1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index d8da30e90db5..04fa6f1808d1 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -35,6 +35,8 @@
 #include <linux/export.h>
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
+#include <video/of_videomode.h>
+#include <video/videomode.h>
 
 /**
  * drm_mode_debug_printmodeline - debug print a mode
@@ -504,6 +506,74 @@ drm_gtf_mode(struct drm_device *dev, int hdisplay, int vdisplay, int vrefresh,
 }
 EXPORT_SYMBOL(drm_gtf_mode);
 
+#if IS_ENABLED(CONFIG_VIDEOMODE)
+int drm_display_mode_from_videomode(const struct videomode *vm,
+                                    struct drm_display_mode *dmode)
+{
+        dmode->hdisplay = vm->hactive;
+        dmode->hsync_start = dmode->hdisplay + vm->hfront_porch;
+        dmode->hsync_end = dmode->hsync_start + vm->hsync_len;
+        dmode->htotal = dmode->hsync_end + vm->hback_porch;
+
+        dmode->vdisplay = vm->vactive;
+        dmode->vsync_start = dmode->vdisplay + vm->vfront_porch;
+        dmode->vsync_end = dmode->vsync_start + vm->vsync_len;
+        dmode->vtotal = dmode->vsync_end + vm->vback_porch;
+
+        dmode->clock = vm->pixelclock / 1000;
+
+        dmode->flags = 0;
+        if (vm->dmt_flags & VESA_DMT_HSYNC_HIGH)
+                dmode->flags |= DRM_MODE_FLAG_PHSYNC;
+        else if (vm->dmt_flags & VESA_DMT_HSYNC_LOW)
+                dmode->flags |= DRM_MODE_FLAG_NHSYNC;
+        if (vm->dmt_flags & VESA_DMT_VSYNC_HIGH)
+                dmode->flags |= DRM_MODE_FLAG_PVSYNC;
+        else if (vm->dmt_flags & VESA_DMT_VSYNC_LOW)
+                dmode->flags |= DRM_MODE_FLAG_NVSYNC;
+        if (vm->data_flags & DISPLAY_FLAGS_INTERLACED)
+                dmode->flags |= DRM_MODE_FLAG_INTERLACE;
+        if (vm->data_flags & DISPLAY_FLAGS_DOUBLESCAN)
+                dmode->flags |= DRM_MODE_FLAG_DBLSCAN;
+        drm_mode_set_name(dmode);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(drm_display_mode_from_videomode);
+#endif
+
+#if IS_ENABLED(CONFIG_OF_VIDEOMODE)
+/**
+ * of_get_drm_display_mode - get a drm_display_mode from devicetree
+ * @np: device_node with the timing specification
+ * @dmode: will be set to the return value
+ * @index: index into the list of display timings in devicetree
+ *
+ * This function is expensive and should only be used, if only one mode is to be
+ * read from DT. To get multiple modes start with of_get_display_timings and
+ * work with that instead.
+ */
+int of_get_drm_display_mode(struct device_node *np,
+                            struct drm_display_mode *dmode, int index)
+{
+        struct videomode vm;
+        int ret;
+
+        ret = of_get_videomode(np, &vm, index);
+        if (ret)
+                return ret;
+
+        drm_display_mode_from_videomode(&vm, dmode);
+
+        pr_debug("%s: got %dx%d display mode from %s\n",
+                of_node_full_name(np), vm.hactive, vm.vactive, np->name);
+        drm_mode_debug_printmodeline(dmode);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(of_get_drm_display_mode);
+#endif
+
 /**
  * drm_mode_set_name - set the name on a mode
  * @mode: name will be set in this mode