drm/dsi: Implement DCS get_power_mode command

Provide a small convenience wrapper that transmits a DCS get_power_mode
command. A set of bitmasks for the mode bits is also provided.

Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index de1d94c..79588c5 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -185,6 +185,12 @@
 	MIPI_DSI_DCS_TEAR_MODE_VHBLANK,
 };
 
+#define MIPI_DSI_DCS_POWER_MODE_DISPLAY (1 << 2)
+#define MIPI_DSI_DCS_POWER_MODE_NORMAL  (1 << 3)
+#define MIPI_DSI_DCS_POWER_MODE_SLEEP   (1 << 4)
+#define MIPI_DSI_DCS_POWER_MODE_PARTIAL (1 << 5)
+#define MIPI_DSI_DCS_POWER_MODE_IDLE    (1 << 6)
+
 ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
 				  const void *data, size_t len);
 ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,
@@ -193,6 +199,7 @@
 			  size_t len);
 int mipi_dsi_dcs_nop(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_soft_reset(struct mipi_dsi_device *dsi);
+int mipi_dsi_dcs_get_power_mode(struct mipi_dsi_device *dsi, u8 *mode);
 int mipi_dsi_dcs_enter_sleep_mode(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_exit_sleep_mode(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_set_display_off(struct mipi_dsi_device *dsi);