i3c: master: Improve initialization of numbered I2C adapters

Add logic to initialize I2C adapters with a specific ID if available,
improving device identification and configuration.

For mixed buses, in addition to the i3c alias, an i2c alias can be added to
assign a fixed bus number to the i2c adapter.

This allows an alias node such as:
    aliases {
        i2c2 = &mixed_bus_a,
        i3c2 = &mixed_bus_a,
        i3c4 = &mixed_bus_b,
    };

    /* assigned "i3c-2" and "i2c-2" */
    mixed_bus_a: i3c-master {
    };

If there is no i2c alias for a mixed bus, the i2c adapter numbers will
remain as is and will be assigned starting after the highest fixed bus
number.

    /* assigned "i3c-4" and likely assigned "i2c-3" */
    mixed_bus_b: i3c-master {
    };

Signed-off-by: Defa Li <[email protected]>
Reviewed-by: Frank Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

drivers/i3c/master.c

@@ -2486,7 +2486,7 @@ static int i3c_master_i2c_adapter_init(struct i3c_master_controller *master)
 	struct i2c_adapter *adap = i3c_master_to_i2c_adapter(master);
 	struct i2c_dev_desc *i2cdev;
 	struct i2c_dev_boardinfo *i2cboardinfo;
-	int ret;
+	int ret, id = -ENODEV;
 
 	adap->dev.parent = master->dev.parent;
 	adap->owner = master->dev.parent->driver->owner;
@@ -2497,7 +2497,15 @@ static int i3c_master_i2c_adapter_init(struct i3c_master_controller *master)
 	adap->timeout = 1000;
 	adap->retries = 3;
 
-	ret = i2c_add_adapter(adap);
+	if (master->dev.of_node)
+		id = of_alias_get_id(master->dev.of_node, "i2c");
+
+	if (id >= 0) {
+		adap->nr = id;
+		ret = i2c_add_numbered_adapter(adap);
+	} else {
+		ret = i2c_add_adapter(adap);
+	}
 	if (ret)
 		return ret;