From: Rustam Adilov <adilov@disroot.org>
Date: Wed, 1 Apr 2026 18:06:42 +0000 (+0500)
Subject: i2c: rtl9300: introduce max length property to driver data
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=98773df61f8416594ac993e8464df596755ee1b8;p=thirdparty%2Flinux.git

i2c: rtl9300: introduce max length property to driver data

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.

Signed-off-by: Rustam Adilov <adilov@disroot.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-3-adilov@disroot.org
---

diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
index 9bf4c6b08e05a..2cada6038b44f 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[] = {