// SPDX-License-Identifier: GPL-2.0
/*
 * Helpers for DMA ops implementations.  These generally rely on the fact that
 * the allocated memory contains normal pages in the direct kernel mapping.
 */
#include <linux/dma-map-ops.h>
#include <linux/iommu-dma.h>

static struct page *dma_common_vaddr_to_page(void *cpu_addr)
{
        if (is_vmalloc_addr(cpu_addr))
                return vmalloc_to_page(cpu_addr);
        return virt_to_page(cpu_addr);
}

/*
 * Create scatter-list for the already allocated DMA buffer.
 */
int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
                 void *cpu_addr, dma_addr_t dma_addr, size_t size,
                 unsigned long attrs)
{
        struct page *page = dma_common_vaddr_to_page(cpu_addr);
        int ret;

        ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
        if (!ret)
                sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
        return ret;
}

/*
 * Create userspace mapping for the DMA-coherent memory.
 */
int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
                void *cpu_addr, dma_addr_t dma_addr, size_t size,
                unsigned long attrs)
{
#ifdef CONFIG_MMU
        unsigned long user_count = vma_pages(vma);
        unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        unsigned long off = vma->vm_pgoff;
        struct page *page = dma_common_vaddr_to_page(cpu_addr);
        int ret = -ENXIO;

        vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);

        if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
                return ret;

        if (off >= count || user_count > count - off)
                return -ENXIO;

        return remap_pfn_range(vma, vma->vm_start,
                        page_to_pfn(page) + vma->vm_pgoff,
                        user_count << PAGE_SHIFT, vma->vm_page_prot);
#else
        return -ENXIO;
#endif /* CONFIG_MMU */
}

struct page *dma_common_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        struct page *page;
        phys_addr_t phys;

        page = dma_alloc_contiguous(dev, size, gfp);
        if (!page)
                page = alloc_pages_node(dev_to_node(dev), gfp, get_order(size));
        if (!page)
                return NULL;

        phys = page_to_phys(page);
        if (use_dma_iommu(dev))
                *dma_handle = iommu_dma_map_phys(dev, phys, size, dir,
                                                 DMA_ATTR_SKIP_CPU_SYNC);
        else
                *dma_handle = ops->map_phys(dev, phys, size, dir,
                                            DMA_ATTR_SKIP_CPU_SYNC);
        if (*dma_handle == DMA_MAPPING_ERROR) {
                dma_free_contiguous(dev, page, size);
                return NULL;
        }

        memset(page_address(page), 0, size);
        return page;
}

void dma_common_free_pages(struct device *dev, size_t size, struct page *page,
                dma_addr_t dma_handle, enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (use_dma_iommu(dev))
                iommu_dma_unmap_phys(dev, dma_handle, size, dir,
                                     DMA_ATTR_SKIP_CPU_SYNC);
        else if (ops->unmap_phys)
                ops->unmap_phys(dev, dma_handle, size, dir,
                                DMA_ATTR_SKIP_CPU_SYNC);
        dma_free_contiguous(dev, page, size);
}