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: NDave Airlie <airlied@redhat.com>
Acked-by: NPeter Jones <pjones@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/intel_fb.c

@@ -504,6 +504,14 @@ static int intelfb_create(struct drm_device *dev, uint32_t fb_width,
 	info->fbops = &intelfb_ops;
 
 	info->fix.line_length = fb->pitch;
+
+	/* setup aperture base/size for vesafb takeover */
+	info->aperture_base = dev->mode_config.fb_base;
+	if (IS_I9XX(dev))
+		info->aperture_size = pci_resource_len(dev->pdev, 2);
+	else
+		info->aperture_size = pci_resource_len(dev->pdev, 0);
+
 	info->fix.smem_start = dev->mode_config.fb_base + obj_priv->gtt_offset;
 	info->fix.smem_len = size;
 

drivers/video/efifb.c

@@ -280,6 +280,9 @@ static int __init efifb_probe(struct platform_device *dev)
 	info->pseudo_palette = info->par;
 	info->par = NULL;
 
+	info->aperture_base = efifb_fix.smem_start;
+	info->aperture_size = size_total;
+
 	info->screen_base = ioremap(efifb_fix.smem_start, efifb_fix.smem_len);
 	if (!info->screen_base) {
 		printk(KERN_ERR "efifb: abort, cannot ioremap video memory "
@@ -337,7 +340,7 @@ static int __init efifb_probe(struct platform_device *dev)
 	info->fbops = &efifb_ops;
 	info->var = efifb_defined;
 	info->fix = efifb_fix;
-	info->flags = FBINFO_FLAG_DEFAULT;
+	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE;
 
 	if ((err = fb_alloc_cmap(&info->cmap, 256, 0)) < 0) {
 		printk(KERN_ERR "efifb: cannot allocate colormap\n");

drivers/video/fbmem.c

@@ -1462,6 +1462,16 @@ static int fb_check_foreignness(struct fb_info *fi)
 	return 0;
 }
 
+static bool fb_do_apertures_overlap(struct fb_info *gen, struct fb_info *hw)
+{
+	/* is the generic aperture base the same as the HW one */
+	if (gen->aperture_base == hw->aperture_base)
+		return true;
+	/* is the generic aperture base inside the hw base->hw base+size */
+	if (gen->aperture_base > hw->aperture_base && gen->aperture_base <= hw->aperture_base + hw->aperture_size)
+		return true;
+	return false;
+}
 /**
  *	register_framebuffer - registers a frame buffer device
  *	@fb_info: frame buffer info structure
@@ -1485,6 +1495,23 @@ register_framebuffer(struct fb_info *fb_info)
 	if (fb_check_foreignness(fb_info))
 		return -ENOSYS;
 
+	/* check all firmware fbs and kick off if the base addr overlaps */
+	for (i = 0 ; i < FB_MAX; i++) {
+		if (!registered_fb[i])
+			continue;
+
+		if (registered_fb[i]->flags & FBINFO_MISC_FIRMWARE) {
+			if (fb_do_apertures_overlap(registered_fb[i], fb_info)) {
+				printk(KERN_ERR "fb: conflicting fb hw usage "
+				       "%s vs %s - removing generic driver\n",
+				       fb_info->fix.id,
+				       registered_fb[i]->fix.id);
+				unregister_framebuffer(registered_fb[i]);
+				break;
+			}
+		}
+	}
+
 	num_registered_fb++;
 	for (i = 0 ; i < FB_MAX; i++)
 		if (!registered_fb[i])
@@ -1586,6 +1613,10 @@ unregister_framebuffer(struct fb_info *fb_info)
 	device_destroy(fb_class, MKDEV(FB_MAJOR, i));
 	event.info = fb_info;
 	fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
+
+	/* this may free fb info */
+	if (fb_info->fbops->fb_destroy)
+		fb_info->fbops->fb_destroy(fb_info);
 done:
 	return ret;
 }

drivers/video/vesafb.c

@@ -174,8 +174,17 @@ static int vesafb_setcolreg(unsigned regno, unsigned red, unsigned green,
 	return err;
 }
 
+static void vesafb_destroy(struct fb_info *info)
+{
+	if (info->screen_base)
+		iounmap(info->screen_base);
+	release_mem_region(info->aperture_base, info->aperture_size);
+	framebuffer_release(info);
+}
+
 static struct fb_ops vesafb_ops = {
 	.owner		= THIS_MODULE,
+	.fb_destroy     = vesafb_destroy,
 	.fb_setcolreg	= vesafb_setcolreg,
 	.fb_pan_display	= vesafb_pan_display,
 	.fb_fillrect	= cfb_fillrect,
@@ -286,6 +295,10 @@ static int __init vesafb_probe(struct platform_device *dev)
 	info->pseudo_palette = info->par;
 	info->par = NULL;
 
+	/* set vesafb aperture size for generic probing */
+	info->aperture_base = screen_info.lfb_base;
+	info->aperture_size = size_total;
+
 	info->screen_base = ioremap(vesafb_fix.smem_start, vesafb_fix.smem_len);
 	if (!info->screen_base) {
 		printk(KERN_ERR
@@ -437,7 +450,7 @@ static int __init vesafb_probe(struct platform_device *dev)
 	info->fbops = &vesafb_ops;
 	info->var = vesafb_defined;
 	info->fix = vesafb_fix;
-	info->flags = FBINFO_FLAG_DEFAULT |
+	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE |
 		(ypan ? FBINFO_HWACCEL_YPAN : 0);
 
 	if (!ypan)

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
@@ -855,6 +860,11 @@ struct fb_info {
 	void *fbcon_par;                /* fbcon use-only private area */
 	/* From here on everything is device dependent */
 	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