/*
   * GPIO driver for the TS-4800 board
   *
   * Copyright (c) 2016 - Savoir-faire Linux
   *
   * This file is licensed under the terms of the GNU General Public
   * License version 2. This program is licensed "as is" without any
   * warranty of any kind, whether express or implied.
   */
  
  #include <linux/gpio/driver.h>

  #include <linux/module.h>

  #include <linux/of_address.h>
  #include <linux/of_device.h>
  #include <linux/platform_device.h>
  
  #define DEFAULT_PIN_NUMBER      16
  #define INPUT_REG_OFFSET        0x00
  #define OUTPUT_REG_OFFSET       0x02
  #define DIRECTION_REG_OFFSET    0x04
  
  static int ts4800_gpio_probe(struct platform_device *pdev)
  {
  	struct device_node *node;
  	struct gpio_chip *chip;

  	void __iomem *base_addr;
  	int retval;
  	u32 ngpios;
  
  	chip = devm_kzalloc(&pdev->dev, sizeof(struct gpio_chip), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;

  	base_addr = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(base_addr))
  		return PTR_ERR(base_addr);
  
  	node = pdev->dev.of_node;
  	if (!node)
  		return -EINVAL;
  
  	retval = of_property_read_u32(node, "ngpios", &ngpios);
  	if (retval == -EINVAL)
  		ngpios = DEFAULT_PIN_NUMBER;
  	else if (retval)
  		return retval;
  
  	retval = bgpio_init(chip, &pdev->dev, 2, base_addr + INPUT_REG_OFFSET,
  			    base_addr + OUTPUT_REG_OFFSET, NULL,

  			    base_addr + DIRECTION_REG_OFFSET, NULL, 0);

  	if (retval) {
  		dev_err(&pdev->dev, "bgpio_init failed
  ");
  		return retval;
  	}

  	chip->ngpio = ngpios;
  
  	platform_set_drvdata(pdev, chip);

  	return devm_gpiochip_add_data(&pdev->dev, chip, NULL);

  }
  
  static const struct of_device_id ts4800_gpio_of_match[] = {
  	{ .compatible = "technologic,ts4800-gpio", },
  	{},
  };

  MODULE_DEVICE_TABLE(of, ts4800_gpio_of_match);

  
  static struct platform_driver ts4800_gpio_driver = {
  	.driver = {
  		   .name = "ts4800-gpio",
  		   .of_match_table = ts4800_gpio_of_match,
  		   },
  	.probe = ts4800_gpio_probe,

  };
  
  module_platform_driver_probe(ts4800_gpio_driver, ts4800_gpio_probe);
  
  MODULE_AUTHOR("Julien Grossholtz <julien.grossholtz@savoirfairelinux.com>");
  MODULE_DESCRIPTION("TS4800 FPGA GPIO driver");
  MODULE_LICENSE("GPL v2");