fbdev: add support for handoff from firmware to hw framebuffers

With KMS we have ran into an issue where we really want the KMS fb driver
to be the one running the console, so panics etc can be shown by switching
out of X etc.

However with vesafb/efifb built-in, we end up with those on fb0 and the
KMS fb driver on fb1, driving the same piece of hw, so this adds an fb
info flag to denote a firmware fbdev, and adds a new aperture base/size
range which can be compared when the hw drivers are installed to see if
there is a conflict with a firmware driver, and if there is the firmware
driver is unregistered and the hw driver takes over.

It uses new aperture_base/size members instead of comparing on the fix
smem_start/length, as smem_start/length might for example only cover the
first 1MB of the PCI aperture, and we could allocate the kms fb from 8MB
into the aperture, thus they would never overlap.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Dave Airlie <airlied@redhat.com>
Acked-by: Peter Jones <pjones@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 330c4b1bfcaa..3c5562a52167 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -677,6 +677,9 @@ struct fb_ops {
         /* get capability given var */
         void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,
                             struct fb_var_screeninfo *var);
+
+        /* teardown any resources to do with this framebuffer */
+        void (*fb_destroy)(struct fb_info *info);
 };
 
 #ifdef CONFIG_FB_TILEBLITTING
@@ -786,6 +789,8 @@ struct fb_tile_ops {
 #define FBINFO_MISC_USEREVENT          0x10000 /* event request
                                                   from userspace */
 #define FBINFO_MISC_TILEBLITTING       0x20000 /* use tile blitting */
+#define FBINFO_MISC_FIRMWARE           0x40000 /* a replaceable firmware
+                                                  inited framebuffer */
 
 /* A driver may set this flag to indicate that it does want a set_par to be
  * called every time when fbcon_switch is executed. The advantage is that with
@@ -854,7 +859,12 @@ struct fb_info {
         u32 state;                      /* Hardware state i.e suspend */
         void *fbcon_par;                /* fbcon use-only private area */
         /* From here on everything is device dependent */
-        void *par;      
+        void *par;
+        /* we need the PCI or similiar aperture base/size not
+           smem_start/size as smem_start may just be an object
+           allocated inside the aperture so may not actually overlap */
+        resource_size_t aperture_base;
+        resource_size_t aperture_size;
 };
 
 #ifdef MODULE