/*
 * Coherent per-device memory handling.
 * Borrowed from i386
 */
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>

struct dma_coherent_mem {
        void            *virt_base;
        dma_addr_t      device_base;
        unsigned long   pfn_base;
        int             size;
        int             flags;
        unsigned long   *bitmap;
        spinlock_t      spinlock;
};

static bool dma_init_coherent_memory(
        phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags,
        struct dma_coherent_mem **mem)
{
        struct dma_coherent_mem *dma_mem = NULL;
        void __iomem *mem_base = NULL;
        int pages = size >> PAGE_SHIFT;
        int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);

        if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
                goto out;
        if (!size)
                goto out;

        if (flags & DMA_MEMORY_MAP)
                mem_base = memremap(phys_addr, size, MEMREMAP_WC);
        else
                mem_base = ioremap(phys_addr, size);
        if (!mem_base)
                goto out;

        dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
        if (!dma_mem)
                goto out;
        dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
        if (!dma_mem->bitmap)
                goto out;

        dma_mem->virt_base = mem_base;
        dma_mem->device_base = device_addr;
        dma_mem->pfn_base = PFN_DOWN(phys_addr);
        dma_mem->size = pages;
        dma_mem->flags = flags;
        spin_lock_init(&dma_mem->spinlock);

        *mem = dma_mem;
        return true;

out:
        kfree(dma_mem);
        if (mem_base) {
                if (flags & DMA_MEMORY_MAP)
                        memunmap(mem_base);
                else
                        iounmap(mem_base);
        }
        return false;
}

static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
{
        if (!mem)
                return;

        if (mem->flags & DMA_MEMORY_MAP)
                memunmap(mem->virt_base);
        else
                iounmap(mem->virt_base);
        kfree(mem->bitmap);
        kfree(mem);
}

static int dma_assign_coherent_memory(struct device *dev,
                                      struct dma_coherent_mem *mem)
{
        if (dev->dma_mem)
                return -EBUSY;

        dev->dma_mem = mem;
        /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */

        return 0;
}

int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
                                dma_addr_t device_addr, size_t size, int flags)
{
        struct dma_coherent_mem *mem;

        if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
                                      &mem))
                return 0;

        if (dma_assign_coherent_memory(dev, mem) == 0)
                return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;

        dma_release_coherent_memory(mem);
        return 0;
}
EXPORT_SYMBOL(dma_declare_coherent_memory);

void dma_release_declared_memory(struct device *dev)
{
        struct dma_coherent_mem *mem = dev->dma_mem;

        if (!mem)
                return;
        dma_release_coherent_memory(mem);
        dev->dma_mem = NULL;
}
EXPORT_SYMBOL(dma_release_declared_memory);

void *dma_mark_declared_memory_occupied(struct device *dev,
                                        dma_addr_t device_addr, size_t size)
{
        struct dma_coherent_mem *mem = dev->dma_mem;
        unsigned long flags;
        int pos, err;

        size += device_addr & ~PAGE_MASK;

        if (!mem)
                return ERR_PTR(-EINVAL);

        spin_lock_irqsave(&mem->spinlock, flags);
        pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
        err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
        spin_unlock_irqrestore(&mem->spinlock, flags);

        if (err != 0)
                return ERR_PTR(err);
        return mem->virt_base + (pos << PAGE_SHIFT);
}
EXPORT_SYMBOL(dma_mark_declared_memory_occupied);

/**
 * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
 *
 * @dev:        device from which we allocate memory
 * @size:       size of requested memory area
 * @dma_handle: This will be filled with the correct dma handle
 * @ret:        This pointer will be filled with the virtual address
 *              to allocated area.
 *
 * This function should be only called from per-arch dma_alloc_coherent()
 * to support allocation from per-device coherent memory pools.
 *
 * Returns 0 if dma_alloc_coherent should continue with allocating from
 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 */
int dma_alloc_from_coherent(struct device *dev, ssize_t size,
                                       dma_addr_t *dma_handle, void **ret)
{
        struct dma_coherent_mem *mem;
        int order = get_order(size);
        unsigned long flags;
        int pageno;

        if (!dev)
                return 0;
        mem = dev->dma_mem;
        if (!mem)
                return 0;

        *ret = NULL;
        spin_lock_irqsave(&mem->spinlock, flags);

        if (unlikely(size > (mem->size << PAGE_SHIFT)))
                goto err;

        pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
        if (unlikely(pageno < 0))
                goto err;

        /*
         * Memory was found in the per-device area.
         */
        *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
        *ret = mem->virt_base + (pageno << PAGE_SHIFT);
        if (mem->flags & DMA_MEMORY_MAP)
                memset(*ret, 0, size);
        else
                memset_io(*ret, 0, size);
        spin_unlock_irqrestore(&mem->spinlock, flags);

        return 1;

err:
        spin_unlock_irqrestore(&mem->spinlock, flags);
        /*
         * In the case where the allocation can not be satisfied from the
         * per-device area, try to fall back to generic memory if the
         * constraints allow it.
         */
        return mem->flags & DMA_MEMORY_EXCLUSIVE;
}
EXPORT_SYMBOL(dma_alloc_from_coherent);

/**
 * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
 * @dev:        device from which the memory was allocated
 * @order:      the order of pages allocated
 * @vaddr:      virtual address of allocated pages
 *
 * This checks whether the memory was allocated from the per-device
 * coherent memory pool and if so, releases that memory.
 *
 * Returns 1 if we correctly released the memory, or 0 if
 * dma_release_coherent() should proceed with releasing memory from
 * generic pools.
 */
int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
{
        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;

        if (mem && vaddr >= mem->virt_base && vaddr <
                   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
                int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
                unsigned long flags;

                spin_lock_irqsave(&mem->spinlock, flags);
                bitmap_release_region(mem->bitmap, page, order);
                spin_unlock_irqrestore(&mem->spinlock, flags);
                return 1;
        }
        return 0;
}
EXPORT_SYMBOL(dma_release_from_coherent);

/**
 * dma_mmap_from_coherent() - try to mmap the memory allocated from
 * per-device coherent memory pool to userspace
 * @dev:        device from which the memory was allocated
 * @vma:        vm_area for the userspace memory
 * @vaddr:      cpu address returned by dma_alloc_from_coherent
 * @size:       size of the memory buffer allocated by dma_alloc_from_coherent
 * @ret:        result from remap_pfn_range()
 *
 * This checks whether the memory was allocated from the per-device
 * coherent memory pool and if so, maps that memory to the provided vma.
 *
 * Returns 1 if we correctly mapped the memory, or 0 if the caller should
 * proceed with mapping memory from generic pools.
 */
int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
                           void *vaddr, size_t size, int *ret)
{
        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;

        if (mem && vaddr >= mem->virt_base && vaddr + size <=
                   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
                unsigned long off = vma->vm_pgoff;
                int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
                int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
                int count = size >> PAGE_SHIFT;

                *ret = -ENXIO;
                if (off < count && user_count <= count - off) {
                        unsigned long pfn = mem->pfn_base + start + off;
                        *ret = remap_pfn_range(vma, vma->vm_start, pfn,
                                               user_count << PAGE_SHIFT,
                                               vma->vm_page_prot);
                }
                return 1;
        }
        return 0;
}
EXPORT_SYMBOL(dma_mmap_from_coherent);

/*
 * Support for reserved memory regions defined in device tree
 */
#ifdef CONFIG_OF_RESERVED_MEM
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>

static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
{
        struct dma_coherent_mem *mem = rmem->priv;

        if (!mem &&
            !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
                                      DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
                                      &mem)) {
                pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
                        &rmem->base, (unsigned long)rmem->size / SZ_1M);
                return -ENODEV;
        }
        rmem->priv = mem;
        dma_assign_coherent_memory(dev, mem);
        return 0;
}

static void rmem_dma_device_release(struct reserved_mem *rmem,
                                    struct device *dev)
{
        dev->dma_mem = NULL;
}

static const struct reserved_mem_ops rmem_dma_ops = {
        .device_init    = rmem_dma_device_init,
        .device_release = rmem_dma_device_release,
};

static int __init rmem_dma_setup(struct reserved_mem *rmem)
{
        unsigned long node = rmem->fdt_node;

        if (of_get_flat_dt_prop(node, "reusable", NULL))
                return -EINVAL;

#ifdef CONFIG_ARM
        if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
                pr_err("Reserved memory: regions without no-map are not yet supported\n");
                return -EINVAL;
        }
#endif

        rmem->ops = &rmem_dma_ops;
        pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
                &rmem->base, (unsigned long)rmem->size / SZ_1M);
        return 0;
}
RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
#endif