drm/omap: dsi: add generic transfer function

This prepares the driver for becoming a mipi_dsi_host implementation,
which provides a generic transfer function instead of all kind of
different read/write functions. The implementation will become more
elegant after unexporting the specific functions in the following
patches.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215104657.802264-6-tomi.valkeinen@ti.com

drivers/gpu/drm/omapdrm/dss/dsi.c

@@ -4840,6 +4840,58 @@ static void dsi_release_vc(struct omap_dss_device *dssdev, int channel)
 	}
 }
 
+static ssize_t omap_dsi_transfer(struct omap_dss_device *dssdev,
+				 const struct mipi_dsi_msg *msg)
+{
+	/*
+	 * TODO: no_sync can be used to optimize performance by sending e.g.
+	 * column and page information without syncing in between. It's not
+	 * absolutely required, so postpone this feature for now.
+	 */
+	bool no_sync = false;
+	u16 val;
+
+	switch (msg->type) {
+	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
+	case MIPI_DSI_GENERIC_LONG_WRITE:
+		if (no_sync)
+			return dsi_vc_generic_write_nosync(dssdev, msg->channel,
+							   msg->tx_buf,
+							   msg->tx_len);
+		else
+			return dsi_vc_generic_write(dssdev, msg->channel,
+						    msg->tx_buf, msg->tx_len);
+	case MIPI_DSI_DCS_SHORT_WRITE:
+	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
+	case MIPI_DSI_DCS_LONG_WRITE:
+		if (no_sync)
+			return dsi_vc_dcs_write_nosync(dssdev, msg->channel,
+						       msg->tx_buf,
+						       msg->tx_len);
+		else
+			return dsi_vc_dcs_write(dssdev, msg->channel,
+						msg->tx_buf, msg->tx_len);
+	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
+		return dsi_vc_generic_read(dssdev, msg->channel,
+					   msg->tx_buf, msg->tx_len,
+					   msg->rx_buf, msg->rx_len);
+	case MIPI_DSI_DCS_READ:
+		return dsi_vc_dcs_read(dssdev, msg->channel,
+				       ((u8 *)msg->tx_buf)[0],
+				       msg->rx_buf, msg->rx_len);
+	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
+		val = le16_to_cpu(*((__le16 *)msg->tx_buf));
+		return dsi_vc_set_max_rx_packet_size(dssdev, msg->channel, val);
+	case MIPI_DSI_NULL_PACKET:
+		return dsi_vc_send_null(to_dsi_data(dssdev), msg->channel);
+	}
+
+	return -EINVAL;
+}
 
 static int dsi_get_clocks(struct dsi_data *dsi)
 {
@@ -4894,6 +4946,8 @@ static const struct omap_dss_device_ops dsi_ops = {
 		.set_vc_id = dsi_set_vc_id,
 		.release_vc = dsi_release_vc,
 
+		.transfer = omap_dsi_transfer,
+
 		.dcs_write = dsi_vc_dcs_write,
 		.dcs_write_nosync = dsi_vc_dcs_write_nosync,
 		.dcs_read = dsi_vc_dcs_read,

drivers/gpu/drm/omapdrm/dss/omapdss.h

@@ -311,6 +311,9 @@ struct omapdss_dsi_ops {
 	void (*release_vc)(struct omap_dss_device *dssdev, int channel);
 
 	/* data transfer */
+	ssize_t (*transfer)(struct omap_dss_device *dssdev,
+			    const struct mipi_dsi_msg *msg);
+
 	int (*dcs_write)(struct omap_dss_device *dssdev, int channel,
 			const u8 *data, int len);
 	int (*dcs_write_nosync)(struct omap_dss_device *dssdev, int channel,