soc: aspeed: lpc-snoop: Lift channel config to const structs

The shifts and masks for each channel are defined by hardware and
are not something that changes at runtime. Accordingly, describe the
information in an array of const structs and associate elements with
each channel instance, removing the need for the switch and handling of
its default case.

Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-10-3cdd59c934d3@codeconstruct.com.au
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Author: amboar

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

@@ -63,7 +63,16 @@ enum aspeed_lpc_snoop_index {
 	ASPEED_LPC_SNOOP_INDEX_MAX = ASPEED_LPC_SNOOP_INDEX_1,
 };
 
+struct aspeed_lpc_snoop_channel_cfg {
+	enum aspeed_lpc_snoop_index index;
+	u32 hicr5_en;
+	u32 snpwadr_mask;
+	u32 snpwadr_shift;
+	u32 hicrb_en;
+};
+
 struct aspeed_lpc_snoop_channel {
+	const struct aspeed_lpc_snoop_channel_cfg *cfg;
 	bool enabled;
 	struct kfifo		fifo;
 	wait_queue_head_t	wq;
@@ -77,6 +86,23 @@ struct aspeed_lpc_snoop {
 	struct aspeed_lpc_snoop_channel chan[ASPEED_LPC_SNOOP_INDEX_MAX + 1];
 };
 
+static const struct aspeed_lpc_snoop_channel_cfg channel_cfgs[ASPEED_LPC_SNOOP_INDEX_MAX + 1] = {
+	{
+		.index = ASPEED_LPC_SNOOP_INDEX_0,
+		.hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
+		.snpwadr_mask = SNPWADR_CH0_MASK,
+		.snpwadr_shift = SNPWADR_CH0_SHIFT,
+		.hicrb_en = HICRB_ENSNP0D,
+	},
+	{
+		.index = ASPEED_LPC_SNOOP_INDEX_1,
+		.hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
+		.snpwadr_mask = SNPWADR_CH1_MASK,
+		.snpwadr_shift = SNPWADR_CH1_SHIFT,
+		.hicrb_en = HICRB_ENSNP1D,
+	},
+};
+
 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)
 {
 	return container_of(file->private_data,
@@ -189,28 +215,27 @@ static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
 }
 
 __attribute__((nonnull))
-static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
-				   struct device *dev,
-				   enum aspeed_lpc_snoop_index index, u16 lpc_port)
+static int aspeed_lpc_enable_snoop(struct device *dev,
+				    struct aspeed_lpc_snoop *lpc_snoop,
+				    struct aspeed_lpc_snoop_channel *channel,
+				    const struct aspeed_lpc_snoop_channel_cfg *cfg,
+				    u16 lpc_port)
 {
 	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;
 
-	channel = &lpc_snoop->chan[index];
-
 	if (WARN_ON(channel->enabled))
 		return -EBUSY;
 
 	init_waitqueue_head(&channel->wq);
 
+	channel->cfg = cfg;
 	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);
+		devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, cfg->index);
 	if (!channel->miscdev.name)
 		return -ENOMEM;
 
@@ -223,69 +248,32 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
 		goto err_free_fifo;
 
 	/* Enable LPC snoop channel at requested port */
-	switch (index) {
-	case 0:
-		hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;
-		snpwadr_mask = SNPWADR_CH0_MASK;
-		snpwadr_shift = SNPWADR_CH0_SHIFT;
-		hicrb_en = HICRB_ENSNP0D;
-		break;
-	case 1:
-		hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;
-		snpwadr_mask = SNPWADR_CH1_MASK;
-		snpwadr_shift = SNPWADR_CH1_SHIFT;
-		hicrb_en = HICRB_ENSNP1D;
-		break;
-	default:
-		rc = -EINVAL;
-		goto err_misc_deregister;
-	}
-
-	regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
-	regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
-			   lpc_port << snpwadr_shift);
+	regmap_set_bits(lpc_snoop->regmap, HICR5, cfg->hicr5_en);
+	regmap_update_bits(lpc_snoop->regmap, SNPWADR, cfg->snpwadr_mask,
+			   lpc_port << cfg->snpwadr_shift);
 
 	model_data = of_device_get_match_data(dev);
 	if (model_data && model_data->has_hicrb_ensnp)
-		regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
+		regmap_set_bits(lpc_snoop->regmap, HICRB, cfg->hicrb_en);
 
 	channel->enabled = true;
 
 	return 0;
 
-err_misc_deregister:
-	misc_deregister(&channel->miscdev);
 err_free_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)
+				     struct aspeed_lpc_snoop_channel *channel)
 {
-	struct aspeed_lpc_snoop_channel *channel;
-
-	channel = &lpc_snoop->chan[index];
-
 	if (!channel->enabled)
 		return;
 
 	/* Disable interrupts along with the device */
-	switch (index) {
-	case 0:
-		regmap_update_bits(lpc_snoop->regmap, HICR5,
-				   HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
-				   0);
-		break;
-	case 1:
-		regmap_update_bits(lpc_snoop->regmap, HICR5,
-				   HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
-				   0);
-		break;
-	default:
-		return;
-	}
+	regmap_clear_bits(lpc_snoop->regmap, HICR5, channel->cfg->hicr5_en);
 
 	channel->enabled = false;
 	/* Consider improving safety wrt concurrent reader(s) */
@@ -298,8 +286,8 @@ 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);
+	aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[0]);
+	aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[1]);
 }
 
 static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
@@ -338,14 +326,17 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
+	static_assert(ARRAY_SIZE(channel_cfgs) == ARRAY_SIZE(lpc_snoop->chan),
+		"Broken implementation assumption regarding cfg count");
 	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;
 
-		rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, idx, port);
+		rc = aspeed_lpc_enable_snoop(dev, lpc_snoop, &lpc_snoop->chan[idx],
+					     &channel_cfgs[idx], port);
 		if (rc)
 			goto cleanup_channels;
 	}