[PATCH 4/5] i2c: mt7621: limit SCL_STRETCH only to Mediatek SoC

Christian Marangi
2025-07-19T12:56:37Z

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