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>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -602,6 +602,31 @@ int mipi_dsi_dcs_soft_reset(struct mipi_dsi_device *dsi)
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_soft_reset);
 
+/**
+ * mipi_dsi_dcs_get_power_mode() - query the display module's current power
+ *    mode
+ * @dsi: DSI peripheral device
+ * @mode: return location for the current power mode
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int mipi_dsi_dcs_get_power_mode(struct mipi_dsi_device *dsi, u8 *mode)
+{
+	ssize_t err;
+
+	err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_POWER_MODE, mode,
+				sizeof(*mode));
+	if (err <= 0) {
+		if (err == 0)
+			err = -ENODATA;
+
+		return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_get_power_mode);
+
 /**
  * mipi_dsi_dcs_enter_sleep_mode() - disable all unnecessary blocks inside the
  *    display module except interface communication

include/drm/drm_mipi_dsi.h

@@ -185,6 +185,12 @@ enum mipi_dsi_dcs_tear_mode {
 	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 @@ ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
 			  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);