Function dcache_inv_poc_dma

freebsd/arm/include/cpu-v6.h:561–576

* Discard D-cache lines to PoC, prior to overwrite by DMA engine. * * Normal invalidation does L2 then L1 to ensure that stale data from L2 doesn't * flow into L1 while invalidating. This routine is intended to be used only * when invalidating a buffer before a DMA operation loads new data into memory. * The concern in this case is that dirty lines are not evicted to main memory, * overwrit

 * that an evicted L1 line doesn't flow to L2 after the L2 has been cleaned.
 */
static __inline void
dcache_inv_poc_dma(vm_offset_t va, vm_paddr_t pa, vm_size_t size)
{
	vm_offset_t eva = va + size;

	/* invalidate L1 first */
	dsb();
	va &= ~cpuinfo.dcache_line_mask;
	for ( ; va < eva; va += cpuinfo.dcache_line_size) {
		_CP15_DCIMVAC(va);
	}
	dsb();

	/* then L2 */
	cpu_l2cache_inv_range(pa, size);
}

/*
 * Write back D-cache to PoC