linux-kernel - [PATCH v2 4/5] i2c: mt7621: limit SCL

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Message-ID: <20250721180710.2116-5-ansuelsmth@gmail.com>
Date: Mon, 21 Jul 2025 20:05:55 +0200
From: Christian Marangi <ansuelsmth@...il.com>
To: Stefan Roese <sr@...x.de>,
	Andi Shyti <andi.shyti@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	linux-i2c@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Cc: Christian Marangi <ansuelsmth@...il.com>
Subject: [PATCH v2 4/5] i2c: mt7621: limit SCL_STRETCH only to Mediatek SoC

The same I2C driver is also used for Airoha SoC with the only difference
that the i2c_reset should not enable SCL_STRETCH for Airoha SoC.

Introduce a new compatible for Airoha and limit the SCL_STRETCH only to
mediatek SoC.

Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
---
 drivers/i2c/busses/i2c-mt7621.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
index 58c3da92cea3..b4dc1fb269a6 100644
--- a/drivers/i2c/busses/i2c-mt7621.c
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -88,6 +88,7 @@ static int mtk_i2c_wait_idle(struct mtk_i2c *i2c, bool atomic)
 
 static void mtk_i2c_reset(struct mtk_i2c *i2c)
 {
+	u32 reg;
 	int ret;
 
 	ret = device_reset(i2c->adap.dev.parent);
@@ -98,8 +99,12 @@ static void mtk_i2c_reset(struct mtk_i2c *i2c)
 	 * Don't set SM0CTL0_ODRAIN as its bit meaning is inverted. To
 	 * configure open-drain mode, this bit needs to be cleared.
 	 */
-	iowrite32(((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN |
-		  SM0CTL0_SCL_STRETCH, i2c->base + REG_SM0CTL0_REG);
+	reg = ((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN;
+	/* Set SCL_STRETCH only for Mediatek SoC */
+	if (device_is_compatible(i2c->dev, "mediatek,mt7621-i2c"))
+		reg |= SM0CTL0_SCL_STRETCH;
+
+	iowrite32(reg, i2c->base + REG_SM0CTL0_REG);
 	iowrite32(0, i2c->base + REG_SM0CFG2_REG);
 	/* Clear any pending interrupt */
 	iowrite32(1, i2c->base + REG_PINTEN_REG);
@@ -276,6 +281,7 @@ static const struct i2c_algorithm mtk_i2c_algo = {
 
 static const struct of_device_id i2c_mtk_dt_ids[] = {
 	{ .compatible = "mediatek,mt7621-i2c" },
+	{ .compatible = "airoha,an7581-i2c" },
 	{ /* sentinel */ }
 };
 
-- 
2.50.0