/*
   * Copyright (C) 2013 Altera Corporation
   * Based on gpio-mpc8xxx.c
   *
   * 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; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <linux/io.h>

  #include <linux/module.h>

  #include <linux/of_gpio.h>
  #include <linux/platform_device.h>
  
  #define ALTERA_GPIO_MAX_NGPIO		32
  #define ALTERA_GPIO_DATA		0x0
  #define ALTERA_GPIO_DIR			0x4
  #define ALTERA_GPIO_IRQ_MASK		0x8
  #define ALTERA_GPIO_EDGE_CAP		0xc
  
  /**
  * struct altera_gpio_chip
  * @mmchip		: memory mapped chip structure.
  * @gpio_lock		: synchronization lock so that new irq/set/get requests
  			  will be blocked until the current one completes.
  * @interrupt_trigger	: specifies the hardware configured IRQ trigger type
  			  (rising, falling, both, high)
  * @mapped_irq		: kernel mapped irq number.
  */
  struct altera_gpio_chip {
  	struct of_mm_gpio_chip mmchip;
  	spinlock_t gpio_lock;
  	int interrupt_trigger;
  	int mapped_irq;
  };
  
  static void altera_gpio_irq_unmask(struct irq_data *d)
  {
  	struct altera_gpio_chip *altera_gc;
  	struct of_mm_gpio_chip *mm_gc;
  	unsigned long flags;
  	u32 intmask;

  	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

  	mm_gc = &altera_gc->mmchip;
  
  	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
  	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
  	/* Set ALTERA_GPIO_IRQ_MASK bit to unmask */
  	intmask |= BIT(irqd_to_hwirq(d));
  	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
  	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
  }
  
  static void altera_gpio_irq_mask(struct irq_data *d)
  {
  	struct altera_gpio_chip *altera_gc;
  	struct of_mm_gpio_chip *mm_gc;
  	unsigned long flags;
  	u32 intmask;

  	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

  	mm_gc = &altera_gc->mmchip;
  
  	spin_lock_irqsave(&altera_gc->gpio_lock, flags);
  	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
  	/* Clear ALTERA_GPIO_IRQ_MASK bit to mask */
  	intmask &= ~BIT(irqd_to_hwirq(d));
  	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
  	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);
  }
  
  /**
   * This controller's IRQ type is synthesized in hardware, so this function
   * just checks if the requested set_type matches the synthesized IRQ type
   */
  static int altera_gpio_irq_set_type(struct irq_data *d,
  				   unsigned int type)
  {
  	struct altera_gpio_chip *altera_gc;

  	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

  
  	if (type == IRQ_TYPE_NONE)
  		return 0;
  	if (type == IRQ_TYPE_LEVEL_HIGH &&
  		altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH)
  		return 0;
  	if (type == IRQ_TYPE_EDGE_RISING &&
  		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_RISING)
  		return 0;
  	if (type == IRQ_TYPE_EDGE_FALLING &&
  		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_FALLING)
  		return 0;
  	if (type == IRQ_TYPE_EDGE_BOTH &&
  		altera_gc->interrupt_trigger == IRQ_TYPE_EDGE_BOTH)
  		return 0;
  
  	return -EINVAL;
  }

  static unsigned int altera_gpio_irq_startup(struct irq_data *d)
  {

  	altera_gpio_irq_unmask(d);
  
  	return 0;
  }
  
  static struct irq_chip altera_irq_chip = {
  	.name		= "altera-gpio",
  	.irq_mask	= altera_gpio_irq_mask,
  	.irq_unmask	= altera_gpio_irq_unmask,
  	.irq_set_type	= altera_gpio_irq_set_type,
  	.irq_startup	= altera_gpio_irq_startup,
  	.irq_shutdown	= altera_gpio_irq_mask,
  };
  
  static int altera_gpio_get(struct gpio_chip *gc, unsigned offset)
  {
  	struct of_mm_gpio_chip *mm_gc;
  
  	mm_gc = to_of_mm_gpio_chip(gc);
  
  	return !!(readl(mm_gc->regs + ALTERA_GPIO_DATA) & BIT(offset));
  }
  
  static void altera_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
  {
  	struct of_mm_gpio_chip *mm_gc;
  	struct altera_gpio_chip *chip;
  	unsigned long flags;
  	unsigned int data_reg;
  
  	mm_gc = to_of_mm_gpio_chip(gc);

  	chip = gpiochip_get_data(gc);

  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
  	if (value)
  		data_reg |= BIT(offset);
  	else
  		data_reg &= ~BIT(offset);
  	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  }
  
  static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
  {
  	struct of_mm_gpio_chip *mm_gc;
  	struct altera_gpio_chip *chip;
  	unsigned long flags;
  	unsigned int gpio_ddr;
  
  	mm_gc = to_of_mm_gpio_chip(gc);

  	chip = gpiochip_get_data(gc);

  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  	/* Set pin as input, assumes software controlled IP */
  	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
  	gpio_ddr &= ~BIT(offset);
  	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  
  	return 0;
  }
  
  static int altera_gpio_direction_output(struct gpio_chip *gc,
  		unsigned offset, int value)
  {
  	struct of_mm_gpio_chip *mm_gc;
  	struct altera_gpio_chip *chip;
  	unsigned long flags;
  	unsigned int data_reg, gpio_ddr;
  
  	mm_gc = to_of_mm_gpio_chip(gc);

  	chip = gpiochip_get_data(gc);

  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  	/* Sets the GPIO value */
  	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);
  	if (value)
  		data_reg |= BIT(offset);
  	else
  		data_reg &= ~BIT(offset);
  	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);
  
  	/* Set pin as output, assumes software controlled IP */
  	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);
  	gpio_ddr |= BIT(offset);
  	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  
  	return 0;
  }

  static void altera_gpio_irq_edge_handler(struct irq_desc *desc)

  {
  	struct altera_gpio_chip *altera_gc;
  	struct irq_chip *chip;
  	struct of_mm_gpio_chip *mm_gc;
  	struct irq_domain *irqdomain;
  	unsigned long status;
  	int i;

  	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));

  	chip = irq_desc_get_chip(desc);
  	mm_gc = &altera_gc->mmchip;
  	irqdomain = altera_gc->mmchip.gc.irqdomain;
  
  	chained_irq_enter(chip, desc);
  
  	while ((status =
  	      (readl(mm_gc->regs + ALTERA_GPIO_EDGE_CAP) &
  	      readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK)))) {
  		writel(status, mm_gc->regs + ALTERA_GPIO_EDGE_CAP);
  		for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
  			generic_handle_irq(irq_find_mapping(irqdomain, i));
  		}
  	}
  
  	chained_irq_exit(chip, desc);
  }

  static void altera_gpio_irq_leveL_high_handler(struct irq_desc *desc)

  {
  	struct altera_gpio_chip *altera_gc;
  	struct irq_chip *chip;
  	struct of_mm_gpio_chip *mm_gc;
  	struct irq_domain *irqdomain;
  	unsigned long status;
  	int i;

  	altera_gc = gpiochip_get_data(irq_desc_get_handler_data(desc));

  	chip = irq_desc_get_chip(desc);
  	mm_gc = &altera_gc->mmchip;
  	irqdomain = altera_gc->mmchip.gc.irqdomain;
  
  	chained_irq_enter(chip, desc);
  
  	status = readl(mm_gc->regs + ALTERA_GPIO_DATA);
  	status &= readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
  
  	for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
  		generic_handle_irq(irq_find_mapping(irqdomain, i));
  	}
  	chained_irq_exit(chip, desc);
  }

  static int altera_gpio_probe(struct platform_device *pdev)

  {
  	struct device_node *node = pdev->dev.of_node;
  	int reg, ret;
  	struct altera_gpio_chip *altera_gc;
  
  	altera_gc = devm_kzalloc(&pdev->dev, sizeof(*altera_gc), GFP_KERNEL);
  	if (!altera_gc)
  		return -ENOMEM;
  
  	spin_lock_init(&altera_gc->gpio_lock);
  
  	if (of_property_read_u32(node, "altr,ngpio", &reg))
  		/* By default assume maximum ngpio */
  		altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
  	else
  		altera_gc->mmchip.gc.ngpio = reg;
  
  	if (altera_gc->mmchip.gc.ngpio > ALTERA_GPIO_MAX_NGPIO) {
  		dev_warn(&pdev->dev,
  			"ngpio is greater than %d, defaulting to %d
  ",
  			ALTERA_GPIO_MAX_NGPIO, ALTERA_GPIO_MAX_NGPIO);
  		altera_gc->mmchip.gc.ngpio = ALTERA_GPIO_MAX_NGPIO;
  	}
  
  	altera_gc->mmchip.gc.direction_input	= altera_gpio_direction_input;
  	altera_gc->mmchip.gc.direction_output	= altera_gpio_direction_output;
  	altera_gc->mmchip.gc.get		= altera_gpio_get;
  	altera_gc->mmchip.gc.set		= altera_gpio_set;
  	altera_gc->mmchip.gc.owner		= THIS_MODULE;

  	altera_gc->mmchip.gc.parent		= &pdev->dev;

  	ret = of_mm_gpiochip_add_data(node, &altera_gc->mmchip, altera_gc);

  	if (ret) {
  		dev_err(&pdev->dev, "Failed adding memory mapped gpiochip
  ");
  		return ret;
  	}
  
  	platform_set_drvdata(pdev, altera_gc);
  
  	altera_gc->mapped_irq = platform_get_irq(pdev, 0);
  
  	if (altera_gc->mapped_irq < 0)
  		goto skip_irq;
  
  	if (of_property_read_u32(node, "altr,interrupt-type", &reg)) {
  		ret = -EINVAL;
  		dev_err(&pdev->dev,
  			"altr,interrupt-type value not set in device tree
  ");
  		goto teardown;
  	}
  	altera_gc->interrupt_trigger = reg;
  
  	ret = gpiochip_irqchip_add(&altera_gc->mmchip.gc, &altera_irq_chip, 0,
  		handle_simple_irq, IRQ_TYPE_NONE);
  
  	if (ret) {

  		dev_err(&pdev->dev, "could not add irqchip
  ");
  		goto teardown;

  	}
  
  	gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
  		&altera_irq_chip,
  		altera_gc->mapped_irq,
  		altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH ?
  		altera_gpio_irq_leveL_high_handler :
  		altera_gpio_irq_edge_handler);
  
  skip_irq:
  	return 0;
  teardown:

  	of_mm_gpiochip_remove(&altera_gc->mmchip);

  	pr_err("%s: registration failed with status %d
  ",
  		node->full_name, ret);
  
  	return ret;
  }
  
  static int altera_gpio_remove(struct platform_device *pdev)
  {
  	struct altera_gpio_chip *altera_gc = platform_get_drvdata(pdev);

  	of_mm_gpiochip_remove(&altera_gc->mmchip);

  	return 0;

  }
  
  static const struct of_device_id altera_gpio_of_match[] = {
  	{ .compatible = "altr,pio-1.0", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, altera_gpio_of_match);
  
  static struct platform_driver altera_gpio_driver = {
  	.driver = {
  		.name	= "altera_gpio",
  		.of_match_table = of_match_ptr(altera_gpio_of_match),
  	},
  	.probe		= altera_gpio_probe,
  	.remove		= altera_gpio_remove,
  };
  
  static int __init altera_gpio_init(void)
  {
  	return platform_driver_register(&altera_gpio_driver);
  }
  subsys_initcall(altera_gpio_init);
  
  static void __exit altera_gpio_exit(void)
  {
  	platform_driver_unregister(&altera_gpio_driver);
  }
  module_exit(altera_gpio_exit);
  
  MODULE_AUTHOR("Tien Hock Loh <thloh@altera.com>");
  MODULE_DESCRIPTION("Altera GPIO driver");
  MODULE_LICENSE("GPL");