linux/include/linux/vgaarb.h
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   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#include <video/vga.h>
  35
  36/* Legacy VGA regions */
  37#define VGA_RSRC_NONE          0x00
  38#define VGA_RSRC_LEGACY_IO     0x01
  39#define VGA_RSRC_LEGACY_MEM    0x02
  40#define VGA_RSRC_LEGACY_MASK   (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
  41/* Non-legacy access */
  42#define VGA_RSRC_NORMAL_IO     0x04
  43#define VGA_RSRC_NORMAL_MEM    0x08
  44
  45/* Passing that instead of a pci_dev to use the system "default"
  46 * device, that is the one used by vgacon. Archs will probably
  47 * have to provide their own vga_default_device();
  48 */
  49#define VGA_DEFAULT_DEVICE     (NULL)
  50
  51struct pci_dev;
  52
  53/* For use by clients */
  54
  55/**
  56 *     vga_set_legacy_decoding
  57 *
  58 *     @pdev: pci device of the VGA card
  59 *     @decodes: bit mask of what legacy regions the card decodes
  60 *
  61 *     Indicates to the arbiter if the card decodes legacy VGA IOs,
  62 *     legacy VGA Memory, both, or none. All cards default to both,
  63 *     the card driver (fbdev for example) should tell the arbiter
  64 *     if it has disabled legacy decoding, so the card can be left
  65 *     out of the arbitration process (and can be safe to take
  66 *     interrupts at any time.
  67 */
  68extern void vga_set_legacy_decoding(struct pci_dev *pdev,
  69                                    unsigned int decodes);
  70
  71/**
  72 *     vga_get         - acquire & locks VGA resources
  73 *
  74 *     @pdev: pci device of the VGA card or NULL for the system default
  75 *     @rsrc: bit mask of resources to acquire and lock
  76 *     @interruptible: blocking should be interruptible by signals ?
  77 *
  78 *     This function acquires VGA resources for the given
  79 *     card and mark those resources locked. If the resource requested
  80 *     are "normal" (and not legacy) resources, the arbiter will first check
  81 *     wether the card is doing legacy decoding for that type of resource. If
  82 *     yes, the lock is "converted" into a legacy resource lock.
  83 *     The arbiter will first look for all VGA cards that might conflict
  84 *     and disable their IOs and/or Memory access, including VGA forwarding
  85 *     on P2P bridges if necessary, so that the requested resources can
  86 *     be used. Then, the card is marked as locking these resources and
  87 *     the IO and/or Memory accesse are enabled on the card (including
  88 *     VGA forwarding on parent P2P bridges if any).
  89 *     This function will block if some conflicting card is already locking
  90 *     one of the required resources (or any resource on a different bus
  91 *     segment, since P2P bridges don't differenciate VGA memory and IO
  92 *     afaik). You can indicate wether this blocking should be interruptible
  93 *     by a signal (for userland interface) or not.
  94 *     Must not be called at interrupt time or in atomic context.
  95 *     If the card already owns the resources, the function succeeds.
  96 *     Nested calls are supported (a per-resource counter is maintained)
  97 */
  98
  99#if defined(CONFIG_VGA_ARB)
 100extern int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible);
 101#else
 102static inline int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) { return 0; }
 103#endif
 104
 105/**
 106 *     vga_get_interruptible
 107 *
 108 *     Shortcut to vga_get
 109 */
 110
 111static inline int vga_get_interruptible(struct pci_dev *pdev,
 112                                        unsigned int rsrc)
 113{
 114       return vga_get(pdev, rsrc, 1);
 115}
 116
 117/**
 118 *     vga_get_uninterruptible
 119 *
 120 *     Shortcut to vga_get
 121 */
 122
 123static inline int vga_get_uninterruptible(struct pci_dev *pdev,
 124                                          unsigned int rsrc)
 125{
 126       return vga_get(pdev, rsrc, 0);
 127}
 128
 129/**
 130 *     vga_tryget      - try to acquire & lock legacy VGA resources
 131 *
 132 *     @pdev: pci devivce of VGA card or NULL for system default
 133 *     @rsrc: bit mask of resources to acquire and lock
 134 *
 135 *     This function performs the same operation as vga_get(), but
 136 *     will return an error (-EBUSY) instead of blocking if the resources
 137 *     are already locked by another card. It can be called in any context
 138 */
 139
 140#if defined(CONFIG_VGA_ARB)
 141extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
 142#else
 143static inline int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) { return 0; }
 144#endif
 145
 146/**
 147 *     vga_put         - release lock on legacy VGA resources
 148 *
 149 *     @pdev: pci device of VGA card or NULL for system default
 150 *     @rsrc: but mask of resource to release
 151 *
 152 *     This function releases resources previously locked by vga_get()
 153 *     or vga_tryget(). The resources aren't disabled right away, so
 154 *     that a subsequence vga_get() on the same card will succeed
 155 *     immediately. Resources have a counter, so locks are only
 156 *     released if the counter reaches 0.
 157 */
 158
 159#if defined(CONFIG_VGA_ARB)
 160extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 161#else
 162#define vga_put(pdev, rsrc)
 163#endif
 164
 165
 166/**
 167 *     vga_default_device
 168 *
 169 *     This can be defined by the platform. The default implementation
 170 *     is rather dumb and will probably only work properly on single
 171 *     vga card setups and/or x86 platforms.
 172 *
 173 *     If your VGA default device is not PCI, you'll have to return
 174 *     NULL here. In this case, I assume it will not conflict with
 175 *     any PCI card. If this is not true, I'll have to define two archs
 176 *     hooks for enabling/disabling the VGA default device if that is
 177 *     possible. This may be a problem with real _ISA_ VGA cards, in
 178 *     addition to a PCI one. I don't know at this point how to deal
 179 *     with that card. Can theirs IOs be disabled at all ? If not, then
 180 *     I suppose it's a matter of having the proper arch hook telling
 181 *     us about it, so we basically never allow anybody to succeed a
 182 *     vga_get()...
 183 */
 184
 185#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 186#ifdef CONFIG_VGA_ARB
 187extern struct pci_dev *vga_default_device(void);
 188extern void vga_set_default_device(struct pci_dev *pdev);
 189#else
 190static inline struct pci_dev *vga_default_device(void) { return NULL; };
 191static inline void vga_set_default_device(struct pci_dev *pdev) { };
 192#endif
 193#endif
 194
 195/**
 196 *     vga_conflicts
 197 *
 198 *     Architectures should define this if they have several
 199 *     independent PCI domains that can afford concurrent VGA
 200 *     decoding
 201 */
 202
 203#ifndef __ARCH_HAS_VGA_CONFLICT
 204static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
 205{
 206       return 1;
 207}
 208#endif
 209
 210/**
 211 *      vga_client_register
 212 *
 213 *      @pdev: pci device of the VGA client
 214 *      @cookie: client cookie to be used in callbacks
 215 *      @irq_set_state: irq state change callback
 216 *      @set_vga_decode: vga decode change callback
 217 *
 218 *      return value: 0 on success, -1 on failure
 219 *      Register a client with the VGA arbitration logic
 220 *
 221 *      Clients have two callback mechanisms they can use.
 222 *      irq enable/disable callback -
 223 *              If a client can't disable its GPUs VGA resources, then we
 224 *              need to be able to ask it to turn off its irqs when we
 225 *              turn off its mem and io decoding.
 226 *      set_vga_decode
 227 *              If a client can disable its GPU VGA resource, it will
 228 *              get a callback from this to set the encode/decode state
 229 *
 230 * Rationale: we cannot disable VGA decode resources unconditionally
 231 * some single GPU laptops seem to require ACPI or BIOS access to the
 232 * VGA registers to control things like backlights etc.
 233 * Hopefully newer multi-GPU laptops do something saner, and desktops
 234 * won't have any special ACPI for this.
 235 * They driver will get a callback when VGA arbitration is first used
 236 * by userspace since we some older X servers have issues.
 237 */
 238#if defined(CONFIG_VGA_ARB)
 239int vga_client_register(struct pci_dev *pdev, void *cookie,
 240                        void (*irq_set_state)(void *cookie, bool state),
 241                        unsigned int (*set_vga_decode)(void *cookie, bool state));
 242#else
 243static inline int vga_client_register(struct pci_dev *pdev, void *cookie,
 244                                      void (*irq_set_state)(void *cookie, bool state),
 245                                      unsigned int (*set_vga_decode)(void *cookie, bool state))
 246{
 247        return 0;
 248}
 249#endif
 250
 251#endif /* LINUX_VGA_H */
 252
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