[PATCH v2 2/8] i2c: rtl9300: introduce max length property to driver data

Rustam Adilov
2026-03-19T17:59:29Z

In RTL9607C i2c controller, theoretical maximum the data length
can be is 4 bytes as opposed to 16 bytes on rtl9300 and rtl9310.

Introduce a new property to the driver data struct for that.
Adjust if statement in prepare_xfer function to follow that new
property instead of the hardcoded value.

Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Rustam Adilov <adilov@disroot.org>
---
drivers/i2c/busses/i2c-rtl9300.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
index 9bf4c6b08e05..2cada6038b44 100644
--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -64,11 +64,14 @@ struct rtl9300_i2c_drv_data {
u32 rd_reg;
u32 wd_reg;
u8 max_nchan;
+ u8 max_data_len;
};

#define RTL9300_I2C_MUX_NCHAN 8
#define RTL9310_I2C_MUX_NCHAN 12

+#define RTL9300_I2C_MAX_DATA_LEN 16
+
struct rtl9300_i2c {
struct regmap *regmap;
struct device *dev;
@@ -210,9 +213,11 @@ static int rtl9300_i2c_writel(struct rtl9300_i2c *i2c, u32 data)

static int rtl9300_i2c_prepare_xfer(struct rtl9300_i2c *i2c, struct rtl9300_i2c_xfer *xfer)
{
+ const struct rtl9300_i2c_drv_data *drv_data;
int ret;

- if (xfer->data_len < 1 || xfer->data_len > 16)
+ drv_data = device_get_match_data(i2c->dev);
+ if (xfer->data_len < 1 || xfer->data_len > drv_data->max_data_len)
return -EINVAL;

ret = regmap_field_write(i2c->fields[F_DEV_ADDR], xfer->dev_addr);
@@ -505,6 +510,7 @@ static const struct rtl9300_i2c_drv_data rtl9300_i2c_drv_data = {
.rd_reg = RTL9300_I2C_MST_DATA_WORD0,
.wd_reg = RTL9300_I2C_MST_DATA_WORD0,
.max_nchan = RTL9300_I2C_MUX_NCHAN,
+ .max_data_len = RTL9300_I2C_MAX_DATA_LEN,
};

static const struct rtl9300_i2c_drv_data rtl9310_i2c_drv_data = {
@@ -526,6 +532,7 @@ static const struct rtl9300_i2c_drv_data rtl9310_i2c_drv_data = {
.rd_reg = RTL9310_I2C_MST_DATA_CTRL,
.wd_reg = RTL9310_I2C_MST_DATA_CTRL,
.max_nchan = RTL9310_I2C_MUX_NCHAN,
+ .max_data_len = RTL9300_I2C_MAX_DATA_LEN,
};

static const struct of_device_id i2c_rtl9300_dt_ids[] = {
--
2.53.0