[PATCH v2 4/8] i2c: rtl9300: introduce a property for 8 bit width reg address

Rustam Adilov
2026-03-19T17:59:34Z

In RTL9607C i2c controller, in order to indicate that the width of
memory address is 8 bits, 0 is written to MEM_ADDR_WIDTH field as
opposed to 1 for RTL9300 and RTL9310.

Introduce a new property to a driver data to indicate what value
need to written to MEM_ADDR_WIDTH field for this case.

Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Rustam Adilov <adilov@disroot.org>
---
drivers/i2c/busses/i2c-rtl9300.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
index e40b4692a3fa..ffbc6c52861b 100644
--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -66,6 +66,7 @@ struct rtl9300_i2c_drv_data {
u32 wd_reg;
u8 max_nchan;
u8 max_data_len;
+ u8 reg_addr_8bit_len;
};

#define RTL9300_I2C_MUX_NCHAN 8
@@ -111,6 +112,7 @@ struct rtl9300_i2c_xfer {
#define RTL9300_I2C_MST_DATA_WORD2 0x10
#define RTL9300_I2C_MST_DATA_WORD3 0x14
#define RTL9300_I2C_MST_GLB_CTRL 0x384
+#define RTL9300_REG_ADDR_8BIT_LEN 1

#define RTL9310_I2C_MST_IF_CTRL 0x1004
#define RTL9310_I2C_MST_IF_SEL 0x1008
@@ -305,6 +307,7 @@ static int rtl9300_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned s
union i2c_smbus_data *data)
{
struct rtl9300_i2c_chan *chan = i2c_get_adapdata(adap);
+ const struct rtl9300_i2c_drv_data *drv_data;
struct rtl9300_i2c *i2c = chan->i2c;
struct rtl9300_i2c_xfer xfer = {0};
int ret;
@@ -314,6 +317,7 @@ static int rtl9300_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned s

guard(rtl9300_i2c)(i2c);

+ drv_data = device_get_match_data(i2c->dev);
ret = rtl9300_i2c_config_chan(i2c, chan);
if (ret)
return ret;
@@ -321,7 +325,7 @@ static int rtl9300_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned s
xfer.dev_addr = addr & 0x7f;
xfer.write = (read_write == I2C_SMBUS_WRITE);
xfer.reg_addr = command;
- xfer.reg_addr_len = 1;
+ xfer.reg_addr_len = drv_data->reg_addr_8bit_len;

switch (size) {
case I2C_SMBUS_BYTE:
@@ -513,6 +517,7 @@ static const struct rtl9300_i2c_drv_data rtl9300_i2c_drv_data = {
.wd_reg = RTL9300_I2C_MST_DATA_WORD0,
.max_nchan = RTL9300_I2C_MUX_NCHAN,
.max_data_len = RTL9300_I2C_MAX_DATA_LEN,
+ .reg_addr_8bit_len = RTL9300_REG_ADDR_8BIT_LEN,
};

static const struct rtl9300_i2c_drv_data rtl9310_i2c_drv_data = {
@@ -536,6 +541,7 @@ static const struct rtl9300_i2c_drv_data rtl9310_i2c_drv_data = {
.wd_reg = RTL9310_I2C_MST_DATA_CTRL,
.max_nchan = RTL9310_I2C_MUX_NCHAN,
.max_data_len = RTL9300_I2C_MAX_DATA_LEN,
+ .reg_addr_8bit_len = RTL9300_REG_ADDR_8BIT_LEN,
};

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