Modifiy your printer.cfg with the following code to enable sensorless homing：
[stepper_y]
step_pin: PB10
dir_pin: PB2
enable_pin: !PB11
rotation_distance: 40
full_steps_per_rotation: 200
microsteps: 32
endstop_pin: tmc2209_stepper_y:virtual_endstop
homing_retract_dist: 0
position_endstop: 250
position_min: 0
position_max: 250
homing_speed: 70
homing_positive_dir: true
[tmc2209 stepper_y]
uart_pin: PC11
tx_pin: PC10
diag_pin: ^PC1
uart_address: 2
run_current: 0.5
interpolate: False
stealthchop_threshold: 0
driver_SGTHRS: 120 # tune this once it's working.# tune this once it's working.In addition, make sure the Y_DIAG jumper is installed on the SKR.
The next step is tuning the your sensorless homing setup, please read this guide.