sorry, this is my mistake, for imx8mp, you can download SDK from
"https://mcuxpresso.nxp.com/en/welcome"
i.mx8mp flexcan is similar as imx8/imx8x, so you can download SDK for imx8/imx8x
The sample apps are under driver_examples/flexcan directory,
The driver code is located under devices/MIMX8ML8/drivers directory