drm: add KGDB/KDB support

Implement the callbacks for KDB entry/exit via the drm helpers.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

drivers/gpu/drm/drm_fb_helper.c

@@ -241,6 +241,80 @@ static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
 	return 0;
 }
 
+int drm_fb_helper_debug_enter(struct fb_info *info)
+{
+	struct drm_fb_helper *helper = info->par;
+	struct drm_crtc_helper_funcs *funcs;
+	int i;
+
+	if (list_empty(&kernel_fb_helper_list))
+		return false;
+
+	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
+		for (i = 0; i < helper->crtc_count; i++) {
+			struct drm_mode_set *mode_set =
+				&helper->crtc_info[i].mode_set;
+
+			if (!mode_set->crtc->enabled)
+				continue;
+
+			funcs =	mode_set->crtc->helper_private;
+			funcs->mode_set_base_atomic(mode_set->crtc,
+						    mode_set->fb,
+						    mode_set->x,
+						    mode_set->y);
+
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_debug_enter);
+
+/* Find the real fb for a given fb helper CRTC */
+static struct drm_framebuffer *drm_mode_config_fb(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_crtc *c;
+
+	list_for_each_entry(c, &dev->mode_config.crtc_list, head) {
+		if (crtc->base.id == c->base.id)
+			return c->fb;
+	}
+
+	return NULL;
+}
+
+int drm_fb_helper_debug_leave(struct fb_info *info)
+{
+	struct drm_fb_helper *helper = info->par;
+	struct drm_crtc *crtc;
+	struct drm_crtc_helper_funcs *funcs;
+	struct drm_framebuffer *fb;
+	int i;
+
+	for (i = 0; i < helper->crtc_count; i++) {
+		struct drm_mode_set *mode_set = &helper->crtc_info[i].mode_set;
+		crtc = mode_set->crtc;
+		funcs = crtc->helper_private;
+		fb = drm_mode_config_fb(crtc);
+
+		if (!crtc->enabled)
+			continue;
+
+		if (!fb) {
+			DRM_ERROR("no fb to restore??\n");
+			continue;
+		}
+
+		funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
+					    crtc->y);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_debug_leave);
+
 bool drm_fb_helper_force_kernel_mode(void)
 {
 	int i = 0;

include/drm/drm_crtc_helper.h

@@ -60,6 +60,8 @@ struct drm_crtc_helper_funcs {
 	/* Move the crtc on the current fb to the given position *optional* */
 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
 			     struct drm_framebuffer *old_fb);
+	int (*mode_set_base_atomic)(struct drm_crtc *crtc,
+				    struct drm_framebuffer *fb, int x, int y);
 
 	/* reload the current crtc LUT */
 	void (*load_lut)(struct drm_crtc *crtc);

include/drm/drm_fb_helper.h

@@ -32,6 +32,8 @@
 
 struct drm_fb_helper;
 
+#include <linux/kgdb.h>
+
 struct drm_fb_helper_crtc {
 	uint32_t crtc_id;
 	struct drm_mode_set mode_set;
@@ -78,6 +80,7 @@ struct drm_fb_helper_connector {
 
 struct drm_fb_helper {
 	struct drm_framebuffer *fb;
+	struct drm_framebuffer *saved_fb;
 	struct drm_device *dev;
 	struct drm_display_mode *mode;
 	int crtc_count;
@@ -126,5 +129,7 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
 bool drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
 bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel);
 int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper);
+int drm_fb_helper_debug_enter(struct fb_info *info);
+int drm_fb_helper_debug_leave(struct fb_info *info);
 
 #endif