// SPDX-License-Identifier: GPL-2.0-only
/*
 *  PowerPC version derived from arch/arm/mm/consistent.c
 *    Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
 *
 *  Copyright (C) 2000 Russell King
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>

#include <asm/tlbflush.h>
#include <asm/dma.h>

/*
 * make an area consistent.
 */
static void __dma_sync(void *vaddr, size_t size, int direction)
{
        unsigned long start = (unsigned long)vaddr;
        unsigned long end   = start + size;

        switch (direction) {
        case DMA_NONE:
                BUG();
        case DMA_FROM_DEVICE:
                /*
                 * invalidate only when cache-line aligned otherwise there is
                 * the potential for discarding uncommitted data from the cache
                 */
                if ((start | end) & (L1_CACHE_BYTES - 1))
                        flush_dcache_range(start, end);
                else
                        invalidate_dcache_range(start, end);
                break;
        case DMA_TO_DEVICE:             /* writeback only */
                clean_dcache_range(start, end);
                break;
        case DMA_BIDIRECTIONAL: /* writeback and invalidate */
                flush_dcache_range(start, end);
                break;
        }
}

#ifdef CONFIG_HIGHMEM
/*
 * __dma_sync_page() implementation for systems using highmem.
 * In this case, each page of a buffer must be kmapped/kunmapped
 * in order to have a virtual address for __dma_sync(). This must
 * not sleep so kmap_atomic()/kunmap_atomic() are used.
 *
 * Note: yes, it is possible and correct to have a buffer extend
 * beyond the first page.
 */
static inline void __dma_sync_page_highmem(struct page *page,
                unsigned long offset, size_t size, int direction)
{
        size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
        size_t cur_size = seg_size;
        unsigned long flags, start, seg_offset = offset;
        int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
        int seg_nr = 0;

        local_irq_save(flags);

        do {
                start = (unsigned long)kmap_atomic(page + seg_nr) + seg_offset;

                /* Sync this buffer segment */
                __dma_sync((void *)start, seg_size, direction);
                kunmap_atomic((void *)start);
                seg_nr++;

                /* Calculate next buffer segment size */
                seg_size = min((size_t)PAGE_SIZE, size - cur_size);

                /* Add the segment size to our running total */
                cur_size += seg_size;
                seg_offset = 0;
        } while (seg_nr < nr_segs);

        local_irq_restore(flags);
}
#endif /* CONFIG_HIGHMEM */

/*
 * __dma_sync_page makes memory consistent. identical to __dma_sync, but
 * takes a struct page instead of a virtual address
 */
static void __dma_sync_page(phys_addr_t paddr, size_t size, int dir)
{
        struct page *page = pfn_to_page(paddr >> PAGE_SHIFT);
        unsigned offset = paddr & ~PAGE_MASK;

#ifdef CONFIG_HIGHMEM
        __dma_sync_page_highmem(page, offset, size, dir);
#else
        unsigned long start = (unsigned long)page_address(page) + offset;
        __dma_sync((void *)start, size, dir);
#endif
}

void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
{
        __dma_sync_page(paddr, size, dir);
}

void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
                enum dma_data_direction dir)
{
        __dma_sync_page(paddr, size, dir);
}

void arch_dma_prep_coherent(struct page *page, size_t size)
{
        unsigned long kaddr = (unsigned long)page_address(page);

        flush_dcache_range(kaddr, kaddr + size);
}