/*
   * AMD CS5535/CS5536 GPIO driver
   * Copyright (C) 2006  Advanced Micro Devices, Inc.
   * Copyright (C) 2007-2009  Andres Salomon <dilinger@collabora.co.uk>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public License
   * as published by the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/spinlock.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/gpio.h>
  #include <linux/io.h>
  #include <linux/cs5535.h>
  #include <asm/msr.h>
  
  #define DRV_NAME "cs5535-gpio"
  
  /*
   * Some GPIO pins
   *  31-29,23 : reserved (always mask out)
   *  28       : Power Button
   *  26       : PME#
   *  22-16    : LPC
   *  14,15    : SMBus
   *  9,8      : UART1
   *  7        : PCI INTB
   *  3,4      : UART2/DDC
   *  2        : IDE_IRQ0
   *  1        : AC_BEEP
   *  0        : PCI INTA
   *
   * If a mask was not specified, allow all except
   * reserved and Power Button
   */
  #define GPIO_DEFAULT_MASK 0x0F7FFFFF
  
  static ulong mask = GPIO_DEFAULT_MASK;
  module_param_named(mask, mask, ulong, 0444);
  MODULE_PARM_DESC(mask, "GPIO channel mask.");
  
  static struct cs5535_gpio_chip {
  	struct gpio_chip chip;
  	resource_size_t base;
  
  	struct platform_device *pdev;
  	spinlock_t lock;
  } cs5535_gpio_chip;
  
  /*
   * The CS5535/CS5536 GPIOs support a number of extra features not defined
   * by the gpio_chip API, so these are exported.  For a full list of the
   * registers, see include/linux/cs5535.h.
   */
  
  static void errata_outl(struct cs5535_gpio_chip *chip, u32 val,
  		unsigned int reg)
  {
  	unsigned long addr = chip->base + 0x80 + reg;
  
  	/*
  	 * According to the CS5536 errata (#36), after suspend
  	 * a write to the high bank GPIO register will clear all
  	 * non-selected bits; the recommended workaround is a
  	 * read-modify-write operation.
  	 *
  	 * Don't apply this errata to the edge status GPIOs, as writing
  	 * to their lower bits will clear them.
  	 */
  	if (reg != GPIO_POSITIVE_EDGE_STS && reg != GPIO_NEGATIVE_EDGE_STS) {
  		if (val & 0xffff)
  			val |= (inl(addr) & 0xffff); /* ignore the high bits */
  		else
  			val |= (inl(addr) ^ (val >> 16));
  	}
  	outl(val, addr);
  }
  
  static void __cs5535_gpio_set(struct cs5535_gpio_chip *chip, unsigned offset,
  		unsigned int reg)
  {
  	if (offset < 16)
  		/* low bank register */
  		outl(1 << offset, chip->base + reg);
  	else
  		/* high bank register */
  		errata_outl(chip, 1 << (offset - 16), reg);
  }
  
  void cs5535_gpio_set(unsigned offset, unsigned int reg)
  {
  	struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
  	unsigned long flags;
  
  	spin_lock_irqsave(&chip->lock, flags);
  	__cs5535_gpio_set(chip, offset, reg);
  	spin_unlock_irqrestore(&chip->lock, flags);
  }
  EXPORT_SYMBOL_GPL(cs5535_gpio_set);
  
  static void __cs5535_gpio_clear(struct cs5535_gpio_chip *chip, unsigned offset,
  		unsigned int reg)
  {
  	if (offset < 16)
  		/* low bank register */
  		outl(1 << (offset + 16), chip->base + reg);
  	else
  		/* high bank register */
  		errata_outl(chip, 1 << offset, reg);
  }
  
  void cs5535_gpio_clear(unsigned offset, unsigned int reg)
  {
  	struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
  	unsigned long flags;
  
  	spin_lock_irqsave(&chip->lock, flags);
  	__cs5535_gpio_clear(chip, offset, reg);
  	spin_unlock_irqrestore(&chip->lock, flags);
  }
  EXPORT_SYMBOL_GPL(cs5535_gpio_clear);
  
  int cs5535_gpio_isset(unsigned offset, unsigned int reg)
  {
  	struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
  	unsigned long flags;
  	long val;
  
  	spin_lock_irqsave(&chip->lock, flags);
  	if (offset < 16)
  		/* low bank register */
  		val = inl(chip->base + reg);
  	else {
  		/* high bank register */
  		val = inl(chip->base + 0x80 + reg);
  		offset -= 16;
  	}
  	spin_unlock_irqrestore(&chip->lock, flags);
  
  	return (val & (1 << offset)) ? 1 : 0;
  }
  EXPORT_SYMBOL_GPL(cs5535_gpio_isset);
  
  int cs5535_gpio_set_irq(unsigned group, unsigned irq)
  {
  	uint32_t lo, hi;
  
  	if (group > 7 || irq > 15)
  		return -EINVAL;
  
  	rdmsr(MSR_PIC_ZSEL_HIGH, lo, hi);
  
  	lo &= ~(0xF << (group * 4));
  	lo |= (irq & 0xF) << (group * 4);
  
  	wrmsr(MSR_PIC_ZSEL_HIGH, lo, hi);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(cs5535_gpio_set_irq);
  
  void cs5535_gpio_setup_event(unsigned offset, int pair, int pme)
  {
  	struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
  	uint32_t shift = (offset % 8) * 4;
  	unsigned long flags;
  	uint32_t val;
  
  	if (offset >= 24)
  		offset = GPIO_MAP_W;
  	else if (offset >= 16)
  		offset = GPIO_MAP_Z;
  	else if (offset >= 8)
  		offset = GPIO_MAP_Y;
  	else
  		offset = GPIO_MAP_X;
  
  	spin_lock_irqsave(&chip->lock, flags);
  	val = inl(chip->base + offset);
  
  	/* Clear whatever was there before */
  	val &= ~(0xF << shift);
  
  	/* Set the new value */
  	val |= ((pair & 7) << shift);
  
  	/* Set the PME bit if this is a PME event */
  	if (pme)
  		val |= (1 << (shift + 3));
  
  	outl(val, chip->base + offset);
  	spin_unlock_irqrestore(&chip->lock, flags);
  }
  EXPORT_SYMBOL_GPL(cs5535_gpio_setup_event);
  
  /*
   * Generic gpio_chip API support.
   */
  
  static int chip_gpio_request(struct gpio_chip *c, unsigned offset)
  {
  	struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
  	unsigned long flags;
  
  	spin_lock_irqsave(&chip->lock, flags);
  
  	/* check if this pin is available */
  	if ((mask & (1 << offset)) == 0) {
  		dev_info(&chip->pdev->dev,
  			"pin %u is not available (check mask)
  ", offset);
  		spin_unlock_irqrestore(&chip->lock, flags);
  		return -EINVAL;
  	}
  
  	/* disable output aux 1 & 2 on this pin */
  	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX1);
  	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX2);
  
  	/* disable input aux 1 on this pin */
  	__cs5535_gpio_clear(chip, offset, GPIO_INPUT_AUX1);
  
  	spin_unlock_irqrestore(&chip->lock, flags);
  
  	return 0;
  }
  
  static int chip_gpio_get(struct gpio_chip *chip, unsigned offset)
  {
  	return cs5535_gpio_isset(offset, GPIO_READ_BACK);
  }
  
  static void chip_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
  {
  	if (val)
  		cs5535_gpio_set(offset, GPIO_OUTPUT_VAL);
  	else
  		cs5535_gpio_clear(offset, GPIO_OUTPUT_VAL);
  }
  
  static int chip_direction_input(struct gpio_chip *c, unsigned offset)
  {
  	struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
  	unsigned long flags;
  
  	spin_lock_irqsave(&chip->lock, flags);
  	__cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
  	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_ENABLE);
  	spin_unlock_irqrestore(&chip->lock, flags);
  
  	return 0;
  }
  
  static int chip_direction_output(struct gpio_chip *c, unsigned offset, int val)
  {
  	struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
  	unsigned long flags;
  
  	spin_lock_irqsave(&chip->lock, flags);
  
  	__cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
  	__cs5535_gpio_set(chip, offset, GPIO_OUTPUT_ENABLE);
  	if (val)
  		__cs5535_gpio_set(chip, offset, GPIO_OUTPUT_VAL);
  	else
  		__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_VAL);
  
  	spin_unlock_irqrestore(&chip->lock, flags);
  
  	return 0;
  }
  
  static const char * const cs5535_gpio_names[] = {
  	"GPIO0", "GPIO1", "GPIO2", "GPIO3",
  	"GPIO4", "GPIO5", "GPIO6", "GPIO7",
  	"GPIO8", "GPIO9", "GPIO10", "GPIO11",
  	"GPIO12", "GPIO13", "GPIO14", "GPIO15",
  	"GPIO16", "GPIO17", "GPIO18", "GPIO19",
  	"GPIO20", "GPIO21", "GPIO22", NULL,
  	"GPIO24", "GPIO25", "GPIO26", "GPIO27",
  	"GPIO28", NULL, NULL, NULL,
  };
  
  static struct cs5535_gpio_chip cs5535_gpio_chip = {
  	.chip = {
  		.owner = THIS_MODULE,
  		.label = DRV_NAME,
  
  		.base = 0,
  		.ngpio = 32,
  		.names = cs5535_gpio_names,
  		.request = chip_gpio_request,
  
  		.get = chip_gpio_get,
  		.set = chip_gpio_set,
  
  		.direction_input = chip_direction_input,
  		.direction_output = chip_direction_output,
  	},
  };
  
  static int cs5535_gpio_probe(struct platform_device *pdev)
  {
  	struct resource *res;
  	int err = -EIO;
  	ulong mask_orig = mask;
  
  	/* There are two ways to get the GPIO base address; one is by
  	 * fetching it from MSR_LBAR_GPIO, the other is by reading the
  	 * PCI BAR info.  The latter method is easier (especially across
  	 * different architectures), so we'll stick with that for now.  If
  	 * it turns out to be unreliable in the face of crappy BIOSes, we
  	 * can always go back to using MSRs.. */
  
  	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
  	if (!res) {
  		dev_err(&pdev->dev, "can't fetch device resource info
  ");
  		goto done;
  	}
  
  	if (!request_region(res->start, resource_size(res), pdev->name)) {
  		dev_err(&pdev->dev, "can't request region
  ");
  		goto done;
  	}
  
  	/* set up the driver-specific struct */
  	cs5535_gpio_chip.base = res->start;
  	cs5535_gpio_chip.pdev = pdev;
  	spin_lock_init(&cs5535_gpio_chip.lock);
  
  	dev_info(&pdev->dev, "reserved resource region %pR
  ", res);
  
  	/* mask out reserved pins */
  	mask &= 0x1F7FFFFF;
  
  	/* do not allow pin 28, Power Button, as there's special handling
  	 * in the PMC needed. (note 12, p. 48) */
  	mask &= ~(1 << 28);
  
  	if (mask_orig != mask)
  		dev_info(&pdev->dev, "mask changed from 0x%08lX to 0x%08lX
  ",
  				mask_orig, mask);
  
  	/* finally, register with the generic GPIO API */
  	err = gpiochip_add(&cs5535_gpio_chip.chip);
  	if (err)
  		goto release_region;
  
  	return 0;
  
  release_region:
  	release_region(res->start, resource_size(res));
  done:
  	return err;
  }
  
  static int cs5535_gpio_remove(struct platform_device *pdev)
  {
  	struct resource *r;
  	int err;
  
  	err = gpiochip_remove(&cs5535_gpio_chip.chip);
  	if (err) {
  		/* uhh? */
  		dev_err(&pdev->dev, "unable to remove gpio_chip?
  ");
  		return err;
  	}
  
  	r = platform_get_resource(pdev, IORESOURCE_IO, 0);
  	release_region(r->start, resource_size(r));
  	return 0;
  }
  
  static struct platform_driver cs5535_gpio_driver = {
  	.driver = {
  		.name = DRV_NAME,
  		.owner = THIS_MODULE,
  	},
  	.probe = cs5535_gpio_probe,
  	.remove = cs5535_gpio_remove,
  };
  
  module_platform_driver(cs5535_gpio_driver);
  
  MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
  MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:" DRV_NAME);