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TOMOYO Linux Cross Reference
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 
 51 struct 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  */
 68 extern 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  *     whether 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 whether 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)
100 extern int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible);
101 #else
102 static 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 
111 static 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 
123 static 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)
141 extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
142 #else
143 static 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)
160 extern 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
187 extern struct pci_dev *vga_default_device(void);
188 extern void vga_set_default_device(struct pci_dev *pdev);
189 #else
190 static inline struct pci_dev *vga_default_device(void) { return NULL; };
191 static 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
204 static 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)
239 int 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
243 static 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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