include/linux/vgaarb.h

   1 /*
   2  * The VGA aribiter manages VGA space routing and VGA resource decode to
   3  * allow multiple VGA devices to be used in a system in a safe way.
   4  *
   5  * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
   6  * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
   7  * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
   8  */
   9
  10 #ifndef LINUX_VGA_H
  11
  12 #include <asm/vga.h>
  13
  14 /* Legacy VGA regions */
  15 #define VGA_RSRC_NONE          0x00
  16 #define VGA_RSRC_LEGACY_IO     0x01
  17 #define VGA_RSRC_LEGACY_MEM    0x02
  18 #define VGA_RSRC_LEGACY_MASK   (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
  19 /* Non-legacy access */
  20 #define VGA_RSRC_NORMAL_IO     0x04
  21 #define VGA_RSRC_NORMAL_MEM    0x08
  22
  23 /* Passing that instead of a pci_dev to use the system "default"
  24  * device, that is the one used by vgacon. Archs will probably
  25  * have to provide their own vga_default_device();
  26  */
  27 #define VGA_DEFAULT_DEVICE     (NULL)
  28
  29 /* For use by clients */
  30
  31 /**
  32  *     vga_set_legacy_decoding
  33  *
  34  *     @pdev: pci device of the VGA card
  35  *     @decodes: bit mask of what legacy regions the card decodes
  36  *
  37  *     Indicates to the arbiter if the card decodes legacy VGA IOs,
  38  *     legacy VGA Memory, both, or none. All cards default to both,
  39  *     the card driver (fbdev for example) should tell the arbiter
  40  *     if it has disabled legacy decoding, so the card can be left
  41  *     out of the arbitration process (and can be safe to take
  42  *     interrupts at any time.
  43  */
  44 extern void vga_set_legacy_decoding(struct pci_dev *pdev,
  45                                     unsigned int decodes);
  46
  47 /**
  48  *     vga_get         - acquire & locks VGA resources
  49  *
  50  *     @pdev: pci device of the VGA card or NULL for the system default
  51  *     @rsrc: bit mask of resources to acquire and lock
  52  *     @interruptible: blocking should be interruptible by signals ?
  53  *
  54  *     This function acquires VGA resources for the given
  55  *     card and mark those resources locked. If the resource requested
  56  *     are "normal" (and not legacy) resources, the arbiter will first check
  57  *     wether the card is doing legacy decoding for that type of resource. If
  58  *     yes, the lock is "converted" into a legacy resource lock.
  59  *     The arbiter will first look for all VGA cards that might conflict
  60  *     and disable their IOs and/or Memory access, inlcuding VGA forwarding
  61  *     on P2P bridges if necessary, so that the requested resources can
  62  *     be used. Then, the card is marked as locking these resources and
  63  *     the IO and/or Memory accesse are enabled on the card (including
  64  *     VGA forwarding on parent P2P bridges if any).
  65  *     This function will block if some conflicting card is already locking
  66  *     one of the required resources (or any resource on a different bus
  67  *     segment, since P2P bridges don't differenciate VGA memory and IO
  68  *     afaik). You can indicate wether this blocking should be interruptible
  69  *     by a signal (for userland interface) or not.
  70  *     Must not be called at interrupt time or in atomic context.
  71  *     If the card already owns the resources, the function succeeds.
  72  *     Nested calls are supported (a per-resource counter is maintained)
  73  */
  74
  75 extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
  76                                                                                         int interruptible);
  77
  78 /**
  79  *     vga_get_interruptible
  80  *
  81  *     Shortcut to vga_get
  82  */
  83
  84 static inline int vga_get_interruptible(struct pci_dev *pdev,
  85                                         unsigned int rsrc)
  86 {
  87        return vga_get(pdev, rsrc, 1);
  88 }
  89
  90 /**
  91  *     vga_get_uninterruptible
  92  *
  93  *     Shortcut to vga_get
  94  */
  95
  96 static inline int vga_get_uninterruptible(struct pci_dev *pdev,
  97                                           unsigned int rsrc)
  98 {
  99        return vga_get(pdev, rsrc, 0);
 100 }
 101
 102 /**
 103  *     vga_tryget      - try to acquire & lock legacy VGA resources
 104  *
 105  *     @pdev: pci devivce of VGA card or NULL for system default
 106  *     @rsrc: bit mask of resources to acquire and lock
 107  *
 108  *     This function performs the same operation as vga_get(), but
 109  *     will return an error (-EBUSY) instead of blocking if the resources
 110  *     are already locked by another card. It can be called in any context
 111  */
 112
 113 extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
 114
 115 /**
 116  *     vga_put         - release lock on legacy VGA resources
 117  *
 118  *     @pdev: pci device of VGA card or NULL for system default
 119  *     @rsrc: but mask of resource to release
 120  *
 121  *     This function releases resources previously locked by vga_get()
 122  *     or vga_tryget(). The resources aren't disabled right away, so
 123  *     that a subsequence vga_get() on the same card will succeed
 124  *     immediately. Resources have a counter, so locks are only
 125  *     released if the counter reaches 0.
 126  */
 127
 128 extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 129
 130
 131 /**
 132  *     vga_default_device
 133  *
 134  *     This can be defined by the platform. The default implementation
 135  *     is rather dumb and will probably only work properly on single
 136  *     vga card setups and/or x86 platforms.
 137  *
 138  *     If your VGA default device is not PCI, you'll have to return
 139  *     NULL here. In this case, I assume it will not conflict with
 140  *     any PCI card. If this is not true, I'll have to define two archs
 141  *     hooks for enabling/disabling the VGA default device if that is
 142  *     possible. This may be a problem with real _ISA_ VGA cards, in
 143  *     addition to a PCI one. I don't know at this point how to deal
 144  *     with that card. Can theirs IOs be disabled at all ? If not, then
 145  *     I suppose it's a matter of having the proper arch hook telling
 146  *     us about it, so we basically never allow anybody to succeed a
 147  *     vga_get()...
 148  */
 149
 150 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 151 extern struct pci_dev *vga_default_device(void);
 152 #endif
 153
 154 /**
 155  *     vga_conflicts
 156  *
 157  *     Architectures should define this if they have several
 158  *     independant PCI domains that can afford concurrent VGA
 159  *     decoding
 160  */
 161
 162 #ifndef __ARCH_HAS_VGA_CONFLICT
 163 static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
 164 {
 165        return 1;
 166 }
 167 #endif
 168
 169 /**
 170  *      vga_client_register
 171  *
 172  *      @pdev: pci device of the VGA client
 173  *      @cookie: client cookie to be used in callbacks
 174  *      @irq_set_state: irq state change callback
 175  *      @set_vga_decode: vga decode change callback
 176  *
 177  *      return value: 0 on success, -1 on failure
 178  *      Register a client with the VGA arbitration logic
 179  *
 180  *      Clients have two callback mechanisms they can use.
 181  *      irq enable/disable callback -
 182  *              If a client can't disable its GPUs VGA resources, then we
 183  *              need to be able to ask it to turn off its irqs when we
 184  *              turn off its mem and io decoding.
 185  *      set_vga_decode
 186  *              If a client can disable its GPU VGA resource, it will
 187  *              get a callback from this to set the encode/decode state
 188  *
 189  * Rationale: we cannot disable VGA decode resources unconditionally
 190  * some single GPU laptops seem to require ACPI or BIOS access to the
 191  * VGA registers to control things like backlights etc.
 192  * Hopefully newer multi-GPU laptops do something saner, and desktops
 193  * won't have any special ACPI for this.
 194  * They driver will get a callback when VGA arbitration is first used
 195  * by userspace since we some older X servers have issues.
 196  */
 197 #if defined(CONFIG_VGA_ARB)
 198 int vga_client_register(struct pci_dev *pdev, void *cookie,
 199                         void (*irq_set_state)(void *cookie, bool state),
 200                         unsigned int (*set_vga_decode)(void *cookie, bool state));
 201 #else
 202 static inline int vga_client_register(struct pci_dev *pdev, void *cookie,
 203                                       void (*irq_set_state)(void *cookie, bool state),
 204                                       unsigned int (*set_vga_decode)(void *cookie, bool state))
 205 {
 206         return 0;
 207 }
 208 #endif
 209
 210 #endif /* LINUX_VGA_H */