When I tried to fix the watchdog of rt2800, I found that sometimes
the watchdog can not reset the hung device. This is because the
queue is not completely stuck, it just becomes very slow. The MTK
vendor driver for the new chip MT7603/MT7612 has a DMA busy watchdog
to detect device hangs by checking DMA busy status. This watchdog
implementation is something similar to it. To reduce unnecessary
reset, we can check the INT_SOURCE_CSR register together as I found
that when the radio hung, the RX/TX coherent interrupt will always
stuck at triggered state.

The 'watchdog' module parameter has been extended to control all
watchdogs(0=disabled, 1=hang watchdog, 2=DMA watchdog, 3=both). This
new watchdog function is a slight schedule and it won't affect the
transmission speed. So we can turn on it by default. Due to the
INT_SOURCE_CSR register is invalid on rt2800 USB NICs, the DMA busy
watchdog will be automatically disabled for them.

Tested on MT7620 and RT5350.
Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/TYAP286MB0315D7462CE08A119A99DE34BCA4A@TYAP286MB0315.JPNP286.PROD.OUTLOOK.COM