michallenc commented on code in PR #6614:
URL: https://github.com/apache/incubator-nuttx/pull/6614#discussion_r922208583
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arch/arm/src/samv7/sam_xdmac.c:
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@@ -1921,6 +1936,130 @@ int sam_dmarxsetup(DMA_HANDLE handle, uint32_t paddr,
uint32_t maddr,
return ret;
}
+/****************************************************************************
+ * Name: sam_dmarxsetup_circular
+ *
+ * Description:
+ * Configure DMA for receipt of two circular buffers for peripheral to
+ * memory transfer. Function sam_dmastart_circular() needs to be called
+ * to start the transfer. Only peripheral to memory transfer is currently
+ * supported.
+ *
+ * Input Parameters:
+ * handle - DMA handler
+ * descr - array with DMA descriptors
+ * maddr - array of memory addresses (i.e. destination addresses)
+ * paddr - peripheral address (i.e. source address)
+ * nbytes - number of bytes to transfer
+ * ndescrs - number of descriptors (i.e. the lenght of descr array)
+ *
+ ****************************************************************************/
+
+int sam_dmarxsetup_circular(DMA_HANDLE handle,
+ struct chnext_view1_s *descr[],
+ uint32_t maddr[],
+ uint32_t paddr,
+ size_t nbytes,
+ uint8_t ndescrs)
+{
+ struct sam_xdmach_s *xdmach = (struct sam_xdmach_s *)handle;
+ uint32_t cubc;
+ uint8_t nextdescr;
+ int i;
+
+ /* Set circular as true */
+
+ xdmach->circular = true;
+
+ xdmach->cc = sam_rxcc(xdmach);
+
+ /* Calculate the number of transfers for CUBC */
+
+ cubc = sam_cubc(xdmach, nbytes);
+ cubc |= (CHNEXT_UBC_NDE | CHNEXT_UBC_NVIEW_1 | CHNEXT_UBC_NDEN |
+ CHNEXT_UBC_NSEN);
+
+ nextdescr = 0;
+
+ for (i = ndescrs - 1; i >= 0; i--)
+ {
+ descr[i]->cnda = (uint32_t)descr[nextdescr]; /* Next Descriptor
Address */
+ descr[i]->cubc = cubc; /* Channel Microblock
Control Register */
+ descr[i]->csa = paddr; /* Source address */
+ descr[i]->cda = maddr[i]; /* Destination address */
+
+ /* Clean data cache */
+
+ up_clean_dcache((uintptr_t)descr[i],
+ (uintptr_t)descr[i] +
+ sizeof(struct chnext_view1_s));
+ up_clean_dcache((uintptr_t)maddr[i], (uintptr_t)(maddr + nbytes));
Review Comment:
Good spot, that could create some mess when cleaning the cache. Others
should be done too.
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