drm/i915/debugfs: add a separate debugfs file for VBT

In the future the VBT might not be in mailbox #4 of the ACPI OpRegion,
thus unavailable in i915_opregion, so add a separate file for the VBT.

v2: Drop the locking as unneeded (Chris)
v3: Rebase

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450178232-27780-1-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1857,6 +1857,19 @@ static int i915_opregion(struct seq_file *m, void *unused)
 	return 0;
 }
 
+static int i915_vbt(struct seq_file *m, void *unused)
+{
+	struct drm_info_node *node = m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_opregion *opregion = &dev_priv->opregion;
+
+	if (opregion->vbt)
+		seq_write(m, opregion->vbt, opregion->vbt_size);
+
+	return 0;
+}
+
 static int i915_gem_framebuffer_info(struct seq_file *m, void *data)
 {
 	struct drm_info_node *node = m->private;
@@ -5325,6 +5338,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
 	{"i915_ips_status", i915_ips_status, 0},
 	{"i915_sr_status", i915_sr_status, 0},
 	{"i915_opregion", i915_opregion, 0},
+	{"i915_vbt", i915_vbt, 0},
 	{"i915_gem_framebuffer", i915_gem_framebuffer_info, 0},
 	{"i915_context_status", i915_context_status, 0},
 	{"i915_dump_lrc", i915_dump_lrc, 0},

drivers/gpu/drm/i915/i915_drv.h

@@ -458,6 +458,7 @@ struct intel_opregion {
 	u32 swsci_sbcb_sub_functions;
 	struct opregion_asle *asle;
 	const void *vbt;
+	u32 vbt_size;
 	u32 *lid_state;
 	struct work_struct asle_work;
 };

drivers/gpu/drm/i915/intel_opregion.c

@@ -993,6 +993,7 @@ int intel_opregion_setup(struct drm_device *dev)
 		if (intel_bios_is_valid_vbt(vbt, vbt_size)) {
 			DRM_DEBUG_KMS("Found valid VBT in ACPI OpRegion\n");
 			opregion->vbt = vbt;
+			opregion->vbt_size = vbt_size;
 		}
 	}