/*
   * Xilinx gpio driver for xps/axi_gpio IP.
   *
   * Copyright 2008 - 2013 Xilinx, Inc.
   *
   * 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.
   *
   * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include <linux/bitops.h>
  #include <linux/init.h>
  #include <linux/errno.h>
  #include <linux/module.h>
  #include <linux/of_device.h>
  #include <linux/of_platform.h>
  #include <linux/of_gpio.h>
  #include <linux/io.h>
  #include <linux/gpio.h>
  #include <linux/slab.h>
  
  /* Register Offset Definitions */
  #define XGPIO_DATA_OFFSET   (0x0)	/* Data register  */
  #define XGPIO_TRI_OFFSET    (0x4)	/* I/O direction register  */
  
  #define XGPIO_CHANNEL_OFFSET	0x8
  
  /* Read/Write access to the GPIO registers */
  #ifdef CONFIG_ARCH_ZYNQ
  # define xgpio_readreg(offset)		readl(offset)
  # define xgpio_writereg(offset, val)	writel(val, offset)
  #else
  # define xgpio_readreg(offset)		__raw_readl(offset)
  # define xgpio_writereg(offset, val)	__raw_writel(val, offset)
  #endif
  
  /**
   * struct xgpio_instance - Stores information about GPIO device
   * struct of_mm_gpio_chip mmchip: OF GPIO chip for memory mapped banks
   * gpio_state: GPIO state shadow register
   * gpio_dir: GPIO direction shadow register
   * offset: GPIO channel offset
   * gpio_lock: Lock used for synchronization
   */
  struct xgpio_instance {
  	struct of_mm_gpio_chip mmchip;
  	u32 gpio_state;
  	u32 gpio_dir;
  	u32 offset;
  	spinlock_t gpio_lock;
  };
  
  /**
   * xgpio_get - Read the specified signal of the GPIO device.
   * @gc:     Pointer to gpio_chip device structure.
   * @gpio:   GPIO signal number.
   *
   * This function reads the specified signal of the GPIO device. It returns 0 if
   * the signal clear, 1 if signal is set or negative value on error.
   */
  static int xgpio_get(struct gpio_chip *gc, unsigned int gpio)
  {
  	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  	struct xgpio_instance *chip =
  	    container_of(mm_gc, struct xgpio_instance, mmchip);
  
  	void __iomem *regs = mm_gc->regs + chip->offset;
  
  	return !!(xgpio_readreg(regs + XGPIO_DATA_OFFSET) & BIT(gpio));
  }
  
  /**
   * xgpio_set - Write the specified signal of the GPIO device.
   * @gc:     Pointer to gpio_chip device structure.
   * @gpio:   GPIO signal number.
   * @val:    Value to be written to specified signal.
   *
   * This function writes the specified value in to the specified signal of the
   * GPIO device.
   */
  static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
  {
  	unsigned long flags;
  	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  	struct xgpio_instance *chip =
  	    container_of(mm_gc, struct xgpio_instance, mmchip);
  	void __iomem *regs = mm_gc->regs;
  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  
  	/* Write to GPIO signal and set its direction to output */
  	if (val)
  		chip->gpio_state |= BIT(gpio);
  	else
  		chip->gpio_state &= ~BIT(gpio);
  
  	xgpio_writereg(regs + chip->offset + XGPIO_DATA_OFFSET,
  							 chip->gpio_state);
  
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  }
  
  /**
   * xgpio_dir_in - Set the direction of the specified GPIO signal as input.
   * @gc:     Pointer to gpio_chip device structure.
   * @gpio:   GPIO signal number.
   *
   * This function sets the direction of specified GPIO signal as input.
   * It returns 0 if direction of GPIO signals is set as input otherwise it
   * returns negative error value.
   */
  static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
  {
  	unsigned long flags;
  	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  	struct xgpio_instance *chip =
  	    container_of(mm_gc, struct xgpio_instance, mmchip);
  	void __iomem *regs = mm_gc->regs;
  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  
  	/* Set the GPIO bit in shadow register and set direction as input */
  	chip->gpio_dir |= BIT(gpio);
  	xgpio_writereg(regs + chip->offset + XGPIO_TRI_OFFSET, chip->gpio_dir);
  
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  
  	return 0;
  }
  
  /**
   * xgpio_dir_out - Set the direction of the specified GPIO signal as output.
   * @gc:     Pointer to gpio_chip device structure.
   * @gpio:   GPIO signal number.
   * @val:    Value to be written to specified signal.
   *
   * This function sets the direction of specified GPIO signal as output. If all
   * GPIO signals of GPIO chip is configured as input then it returns
   * error otherwise it returns 0.
   */
  static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
  {
  	unsigned long flags;
  	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
  	struct xgpio_instance *chip =
  	    container_of(mm_gc, struct xgpio_instance, mmchip);
  	void __iomem *regs = mm_gc->regs;
  
  	spin_lock_irqsave(&chip->gpio_lock, flags);
  
  	/* Write state of GPIO signal */
  	if (val)
  		chip->gpio_state |= BIT(gpio);
  	else
  		chip->gpio_state &= ~BIT(gpio);
  	xgpio_writereg(regs + chip->offset + XGPIO_DATA_OFFSET,
  		       chip->gpio_state);
  
  	/* Clear the GPIO bit in shadow register and set direction as output */
  	chip->gpio_dir &= ~BIT(gpio);
  	xgpio_writereg(regs + chip->offset + XGPIO_TRI_OFFSET, chip->gpio_dir);
  
  	spin_unlock_irqrestore(&chip->gpio_lock, flags);
  
  	return 0;
  }
  
  /**
   * xgpio_save_regs - Set initial values of GPIO pins
   * @mm_gc: pointer to memory mapped GPIO chip structure
   */
  static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc)
  {
  	struct xgpio_instance *chip =
  	    container_of(mm_gc, struct xgpio_instance, mmchip);
  
  	xgpio_writereg(mm_gc->regs + chip->offset + XGPIO_DATA_OFFSET,
  							chip->gpio_state);
  	xgpio_writereg(mm_gc->regs + chip->offset + XGPIO_TRI_OFFSET,
  							 chip->gpio_dir);
  }
  
  /**
   * xgpio_of_probe - Probe method for the GPIO device.
   * @np: pointer to device tree node
   *
   * This function probes the GPIO device in the device tree. It initializes the
   * driver data structure. It returns 0, if the driver is bound to the GPIO
   * device, or a negative value if there is an error.
   */
  static int xgpio_of_probe(struct device_node *np)
  {
  	struct xgpio_instance *chip;
  	int status = 0;
  	const u32 *tree_info;
  
  	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;
  
  	/* Update GPIO state shadow register with default value */
  	of_property_read_u32(np, "xlnx,dout-default", &chip->gpio_state);
  
  	/* By default, all pins are inputs */
  	chip->gpio_dir = 0xFFFFFFFF;
  
  	/* Update GPIO direction shadow register with default value */
  	of_property_read_u32(np, "xlnx,tri-default", &chip->gpio_dir);
  
  	/* By default assume full GPIO controller */
  	chip->mmchip.gc.ngpio = 32;
  
  	/* Check device node and parent device node for device width */
  	of_property_read_u32(np, "xlnx,gpio-width",
  			      (u32 *)&chip->mmchip.gc.ngpio);
  
  	spin_lock_init(&chip->gpio_lock);
  
  	chip->mmchip.gc.direction_input = xgpio_dir_in;
  	chip->mmchip.gc.direction_output = xgpio_dir_out;
  	chip->mmchip.gc.get = xgpio_get;
  	chip->mmchip.gc.set = xgpio_set;
  
  	chip->mmchip.save_regs = xgpio_save_regs;
  
  	/* Call the OF gpio helper to setup and register the GPIO device */
  	status = of_mm_gpiochip_add(np, &chip->mmchip);
  	if (status) {
  		kfree(chip);
  		pr_err("%s: error in probe function with status %d
  ",
  		       np->full_name, status);
  		return status;
  	}
  
  	pr_info("XGpio: %s: registered, base is %d
  ", np->full_name,
  							chip->mmchip.gc.base);
  
  	tree_info = of_get_property(np, "xlnx,is-dual", NULL);
  	if (tree_info && be32_to_cpup(tree_info)) {
  		chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  		if (!chip)
  			return -ENOMEM;
  
  		/* Add dual channel offset */
  		chip->offset = XGPIO_CHANNEL_OFFSET;
  
  		/* Update GPIO state shadow register with default value */
  		of_property_read_u32(np, "xlnx,dout-default-2",
  				     &chip->gpio_state);
  
  		/* By default, all pins are inputs */
  		chip->gpio_dir = 0xFFFFFFFF;
  
  		/* Update GPIO direction shadow register with default value */
  		of_property_read_u32(np, "xlnx,tri-default-2", &chip->gpio_dir);
  
  		/* By default assume full GPIO controller */
  		chip->mmchip.gc.ngpio = 32;
  
  		/* Check device node and parent device node for device width */
  		of_property_read_u32(np, "xlnx,gpio2-width",
  				     (u32 *)&chip->mmchip.gc.ngpio);
  
  		spin_lock_init(&chip->gpio_lock);
  
  		chip->mmchip.gc.direction_input = xgpio_dir_in;
  		chip->mmchip.gc.direction_output = xgpio_dir_out;
  		chip->mmchip.gc.get = xgpio_get;
  		chip->mmchip.gc.set = xgpio_set;
  
  		chip->mmchip.save_regs = xgpio_save_regs;
  
  		/* Call the OF gpio helper to setup and register the GPIO dev */
  		status = of_mm_gpiochip_add(np, &chip->mmchip);
  		if (status) {
  			kfree(chip);
  			pr_err("%s: error in probe function with status %d
  ",
  			np->full_name, status);
  			return status;
  		}
  		pr_info("XGpio: %s: dual channel registered, base is %d
  ",
  					np->full_name, chip->mmchip.gc.base);
  	}
  
  	return 0;
  }
  
  static struct of_device_id xgpio_of_match[] = {
  	{ .compatible = "xlnx,xps-gpio-1.00.a", },
  	{ /* end of list */ },
  };
  
  static int __init xgpio_init(void)
  {
  	struct device_node *np;
  
  	for_each_matching_node(np, xgpio_of_match)
  		xgpio_of_probe(np);
  
  	return 0;
  }
  
  /* Make sure we get initialized before anyone else tries to use us */
  subsys_initcall(xgpio_init);
  /* No exit call at the moment as we cannot unregister of GPIO chips */
  
  MODULE_AUTHOR("Xilinx, Inc.");
  MODULE_DESCRIPTION("Xilinx GPIO driver");
  MODULE_LICENSE("GPL");