[PATCH v2 0/5] i2c: mt7621: improve support for Airoha

[PATCH v2 0/5] i2c: mt7621: improve support for Airoha

[Christian Marangi]

This small series improve support for Airoha SoC that use the
same MT7621 implementation. Some additional tweak are required
to better support it.

Also we add support for atomic variant of .xfer required for
some attached pheriperals on the Airoha SoC.

Changes v2:
- Fix compatible order for schema patch

Christian Marangi (5):
  i2c: mt7621: rework cmd/wait OPs to support atomic afer variant
  i2c: mt7621: clear pending interrupt on i2c reset
  dt-bindings: i2c: mt7621: Document an7581 compatible
  i2c: mt7621: limit SCL_STRETCH only to Mediatek SoC
  i2c: mt7621: make device reset optional

 .../bindings/i2c/mediatek,mt7621-i2c.yaml     | 14 +++-
 drivers/i2c/busses/i2c-mt7621.c               | 73 +++++++++++++------
 2 files changed, 64 insertions(+), 23 deletions(-)

-- 
2.50.0

[PATCH v2 1/5] i2c: mt7621: rework cmd/wait OPs to support atomic afer variant

[Christian Marangi]

It was reported the need for atomic operation on some Airoha SoC that
makes use of I2C bus. Rework the cmd/wait OPs to suppor the xfer_atomic
variant. To support this it's mainlin needed to do the readl poll in
atomic context.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/i2c/busses/i2c-mt7621.c | 59 ++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
index 2103f21f9ddd..c0e13f9af3e5 100644
--- a/drivers/i2c/busses/i2c-mt7621.c
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -67,14 +67,19 @@ struct mtk_i2c {
 	struct clk *clk;
 };
 
-static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
+static int mtk_i2c_wait_idle(struct mtk_i2c *i2c, bool atomic)
 {
 	int ret;
 	u32 val;
 
-	ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG,
-					 val, !(val & SM0CTL1_TRI),
-					 10, TIMEOUT_MS * 1000);
+	if (atomic)
+		ret = readl_relaxed_poll_timeout_atomic(i2c->base + REG_SM0CTL1_REG,
+							val, !(val & SM0CTL1_TRI),
+							10, TIMEOUT_MS * 1000);
+	else
+		ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG,
+						 val, !(val & SM0CTL1_TRI),
+						 10, TIMEOUT_MS * 1000);
 	if (ret)
 		dev_dbg(i2c->dev, "idle err(%d)\n", ret);
 
@@ -117,27 +122,28 @@ static int mtk_i2c_check_ack(struct mtk_i2c *i2c, u32 expected)
 	return ((ack & ack_expected) == ack_expected) ? 0 : -ENXIO;
 }
 
-static int mtk_i2c_start(struct mtk_i2c *i2c)
+static int mtk_i2c_start(struct mtk_i2c *i2c, bool atomic)
 {
 	iowrite32(SM0CTL1_START | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
-	return mtk_i2c_wait_idle(i2c);
+	return mtk_i2c_wait_idle(i2c, atomic);
 }
 
-static int mtk_i2c_stop(struct mtk_i2c *i2c)
+static int mtk_i2c_stop(struct mtk_i2c *i2c, bool atomic)
 {
 	iowrite32(SM0CTL1_STOP | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
-	return mtk_i2c_wait_idle(i2c);
+	return mtk_i2c_wait_idle(i2c, atomic);
 }
 
-static int mtk_i2c_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len)
+static int mtk_i2c_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len,
+		       bool atomic)
 {
 	iowrite32(cmd | SM0CTL1_TRI | SM0CTL1_PGLEN(page_len),
 		  i2c->base + REG_SM0CTL1_REG);
-	return mtk_i2c_wait_idle(i2c);
+	return mtk_i2c_wait_idle(i2c, atomic);
 }
 
-static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
-			int num)
+static int mtk_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			       int num, bool atomic)
 {
 	struct mtk_i2c *i2c;
 	struct i2c_msg *pmsg;
@@ -152,12 +158,12 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		pmsg = &msgs[i];
 
 		/* wait hardware idle */
-		ret = mtk_i2c_wait_idle(i2c);
+		ret = mtk_i2c_wait_idle(i2c, atomic);
 		if (ret)
 			goto err_timeout;
 
 		/* start sequence */
-		ret = mtk_i2c_start(i2c);
+		ret = mtk_i2c_start(i2c, atomic);
 		if (ret)
 			goto err_timeout;
 
@@ -169,14 +175,16 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			if (pmsg->flags & I2C_M_RD)
 				addr |= 1;
 			iowrite32(addr, i2c->base + REG_SM0D0_REG);
-			ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 2);
+			ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 2,
+					  atomic);
 			if (ret)
 				goto err_timeout;
 		} else {
 			/* 7 bits address */
 			addr = i2c_8bit_addr_from_msg(pmsg);
 			iowrite32(addr, i2c->base + REG_SM0D0_REG);
-			ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 1);
+			ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 1,
+					  atomic);
 			if (ret)
 				goto err_timeout;
 		}
@@ -202,7 +210,7 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 				cmd = SM0CTL1_WRITE;
 			}
 
-			ret = mtk_i2c_cmd(i2c, cmd, page_len);
+			ret = mtk_i2c_cmd(i2c, cmd, page_len, atomic);
 			if (ret)
 				goto err_timeout;
 
@@ -222,7 +230,7 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		}
 	}
 
-	ret = mtk_i2c_stop(i2c);
+	ret = mtk_i2c_stop(i2c, atomic);
 	if (ret)
 		goto err_timeout;
 
@@ -230,7 +238,7 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	return i;
 
 err_ack:
-	ret = mtk_i2c_stop(i2c);
+	ret = mtk_i2c_stop(i2c, atomic);
 	if (ret)
 		goto err_timeout;
 	return -ENXIO;
@@ -241,6 +249,18 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	return ret;
 }
 
+static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			int num)
+{
+	return mtk_i2c_xfer_common(adap, msgs, num, false);
+}
+
+static int mtk_i2c_xfer_atomic(struct i2c_adapter *adap,
+			       struct i2c_msg *msgs, int num)
+{
+	return mtk_i2c_xfer_common(adap, msgs, num, true);
+}
+
 static u32 mtk_i2c_func(struct i2c_adapter *a)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
@@ -248,6 +268,7 @@ static u32 mtk_i2c_func(struct i2c_adapter *a)
 
 static const struct i2c_algorithm mtk_i2c_algo = {
 	.xfer = mtk_i2c_xfer,
+	.xfer_atomic = mtk_i2c_xfer_atomic,
 	.functionality = mtk_i2c_func,
 };
 
-- 
2.50.0

[PATCH v2 2/5] i2c: mt7621: clear pending interrupt on i2c reset

[Christian Marangi]

On resetting the i2c bus, clear any pending interrupt to have a more
consistent state on the next operation.

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

diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
index c0e13f9af3e5..58c3da92cea3 100644
--- a/drivers/i2c/busses/i2c-mt7621.c
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -101,6 +101,8 @@ static void mtk_i2c_reset(struct mtk_i2c *i2c)
 	iowrite32(((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN |
 		  SM0CTL0_SCL_STRETCH, i2c->base + REG_SM0CTL0_REG);
 	iowrite32(0, i2c->base + REG_SM0CFG2_REG);
+	/* Clear any pending interrupt */
+	iowrite32(1, i2c->base + REG_PINTEN_REG);
 }
 
 static void mtk_i2c_dump_reg(struct mtk_i2c *i2c)
-- 
2.50.0

[PATCH v2 3/5] 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 a dedicated reset line to reset it.

Add a dedicated compatible for the Airoha AN7581 SoC and reject the
unsupported property.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 .../bindings/i2c/mediatek,mt7621-i2c.yaml          | 14 +++++++++++++-
 1 file changed, 13 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..8223fbc74f14 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
@@ -38,6 +40,16 @@ required:
   - "#address-cells"
   - "#size-cells"
 
+if:
+  properties:
+    compatible:
+      contains:
+        const: airoha,an7581-i2c
+then:
+  properties:
+    resets: false
+    reset-names: false
+
 unevaluatedProperties: false
 
 examples:
-- 
2.50.0

[PATCH v2 4/5] 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>
---
 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

[PATCH v2 5/5] i2c: mt7621: make device reset optional

[Christian Marangi]

Airoha SoC that makes use of the same Mediatek I2C driver/logic doesn't
have reset line for I2C so use optional device_reset variant.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/i2c/busses/i2c-mt7621.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
index b4dc1fb269a6..6e3848f163f0 100644
--- a/drivers/i2c/busses/i2c-mt7621.c
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -91,7 +91,7 @@ static void mtk_i2c_reset(struct mtk_i2c *i2c)
 	u32 reg;
 	int ret;
 
-	ret = device_reset(i2c->adap.dev.parent);
+	ret = device_reset_optional(i2c->adap.dev.parent);
 	if (ret)
 		dev_err(i2c->dev, "I2C reset failed!\n");
 
-- 
2.50.0

Re: [PATCH v2 3/5] dt-bindings: i2c: mt7621: Document an7581 compatible

[Rob Herring (Arm)]

On Mon, 21 Jul 2025 20:05:54 +0200, Christian Marangi wrote:
> Airoha SoC implement the same Mediatek logic for I2C bus with the only
> difference of not having a dedicated reset line to reset it.
> 
> Add a dedicated compatible for the Airoha AN7581 SoC and reject the
> unsupported property.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> ---
>  .../bindings/i2c/mediatek,mt7621-i2c.yaml          | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>