linux/arch/nds32/kernel/dma.c

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2005-2017 Andes Technology Corporation

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/dma-noncoherent.h>
#include <linux/cache.h>
#include <linux/highmem.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/proc-fns.h>

static inline void cache_op(phys_addr_t paddr, size_t size,
		void (*fn)(unsigned long start, unsigned long end))
{
	struct page *page = pfn_to_page(paddr >> PAGE_SHIFT);
	unsigned offset = paddr & ~PAGE_MASK;
	size_t left = size;
	unsigned long start;

	do {
		size_t len = left;

		if (PageHighMem(page)) {
			void *addr;

			if (offset + len > PAGE_SIZE) {
				if (offset >= PAGE_SIZE) {
					page += offset >> PAGE_SHIFT;
					offset &= ~PAGE_MASK;
				}
				len = PAGE_SIZE - offset;
			}

			addr = kmap_atomic(page);
			start = (unsigned long)(addr + offset);
			fn(start, start + len);
			kunmap_atomic(addr);
		} else {
			start = (unsigned long)phys_to_virt(paddr);
			fn(start, start + size);
		}
		offset = 0;
		page++;
		left -= len;
	} while (left);
}

void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
		enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_FROM_DEVICE:
		break;
	case DMA_TO_DEVICE:
	case DMA_BIDIRECTIONAL:
		cache_op(paddr, size, cpu_dma_wb_range);
		break;
	default:
		BUG();
	}
}

void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
		enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_TO_DEVICE:
		break;
	case DMA_FROM_DEVICE:
	case DMA_BIDIRECTIONAL:
		cache_op(paddr, size, cpu_dma_inval_range);
		break;
	default:
		BUG();
	}
}

void arch_dma_prep_coherent(struct page *page, size_t size)
{
	cache_op(page_to_phys(page), size, cpu_dma_wbinval_range);
}