/*
   * RDC321x GPIO driver
   *
   * Copyright (C) 2008, Volker Weiss <dev@tintuc.de>
   * Copyright (C) 2007-2010 Florian Fainelli <florian@openwrt.org>
   *
   * 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, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   *
   */
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include <linux/platform_device.h>
  #include <linux/pci.h>
  #include <linux/gpio.h>
  #include <linux/mfd/rdc321x.h>
  #include <linux/slab.h>
  
  struct rdc321x_gpio {
  	spinlock_t		lock;
  	struct pci_dev		*sb_pdev;
  	u32			data_reg[2];
  	int			reg1_ctrl_base;
  	int			reg1_data_base;
  	int			reg2_ctrl_base;
  	int			reg2_data_base;
  	struct gpio_chip	chip;
  };
  
  /* read GPIO pin */
  static int rdc_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
  {
  	struct rdc321x_gpio *gpch;
  	u32 value = 0;
  	int reg;
  
  	gpch = container_of(chip, struct rdc321x_gpio, chip);
  	reg = gpio < 32 ? gpch->reg1_data_base : gpch->reg2_data_base;
  
  	spin_lock(&gpch->lock);
  	pci_write_config_dword(gpch->sb_pdev, reg,
  					gpch->data_reg[gpio < 32 ? 0 : 1]);
  	pci_read_config_dword(gpch->sb_pdev, reg, &value);
  	spin_unlock(&gpch->lock);
  
  	return (1 << (gpio & 0x1f)) & value ? 1 : 0;
  }
  
  static void rdc_gpio_set_value_impl(struct gpio_chip *chip,
  				unsigned gpio, int value)
  {
  	struct rdc321x_gpio *gpch;
  	int reg = (gpio < 32) ? 0 : 1;
  
  	gpch = container_of(chip, struct rdc321x_gpio, chip);
  
  	if (value)
  		gpch->data_reg[reg] |= 1 << (gpio & 0x1f);
  	else
  		gpch->data_reg[reg] &= ~(1 << (gpio & 0x1f));
  
  	pci_write_config_dword(gpch->sb_pdev,
  			reg ? gpch->reg2_data_base : gpch->reg1_data_base,
  			gpch->data_reg[reg]);
  }
  
  /* set GPIO pin to value */
  static void rdc_gpio_set_value(struct gpio_chip *chip,
  				unsigned gpio, int value)
  {
  	struct rdc321x_gpio *gpch;
  
  	gpch = container_of(chip, struct rdc321x_gpio, chip);
  	spin_lock(&gpch->lock);
  	rdc_gpio_set_value_impl(chip, gpio, value);
  	spin_unlock(&gpch->lock);
  }
  
  static int rdc_gpio_config(struct gpio_chip *chip,
  				unsigned gpio, int value)
  {
  	struct rdc321x_gpio *gpch;
  	int err;
  	u32 reg;
  
  	gpch = container_of(chip, struct rdc321x_gpio, chip);
  
  	spin_lock(&gpch->lock);
  	err = pci_read_config_dword(gpch->sb_pdev, gpio < 32 ?
  			gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, &reg);
  	if (err)
  		goto unlock;
  
  	reg |= 1 << (gpio & 0x1f);
  
  	err = pci_write_config_dword(gpch->sb_pdev, gpio < 32 ?
  			gpch->reg1_ctrl_base : gpch->reg2_ctrl_base, reg);
  	if (err)
  		goto unlock;
  
  	rdc_gpio_set_value_impl(chip, gpio, value);
  
  unlock:
  	spin_unlock(&gpch->lock);
  
  	return err;
  }
  
  /* configure GPIO pin as input */
  static int rdc_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
  {
  	return rdc_gpio_config(chip, gpio, 1);
  }
  
  /*
   * Cache the initial value of both GPIO data registers
   */
  static int rdc321x_gpio_probe(struct platform_device *pdev)
  {
  	int err;
  	struct resource *r;
  	struct rdc321x_gpio *rdc321x_gpio_dev;
  	struct rdc321x_gpio_pdata *pdata;
  
  	pdata = dev_get_platdata(&pdev->dev);
  	if (!pdata) {
  		dev_err(&pdev->dev, "no platform data supplied
  ");
  		return -ENODEV;
  	}
  
  	rdc321x_gpio_dev = kzalloc(sizeof(struct rdc321x_gpio), GFP_KERNEL);
  	if (!rdc321x_gpio_dev) {
  		dev_err(&pdev->dev, "failed to allocate private data
  ");
  		return -ENOMEM;
  	}
  
  	r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg1");
  	if (!r) {
  		dev_err(&pdev->dev, "failed to get gpio-reg1 resource
  ");
  		err = -ENODEV;
  		goto out_free;
  	}
  
  	spin_lock_init(&rdc321x_gpio_dev->lock);
  	rdc321x_gpio_dev->sb_pdev = pdata->sb_pdev;
  	rdc321x_gpio_dev->reg1_ctrl_base = r->start;
  	rdc321x_gpio_dev->reg1_data_base = r->start + 0x4;
  
  	r = platform_get_resource_byname(pdev, IORESOURCE_IO, "gpio-reg2");
  	if (!r) {
  		dev_err(&pdev->dev, "failed to get gpio-reg2 resource
  ");
  		err = -ENODEV;
  		goto out_free;
  	}
  
  	rdc321x_gpio_dev->reg2_ctrl_base = r->start;
  	rdc321x_gpio_dev->reg2_data_base = r->start + 0x4;
  
  	rdc321x_gpio_dev->chip.label = "rdc321x-gpio";
  	rdc321x_gpio_dev->chip.owner = THIS_MODULE;
  	rdc321x_gpio_dev->chip.direction_input = rdc_gpio_direction_input;
  	rdc321x_gpio_dev->chip.direction_output = rdc_gpio_config;
  	rdc321x_gpio_dev->chip.get = rdc_gpio_get_value;
  	rdc321x_gpio_dev->chip.set = rdc_gpio_set_value;
  	rdc321x_gpio_dev->chip.base = 0;
  	rdc321x_gpio_dev->chip.ngpio = pdata->max_gpios;
  
  	platform_set_drvdata(pdev, rdc321x_gpio_dev);
  
  	/* This might not be, what others (BIOS, bootloader, etc.)
  	   wrote to these registers before, but it's a good guess. Still
  	   better than just using 0xffffffff. */
  	err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
  					rdc321x_gpio_dev->reg1_data_base,
  					&rdc321x_gpio_dev->data_reg[0]);
  	if (err)
  		goto out_free;
  
  	err = pci_read_config_dword(rdc321x_gpio_dev->sb_pdev,
  					rdc321x_gpio_dev->reg2_data_base,
  					&rdc321x_gpio_dev->data_reg[1]);
  	if (err)
  		goto out_free;
  
  	dev_info(&pdev->dev, "registering %d GPIOs
  ",
  					rdc321x_gpio_dev->chip.ngpio);
  	return gpiochip_add(&rdc321x_gpio_dev->chip);
  
  out_free:
  	kfree(rdc321x_gpio_dev);
  	return err;
  }
  
  static int rdc321x_gpio_remove(struct platform_device *pdev)
  {
  	int ret;
  	struct rdc321x_gpio *rdc321x_gpio_dev = platform_get_drvdata(pdev);
  
  	ret = gpiochip_remove(&rdc321x_gpio_dev->chip);
  	if (ret)
  		dev_err(&pdev->dev, "failed to unregister chip
  ");
  
  	kfree(rdc321x_gpio_dev);
  
  	return ret;
  }
  
  static struct platform_driver rdc321x_gpio_driver = {
  	.driver.name	= "rdc321x-gpio",
  	.driver.owner	= THIS_MODULE,
  	.probe		= rdc321x_gpio_probe,
  	.remove		= rdc321x_gpio_remove,
  };
  
  module_platform_driver(rdc321x_gpio_driver);
  
  MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
  MODULE_DESCRIPTION("RDC321x GPIO driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:rdc321x-gpio");