[PATCH v3 1/2] dt-bindings: i2c: mt7621: Document an7581 compatible

[PATCH v3 1/2] dt-bindings: i2c: mt7621: Document an7581 compatible

[Christian Marangi]

Airoha SoC implement the same Mediatek logic for I2C bus with the only
difference of not having SCL_STRETCH bit.

Add a dedicated compatible for the Airoha AN7581 SoC to account for this
minor bit variant.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
---
Changes v3:
- Fix typo for account
Changes v2:
- Add ACK tag

 .../devicetree/bindings/i2c/mediatek,mt7621-i2c.yaml          | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/i2c/mediatek,mt7621-i2c.yaml b/Documentation/devicetree/bindings/i2c/mediatek,mt7621-i2c.yaml
index 118ec00fc190..e6ea5bc1c681 100644
--- a/Documentation/devicetree/bindings/i2c/mediatek,mt7621-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/mediatek,mt7621-i2c.yaml
@@ -14,7 +14,9 @@ allOf:
 
 properties:
   compatible:
-    const: mediatek,mt7621-i2c
+    enum:
+      - airoha,an7581-i2c
+      - mediatek,mt7621-i2c
 
   reg:
     maxItems: 1
-- 
2.55.0

[PATCH v3 2/2] i2c: mt7621: limit SCL_STRETCH only to Mediatek SoC

[Christian Marangi]

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@gmail.com>
---
Changes v2:
- Use match data for storage

 drivers/i2c/busses/i2c-mt7621.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
index 0a288c998419..fa1f32d4f046 100644
--- a/drivers/i2c/busses/i2c-mt7621.c
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -57,9 +57,14 @@
 /* timeout waiting for I2C devices to respond */
 #define TIMEOUT_MS		1000
 
+struct mtk_i2c_data {
+	bool have_scl_stretch;
+};
+
 struct mtk_i2c {
 	void __iomem *base;
 	struct device *dev;
+	const struct mtk_i2c_data *data;
 	struct i2c_adapter adap;
 	u32 bus_freq;
 	u32 clk_div;
@@ -83,6 +88,7 @@ static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
 
 static void mtk_i2c_reset(struct mtk_i2c *i2c)
 {
+	u32 reg;
 	int ret;
 
 	ret = device_reset(i2c->adap.dev.parent);
@@ -93,8 +99,11 @@ 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;
+	if (i2c->data->have_scl_stretch)
+		reg |= SM0CTL0_SCL_STRETCH;
+
+	iowrite32(reg, i2c->base + REG_SM0CTL0_REG);
 	iowrite32(0, i2c->base + REG_SM0CFG2_REG);
 }
 
@@ -247,8 +256,17 @@ static const struct i2c_algorithm mtk_i2c_algo = {
 	.functionality = mtk_i2c_func,
 };
 
+static const struct mtk_i2c_data i2c_mt7621_data = {
+	.have_scl_stretch = true,
+};
+
+static const struct mtk_i2c_data i2c_an7581_data = {
+	.have_scl_stretch = false,
+};
+
 static const struct of_device_id i2c_mtk_dt_ids[] = {
-	{ .compatible = "mediatek,mt7621-i2c" },
+	{ .compatible = "mediatek,mt7621-i2c", .data = &i2c_mt7621_data },
+	{ .compatible = "airoha,an7581-i2c", .data = &i2c_an7581_data },
 	{ /* sentinel */ }
 };
 
@@ -286,6 +304,7 @@ static int mtk_i2c_probe(struct platform_device *pdev)
 	}
 
 	i2c->dev = &pdev->dev;
+	i2c->data = device_get_match_data(&pdev->dev);
 
 	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 				 &i2c->bus_freq))
-- 
2.55.0

Re: [PATCH v3 1/2] dt-bindings: i2c: mt7621: Document an7581 compatible

[Wolfram Sang]

On Tue, Nov 03, 2026 at 10:05:40PM +0100, Christian Marangi wrote:
> Airoha SoC implement the same Mediatek logic for I2C bus with the only
> difference of not having SCL_STRETCH bit.
> 
> Add a dedicated compatible for the Airoha AN7581 SoC to account for this
> minor bit variant.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> Acked-by: Rob Herring (Arm) <robh@kernel.org>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Will apply it to my for-andi branch.

Re: [PATCH v3 2/2] i2c: mt7621: limit SCL_STRETCH only to Mediatek SoC

[Wolfram Sang]

On Tue, Nov 03, 2026 at 10:05:41PM +0100, Christian Marangi wrote:
> 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@gmail.com>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Will apply it to my for-andi branch.