211 lines
7.4 KiB
C
211 lines
7.4 KiB
C
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/*
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* The VGA aribiter manages VGA space routing and VGA resource decode to
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* allow multiple VGA devices to be used in a system in a safe way.
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*
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* (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
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* (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
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* (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
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*/
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#ifndef LINUX_VGA_H
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#include <asm/vga.h>
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/* Legacy VGA regions */
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#define VGA_RSRC_NONE 0x00
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#define VGA_RSRC_LEGACY_IO 0x01
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#define VGA_RSRC_LEGACY_MEM 0x02
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#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
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/* Non-legacy access */
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#define VGA_RSRC_NORMAL_IO 0x04
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#define VGA_RSRC_NORMAL_MEM 0x08
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/* Passing that instead of a pci_dev to use the system "default"
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* device, that is the one used by vgacon. Archs will probably
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* have to provide their own vga_default_device();
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*/
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#define VGA_DEFAULT_DEVICE (NULL)
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/* For use by clients */
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/**
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* vga_set_legacy_decoding
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*
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* @pdev: pci device of the VGA card
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* @decodes: bit mask of what legacy regions the card decodes
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*
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* Indicates to the arbiter if the card decodes legacy VGA IOs,
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* legacy VGA Memory, both, or none. All cards default to both,
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* the card driver (fbdev for example) should tell the arbiter
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* if it has disabled legacy decoding, so the card can be left
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* out of the arbitration process (and can be safe to take
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* interrupts at any time.
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*/
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extern void vga_set_legacy_decoding(struct pci_dev *pdev,
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unsigned int decodes);
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/**
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* vga_get - acquire & locks VGA resources
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*
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* @pdev: pci device of the VGA card or NULL for the system default
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* @rsrc: bit mask of resources to acquire and lock
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* @interruptible: blocking should be interruptible by signals ?
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*
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* This function acquires VGA resources for the given
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* card and mark those resources locked. If the resource requested
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* are "normal" (and not legacy) resources, the arbiter will first check
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* wether the card is doing legacy decoding for that type of resource. If
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* yes, the lock is "converted" into a legacy resource lock.
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* The arbiter will first look for all VGA cards that might conflict
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* and disable their IOs and/or Memory access, inlcuding VGA forwarding
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* on P2P bridges if necessary, so that the requested resources can
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* be used. Then, the card is marked as locking these resources and
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* the IO and/or Memory accesse are enabled on the card (including
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* VGA forwarding on parent P2P bridges if any).
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* This function will block if some conflicting card is already locking
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* one of the required resources (or any resource on a different bus
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* segment, since P2P bridges don't differenciate VGA memory and IO
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* afaik). You can indicate wether this blocking should be interruptible
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* by a signal (for userland interface) or not.
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* Must not be called at interrupt time or in atomic context.
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* If the card already owns the resources, the function succeeds.
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* Nested calls are supported (a per-resource counter is maintained)
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*/
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extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
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int interruptible);
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/**
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* vga_get_interruptible
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*
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* Shortcut to vga_get
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*/
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static inline int vga_get_interruptible(struct pci_dev *pdev,
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unsigned int rsrc)
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{
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return vga_get(pdev, rsrc, 1);
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}
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/**
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* vga_get_uninterruptible
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*
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* Shortcut to vga_get
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*/
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static inline int vga_get_uninterruptible(struct pci_dev *pdev,
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unsigned int rsrc)
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{
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return vga_get(pdev, rsrc, 0);
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}
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/**
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* vga_tryget - try to acquire & lock legacy VGA resources
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*
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* @pdev: pci devivce of VGA card or NULL for system default
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* @rsrc: bit mask of resources to acquire and lock
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*
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* This function performs the same operation as vga_get(), but
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* will return an error (-EBUSY) instead of blocking if the resources
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* are already locked by another card. It can be called in any context
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*/
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extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
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/**
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* vga_put - release lock on legacy VGA resources
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*
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* @pdev: pci device of VGA card or NULL for system default
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* @rsrc: but mask of resource to release
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*
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* This function releases resources previously locked by vga_get()
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* or vga_tryget(). The resources aren't disabled right away, so
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* that a subsequence vga_get() on the same card will succeed
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* immediately. Resources have a counter, so locks are only
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* released if the counter reaches 0.
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*/
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extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
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/**
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* vga_default_device
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*
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* This can be defined by the platform. The default implementation
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* is rather dumb and will probably only work properly on single
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* vga card setups and/or x86 platforms.
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*
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* If your VGA default device is not PCI, you'll have to return
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* NULL here. In this case, I assume it will not conflict with
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* any PCI card. If this is not true, I'll have to define two archs
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* hooks for enabling/disabling the VGA default device if that is
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* possible. This may be a problem with real _ISA_ VGA cards, in
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* addition to a PCI one. I don't know at this point how to deal
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* with that card. Can theirs IOs be disabled at all ? If not, then
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* I suppose it's a matter of having the proper arch hook telling
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* us about it, so we basically never allow anybody to succeed a
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* vga_get()...
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*/
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#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
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extern struct pci_dev *vga_default_device(void);
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#endif
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/**
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* vga_conflicts
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*
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* Architectures should define this if they have several
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* independant PCI domains that can afford concurrent VGA
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* decoding
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*/
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#ifndef __ARCH_HAS_VGA_CONFLICT
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static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
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{
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return 1;
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}
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#endif
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/**
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* vga_client_register
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*
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* @pdev: pci device of the VGA client
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* @cookie: client cookie to be used in callbacks
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* @irq_set_state: irq state change callback
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* @set_vga_decode: vga decode change callback
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*
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* return value: 0 on success, -1 on failure
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* Register a client with the VGA arbitration logic
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*
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* Clients have two callback mechanisms they can use.
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* irq enable/disable callback -
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* If a client can't disable its GPUs VGA resources, then we
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* need to be able to ask it to turn off its irqs when we
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* turn off its mem and io decoding.
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* set_vga_decode
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* If a client can disable its GPU VGA resource, it will
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* get a callback from this to set the encode/decode state
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*
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* Rationale: we cannot disable VGA decode resources unconditionally
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* some single GPU laptops seem to require ACPI or BIOS access to the
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* VGA registers to control things like backlights etc.
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* Hopefully newer multi-GPU laptops do something saner, and desktops
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* won't have any special ACPI for this.
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* They driver will get a callback when VGA arbitration is first used
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* by userspace since we some older X servers have issues.
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*/
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#if defined(CONFIG_VGA_ARB)
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int vga_client_register(struct pci_dev *pdev, void *cookie,
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void (*irq_set_state)(void *cookie, bool state),
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unsigned int (*set_vga_decode)(void *cookie, bool state));
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#else
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static inline int vga_client_register(struct pci_dev *pdev, void *cookie,
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void (*irq_set_state)(void *cookie, bool state),
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unsigned int (*set_vga_decode)(void *cookie, bool state))
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{
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return 0;
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}
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#endif
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#endif /* LINUX_VGA_H */
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