DMA_IRQ_PEND_REG0
DMA_WRITE(sc, DMA_IRQ_PEND_REG0, ~0);
pend0 = DMA_READ(sc, DMA_IRQ_PEND_REG0);
DMA_WRITE(sc, DMA_IRQ_PEND_REG0, pend0);
#define DMA_IRQ_PEND_REG(ch) (DMA_IRQ_PEND_REG0 + ((ch) / 8) * 4)