/*

   * The VGA aribiter manages VGA space routing and VGA resource decode to
   * allow multiple VGA devices to be used in a system in a safe way.

   *
   * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
   * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
   * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>

   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS
   * IN THE SOFTWARE.
   *

   */
  
  #ifndef LINUX_VGA_H

  #define LINUX_VGA_H

  
  /* Legacy VGA regions */
  #define VGA_RSRC_NONE	       0x00
  #define VGA_RSRC_LEGACY_IO     0x01
  #define VGA_RSRC_LEGACY_MEM    0x02
  #define VGA_RSRC_LEGACY_MASK   (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
  /* Non-legacy access */
  #define VGA_RSRC_NORMAL_IO     0x04
  #define VGA_RSRC_NORMAL_MEM    0x08
  
  /* Passing that instead of a pci_dev to use the system "default"
   * device, that is the one used by vgacon. Archs will probably
   * have to provide their own vga_default_device();
   */
  #define VGA_DEFAULT_DEVICE     (NULL)
  
  /* For use by clients */
  
  /**
   *     vga_set_legacy_decoding
   *
   *     @pdev: pci device of the VGA card
   *     @decodes: bit mask of what legacy regions the card decodes
   *
   *     Indicates to the arbiter if the card decodes legacy VGA IOs,
   *     legacy VGA Memory, both, or none. All cards default to both,
   *     the card driver (fbdev for example) should tell the arbiter
   *     if it has disabled legacy decoding, so the card can be left
   *     out of the arbitration process (and can be safe to take
   *     interrupts at any time.
   */
  extern void vga_set_legacy_decoding(struct pci_dev *pdev,

  				    unsigned int decodes);

  
  /**
   *     vga_get         - acquire & locks VGA resources
   *

   *     @pdev: pci device of the VGA card or NULL for the system default
   *     @rsrc: bit mask of resources to acquire and lock
   *     @interruptible: blocking should be interruptible by signals ?

   *
   *     This function acquires VGA resources for the given
   *     card and mark those resources locked. If the resource requested
   *     are "normal" (and not legacy) resources, the arbiter will first check
   *     wether the card is doing legacy decoding for that type of resource. If
   *     yes, the lock is "converted" into a legacy resource lock.
   *     The arbiter will first look for all VGA cards that might conflict

   *     and disable their IOs and/or Memory access, including VGA forwarding

   *     on P2P bridges if necessary, so that the requested resources can
   *     be used. Then, the card is marked as locking these resources and
   *     the IO and/or Memory accesse are enabled on the card (including
   *     VGA forwarding on parent P2P bridges if any).
   *     This function will block if some conflicting card is already locking
   *     one of the required resources (or any resource on a different bus
   *     segment, since P2P bridges don't differenciate VGA memory and IO
   *     afaik). You can indicate wether this blocking should be interruptible
   *     by a signal (for userland interface) or not.
   *     Must not be called at interrupt time or in atomic context.
   *     If the card already owns the resources, the function succeeds.
   *     Nested calls are supported (a per-resource counter is maintained)
   */

  #if defined(CONFIG_VGA_ARB)
  extern int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible);
  #else
  static inline int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) { return 0; }
  #endif

  
  /**
   *     vga_get_interruptible
   *
   *     Shortcut to vga_get
   */
  
  static inline int vga_get_interruptible(struct pci_dev *pdev,

  					unsigned int rsrc)

  {
         return vga_get(pdev, rsrc, 1);
  }
  
  /**

   *     vga_get_uninterruptible

   *
   *     Shortcut to vga_get
   */
  
  static inline int vga_get_uninterruptible(struct pci_dev *pdev,

  					  unsigned int rsrc)

  {
         return vga_get(pdev, rsrc, 0);
  }
  
  /**
   *     vga_tryget      - try to acquire & lock legacy VGA resources
   *
   *     @pdev: pci devivce of VGA card or NULL for system default
   *     @rsrc: bit mask of resources to acquire and lock
   *
   *     This function performs the same operation as vga_get(), but
   *     will return an error (-EBUSY) instead of blocking if the resources
   *     are already locked by another card. It can be called in any context
   */

  #if defined(CONFIG_VGA_ARB)

  extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);

  #else
  static inline int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) { return 0; }
  #endif

  
  /**
   *     vga_put         - release lock on legacy VGA resources
   *
   *     @pdev: pci device of VGA card or NULL for system default
   *     @rsrc: but mask of resource to release
   *
   *     This function releases resources previously locked by vga_get()
   *     or vga_tryget(). The resources aren't disabled right away, so
   *     that a subsequence vga_get() on the same card will succeed
   *     immediately. Resources have a counter, so locks are only
   *     released if the counter reaches 0.
   */

  #if defined(CONFIG_VGA_ARB)

  extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);

  #else
  #define vga_put(pdev, rsrc)
  #endif

  
  
  /**
   *     vga_default_device
   *
   *     This can be defined by the platform. The default implementation
   *     is rather dumb and will probably only work properly on single
   *     vga card setups and/or x86 platforms.
   *
   *     If your VGA default device is not PCI, you'll have to return
   *     NULL here. In this case, I assume it will not conflict with
   *     any PCI card. If this is not true, I'll have to define two archs
   *     hooks for enabling/disabling the VGA default device if that is
   *     possible. This may be a problem with real _ISA_ VGA cards, in
   *     addition to a PCI one. I don't know at this point how to deal
   *     with that card. Can theirs IOs be disabled at all ? If not, then
   *     I suppose it's a matter of having the proper arch hook telling
   *     us about it, so we basically never allow anybody to succeed a
   *     vga_get()...
   */
  
  #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
  extern struct pci_dev *vga_default_device(void);
  #endif
  
  /**
   *     vga_conflicts
   *
   *     Architectures should define this if they have several

   *     independent PCI domains that can afford concurrent VGA

   *     decoding
   */
  
  #ifndef __ARCH_HAS_VGA_CONFLICT
  static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
  {
         return 1;
  }
  #endif

  /**
   *	vga_client_register
   *
   *	@pdev: pci device of the VGA client
   *	@cookie: client cookie to be used in callbacks
   *	@irq_set_state: irq state change callback
   *	@set_vga_decode: vga decode change callback
   *
   * 	return value: 0 on success, -1 on failure
   * 	Register a client with the VGA arbitration logic
   *
   *	Clients have two callback mechanisms they can use.
   *	irq enable/disable callback -
   *		If a client can't disable its GPUs VGA resources, then we
   *		need to be able to ask it to turn off its irqs when we
   *		turn off its mem and io decoding.
   *	set_vga_decode
   *		If a client can disable its GPU VGA resource, it will
   *		get a callback from this to set the encode/decode state

   *
   * Rationale: we cannot disable VGA decode resources unconditionally
   * some single GPU laptops seem to require ACPI or BIOS access to the
   * VGA registers to control things like backlights etc.
   * Hopefully newer multi-GPU laptops do something saner, and desktops
   * won't have any special ACPI for this.

   * They driver will get a callback when VGA arbitration is first used
   * by userspace since we some older X servers have issues.

   */

  #if defined(CONFIG_VGA_ARB)

  int vga_client_register(struct pci_dev *pdev, void *cookie,
  			void (*irq_set_state)(void *cookie, bool state),
  			unsigned int (*set_vga_decode)(void *cookie, bool state));

  #else
  static inline int vga_client_register(struct pci_dev *pdev, void *cookie,
  				      void (*irq_set_state)(void *cookie, bool state),
  				      unsigned int (*set_vga_decode)(void *cookie, bool state))
  {
  	return 0;
  }
  #endif

  
  #endif /* LINUX_VGA_H */