[RFC PATCH 3/3] drm/komeda: Allow non-component drm_bridge only endpoints

[Mihail Atanassov]

To support transmitters other than the tda998x, we need to allow
non-component framework bridges to be attached to a dummy drm_encoder in
our driver.

For the existing supported encoder (tda998x), keep the behaviour as-is,
since there's no way to unbind if a drm_bridge module goes away under
our feet.

Signed-off-by: Mihail Atanassov <mihail.atanassov@xxxxxxx>
---
 .../gpu/drm/arm/display/komeda/komeda_dev.h   |   5 +
 .../gpu/drm/arm/display/komeda/komeda_drv.c   |  58 ++++++--
 .../gpu/drm/arm/display/komeda/komeda_kms.c   | 133 +++++++++++++++++-
 .../gpu/drm/arm/display/komeda/komeda_kms.h   |   5 +
 4 files changed, 187 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
index e392b8ffc372..64d2902e2e0c 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
@@ -176,6 +176,11 @@ struct komeda_dev {
 
 	/** @irq: irq number */
 	int irq;
+	/** @has_components:
+	 *
+	 * if true, use the component framework to bind/unbind driver
+	 */
+	bool has_components;
 
 	/** @lock: used to protect dpmode */
 	struct mutex lock;
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_drv.c b/drivers/gpu/drm/arm/display/komeda/komeda_drv.c
index 9ed25ffe0e22..34cfc6a4c3e4 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_drv.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_drv.c
@@ -10,6 +10,8 @@
 #include <linux/component.h>
 #include <linux/pm_runtime.h>
 #include <drm/drm_of.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_encoder.h>
 #include "komeda_dev.h"
 #include "komeda_kms.h"
 
@@ -69,18 +71,35 @@ static int compare_of(struct device *dev, void *data)
 	return dev->of_node == data;
 }
 
-static void komeda_add_slave(struct device *master,
-			     struct component_match **match,
-			     struct device_node *np,
-			     u32 port, u32 endpoint)
+static int komeda_add_slave(struct device *master,
+			    struct komeda_drv *mdrv,
+			    struct component_match **match,
+			    struct device_node *np,
+			    u32 port, u32 endpoint)
 {
 	struct device_node *remote;
+	struct drm_bridge *bridge;
+	int ret = 0;
 
 	remote = of_graph_get_remote_node(np, port, endpoint);
-	if (remote) {
+	if (!remote)
+		return 0;
+
+	if (komeda_remote_device_is_component(np, port, endpoint)) {
+		mdrv->mdev.has_components = true;
 		drm_of_component_match_add(master, match, compare_of, remote);
-		of_node_put(remote);
+		goto exit;
+	}
+
+	bridge = of_drm_find_bridge(remote);
+	if (!bridge) {
+		ret = -EPROBE_DEFER;
+		goto exit;
 	}
+
+exit:
+	of_node_put(remote);
+	return ret;
 }
 
 static int komeda_platform_probe(struct platform_device *pdev)
@@ -89,6 +108,7 @@ static int komeda_platform_probe(struct platform_device *pdev)
 	struct component_match *match = NULL;
 	struct device_node *child;
 	struct komeda_drv *mdrv;
+	int ret;
 
 	if (!dev->of_node)
 		return -ENODEV;
@@ -101,14 +121,27 @@ static int komeda_platform_probe(struct platform_device *pdev)
 		if (of_node_cmp(child->name, "pipeline") != 0)
 			continue;
 
-		/* add connector */
-		komeda_add_slave(dev, &match, child, KOMEDA_OF_PORT_OUTPUT, 0);
-		komeda_add_slave(dev, &match, child, KOMEDA_OF_PORT_OUTPUT, 1);
+		/* attach any remote devices if present */
+		ret = komeda_add_slave(dev, mdrv, &match, child,
+				       KOMEDA_OF_PORT_OUTPUT, 0);
+		if (ret)
+			goto free_mdrv;
+		ret = komeda_add_slave(dev, mdrv, &match, child,
+				       KOMEDA_OF_PORT_OUTPUT, 1);
+		if (ret)
+			goto free_mdrv;
 	}
 
 	dev_set_drvdata(dev, mdrv);
 
-	return component_master_add_with_match(dev, &komeda_master_ops, match);
+	return mdrv->mdev.has_components
+		? component_master_add_with_match(
+			dev, &komeda_master_ops, match)
+		: komeda_bind(dev);
+
+free_mdrv:
+	devm_kfree(dev, mdrv);
+	return ret;
 }
 
 static int komeda_platform_remove(struct platform_device *pdev)
@@ -116,7 +149,10 @@ static int komeda_platform_remove(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct komeda_drv *mdrv = dev_get_drvdata(dev);
 
-	component_master_del(dev, &komeda_master_ops);
+	if (mdrv->mdev.has_components)
+		component_master_del(dev, &komeda_master_ops);
+	else
+		komeda_unbind(dev);
 
 	dev_set_drvdata(dev, NULL);
 	devm_kfree(dev, mdrv);
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
index 03dcf1d7688f..6eb52d1b20a0 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
@@ -6,6 +6,7 @@
  */
 #include <linux/component.h>
 #include <linux/interrupt.h>
+#include <linux/of_graph.h>
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
@@ -14,6 +15,8 @@
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_irq.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_of.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_vblank.h>
 
@@ -267,6 +270,130 @@ static void komeda_kms_mode_config_init(struct komeda_kms_dev *kms,
 	config->helper_private = &komeda_mode_config_helpers;
 }
 
+static void komeda_encoder_destroy(struct drm_encoder *encoder)
+{
+	drm_encoder_cleanup(encoder);
+}
+
+static const struct drm_encoder_funcs komeda_dummy_enc_funcs = {
+	.destroy = komeda_encoder_destroy,
+};
+
+bool komeda_remote_device_is_component(struct device_node *local,
+				       u32 port, u32 endpoint)
+{
+	struct device_node *remote;
+	char const * const component_devices[] = {
+		"nxp,tda998x",
+	};
+	int i;
+	bool ret = false;
+
+	remote = of_graph_get_remote_node(local, port, endpoint);
+	if (!remote)
+		return false;
+
+	/* Coprocessor endpoints are always component based. */
+	if (port != KOMEDA_OF_PORT_OUTPUT) {
+		ret = true;
+		goto exit;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(component_devices); ++i) {
+		if (of_device_is_compatible(remote, component_devices[i])) {
+			ret = true;
+			goto exit;
+		}
+	}
+
+exit:
+	of_node_put(remote);
+	return ret;
+}
+
+static int komeda_encoder_attach_bridge(struct komeda_dev *mdev,
+					struct komeda_kms_dev *kms,
+					struct drm_encoder *encoder,
+					struct device_node *np)
+{
+	struct device_node *remote;
+	struct drm_bridge *bridge;
+	u32 crtcs = 0;
+	int ret = 0;
+
+	if (komeda_remote_device_is_component(np, KOMEDA_OF_PORT_OUTPUT, 0))
+		return 0;
+
+	remote = of_graph_get_remote_node(np, KOMEDA_OF_PORT_OUTPUT, 0);
+	if (!remote)
+		return 0;
+
+	bridge = of_drm_find_bridge(remote);
+	if (!bridge) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	crtcs = drm_of_find_possible_crtcs(&kms->base, remote);
+
+	encoder->possible_crtcs = crtcs ? crtcs : 1;
+
+	ret = drm_encoder_init(&kms->base, encoder,
+			       &komeda_dummy_enc_funcs, DRM_MODE_ENCODER_TMDS,
+			       NULL);
+	if (ret)
+		goto exit;
+
+	ret = drm_bridge_attach(encoder, bridge, NULL);
+	if (ret)
+		goto exit;
+
+exit:
+	of_node_put(remote);
+	return ret;
+}
+
+static int komeda_encoder_attach_bridges(struct komeda_kms_dev *kms,
+					 struct komeda_dev *mdev)
+{
+	int i, err;
+
+	for (i = 0; i < kms->n_crtcs; i++) {
+		err = komeda_encoder_attach_bridge(
+			mdev, kms,
+			&kms->encoders[i], mdev->pipelines[i]->of_node);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int komeda_kms_attach_external(struct komeda_kms_dev *kms,
+				      struct komeda_dev *mdev)
+{
+	int err;
+
+	if (mdev->has_components) {
+		err = component_bind_all(mdev->dev, kms);
+		if (err)
+			return err;
+	}
+
+	err = komeda_encoder_attach_bridges(kms, mdev);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static void komeda_kms_detach_external(struct komeda_dev *mdev,
+				       struct drm_device *drm)
+{
+	if (mdev->has_components)
+		component_unbind_all(mdev->dev, drm);
+}
+
 int komeda_kms_init(struct komeda_kms_dev *kms, struct komeda_dev *mdev)
 {
 	struct drm_device *drm;
@@ -301,7 +428,7 @@ int komeda_kms_init(struct komeda_kms_dev *kms, struct komeda_dev *mdev)
 	if (err)
 		goto cleanup_mode_config;
 
-	err = component_bind_all(mdev->dev, kms);
+	err = komeda_kms_attach_external(kms, mdev);
 	if (err)
 		goto cleanup_mode_config;
 
@@ -332,7 +459,7 @@ int komeda_kms_init(struct komeda_kms_dev *kms, struct komeda_dev *mdev)
 	drm->irq_enabled = false;
 	mdev->funcs->disable_irq(mdev);
 free_component_binding:
-	component_unbind_all(mdev->dev, drm);
+	komeda_kms_detach_external(mdev, drm);
 cleanup_mode_config:
 	drm_mode_config_cleanup(drm);
 	komeda_kms_cleanup_private_objs(kms);
@@ -351,7 +478,7 @@ void komeda_kms_fini(struct komeda_kms_dev *kms)
 	drm_atomic_helper_shutdown(drm);
 	drm->irq_enabled = false;
 	mdev->funcs->disable_irq(mdev);
-	component_unbind_all(mdev->dev, drm);
+	komeda_kms_detach_external(mdev, drm);
 	drm_mode_config_cleanup(drm);
 	komeda_kms_cleanup_private_objs(kms);
 	drm->dev_private = NULL;
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.h b/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
index e81ceb298034..c2856e19d092 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
@@ -12,6 +12,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_device.h>
+#include <drm/drm_encoder.h>
 #include <drm/drm_writeback.h>
 #include <drm/drm_print.h>
 
@@ -123,6 +124,7 @@ struct komeda_kms_dev {
 	int n_crtcs;
 	/** @crtcs: crtcs list */
 	struct komeda_crtc crtcs[KOMEDA_MAX_PIPELINES];
+	struct drm_encoder encoders[KOMEDA_MAX_PIPELINES];
 };
 
 #define to_kplane(p)	container_of(p, struct komeda_plane, base)
@@ -184,4 +186,7 @@ void komeda_crtc_handle_event(struct komeda_crtc   *kcrtc,
 int komeda_kms_init(struct komeda_kms_dev *kms, struct komeda_dev *mdev);
 void komeda_kms_fini(struct komeda_kms_dev *kms);
 
+bool komeda_remote_device_is_component(struct device_node *local,
+				       u32 port, u32 endpoint);
+
 #endif /*_KOMEDA_KMS_H_*/
-- 
2.23.0