drm/tegra: virt: Make IVC channel global

Only one instance of the IVC channel with NvHost Server can exist
at once. As such, to allow instantiating the driver for multiple
engines, make the IVC channel global.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Change-Id: I611158dd4aa92216870a66e4aa5fe15c37984ea8
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2828565
Reviewed-by: Jonathan Hunter <jonathanh@nvidia.com>
Reviewed-by: svc_kernel_abi <svc_kernel_abi@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>

drivers/gpu/drm/tegra/virt.c

@@ -36,12 +36,15 @@ struct tegra_vhost_cmd_msg {
 
 struct virt_engine {
 	struct device *dev;
-	struct tegra_hv_ivc_cookie *cookie;
 	int connection_id;
 
 	struct tegra_drm_client client;
 };
 
+static DEFINE_MUTEX(ivc_cookie_lock);
+static struct tegra_hv_ivc_cookie *ivc_cookie;
+static struct kref ivc_ref;
+
 static inline struct virt_engine *to_virt_engine(struct tegra_drm_client *client)
 {
 	return container_of(client, struct virt_engine, client);
@@ -121,6 +124,16 @@ static int virt_engine_setup_ivc(struct virt_engine *virt)
 	u32 ivc_instance;
 	int err;
 
+	mutex_lock(&ivc_cookie_lock);
+
+	if (ivc_cookie) {
+		err = PTR_ERR_OR_ZERO(ivc_cookie);
+		if (!err)
+			kref_get(&ivc_ref);
+		mutex_unlock(&ivc_cookie_lock);
+		return err;
+	}
+
 	hv = of_parse_phandle(host1x_dn, "nvidia,server-ivc", 0);
 	if (!hv) {
 		dev_err(virt->dev, "nvidia,server-ivc not configured\n");
@@ -133,38 +146,62 @@ static int virt_engine_setup_ivc(struct virt_engine *virt)
 		return -EINVAL;
 	}
 
-	virt->cookie = tegra_hv_ivc_reserve(hv, ivc_instance, NULL);
+	ivc_cookie = tegra_hv_ivc_reserve(hv, ivc_instance, NULL);
-	if (IS_ERR(virt->cookie)) {
+	if (IS_ERR(ivc_cookie)) {
-		dev_err(virt->dev, "IVC channel reservation failed: %ld\n", PTR_ERR(virt->cookie));
+		dev_err(virt->dev, "IVC channel reservation failed: %ld\n", PTR_ERR(ivc_cookie));
-		return PTR_ERR(virt->cookie);
+		return PTR_ERR(ivc_cookie);
 	}
 
-	tegra_hv_ivc_channel_reset(virt->cookie);
+	tegra_hv_ivc_channel_reset(ivc_cookie);
 
-	while (tegra_hv_ivc_channel_notified(virt->cookie))
+	while (tegra_hv_ivc_channel_notified(ivc_cookie))
 		;
 
+	kref_init(&ivc_ref);
+
+	mutex_unlock(&ivc_cookie_lock);
+
 	return 0;
 }
 
-static int virt_engine_transfer(struct virt_engine *virt, void *data, u32 size)
+static void release_ivc_cookie(struct kref *ref)
+{
+	(void)ref;
+
+	tegra_hv_ivc_unreserve(ivc_cookie);
+	mutex_unlock(&ivc_cookie_lock);
+}
+
+static void virt_engine_cleanup(void)
+{
+	kref_put_mutex(&ivc_ref, release_ivc_cookie, &ivc_cookie_lock);
+}
+
+static int virt_engine_transfer(void *data, u32 size)
 {
 	int err;
 
-	while (!tegra_hv_ivc_can_write(virt->cookie))
+	mutex_lock(&ivc_cookie_lock);
+
+	while (!tegra_hv_ivc_can_write(ivc_cookie))
 		;
 
-	err = tegra_hv_ivc_write(virt->cookie, data, size);
+	err = tegra_hv_ivc_write(ivc_cookie, data, size);
-	if (err != size)
+	if (err != size) {
+		mutex_unlock(&ivc_cookie_lock);
 		return -ENOMEM;
+	}
 
-	while (!tegra_hv_ivc_can_read(virt->cookie))
+	while (!tegra_hv_ivc_can_read(ivc_cookie))
 		;
 
-	err = tegra_hv_ivc_read(virt->cookie, data, size);
+	err = tegra_hv_ivc_read(ivc_cookie, data, size);
-	if (err != size)
+	if (err != size) {
+		mutex_unlock(&ivc_cookie_lock);
 		return -EIO;
+	}
 
+	mutex_unlock(&ivc_cookie_lock);
 	return 0;
 }
 
@@ -176,7 +213,7 @@ static int virt_engine_connect(struct virt_engine *virt, u32 module_id)
 	msg.cmd = TEGRA_VHOST_CMD_CONNECT;
 	msg.connect.module = module_id;
 
-	err = virt_engine_transfer(virt, &msg, sizeof(msg));
+	err = virt_engine_transfer(&msg, sizeof(msg));
 	if (err < 0)
 		return err;
 
@@ -191,7 +228,7 @@ static int virt_engine_suspend(struct device *dev)
 	msg.cmd = TEGRA_VHOST_CMD_SUSPEND;
 	msg.connection_id = virt->connection_id;
 
-	return virt_engine_transfer(virt, &msg, sizeof(msg));
+	return virt_engine_transfer(&msg, sizeof(msg));
 }
 
 static int virt_engine_resume(struct device *dev)
@@ -202,7 +239,7 @@ static int virt_engine_resume(struct device *dev)
 	msg.cmd = TEGRA_VHOST_CMD_RESUME;
 	msg.connection_id = virt->connection_id;
 
-	return virt_engine_transfer(virt, &msg, sizeof(msg));
+	return virt_engine_transfer(&msg, sizeof(msg));
 }
 
 static const struct of_device_id tegra_virt_engine_of_match[] = {
@@ -278,7 +315,7 @@ static int virt_engine_probe(struct platform_device *pdev)
 	return 0;
 
 cleanup_ivc:
-	tegra_hv_ivc_unreserve(virt->cookie);
+	virt_engine_cleanup();
 unregister_client:
 	host1x_client_unregister(&virt->client.base);
 
@@ -290,7 +327,7 @@ static int virt_engine_remove(struct platform_device *pdev)
 	struct virt_engine *virt_engine = platform_get_drvdata(pdev);
 	int err;
 
-	tegra_hv_ivc_unreserve(virt_engine->cookie);
+	virt_engine_cleanup();
 
 	err = host1x_client_unregister(&virt_engine->client.base);
 	if (err < 0) {