mcb-lpc: Reallocate memory region to avoid memory overlapping

[ Upstream commit 2025b2c ]

mcb-lpc requests a fixed-size memory region to parse the chameleon
table, however, if the chameleon table is smaller that the allocated
region, it could overlap with the IP Cores' memory regions.

After parsing the chameleon table, drop/reallocate the memory region
with the actual chameleon table size.

Co-developed-by: Jorge Sanjuan Garcia <jorge.sanjuangarcia@duagon.com>
Signed-off-by: Jorge Sanjuan Garcia <jorge.sanjuangarcia@duagon.com>
Signed-off-by: Javier Rodriguez <josejavier.rodriguez@duagon.com>
Signed-off-by: Johannes Thumshirn <jth@kernel.org>
Link: https://lore.kernel.org/r/20230411083329.4506-4-jth@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mcb/mcb-lpc.c

@@ -23,7 +23,7 @@ static int mcb_lpc_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct priv *priv;
-	int ret = 0;
+	int ret = 0, table_size;
 
 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -58,16 +58,43 @@ static int mcb_lpc_probe(struct platform_device *pdev)
 
 	ret = chameleon_parse_cells(priv->bus, priv->mem->start, priv->base);
 	if (ret < 0) {
-		mcb_release_bus(priv->bus);
-		return ret;
+		goto out_mcb_bus;
 	}
 
-	dev_dbg(&pdev->dev, "Found %d cells\n", ret);
+	table_size = ret;
+
+	if (table_size < CHAM_HEADER_SIZE) {
+		/* Release the previous resources */
+		devm_iounmap(&pdev->dev, priv->base);
+		devm_release_mem_region(&pdev->dev, priv->mem->start, resource_size(priv->mem));
+
+		/* Then, allocate it again with the actual chameleon table size */
+		res = devm_request_mem_region(&pdev->dev, priv->mem->start,
+					      table_size,
+					      KBUILD_MODNAME);
+		if (!res) {
+			dev_err(&pdev->dev, "Failed to request PCI memory\n");
+			ret = -EBUSY;
+			goto out_mcb_bus;
+		}
+
+		priv->base = devm_ioremap(&pdev->dev, priv->mem->start, table_size);
+		if (!priv->base) {
+			dev_err(&pdev->dev, "Cannot ioremap\n");
+			ret = -ENOMEM;
+			goto out_mcb_bus;
+		}
+
+		platform_set_drvdata(pdev, priv);
+	}
 
 	mcb_bus_add_devices(priv->bus);
 
 	return 0;
 
+out_mcb_bus:
+	mcb_release_bus(priv->bus);
+	return ret;
 }
 
 static int mcb_lpc_remove(struct platform_device *pdev)