[PATCH v5 3/7] drm: sun4i: dsi: Convert to bridge driver

[Jagan Teki <jagan@amarulasolutions.com>]

Some display panels would come up with a non-DSI output, those
can have an option to connect the DSI host by means of interface
bridge converter.

This DSI to non-DSI interface bridge converter would requires
DSI Host to handle drm bridge functionalities in order to DSI
Host to Interface bridge.

This patch convert the existing to a drm bridge driver with a
built-in encoder support for compatibility with existing
component drivers.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
Changes for v5:
- add atomic APIs
- find host and device variant DSI devices.
Changes for v4, v3:
- none

 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 112 ++++++++++++++++++++-----
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h |   7 ++
 2 files changed, 96 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 43d9c9e5198d..a6a272b55f77 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -21,6 +21,7 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_mipi_dsi.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
@@ -713,10 +714,11 @@ static int sun6i_dsi_start(struct sun6i_dsi *dsi,
 	return 0;
 }
 
-static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
+static void sun6i_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
+					   struct drm_bridge_state *old_bridge_state)
 {
-	struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode;
-	struct sun6i_dsi *dsi = encoder_to_sun6i_dsi(encoder);
+	struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge);
+	struct drm_display_mode *mode = &bridge->encoder->crtc->state->adjusted_mode;
 	struct mipi_dsi_device *device = dsi->device;
 	union phy_configure_opts opts = { };
 	struct phy_configure_opts_mipi_dphy *cfg = &opts.mipi_dphy;
@@ -772,6 +774,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
 	if (dsi->panel)
 		drm_panel_prepare(dsi->panel);
 
+	if (dsi->next_bridge)
+		dsi->next_bridge->funcs->atomic_pre_enable(dsi->next_bridge, old_bridge_state);
+
 	/*
 	 * FIXME: This should be moved after the switch to HS mode.
 	 *
@@ -787,6 +792,9 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
 	if (dsi->panel)
 		drm_panel_enable(dsi->panel);
 
+	if (dsi->next_bridge)
+		dsi->next_bridge->funcs->atomic_enable(dsi->next_bridge, old_bridge_state);
+
 	sun6i_dsi_start(dsi, DSI_START_HSC);
 
 	udelay(1000);
@@ -794,15 +802,19 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
 	sun6i_dsi_start(dsi, DSI_START_HSD);
 }
 
-static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder)
+static void sun6i_dsi_bridge_atomic_disable(struct drm_bridge *bridge,
+					    struct drm_bridge_state *old_bridge_state)
 {
-	struct sun6i_dsi *dsi = encoder_to_sun6i_dsi(encoder);
+	struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge);
 
 	DRM_DEBUG_DRIVER("Disabling DSI output\n");
 
 	if (dsi->panel) {
 		drm_panel_disable(dsi->panel);
 		drm_panel_unprepare(dsi->panel);
+	} else if (dsi->next_bridge) {
+		dsi->next_bridge->funcs->atomic_disable(dsi->next_bridge, old_bridge_state);
+		dsi->next_bridge->funcs->atomic_post_disable(dsi->next_bridge, old_bridge_state);
 	}
 
 	phy_power_off(dsi->dphy);
@@ -842,9 +854,25 @@ static const struct drm_connector_funcs sun6i_dsi_connector_funcs = {
 	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
 };
 
-static const struct drm_encoder_helper_funcs sun6i_dsi_enc_helper_funcs = {
-	.disable	= sun6i_dsi_encoder_disable,
-	.enable		= sun6i_dsi_encoder_enable,
+static int sun6i_dsi_bridge_attach(struct drm_bridge *bridge,
+				   enum drm_bridge_attach_flags flags)
+{
+	struct sun6i_dsi *dsi = bridge_to_sun6i_dsi(bridge);
+
+	if (dsi->next_bridge)
+		return drm_bridge_attach(bridge->encoder, dsi->next_bridge,
+					 NULL, 0);
+
+	return 0;
+}
+
+static const struct drm_bridge_funcs sun6i_dsi_bridge_funcs = {
+	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
+	.atomic_reset		= drm_atomic_helper_bridge_reset,
+	.atomic_enable		= sun6i_dsi_bridge_atomic_enable,
+	.atomic_disable		= sun6i_dsi_bridge_atomic_disable,
+	.attach			= sun6i_dsi_bridge_attach,
 };
 
 static u32 sun6i_dsi_dcs_build_pkt_hdr(struct sun6i_dsi *dsi,
@@ -966,8 +994,6 @@ static int sun6i_dsi_bind(struct device *dev, struct device *master,
 	struct sun6i_dsi *dsi = dev_get_drvdata(dev);
 	int ret;
 
-	drm_encoder_helper_add(&dsi->encoder,
-			       &sun6i_dsi_enc_helper_funcs);
 	ret = drm_simple_encoder_init(drm, &dsi->encoder,
 				      DRM_MODE_ENCODER_DSI);
 	if (ret) {
@@ -976,18 +1002,26 @@ static int sun6i_dsi_bind(struct device *dev, struct device *master,
 	}
 	dsi->encoder.possible_crtcs = BIT(0);
 
-	drm_connector_helper_add(&dsi->connector,
-				 &sun6i_dsi_connector_helper_funcs);
-	ret = drm_connector_init(drm, &dsi->connector,
-				 &sun6i_dsi_connector_funcs,
-				 DRM_MODE_CONNECTOR_DSI);
+	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, 0);
 	if (ret) {
-		dev_err(dsi->dev,
-			"Couldn't initialise the DSI connector\n");
+		dev_err(dsi->dev, "Couldn't attach drm bridge\n");
 		goto err_cleanup_connector;
 	}
 
-	drm_connector_attach_encoder(&dsi->connector, &dsi->encoder);
+	if (dsi->panel) {
+		drm_connector_helper_add(&dsi->connector,
+					 &sun6i_dsi_connector_helper_funcs);
+		ret = drm_connector_init(drm, &dsi->connector,
+					 &sun6i_dsi_connector_funcs,
+					 DRM_MODE_CONNECTOR_DSI);
+		if (ret) {
+			dev_err(dsi->dev,
+				"Couldn't initialise the DSI connector\n");
+			goto err_cleanup_connector;
+		}
+
+		drm_connector_attach_encoder(&dsi->connector, &dsi->encoder);
+	}
 
 	return 0;
 
@@ -1013,16 +1047,46 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host,
 			    struct mipi_dsi_device *device)
 {
 	struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
-	struct drm_panel *panel = of_drm_find_panel(device->dev.of_node);
+	struct device_node *remote = device->dev.of_node;
 	int ret;
 
-	if (IS_ERR(panel))
-		return PTR_ERR(panel);
+	if (!of_device_is_available(remote)) {
+		/**
+		 * I2C interfaced DSI bridges will register DSI host on the
+		 * bridge drivers instead of conventional device.
+		 *
+		 * Those are probed via host of_node instead of device of_node.
+		 */
+		remote = of_graph_get_remote_node(host->dev->of_node, 0, 0);
+		if (!remote)
+			return -ENODEV;
+	}
+
+	dsi->panel = of_drm_find_panel(remote);
+	if (IS_ERR(dsi->panel)) {
+		dsi->panel = NULL;
+
+		dsi->next_bridge = of_drm_find_bridge(remote);
+		if (IS_ERR(dsi->next_bridge)) {
+			dev_err(dsi->dev, "failed to find bridge\n");
+			return PTR_ERR(dsi->next_bridge);
+		}
+	} else {
+		dsi->next_bridge = NULL;
+	}
+
+	of_node_put(remote);
 
-	dsi->panel = panel;
 	dsi->device = device;
 
-	dev_info(host->dev, "Attached device %s\n", device->name);
+	dev_info(host->dev, "Attached %s %s\n",
+		 device->name, dsi->panel ? "panel" : "bridge");
+
+	dsi->bridge.funcs = &sun6i_dsi_bridge_funcs;
+	dsi->bridge.of_node = dsi->dev->of_node;
+	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
+
+	drm_bridge_add(&dsi->bridge);
 
 	ret = component_add(dsi->dev, &sun6i_dsi_ops);
 	if (ret) {
@@ -1040,9 +1104,11 @@ static int sun6i_dsi_detach(struct mipi_dsi_host *host,
 	struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
 
 	dsi->panel = NULL;
+	dsi->next_bridge = NULL;
 	dsi->device = NULL;
 
 	component_del(dsi->dev, &sun6i_dsi_ops);
+	drm_bridge_remove(&dsi->bridge);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
index 61e88ea6044d..d269304691c9 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
@@ -16,6 +16,7 @@
 #define SUN6I_DSI_TCON_DIV	4
 
 struct sun6i_dsi {
+	struct drm_bridge	bridge;
 	struct drm_connector	connector;
 	struct drm_encoder	encoder;
 	struct mipi_dsi_host	host;
@@ -30,6 +31,7 @@ struct sun6i_dsi {
 	struct device		*dev;
 	struct mipi_dsi_device	*device;
 	struct drm_panel	*panel;
+	struct drm_bridge	*next_bridge;
 };
 
 static inline struct sun6i_dsi *host_to_sun6i_dsi(struct mipi_dsi_host *host)
@@ -37,6 +39,11 @@ static inline struct sun6i_dsi *host_to_sun6i_dsi(struct mipi_dsi_host *host)
 	return container_of(host, struct sun6i_dsi, host);
 };
 
+static inline struct sun6i_dsi *bridge_to_sun6i_dsi(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct sun6i_dsi, bridge);
+}
+
 static inline struct sun6i_dsi *connector_to_sun6i_dsi(struct drm_connector *connector)
 {
 	return container_of(connector, struct sun6i_dsi, connector);
-- 
2.25.1