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  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice (including the next
  17  * paragraph) shall be included in all copies or substantial portions of the
  18  * Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  25  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  26  * DEALINGS
  27  * IN THE SOFTWARE.
  28  *
  29  */
  30
  31 #ifndef LINUX_VGA_H
  32 #define LINUX_VGA_H
  33
  34
  35 /* Legacy VGA regions */
  36 #define VGA_RSRC_NONE          0x00
  37 #define VGA_RSRC_LEGACY_IO     0x01
  38 #define VGA_RSRC_LEGACY_MEM    0x02
  39 #define VGA_RSRC_LEGACY_MASK   (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
  40 /* Non-legacy access */
  41 #define VGA_RSRC_NORMAL_IO     0x04
  42 #define VGA_RSRC_NORMAL_MEM    0x08
  43
  44 /* Passing that instead of a pci_dev to use the system "default"
  45  * device, that is the one used by vgacon. Archs will probably
  46  * have to provide their own vga_default_device();
  47  */
  48 #define VGA_DEFAULT_DEVICE     (NULL)
  49
  50 /* For use by clients */
  51
  52 /**
  53  *     vga_set_legacy_decoding
  54  *
  55  *     @pdev: pci device of the VGA card
  56  *     @decodes: bit mask of what legacy regions the card decodes
  57  *
  58  *     Indicates to the arbiter if the card decodes legacy VGA IOs,
  59  *     legacy VGA Memory, both, or none. All cards default to both,
  60  *     the card driver (fbdev for example) should tell the arbiter
  61  *     if it has disabled legacy decoding, so the card can be left
  62  *     out of the arbitration process (and can be safe to take
  63  *     interrupts at any time.
  64  */
  65 extern void vga_set_legacy_decoding(struct pci_dev *pdev,
  66                                     unsigned int decodes);
  67
  68 /**
  69  *     vga_get         - acquire & locks VGA resources
  70  *
  71  *     @pdev: pci device of the VGA card or NULL for the system default
  72  *     @rsrc: bit mask of resources to acquire and lock
  73  *     @interruptible: blocking should be interruptible by signals ?
  74  *
  75  *     This function acquires VGA resources for the given
  76  *     card and mark those resources locked. If the resource requested
  77  *     are "normal" (and not legacy) resources, the arbiter will first check
  78  *     wether the card is doing legacy decoding for that type of resource. If
  79  *     yes, the lock is "converted" into a legacy resource lock.
  80  *     The arbiter will first look for all VGA cards that might conflict
  81  *     and disable their IOs and/or Memory access, including VGA forwarding
  82  *     on P2P bridges if necessary, so that the requested resources can
  83  *     be used. Then, the card is marked as locking these resources and
  84  *     the IO and/or Memory accesse are enabled on the card (including
  85  *     VGA forwarding on parent P2P bridges if any).
  86  *     This function will block if some conflicting card is already locking
  87  *     one of the required resources (or any resource on a different bus
  88  *     segment, since P2P bridges don't differenciate VGA memory and IO
  89  *     afaik). You can indicate wether this blocking should be interruptible
  90  *     by a signal (for userland interface) or not.
  91  *     Must not be called at interrupt time or in atomic context.
  92  *     If the card already owns the resources, the function succeeds.
  93  *     Nested calls are supported (a per-resource counter is maintained)
  94  */
  95
  96 #if defined(CONFIG_VGA_ARB)
  97 extern int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible);
  98 #else
  99 static inline int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) { return 0; }
 100 #endif
 101
 102 /**
 103  *     vga_get_interruptible
 104  *
 105  *     Shortcut to vga_get
 106  */
 107
 108 static inline int vga_get_interruptible(struct pci_dev *pdev,
 109                                         unsigned int rsrc)
 110 {
 111        return vga_get(pdev, rsrc, 1);
 112 }
 113
 114 /**
 115  *     vga_get_uninterruptible
 116  *
 117  *     Shortcut to vga_get
 118  */
 119
 120 static inline int vga_get_uninterruptible(struct pci_dev *pdev,
 121                                           unsigned int rsrc)
 122 {
 123        return vga_get(pdev, rsrc, 0);
 124 }
 125
 126 /**
 127  *     vga_tryget      - try to acquire & lock legacy VGA resources
 128  *
 129  *     @pdev: pci devivce of VGA card or NULL for system default
 130  *     @rsrc: bit mask of resources to acquire and lock
 131  *
 132  *     This function performs the same operation as vga_get(), but
 133  *     will return an error (-EBUSY) instead of blocking if the resources
 134  *     are already locked by another card. It can be called in any context
 135  */
 136
 137 #if defined(CONFIG_VGA_ARB)
 138 extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
 139 #else
 140 static inline int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) { return 0; }
 141 #endif
 142
 143 /**
 144  *     vga_put         - release lock on legacy VGA resources
 145  *
 146  *     @pdev: pci device of VGA card or NULL for system default
 147  *     @rsrc: but mask of resource to release
 148  *
 149  *     This function releases resources previously locked by vga_get()
 150  *     or vga_tryget(). The resources aren't disabled right away, so
 151  *     that a subsequence vga_get() on the same card will succeed
 152  *     immediately. Resources have a counter, so locks are only
 153  *     released if the counter reaches 0.
 154  */
 155
 156 #if defined(CONFIG_VGA_ARB)
 157 extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 158 #else
 159 #define vga_put(pdev, rsrc)
 160 #endif
 161
 162
 163 /**
 164  *     vga_default_device
 165  *
 166  *     This can be defined by the platform. The default implementation
 167  *     is rather dumb and will probably only work properly on single
 168  *     vga card setups and/or x86 platforms.
 169  *
 170  *     If your VGA default device is not PCI, you'll have to return
 171  *     NULL here. In this case, I assume it will not conflict with
 172  *     any PCI card. If this is not true, I'll have to define two archs
 173  *     hooks for enabling/disabling the VGA default device if that is
 174  *     possible. This may be a problem with real _ISA_ VGA cards, in
 175  *     addition to a PCI one. I don't know at this point how to deal
 176  *     with that card. Can theirs IOs be disabled at all ? If not, then
 177  *     I suppose it's a matter of having the proper arch hook telling
 178  *     us about it, so we basically never allow anybody to succeed a
 179  *     vga_get()...
 180  */
 181
 182 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 183 extern struct pci_dev *vga_default_device(void);
 184 #endif
 185
 186 /**
 187  *     vga_conflicts
 188  *
 189  *     Architectures should define this if they have several
 190  *     independent PCI domains that can afford concurrent VGA
 191  *     decoding
 192  */
 193
 194 #ifndef __ARCH_HAS_VGA_CONFLICT
 195 static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
 196 {
 197        return 1;
 198 }
 199 #endif
 200
 201 /**
 202  *      vga_client_register
 203  *
 204  *      @pdev: pci device of the VGA client
 205  *      @cookie: client cookie to be used in callbacks
 206  *      @irq_set_state: irq state change callback
 207  *      @set_vga_decode: vga decode change callback
 208  *
 209  *      return value: 0 on success, -1 on failure
 210  *      Register a client with the VGA arbitration logic
 211  *
 212  *      Clients have two callback mechanisms they can use.
 213  *      irq enable/disable callback -
 214  *              If a client can't disable its GPUs VGA resources, then we
 215  *              need to be able to ask it to turn off its irqs when we
 216  *              turn off its mem and io decoding.
 217  *      set_vga_decode
 218  *              If a client can disable its GPU VGA resource, it will
 219  *              get a callback from this to set the encode/decode state
 220  *
 221  * Rationale: we cannot disable VGA decode resources unconditionally
 222  * some single GPU laptops seem to require ACPI or BIOS access to the
 223  * VGA registers to control things like backlights etc.
 224  * Hopefully newer multi-GPU laptops do something saner, and desktops
 225  * won't have any special ACPI for this.
 226  * They driver will get a callback when VGA arbitration is first used
 227  * by userspace since we some older X servers have issues.
 228  */
 229 #if defined(CONFIG_VGA_ARB)
 230 int vga_client_register(struct pci_dev *pdev, void *cookie,
 231                         void (*irq_set_state)(void *cookie, bool state),
 232                         unsigned int (*set_vga_decode)(void *cookie, bool state));
 233 #else
 234 static inline int vga_client_register(struct pci_dev *pdev, void *cookie,
 235                                       void (*irq_set_state)(void *cookie, bool state),
 236                                       unsigned int (*set_vga_decode)(void *cookie, bool state))
 237 {
 238         return 0;
 239 }
 240 #endif
 241
 242 #endif /* LINUX_VGA_H */