video: Allow temporary colour changes

It is sometimes necessary to highlight some text in a different colour.
Add an easy way to do this and then restore the original console colours.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
index a21fde0..3f89537 100644
--- a/drivers/video/vidconsole-uclass.c
+++ b/drivers/video/vidconsole-uclass.c
@@ -596,6 +596,26 @@
 	return ops->select_font(dev, name, size);
 }
 
+void vidconsole_push_colour(struct udevice *dev, enum colour_idx fg,
+			    enum colour_idx bg, struct vidconsole_colour *old)
+{
+	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
+
+	old->colour_fg = vid_priv->colour_fg;
+	old->colour_bg = vid_priv->colour_bg;
+
+	vid_priv->colour_fg = video_index_to_colour(vid_priv, fg);
+	vid_priv->colour_bg = video_index_to_colour(vid_priv, bg);
+}
+
+void vidconsole_pop_colour(struct udevice *dev, struct vidconsole_colour *old)
+{
+	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
+
+	vid_priv->colour_fg = old->colour_fg;
+	vid_priv->colour_bg = old->colour_bg;
+}
+
 /* Set up the number of rows and colours (rotated drivers override this) */
 static int vidconsole_pre_probe(struct udevice *dev)
 {
diff --git a/include/video_console.h b/include/video_console.h
index 3db9a7e..81d4c4d 100644
--- a/include/video_console.h
+++ b/include/video_console.h
@@ -72,6 +72,17 @@
 };
 
 /**
+ * struct vidconsole_colour - Holds colour information
+ *
+ * @colour_fg:	Foreground colour (pixel value)
+ * @colour_bg:	Background colour (pixel value)
+ */
+struct vidconsole_colour {
+	u32 colour_fg;
+	u32 colour_bg;
+};
+
+/**
  * struct vidconsole_ops - Video console operations
  *
  * These operations work on either an absolute console position (measured
@@ -205,6 +216,25 @@
 int vidconsole_select_font(struct udevice *dev, const char *name, uint size);
 
 /**
+ * vidconsole_push_colour() - Temporarily change the font colour
+ *
+ * @dev:	Device to adjust
+ * @fg:		Foreground colour to select
+ * @bg:		Background colour to select
+ * @old:	Place to store the current colour, so it can be restored
+ */
+void vidconsole_push_colour(struct udevice *dev, enum colour_idx fg,
+			    enum colour_idx bg, struct vidconsole_colour *old);
+
+/**
+ * vidconsole_pop_colour() - Restore the original colour
+ *
+ * @dev:	Device to adjust
+ * @old:	Old colour to be restored
+ */
+void vidconsole_pop_colour(struct udevice *dev, struct vidconsole_colour *old);
+
+/**
  * vidconsole_putc_xy() - write a single character to a position
  *
  * @dev:	Device to write to