soc: aspeed: lpc-snoop: Consolidate channel initialisation

Previously, channel initialisation was a bit perilous with respect to
resource cleanup in error paths. While the implementation had issues,
it at least made an effort to eliminate some of its problems by first
testing whether any channels were enabled, and bailing out if not.

Having improved the robustness of resource handling in probe() we can
now rearrange the initial channel test to be located with the subsequent
test, and rework the unrolled conditional logic to use a loop for an
improvement in readability.

Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-9-3cdd59c934d3@codeconstruct.com.au
Acked-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Author: amboar

drivers/soc/aspeed/aspeed-lpc-snoop.c

@@ -293,12 +293,21 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 	kfifo_free(&channel->fifo);
 }
 
+static void aspeed_lpc_snoop_remove(struct platform_device *pdev)
+{
+	struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
+
+	/* Disable both snoop channels */
+	aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_0);
+	aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_1);
+}
+
 static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
 {
 	struct aspeed_lpc_snoop *lpc_snoop;
-	struct device *dev;
 	struct device_node *np;
-	u32 port;
+	struct device *dev;
+	int idx;
 	int rc;
 
 	dev = &pdev->dev;
@@ -321,12 +330,6 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, lpc_snoop);
 
-	rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
-	if (rc) {
-		dev_err(dev, "no snoop ports configured\n");
-		return -ENODEV;
-	}
-
 	lpc_snoop->clk = devm_clk_get_enabled(dev, NULL);
 	if (IS_ERR(lpc_snoop->clk))
 		return dev_err_probe(dev, PTR_ERR(lpc_snoop->clk), "couldn't get clock");
@@ -335,30 +338,24 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
-	rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, ASPEED_LPC_SNOOP_INDEX_0, port);
-	if (rc)
-		return rc;
+	for (idx = ASPEED_LPC_SNOOP_INDEX_0; idx <= ASPEED_LPC_SNOOP_INDEX_MAX; idx++) {
+		u32 port;
+
+		rc = of_property_read_u32_index(dev->of_node, "snoop-ports", idx, &port);
+		if (rc)
+			break;
 
-	/* Configuration of 2nd snoop channel port is optional */
-	if (of_property_read_u32_index(dev->of_node, "snoop-ports",
-				       1, &port) == 0) {
-		rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, ASPEED_LPC_SNOOP_INDEX_1, port);
-		if (rc) {
-			aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_0);
-			return rc;
-		}
+		rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, idx, port);
+		if (rc)
+			goto cleanup_channels;
 	}
 
-	return 0;
-}
+	return idx == ASPEED_LPC_SNOOP_INDEX_0 ? -ENODEV : 0;
 
-static void aspeed_lpc_snoop_remove(struct platform_device *pdev)
-{
-	struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
+cleanup_channels:
+	aspeed_lpc_snoop_remove(pdev);
 
-	/* Disable both snoop channels */
-	aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_0);
-	aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_1);
+	return rc;
 }
 
 static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {