drm: rcar-du: lvds: Add API to enable/disable clock output

On the D3 and E3 platforms, the LVDS internal PLL supplies the pixel
clock to the DU. This works automatically for LVDS outputs as the LVDS
encoder is enabled through the bridge API, enabling the internal PLL and
clock output. However, when using the DU DPAD output with the LVDS
outputs turned off, the LVDS PLL needs to be controlled manually. Add an
API to do so, to be called by the DU driver.

The drivers/gpu/drm/rcar-du/ directory has to be treated as obj-y
unconditionally, as the LVDS driver could be built-in while the DU
driver is compiled as a module.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.h b/drivers/gpu/drm/rcar-du/rcar_lvds.h
new file mode 100644
index 000000000000..a709cae1bc32
--- /dev/null
+++ b/drivers/gpu/drm/rcar-du/rcar_lvds.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * rcar_lvds.h  --  R-Car LVDS Encoder
+ *
+ * Copyright (C) 2013-2018 Renesas Electronics Corporation
+ *
+ * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.com)
+ */
+
+#ifndef __RCAR_LVDS_H__
+#define __RCAR_LVDS_H__
+
+struct drm_bridge;
+
+#if IS_ENABLED(CONFIG_DRM_RCAR_LVDS)
+int rcar_lvds_clk_enable(struct drm_bridge *bridge, unsigned long freq);
+void rcar_lvds_clk_disable(struct drm_bridge *bridge);
+#else
+static inline int rcar_lvds_clk_enable(struct drm_bridge *bridge,
+				       unsigned long freq)
+{
+	return -ENOSYS;
+}
+static inline void rcar_lvds_clk_disable(struct drm_bridge *bridge) { }
+#endif /* CONFIG_DRM_RCAR_LVDS */
+
+#endif /* __RCAR_LVDS_H__ */