type ?: EV_KEY;
  
  		if (button->wakeup) {
  			dev_err(dev, DRV_NAME " does not support wakeup
  ");
  			return -EINVAL;
  		}
  
  		/*
  		 * Legacy GPIO number so request the GPIO here and
  		 * convert it to descriptor.
  		 */
  		if (!button->gpiod && gpio_is_valid(button->gpio)) {
  			unsigned flags = GPIOF_IN;
  
  			if (button->active_low)
  				flags |= GPIOF_ACTIVE_LOW;
  
  			error = devm_gpio_request_one(&pdev->dev, button->gpio,
  					flags, button->desc ? : DRV_NAME);
  			if (error) {
  				dev_err(dev, "unable to claim gpio %u, err=%d
  ",
  					button->gpio, error);
  				return error;
  			}
  
  			button->gpiod = gpio_to_desc(button->gpio);
  		}
  
  		if (IS_ERR(button->gpiod))
  			return PTR_ERR(button->gpiod);
  
  		bdata->can_sleep = gpiod_cansleep(button->gpiod);
  		bdata->last_state = -1;
  		bdata->threshold = DIV_ROUND_UP(button->debounce_interval,
  						pdata->poll_interval);
  
  		input_set_capability(input, type, button->code);
  		if (type == EV_ABS)
  			gpio_keys_polled_set_abs_params(input, pdata,
  							button->code);
  	}
  
  	bdev->poll_dev = poll_dev;
  	bdev->dev = dev;
  	bdev->pdata = pdata;
  	platform_set_drvdata(pdev, bdev);
  
  	error = input_register_polled_device(poll_dev);
  	if (error) {
  		dev_err(dev, "unable to register polled device, err=%d
  ",
  			error);
  		return error;
  	}
  
  	/* report initial state of the buttons */
  	for (i = 0; i < pdata->nbuttons; i++)
  		gpio_keys_polled_check_state(poll_dev, &pdata->buttons[i],
  					     &bdev->data[i]);
  
  	input_sync(input);
  
  	return 0;
  }
  
  static struct platform_driver gpio_keys_polled_driver = {
  	.probe	= gpio_keys_polled_probe,
  	.driver	= {
  		.name	= DRV_NAME,
  		.of_match_table = gpio_keys_polled_of_match,
  	},
  };
  module_platform_driver(gpio_keys_polled_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
  MODULE_DESCRIPTION("Polled GPIO Buttons driver");
  MODULE_ALIAS("platform:" DRV_NAME);