void dma_resume_channel(int channel)
{
/* Resume - must reinit to where it left off (so the docs say) */
unsigned long control = DMAC_CH_CONTROL(channel);
if ((control & 0x7ff) == 0)
return; /* empty */
DMAC_INT_TC_CLEAR = (1<<channel);
DMAC_INT_ERR_CLEAR = (1<<channel);
DMAC_CH_SRC_ADDR(channel) = DMAC_CH_SRC_ADDR(channel);
DMAC_CH_DST_ADDR(channel) = DMAC_CH_DST_ADDR(channel);
DMAC_CH_LLI(channel) = DMAC_CH_LLI(channel);
DMAC_CH_CONTROL(channel) = control;
bitset32(&DMAC_CH_CONFIGURATION(channel), (1<<0));
}
void dma_enable_channel(int channel, void *src, void *dst, int peri,
int flow_controller, bool src_inc, bool dst_inc,
size_t size, int nwords, void (*callback)(void))
{
dma_callback[channel] = callback;
/* Clear any pending interrupts leftover from previous operation */
DMAC_INT_TC_CLEAR = (1<<channel);
DMAC_INT_ERR_CLEAR = (1<<channel);
DMAC_CH_SRC_ADDR(channel) = (int)src;
DMAC_CH_DST_ADDR(channel) = (int)dst;
/* When LLI is 0 channel is disabled upon transfer completion */
DMAC_CH_LLI(channel) = 0;
/* Channel Control Register */
DMAC_CH_CONTROL(channel) =
((1<<31) /* LLI triggers terminal count interrupt */
/* | (1<<30) */ /* cacheable = 1, non = 0 */
/* | (1<<29) */ /* bufferable = 1, non = 0 */
/* | (1<<28) */ /* privileged = 1, user = 0 */
| (dst_inc? (1<<27): 0) /* specify address increment */
| (src_inc? (1<<26): 0) /* specify address increment */
/* [25:24] */ /* undefined */
| (2<<21) /* dst width = word, 32bit */
| (2<<18) /* src width = word, 32bit */
/* OF uses transfers of 4 * 32 bits words on memory, i2sin, i2sout */
/* OF uses transfers of 8 * 32 bits words on SD */
| (nwords<<15) /* dst size */
| (nwords<<12) /* src size */
| ((size & 0x7ff)<<0)); /* transfer size */
/* Channel Config Register */
DMAC_CH_CONFIGURATION(channel) =
/* [31:19] */ /* Read undefined. Write as zero */
/* (0<<18) */ /* Halt Bit */
/* (0<<17) */ /* Active Bit */
/* (0<<16) */ /* Lock Bit */
(1<<15) /* terminal count interrupt mask */
| (1<<14) /* interrupt error mask */
| (flow_controller<<11) /* flow controller is peripheral or SDMAC */
/* we set the same peripheral as source and destination because we
* always use memory-to-peripheral or peripheral-to-memory transfers */
| (peri<<6) /* dst peripheral */
| (peri<<1) /* src peripheral */
| (1<<0); /* enable channel */
}
