[PATCH v4 1/3] misc: fastrpc: iterate CB nodes manually instead of of_platform_populate

[Vinayak Katoch]

of_platform_populate() only guarantees that child devices are registered,
not that their probes have completed before it returns. This creates a
window where fastrpc_cb_init() may not have run for all context bank
nodes, leaving the channel context partially initialised.

Iterate over the child device tree nodes directly, initialising each
qcom,fastrpc-compute-cb device synchronously. This ensures all context
banks are fully initialised before fastrpc_rpmsg_probe() returns. Since
fastrpc_cb_driver is no longer needed as an independent platform driver,
remove it along with its match table and remove callback. Set
OF_POPULATED_BUS on the rpmsg node so that of_platform_depopulate()
correctly removes the manually created CB devices on teardown.

Signed-off-by: Vinayak Katoch <vinayak.katoch@xxxxxxxxxxxxxxxx>
---
 drivers/misc/fastrpc.c | 83 ++++++++++++++++++--------------------------------
 1 file changed, 29 insertions(+), 54 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index d4fac2caca86..a153107d0085 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -2363,7 +2363,7 @@ static const struct file_operations fastrpc_fops = {
 	.compat_ioctl = fastrpc_device_ioctl,
 };
 
-static int fastrpc_cb_probe(struct platform_device *pdev)
+static int fastrpc_cb_init(struct platform_device *pdev)
 {
 	struct fastrpc_channel_ctx *cctx;
 	struct fastrpc_session_ctx *sess;
@@ -2385,7 +2385,7 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
 	spin_lock_irqsave(&cctx->lock, flags);
 	if (cctx->sesscount >= FASTRPC_MAX_SESSIONS) {
 		spin_unlock_irqrestore(&cctx->lock, flags);
-		dev_err(&pdev->dev, "too many sessions\n");
+		dev_err(dev, "too many sessions\n");
 		return -ENOSPC;
 	}
 	dma_bits = cctx->soc_data->dma_addr_bits_default;
@@ -2419,38 +2419,6 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static void fastrpc_cb_remove(struct platform_device *pdev)
-{
-	struct fastrpc_channel_ctx *cctx = dev_get_drvdata(pdev->dev.parent);
-	struct fastrpc_session_ctx *sess = dev_get_drvdata(&pdev->dev);
-	unsigned long flags;
-	int i;
-
-	spin_lock_irqsave(&cctx->lock, flags);
-	for (i = 0; i < FASTRPC_MAX_SESSIONS; i++) {
-		if (cctx->session[i].sid == sess->sid) {
-			cctx->session[i].valid = false;
-			cctx->sesscount--;
-		}
-	}
-	spin_unlock_irqrestore(&cctx->lock, flags);
-}
-
-static const struct of_device_id fastrpc_match_table[] = {
-	{ .compatible = "qcom,fastrpc-compute-cb" },
-	{ }
-};
-
-static struct platform_driver fastrpc_cb_driver = {
-	.probe = fastrpc_cb_probe,
-	.remove = fastrpc_cb_remove,
-	.driver = {
-		.name = "qcom,fastrpc-cb",
-		.of_match_table = fastrpc_match_table,
-		.suppress_bind_attrs = true,
-	},
-};
-
 static int fastrpc_device_register(struct device *dev, struct fastrpc_channel_ctx *cctx,
 				   bool is_secured, const char *domain)
 {
@@ -2642,12 +2610,29 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 	data->rpdev = rpdev;
 	dev_set_drvdata(&rpdev->dev, data);
 
-	err = of_platform_populate(rdev->of_node, NULL, NULL, rdev);
-	if (err)
-		goto err_deregister_fdev;
+	of_node_set_flag(rdev->of_node, OF_POPULATED_BUS);
+
+	for_each_available_child_of_node_scoped(rdev->of_node, np) {
+		struct platform_device *pdev;
+
+		if (!of_device_is_compatible(np, "qcom,fastrpc-compute-cb"))
+			continue;
+
+		pdev = of_platform_device_create(np, NULL, rdev);
+		if (!pdev) {
+			err = -EINVAL;
+			goto err_depopulate;
+		}
+
+		err = fastrpc_cb_init(pdev);
+		if (err)
+			goto err_depopulate;
+	}
 
 	return 0;
 
+err_depopulate:
+	of_platform_depopulate(rdev);
 err_deregister_fdev:
 	if (data->fdevice)
 		misc_deregister(&data->fdevice->miscdev);
@@ -2677,6 +2662,7 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	struct fastrpc_buf *buf, *b;
 	struct fastrpc_user *user;
 	unsigned long flags;
+	int i;
 
 	/* No invocations past this point */
 	spin_lock_irqsave(&cctx->lock, flags);
@@ -2697,6 +2683,11 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	if (cctx->remote_heap)
 		fastrpc_buf_free(cctx->remote_heap);
 
+	spin_lock_irqsave(&cctx->lock, flags);
+	for (i = 0; i < FASTRPC_MAX_SESSIONS; i++)
+		cctx->session[i].valid = false;
+	spin_unlock_irqrestore(&cctx->lock, flags);
+
 	of_platform_depopulate(&rpdev->dev);
 
 	fastrpc_channel_ctx_put(cctx);
@@ -2786,28 +2777,12 @@ static struct rpmsg_driver fastrpc_driver = {
 
 static int fastrpc_init(void)
 {
-	int ret;
-
-	ret = platform_driver_register(&fastrpc_cb_driver);
-	if (ret < 0) {
-		pr_err("fastrpc: failed to register cb driver\n");
-		return ret;
-	}
-
-	ret = register_rpmsg_driver(&fastrpc_driver);
-	if (ret < 0) {
-		pr_err("fastrpc: failed to register rpmsg driver\n");
-		platform_driver_unregister(&fastrpc_cb_driver);
-		return ret;
-	}
-
-	return 0;
+	return register_rpmsg_driver(&fastrpc_driver);
 }
 module_init(fastrpc_init);
 
 static void fastrpc_exit(void)
 {
-	platform_driver_unregister(&fastrpc_cb_driver);
 	unregister_rpmsg_driver(&fastrpc_driver);
 }
 module_exit(fastrpc_exit);

-- 
2.34.1