linux-kernel - [PATCH 4/8] dmaengine: mediatek: uart-apdma: Get addressing bits from match data

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Message-ID: <20251113122229.23998-5-angelogioacchino.delregno@collabora.com>
Date: Thu, 13 Nov 2025 13:22:25 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: dmaengine@...r.kernel.org
Cc: sean.wang@...iatek.com,
	vkoul@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	matthias.bgg@...il.com,
	angelogioacchino.delregno@...labora.com,
	long.cheng@...iatek.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	kernel@...labora.com
Subject: [PATCH 4/8] dmaengine: mediatek: uart-apdma: Get addressing bits from match data

The only SoC that declares mediatek,dma-33bits in its devicetree
currently is MT6795, which obviously also declares a SoC-specific
compatible string: in preparation for adding new SoCs with 34 bits
addressing, replace the parsing of said vendor property with logic
to get the number of addressing bits from platform data associated
to compatible strings.

While at it, also make the bit_mask variable unsigned and move the
`int rc` declaration as last to beautify the code.

Thanks to the correct declaration of the APDMA node is in all of
the MediaTek device trees that are currently upstream, this commit
brings no functional differences.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/dma/mediatek/mtk-uart-apdma.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c
index 08e15177427b..b906e59f4c6d 100644
--- a/drivers/dma/mediatek/mtk-uart-apdma.c
+++ b/drivers/dma/mediatek/mtk-uart-apdma.c
@@ -468,7 +468,8 @@ static void mtk_uart_apdma_free(struct mtk_uart_apdmadev *mtkd)
 }
 
 static const struct of_device_id mtk_uart_apdma_match[] = {
-	{ .compatible = "mediatek,mt6577-uart-dma", },
+	{ .compatible = "mediatek,mt6577-uart-dma", .data = (void *)32 },
+	{ .compatible = "mediatek,mt6795-uart-dma", .data = (void *)33 },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, mtk_uart_apdma_match);
@@ -477,9 +478,9 @@ static int mtk_uart_apdma_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct mtk_uart_apdmadev *mtkd;
-	int bit_mask = 32, rc;
 	struct mtk_chan *c;
-	unsigned int i;
+	unsigned int bit_mask, i;
+	int rc;
 
 	mtkd = devm_kzalloc(&pdev->dev, sizeof(*mtkd), GFP_KERNEL);
 	if (!mtkd)
@@ -492,12 +493,10 @@ static int mtk_uart_apdma_probe(struct platform_device *pdev)
 		return rc;
 	}
 
-	if (of_property_read_bool(np, "mediatek,dma-33bits"))
+	bit_mask = (unsigned int)(uintptr_t)of_device_get_match_data(&pdev->dev);
+	if (bit_mask > 32)
 		mtkd->support_33bits = true;
 
-	if (mtkd->support_33bits)
-		bit_mask = 33;
-
 	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(bit_mask));
 	if (rc)
 		return rc;
-- 
2.51.1