/*
   * AMD Promontory GPIO driver
   *
   * Copyright (C) 2015 ASMedia Technology Inc.
   * Author: YD Tseng <yd_tseng@asmedia.com.tw>
   *
   * 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/gpio/driver.h>
  #include <linux/spinlock.h>
  #include <linux/acpi.h>
  #include <linux/platform_device.h>
  
  #define PT_TOTAL_GPIO 8
  
  /* PCI-E MMIO register offsets */
  #define PT_DIRECTION_REG   0x00
  #define PT_INPUTDATA_REG   0x04
  #define PT_OUTPUTDATA_REG  0x08
  #define PT_CLOCKRATE_REG   0x0C
  #define PT_SYNC_REG        0x28
  
  struct pt_gpio_chip {
  	struct gpio_chip         gc;
  	void __iomem             *reg_base;

  };

  static int pt_gpio_request(struct gpio_chip *gc, unsigned offset)
  {

  	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);

  	unsigned long flags;
  	u32 using_pins;

  	dev_dbg(gc->parent, "pt_gpio_request offset=%x
  ", offset);

  	spin_lock_irqsave(&gc->bgpio_lock, flags);

  
  	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
  	if (using_pins & BIT(offset)) {

  		dev_warn(gc->parent, "PT GPIO pin %x reconfigured
  ",
  			 offset);

  		spin_unlock_irqrestore(&gc->bgpio_lock, flags);

  		return -EINVAL;
  	}
  
  	writel(using_pins | BIT(offset), pt_gpio->reg_base + PT_SYNC_REG);

  	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

  
  	return 0;
  }
  
  static void pt_gpio_free(struct gpio_chip *gc, unsigned offset)
  {

  	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);

  	unsigned long flags;
  	u32 using_pins;

  	spin_lock_irqsave(&gc->bgpio_lock, flags);

  
  	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
  	using_pins &= ~BIT(offset);
  	writel(using_pins, pt_gpio->reg_base + PT_SYNC_REG);

  	spin_unlock_irqrestore(&gc->bgpio_lock, flags);

  	dev_dbg(gc->parent, "pt_gpio_free offset=%x
  ", offset);

  }

  static int pt_gpio_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct acpi_device *acpi_dev;
  	acpi_handle handle = ACPI_HANDLE(dev);
  	struct pt_gpio_chip *pt_gpio;
  	struct resource *res_mem;
  	int ret = 0;
  
  	if (acpi_bus_get_device(handle, &acpi_dev)) {
  		dev_err(dev, "PT GPIO device node not found
  ");
  		return -ENODEV;
  	}
  
  	pt_gpio = devm_kzalloc(dev, sizeof(struct pt_gpio_chip), GFP_KERNEL);
  	if (!pt_gpio)
  		return -ENOMEM;
  
  	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res_mem) {
  		dev_err(&pdev->dev, "Failed to get MMIO resource for PT GPIO.
  ");
  		return -EINVAL;
  	}
  	pt_gpio->reg_base = devm_ioremap_resource(dev, res_mem);
  	if (IS_ERR(pt_gpio->reg_base)) {
  		dev_err(&pdev->dev, "Failed to map MMIO resource for PT GPIO.
  ");
  		return PTR_ERR(pt_gpio->reg_base);
  	}

  	ret = bgpio_init(&pt_gpio->gc, dev, 4,
  			 pt_gpio->reg_base + PT_INPUTDATA_REG,
  			 pt_gpio->reg_base + PT_OUTPUTDATA_REG, NULL,
  			 pt_gpio->reg_base + PT_DIRECTION_REG, NULL,
  			 BGPIOF_READ_OUTPUT_REG_SET);
  	if (ret) {
  		dev_err(&pdev->dev, "bgpio_init failed
  ");
  		return ret;
  	}

  	pt_gpio->gc.owner            = THIS_MODULE;

  	pt_gpio->gc.request          = pt_gpio_request;
  	pt_gpio->gc.free             = pt_gpio_free;

  	pt_gpio->gc.ngpio            = PT_TOTAL_GPIO;
  #if defined(CONFIG_OF_GPIO)
  	pt_gpio->gc.of_node          = pdev->dev.of_node;
  #endif

  	ret = gpiochip_add_data(&pt_gpio->gc, pt_gpio);

  	if (ret) {
  		dev_err(&pdev->dev, "Failed to register GPIO lib
  ");
  		return ret;
  	}
  
  	platform_set_drvdata(pdev, pt_gpio);
  
  	/* initialize register setting */
  	writel(0, pt_gpio->reg_base + PT_SYNC_REG);
  	writel(0, pt_gpio->reg_base + PT_CLOCKRATE_REG);
  
  	dev_dbg(&pdev->dev, "PT GPIO driver loaded
  ");
  	return ret;
  }
  
  static int pt_gpio_remove(struct platform_device *pdev)
  {
  	struct pt_gpio_chip *pt_gpio = platform_get_drvdata(pdev);
  
  	gpiochip_remove(&pt_gpio->gc);
  
  	return 0;
  }
  
  static const struct acpi_device_id pt_gpio_acpi_match[] = {
  	{ "AMDF030", 0 },

  	{ "AMDIF030", 0 },

  	{ },
  };
  MODULE_DEVICE_TABLE(acpi, pt_gpio_acpi_match);
  
  static struct platform_driver pt_gpio_driver = {
  	.driver = {
  		.name = "pt-gpio",
  		.acpi_match_table = ACPI_PTR(pt_gpio_acpi_match),
  	},
  	.probe = pt_gpio_probe,
  	.remove = pt_gpio_remove,
  };
  
  module_platform_driver(pt_gpio_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("YD Tseng <yd_tseng@asmedia.com.tw>");
  MODULE_DESCRIPTION("AMD Promontory GPIO Driver");