soc: aspeed: lpc-snoop: Rearrange channel paths

Order assignments such that tests for conditions not involving resource
acquisition are ordered before those testing acquired resources, and
order managed resource acquisition before unmanaged where possible. This
way we minimise the amount of manual cleanup required.

In the process, improve readability of the code by introducing a channel
pointer that takes the place of the repeated object lookups.

Acked-by: Jean Delvare <jdelvare@suse.de>
Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-6-3cdd59c934d3@codeconstruct.com.au
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Author: amboar

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

@@ -194,28 +194,30 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 {
 	const struct aspeed_lpc_snoop_model_data *model_data;
 	u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
+	struct aspeed_lpc_snoop_channel *channel;
 	int rc = 0;
 
-	if (WARN_ON(lpc_snoop->chan[index].enabled))
+	channel = &lpc_snoop->chan[index];
+
+	if (WARN_ON(channel->enabled))
 		return -EBUSY;
 
-	init_waitqueue_head(&lpc_snoop->chan[index].wq);
-	/* Create FIFO datastructure */
-	rc = kfifo_alloc(&lpc_snoop->chan[index].fifo,
-			 SNOOP_FIFO_SIZE, GFP_KERNEL);
+	init_waitqueue_head(&channel->wq);
+
+	channel->miscdev.minor = MISC_DYNAMIC_MINOR;
+	channel->miscdev.fops = &snoop_fops;
+	channel->miscdev.parent = dev;
+
+	channel->miscdev.name =
+		devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, index);
+	if (!channel->miscdev.name)
+		return -ENOMEM;
+
+	rc = kfifo_alloc(&channel->fifo, SNOOP_FIFO_SIZE, GFP_KERNEL);
 	if (rc)
 		return rc;
 
-	lpc_snoop->chan[index].miscdev.minor = MISC_DYNAMIC_MINOR;
-	lpc_snoop->chan[index].miscdev.name =
-		devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, index);
-	if (!lpc_snoop->chan[index].miscdev.name) {
-		rc = -ENOMEM;
-		goto err_free_fifo;
-	}
-	lpc_snoop->chan[index].miscdev.fops = &snoop_fops;
-	lpc_snoop->chan[index].miscdev.parent = dev;
-	rc = misc_register(&lpc_snoop->chan[index].miscdev);
+	rc = misc_register(&channel->miscdev);
 	if (rc)
 		goto err_free_fifo;
 
@@ -246,22 +248,26 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 	if (model_data && model_data->has_hicrb_ensnp)
 		regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
 
-	lpc_snoop->chan[index].enabled = true;
+	channel->enabled = true;
 
 	return 0;
 
 err_misc_deregister:
-	misc_deregister(&lpc_snoop->chan[index].miscdev);
+	misc_deregister(&channel->miscdev);
 err_free_fifo:
-	kfifo_free(&lpc_snoop->chan[index].fifo);
+	kfifo_free(&channel->fifo);
 	return rc;
 }
 
 __attribute__((nonnull))
 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 				     enum aspeed_lpc_snoop_index index)
 {
-	if (!lpc_snoop->chan[index].enabled)
+	struct aspeed_lpc_snoop_channel *channel;
+
+	channel = &lpc_snoop->chan[index];
+
+	if (!channel->enabled)
 		return;
 
 	/* Disable interrupts along with the device */
@@ -280,10 +286,10 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 		return;
 	}
 
-	lpc_snoop->chan[index].enabled = false;
+	channel->enabled = false;
 	/* Consider improving safety wrt concurrent reader(s) */
-	misc_deregister(&lpc_snoop->chan[index].miscdev);
-	kfifo_free(&lpc_snoop->chan[index].fifo);
+	misc_deregister(&channel->miscdev);
+	kfifo_free(&channel->fifo);
 }
 
 static int aspeed_lpc_snoop_probe(struct platform_device *pdev)