38.5.2 Clocks
An AHB clock (CLK_CAN_AHB) is required to clock the CAN. This clock can be configured in the Main Clock peripheral (MCLK) before using the CAN, and the default state of CLK_CAN_AHB can be found in the MCLK.AHBMASK register.
A generic clock (GCLK_CAN) is required to clock the CAN. This clock must be configured and enabled in the Generic Clock Controller before using the CAN.
Note: On-Demand Clock request is not supported by the CAN. Ensure to clear the ONDEMAND bit to
zero for the oscillator source that provides the GCLK to the CAN.
This generic clock is asynchronous to the bus clock (CLK_CAN_AHB). Due to this asynchronicity, writes to certain registers will require synchronization between the clock domains.