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/*
* 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>
*/
#ifndef LINUX_VGA_H
#include <asm/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, inlcuding 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)
*/
extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
int interruptible);
/**
* 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
*/
extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
/**
* 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.
*/
extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
/**
* 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
* independant 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.
*/
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));
#endif /* LINUX_VGA_H */
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