// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018 Christoph Hellwig.
 *
 * DMA operations that map physical memory directly without using an IOMMU.
 */
#include <linux/memblock.h> /* for max_pfn */
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/dma-direct.h>
#include <linux/scatterlist.h>
#include <linux/dma-contiguous.h>
#include <linux/dma-noncoherent.h>
#include <linux/pfn.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
#include <linux/swiotlb.h>

/*
 * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
 * it for entirely different regions. In that case the arch code needs to
 * override the variable below for dma-direct to work properly.
 */
unsigned int zone_dma_bits __ro_after_init = 24;

static inline dma_addr_t phys_to_dma_direct(struct device *dev,
                phys_addr_t phys)
{
        if (force_dma_unencrypted(dev))
                return __phys_to_dma(dev, phys);
        return phys_to_dma(dev, phys);
}

static inline struct page *dma_direct_to_page(struct device *dev,
                dma_addr_t dma_addr)
{
        return pfn_to_page(PHYS_PFN(dma_to_phys(dev, dma_addr)));
}

u64 dma_direct_get_required_mask(struct device *dev)
{
        u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT);

        return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
}

static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
                u64 *phys_limit)
{
        u64 dma_limit = min_not_zero(dma_mask, dev->bus_dma_limit);

        if (force_dma_unencrypted(dev))
                *phys_limit = __dma_to_phys(dev, dma_limit);
        else
                *phys_limit = dma_to_phys(dev, dma_limit);

        /*
         * Optimistically try the zone that the physical address mask falls
         * into first.  If that returns memory that isn't actually addressable
         * we will fallback to the next lower zone and try again.
         *
         * Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
         * zones.
         */
        if (*phys_limit <= DMA_BIT_MASK(zone_dma_bits))
                return GFP_DMA;
        if (*phys_limit <= DMA_BIT_MASK(32))
                return GFP_DMA32;
        return 0;
}

static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
        return phys_to_dma_direct(dev, phys) + size - 1 <=
                        min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
}

struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
                gfp_t gfp, unsigned long attrs)
{
        size_t alloc_size = PAGE_ALIGN(size);
        int node = dev_to_node(dev);
        struct page *page = NULL;
        u64 phys_limit;

        if (attrs & DMA_ATTR_NO_WARN)
                gfp |= __GFP_NOWARN;

        /* we always manually zero the memory once we are done: */
        gfp &= ~__GFP_ZERO;
        gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
                        &phys_limit);
        page = dma_alloc_contiguous(dev, alloc_size, gfp);
        if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
                dma_free_contiguous(dev, page, alloc_size);
                page = NULL;
        }
again:
        if (!page)
                page = alloc_pages_node(node, gfp, get_order(alloc_size));
        if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
                dma_free_contiguous(dev, page, size);
                page = NULL;

                if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
                    phys_limit < DMA_BIT_MASK(64) &&
                    !(gfp & (GFP_DMA32 | GFP_DMA))) {
                        gfp |= GFP_DMA32;
                        goto again;
                }

                if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
                        gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
                        goto again;
                }
        }

        return page;
}

void *dma_direct_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
        struct page *page;
        void *ret;

        if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
            dma_alloc_need_uncached(dev, attrs) &&
            !gfpflags_allow_blocking(gfp)) {
                ret = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp);
                if (!ret)
                        return NULL;
                goto done;
        }

        page = __dma_direct_alloc_pages(dev, size, gfp, attrs);
        if (!page)
                return NULL;

        if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
            !force_dma_unencrypted(dev)) {
                /* remove any dirty cache lines on the kernel alias */
                if (!PageHighMem(page))
                        arch_dma_prep_coherent(page, size);
                /* return the page pointer as the opaque cookie */
                ret = page;
                goto done;
        }

        if ((IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
             dma_alloc_need_uncached(dev, attrs)) ||
            (IS_ENABLED(CONFIG_DMA_REMAP) && PageHighMem(page))) {
                /* remove any dirty cache lines on the kernel alias */
                arch_dma_prep_coherent(page, PAGE_ALIGN(size));

                /* create a coherent mapping */
                ret = dma_common_contiguous_remap(page, PAGE_ALIGN(size),
                                dma_pgprot(dev, PAGE_KERNEL, attrs),
                                __builtin_return_address(0));
                if (!ret) {
                        dma_free_contiguous(dev, page, size);
                        return ret;
                }

                memset(ret, 0, size);
                goto done;
        }

        if (PageHighMem(page)) {
                /*
                 * Depending on the cma= arguments and per-arch setup
                 * dma_alloc_contiguous could return highmem pages.
                 * Without remapping there is no way to return them here,
                 * so log an error and fail.
                 */
                dev_info(dev, "Rejecting highmem page from CMA.\n");
                dma_free_contiguous(dev, page, size);
                return NULL;
        }

        ret = page_address(page);
        if (force_dma_unencrypted(dev))
                set_memory_decrypted((unsigned long)ret, 1 << get_order(size));

        memset(ret, 0, size);

        if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
            dma_alloc_need_uncached(dev, attrs)) {
                arch_dma_prep_coherent(page, size);
                ret = uncached_kernel_address(ret);
        }
done:
        if (force_dma_unencrypted(dev))
                *dma_handle = __phys_to_dma(dev, page_to_phys(page));
        else
                *dma_handle = phys_to_dma(dev, page_to_phys(page));
        return ret;
}

void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_addr, unsigned long attrs)
{
        unsigned int page_order = get_order(size);

        if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
            !force_dma_unencrypted(dev)) {
                /* cpu_addr is a struct page cookie, not a kernel address */
                dma_free_contiguous(dev, cpu_addr, size);
                return;
        }

        if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
            dma_free_from_pool(cpu_addr, PAGE_ALIGN(size)))
                return;

        if (force_dma_unencrypted(dev))
                set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);

        if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr))
                vunmap(cpu_addr);

        dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size);
}

void *dma_direct_alloc(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
        if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
            !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
            dma_alloc_need_uncached(dev, attrs))
                return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
        return dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs);
}

void dma_direct_free(struct device *dev, size_t size,
                void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)
{
        if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
            !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
            dma_alloc_need_uncached(dev, attrs))
                arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
        else
                dma_direct_free_pages(dev, size, cpu_addr, dma_addr, attrs);
}

#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
    defined(CONFIG_SWIOTLB)
void dma_direct_sync_single_for_device(struct device *dev,
                dma_addr_t addr, size_t size, enum dma_data_direction dir)
{
        phys_addr_t paddr = dma_to_phys(dev, addr);

        if (unlikely(is_swiotlb_buffer(paddr)))
                swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_DEVICE);

        if (!dev_is_dma_coherent(dev))
                arch_sync_dma_for_device(paddr, size, dir);
}
EXPORT_SYMBOL(dma_direct_sync_single_for_device);

void dma_direct_sync_sg_for_device(struct device *dev,
                struct scatterlist *sgl, int nents, enum dma_data_direction dir)
{
        struct scatterlist *sg;
        int i;

        for_each_sg(sgl, sg, nents, i) {
                phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg));

                if (unlikely(is_swiotlb_buffer(paddr)))
                        swiotlb_tbl_sync_single(dev, paddr, sg->length,
                                        dir, SYNC_FOR_DEVICE);

                if (!dev_is_dma_coherent(dev))
                        arch_sync_dma_for_device(paddr, sg->length,
                                        dir);
        }
}
EXPORT_SYMBOL(dma_direct_sync_sg_for_device);
#endif

#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) || \
    defined(CONFIG_SWIOTLB)
void dma_direct_sync_single_for_cpu(struct device *dev,
                dma_addr_t addr, size_t size, enum dma_data_direction dir)
{
        phys_addr_t paddr = dma_to_phys(dev, addr);

        if (!dev_is_dma_coherent(dev)) {
                arch_sync_dma_for_cpu(paddr, size, dir);
                arch_sync_dma_for_cpu_all();
        }

        if (unlikely(is_swiotlb_buffer(paddr)))
                swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_CPU);
}
EXPORT_SYMBOL(dma_direct_sync_single_for_cpu);

void dma_direct_sync_sg_for_cpu(struct device *dev,
                struct scatterlist *sgl, int nents, enum dma_data_direction dir)
{
        struct scatterlist *sg;
        int i;

        for_each_sg(sgl, sg, nents, i) {
                phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg));

                if (!dev_is_dma_coherent(dev))
                        arch_sync_dma_for_cpu(paddr, sg->length, dir);

                if (unlikely(is_swiotlb_buffer(paddr)))
                        swiotlb_tbl_sync_single(dev, paddr, sg->length, dir,
                                        SYNC_FOR_CPU);
        }

        if (!dev_is_dma_coherent(dev))
                arch_sync_dma_for_cpu_all();
}
EXPORT_SYMBOL(dma_direct_sync_sg_for_cpu);

void dma_direct_unmap_page(struct device *dev, dma_addr_t addr,
                size_t size, enum dma_data_direction dir, unsigned long attrs)
{
        phys_addr_t phys = dma_to_phys(dev, addr);

        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                dma_direct_sync_single_for_cpu(dev, addr, size, dir);

        if (unlikely(is_swiotlb_buffer(phys)))
                swiotlb_tbl_unmap_single(dev, phys, size, size, dir, attrs);
}
EXPORT_SYMBOL(dma_direct_unmap_page);

void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
                int nents, enum dma_data_direction dir, unsigned long attrs)
{
        struct scatterlist *sg;
        int i;

        for_each_sg(sgl, sg, nents, i)
                dma_direct_unmap_page(dev, sg->dma_address, sg_dma_len(sg), dir,
                             attrs);
}
EXPORT_SYMBOL(dma_direct_unmap_sg);
#endif

dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
                unsigned long offset, size_t size, enum dma_data_direction dir,
                unsigned long attrs)
{
        phys_addr_t phys = page_to_phys(page) + offset;
        dma_addr_t dma_addr = phys_to_dma(dev, phys);

        if (unlikely(swiotlb_force == SWIOTLB_FORCE))
                return swiotlb_map(dev, phys, size, dir, attrs);

        if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
                if (swiotlb_force != SWIOTLB_NO_FORCE)
                        return swiotlb_map(dev, phys, size, dir, attrs);

                dev_WARN_ONCE(dev, 1,
                             "DMA addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
                             &dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
                return DMA_MAPPING_ERROR;
        }

        if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
                arch_sync_dma_for_device(phys, size, dir);
        return dma_addr;
}
EXPORT_SYMBOL(dma_direct_map_page);

int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
                enum dma_data_direction dir, unsigned long attrs)
{
        int i;
        struct scatterlist *sg;

        for_each_sg(sgl, sg, nents, i) {
                sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
                                sg->offset, sg->length, dir, attrs);
                if (sg->dma_address == DMA_MAPPING_ERROR)
                        goto out_unmap;
                sg_dma_len(sg) = sg->length;
        }

        return nents;

out_unmap:
        dma_direct_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
        return 0;
}
EXPORT_SYMBOL(dma_direct_map_sg);

dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
                size_t size, enum dma_data_direction dir, unsigned long attrs)
{
        dma_addr_t dma_addr = paddr;

        if (unlikely(!dma_capable(dev, dma_addr, size, false))) {
                dev_err_once(dev,
                             "DMA addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
                             &dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
                WARN_ON_ONCE(1);
                return DMA_MAPPING_ERROR;
        }

        return dma_addr;
}
EXPORT_SYMBOL(dma_direct_map_resource);

int dma_direct_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_direct_to_page(dev, dma_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;
}

#ifdef CONFIG_MMU
bool dma_direct_can_mmap(struct device *dev)
{
        return dev_is_dma_coherent(dev) ||
                IS_ENABLED(CONFIG_DMA_NONCOHERENT_MMAP);
}

int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
                void *cpu_addr, dma_addr_t dma_addr, size_t size,
                unsigned long attrs)
{
        unsigned long user_count = vma_pages(vma);
        unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        unsigned long pfn = PHYS_PFN(dma_to_phys(dev, dma_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 (vma->vm_pgoff >= count || user_count > count - vma->vm_pgoff)
                return -ENXIO;
        return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
                        user_count << PAGE_SHIFT, vma->vm_page_prot);
}
#else /* CONFIG_MMU */
bool dma_direct_can_mmap(struct device *dev)
{
        return false;
}

int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
                void *cpu_addr, dma_addr_t dma_addr, size_t size,
                unsigned long attrs)
{
        return -ENXIO;
}
#endif /* CONFIG_MMU */

int dma_direct_supported(struct device *dev, u64 mask)
{
        u64 min_mask = (max_pfn - 1) << PAGE_SHIFT;

        /*
         * Because 32-bit DMA masks are so common we expect every architecture
         * to be able to satisfy them - either by not supporting more physical
         * memory, or by providing a ZONE_DMA32.  If neither is the case, the
         * architecture needs to use an IOMMU instead of the direct mapping.
         */
        if (mask >= DMA_BIT_MASK(32))
                return 1;

        /*
         * This check needs to be against the actual bit mask value, so
         * use __phys_to_dma() here so that the SME encryption mask isn't
         * part of the check.
         */
        if (IS_ENABLED(CONFIG_ZONE_DMA))
                min_mask = min_t(u64, min_mask, DMA_BIT_MASK(zone_dma_bits));
        return mask >= __phys_to_dma(dev, min_mask);
}

size_t dma_direct_max_mapping_size(struct device *dev)
{
        /* If SWIOTLB is active, use its maximum mapping size */
        if (is_swiotlb_active() &&
            (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
                return swiotlb_max_mapping_size(dev);
        return SIZE_MAX;
}