OP_ENDPTFLUSH
hw_write(ci, OP_ENDPTFLUSH, ~0, ~0);
[OP_ENDPTFLUSH] = 0x74U,
[OP_ENDPTFLUSH] = 0xE0U,
hw_write(ci, OP_ENDPTFLUSH, ~0, BIT(n));
while (hw_read(ci, OP_ENDPTFLUSH, BIT(n)))
hw_write(ci, OP_ENDPTFLUSH, ~0, ~0);