drm/panel: himax-hx8394: Add Panel Rotation Support

Add support for setting the rotation property for the Himax HX8394
panel.

Signed-off-by: Chris Morgan <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panel/panel-himax-hx8394.c

···
 	struct gpio_desc *reset_gpio;
 	struct regulator *vcc;
 	struct regulator *iovcc;
+	enum drm_panel_orientation orientation;
 
 	const struct hx8394_panel_desc *desc;
 };
···
 	return 1;
 }
 
+static enum drm_panel_orientation hx8394_get_orientation(struct drm_panel *panel)
+{
+	struct hx8394 *ctx = panel_to_hx8394(panel);
+
+	return ctx->orientation;
+}
+
 static const struct drm_panel_funcs hx8394_drm_funcs = {
 	.disable   = hx8394_disable,
 	.unprepare = hx8394_unprepare,
 	.prepare   = hx8394_prepare,
 	.enable	   = hx8394_enable,
 	.get_modes = hx8394_get_modes,
+	.get_orientation = hx8394_get_orientation,
 };
 
 static int hx8394_probe(struct mipi_dsi_device *dsi)
···
 	if (IS_ERR(ctx->reset_gpio))
 		return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
 				     "Failed to get reset gpio\n");
+
+	ret = of_drm_get_panel_orientation(dev->of_node, &ctx->orientation);
+	if (ret < 0) {
+		dev_err(dev, "%pOF: failed to get orientation %d\n", dev->of_node, ret);
+		return ret;
+	}
 
 	mipi_dsi_set_drvdata(dsi, ctx);