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From:   Eddie James <eajames@linux.ibm.com>
To:     linux-fsi@lists.ozlabs.org
Cc:     linux-kernel@vger.kernel.org, jk@ozlabs.org, joel@jms.id.au,
        alistair@popple.id.au, andrew@aj.id.au, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
        devicetree@vger.kernel.org
Subject: [PATCH 11/14] fsi: Improve master indexing
Date:   Mon, 12 Jun 2023 14:56:54 -0500
Message-Id: <20230612195657.245125-12-eajames@linux.ibm.com>
In-Reply-To: <20230612195657.245125-1-eajames@linux.ibm.com>
References: <20230612195657.245125-1-eajames@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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Master indexing is problematic if a hub is rescanned while the
root master is being rescanned. Move the IDA free below the device
unregistration, lock the scan mutex in the probe function, and
request a specific idx in the hub driver.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/fsi/fsi-core.c       | 41 ++++++++++++++++++++++--------------
 drivers/fsi/fsi-master-hub.c |  2 ++
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index ec4d02264391..503061a6740b 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -1327,46 +1327,55 @@ static struct class fsi_master_class = {
 int fsi_master_register(struct fsi_master *master)
 {
 	int rc;
-	struct device_node *np;
 
 	mutex_init(&master->scan_lock);
-	master->idx = ida_alloc(&master_ida, GFP_KERNEL);
+
+	if (master->idx) {
+		master->idx = ida_alloc_range(&master_ida, master->idx,
+					      master->idx, GFP_KERNEL);
+		if (master->idx < 0)
+			master->idx = ida_alloc(&master_ida, GFP_KERNEL);
+	} else {
+		master->idx = ida_alloc(&master_ida, GFP_KERNEL);
+	}
+
 	if (master->idx < 0)
 		return master->idx;
 
-	dev_set_name(&master->dev, "fsi%d", master->idx);
+	if (!dev_name(&master->dev))
+		dev_set_name(&master->dev, "fsi%d", master->idx);
+
 	master->dev.class = &fsi_master_class;
 
+	mutex_lock(&master->scan_lock);
 	rc = device_register(&master->dev);
 	if (rc) {
 		ida_free(&master_ida, master->idx);
-		return rc;
-	}
+	} else {
+		struct device_node *np = dev_of_node(&master->dev);
 
-	np = dev_of_node(&master->dev);
-	if (!of_property_read_bool(np, "no-scan-on-init")) {
-		mutex_lock(&master->scan_lock);
-		fsi_master_scan(master);
-		mutex_unlock(&master->scan_lock);
+		if (!of_property_read_bool(np, "no-scan-on-init"))
+			fsi_master_scan(master);
 	}
 
-	return 0;
+	mutex_unlock(&master->scan_lock);
+	return rc;
 }
 EXPORT_SYMBOL_GPL(fsi_master_register);
 
 void fsi_master_unregister(struct fsi_master *master)
 {
-	trace_fsi_master_unregister(master);
+	int idx = master->idx;
 
-	if (master->idx >= 0) {
-		ida_free(&master_ida, master->idx);
-		master->idx = -1;
-	}
+	trace_fsi_master_unregister(master);
 
 	mutex_lock(&master->scan_lock);
 	fsi_master_unscan(master);
+	master->n_links = 0;
 	mutex_unlock(&master->scan_lock);
+
 	device_unregister(&master->dev);
+	ida_free(&master_ida, idx);
 }
 EXPORT_SYMBOL_GPL(fsi_master_unregister);
 
diff --git a/drivers/fsi/fsi-master-hub.c b/drivers/fsi/fsi-master-hub.c
index 6d8b6e8854e5..36da643b3201 100644
--- a/drivers/fsi/fsi-master-hub.c
+++ b/drivers/fsi/fsi-master-hub.c
@@ -12,6 +12,7 @@
 #include <linux/slab.h>
 
 #include "fsi-master.h"
+#include "fsi-slave.h"
 
 #define FSI_ENGID_HUB_MASTER		0x1c
 
@@ -229,6 +230,7 @@ static int hub_master_probe(struct device *dev)
 	hub->master.dev.release = hub_master_release;
 	hub->master.dev.of_node = of_node_get(dev_of_node(dev));
 
+	hub->master.idx = fsi_dev->slave->link + 1;
 	hub->master.n_links = links;
 	hub->master.read = hub_master_read;
 	hub->master.write = hub_master_write;
-- 
2.31.1