/*
 * DMA region bookkeeping routines
 *
 * Copyright (C) 2002 Maas Digital LLC
 *
 * This code is licensed under the GPL.  See the file COPYING in the root
 * directory of the kernel sources for details.
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/scatterlist.h>

#include "dma.h"

/* dma_prog_region */

void dma_prog_region_init(struct dma_prog_region *prog)
{
        prog->kvirt = NULL;
        prog->dev = NULL;
        prog->n_pages = 0;
        prog->bus_addr = 0;
}

int dma_prog_region_alloc(struct dma_prog_region *prog, unsigned long n_bytes,
                          struct pci_dev *dev)
{
        /* round up to page size */
        n_bytes = PAGE_ALIGN(n_bytes);

        prog->n_pages = n_bytes >> PAGE_SHIFT;

        prog->kvirt = pci_alloc_consistent(dev, n_bytes, &prog->bus_addr);
        if (!prog->kvirt) {
                printk(KERN_ERR
                       "dma_prog_region_alloc: pci_alloc_consistent() failed\n");
                dma_prog_region_free(prog);
                return -ENOMEM;
        }

        prog->dev = dev;

        return 0;
}

void dma_prog_region_free(struct dma_prog_region *prog)
{
        if (prog->kvirt) {
                pci_free_consistent(prog->dev, prog->n_pages << PAGE_SHIFT,
                                    prog->kvirt, prog->bus_addr);
        }

        prog->kvirt = NULL;
        prog->dev = NULL;
        prog->n_pages = 0;
        prog->bus_addr = 0;
}

/* dma_region */

/**
 * dma_region_init - clear out all fields but do not allocate anything
 */
void dma_region_init(struct dma_region *dma)
{
        dma->kvirt = NULL;
        dma->dev = NULL;
        dma->n_pages = 0;
        dma->n_dma_pages = 0;
        dma->sglist = NULL;
}

/**
 * dma_region_alloc - allocate the buffer and map it to the IOMMU
 */
int dma_region_alloc(struct dma_region *dma, unsigned long n_bytes,
                     struct pci_dev *dev, int direction)
{
        unsigned int i;

        /* round up to page size */
        n_bytes = PAGE_ALIGN(n_bytes);

        dma->n_pages = n_bytes >> PAGE_SHIFT;

        dma->kvirt = vmalloc_32(n_bytes);
        if (!dma->kvirt) {
                printk(KERN_ERR "dma_region_alloc: vmalloc_32() failed\n");
                goto err;
        }

        /* Clear the ram out, no junk to the user */
        memset(dma->kvirt, 0, n_bytes);

        /* allocate scatter/gather list */
        dma->sglist = vmalloc(dma->n_pages * sizeof(*dma->sglist));
        if (!dma->sglist) {
                printk(KERN_ERR "dma_region_alloc: vmalloc(sglist) failed\n");
                goto err;
        }

        sg_init_table(dma->sglist, dma->n_pages);

        /* fill scatter/gather list with pages */
        for (i = 0; i < dma->n_pages; i++) {
                unsigned long va =
                    (unsigned long)dma->kvirt + (i << PAGE_SHIFT);

                sg_set_page(&dma->sglist[i], vmalloc_to_page((void *)va),
                                PAGE_SIZE, 0);
        }

        /* map sglist to the IOMMU */
        dma->n_dma_pages =
            pci_map_sg(dev, dma->sglist, dma->n_pages, direction);

        if (dma->n_dma_pages == 0) {
                printk(KERN_ERR "dma_region_alloc: pci_map_sg() failed\n");
                goto err;
        }

        dma->dev = dev;
        dma->direction = direction;

        return 0;

      err:
        dma_region_free(dma);
        return -ENOMEM;
}

/**
 * dma_region_free - unmap and free the buffer
 */
void dma_region_free(struct dma_region *dma)
{
        if (dma->n_dma_pages) {
                pci_unmap_sg(dma->dev, dma->sglist, dma->n_pages,
                             dma->direction);
                dma->n_dma_pages = 0;
                dma->dev = NULL;
        }

        vfree(dma->sglist);
        dma->sglist = NULL;

        vfree(dma->kvirt);
        dma->kvirt = NULL;
        dma->n_pages = 0;
}

/* find the scatterlist index and remaining offset corresponding to a
   given offset from the beginning of the buffer */
static inline int dma_region_find(struct dma_region *dma, unsigned long offset,
                                  unsigned int start, unsigned long *rem)
{
        int i;
        unsigned long off = offset;

        for (i = start; i < dma->n_dma_pages; i++) {
                if (off < sg_dma_len(&dma->sglist[i])) {
                        *rem = off;
                        break;
                }

                off -= sg_dma_len(&dma->sglist[i]);
        }

        BUG_ON(i >= dma->n_dma_pages);

        return i;
}

/**
 * dma_region_offset_to_bus - get bus address of an offset within a DMA region
 *
 * Returns the DMA bus address of the byte with the given @offset relative to
 * the beginning of the @dma.
 */
dma_addr_t dma_region_offset_to_bus(struct dma_region * dma,
                                    unsigned long offset)
{
        unsigned long rem = 0;

        struct scatterlist *sg =
            &dma->sglist[dma_region_find(dma, offset, 0, &rem)];
        return sg_dma_address(sg) + rem;
}

/**
 * dma_region_sync_for_cpu - sync the CPU's view of the buffer
 */
void dma_region_sync_for_cpu(struct dma_region *dma, unsigned long offset,
                             unsigned long len)
{
        int first, last;
        unsigned long rem = 0;

        if (!len)
                len = 1;

        first = dma_region_find(dma, offset, 0, &rem);
        last = dma_region_find(dma, rem + len - 1, first, &rem);

        pci_dma_sync_sg_for_cpu(dma->dev, &dma->sglist[first], last - first + 1,
                                dma->direction);
}

/**
 * dma_region_sync_for_device - sync the IO bus' view of the buffer
 */
void dma_region_sync_for_device(struct dma_region *dma, unsigned long offset,
                                unsigned long len)
{
        int first, last;
        unsigned long rem = 0;

        if (!len)
                len = 1;

        first = dma_region_find(dma, offset, 0, &rem);
        last = dma_region_find(dma, rem + len - 1, first, &rem);

        pci_dma_sync_sg_for_device(dma->dev, &dma->sglist[first],
                                   last - first + 1, dma->direction);
}

#ifdef CONFIG_MMU

static int dma_region_pagefault(struct vm_area_struct *vma,
                                struct vm_fault *vmf)
{
        struct dma_region *dma = (struct dma_region *)vma->vm_private_data;

        if (!dma->kvirt)
                return VM_FAULT_SIGBUS;

        if (vmf->pgoff >= dma->n_pages)
                return VM_FAULT_SIGBUS;

        vmf->page = vmalloc_to_page(dma->kvirt + (vmf->pgoff << PAGE_SHIFT));
        get_page(vmf->page);
        return 0;
}

static const struct vm_operations_struct dma_region_vm_ops = {
        .fault = dma_region_pagefault,
};

/**
 * dma_region_mmap - map the buffer into a user space process
 */
int dma_region_mmap(struct dma_region *dma, struct file *file,
                    struct vm_area_struct *vma)
{
        unsigned long size;

        if (!dma->kvirt)
                return -EINVAL;

        /* must be page-aligned (XXX: comment is wrong, we could allow pgoff) */
        if (vma->vm_pgoff != 0)
                return -EINVAL;

        /* check the length */
        size = vma->vm_end - vma->vm_start;
        if (size > (dma->n_pages << PAGE_SHIFT))
                return -EINVAL;

        vma->vm_ops = &dma_region_vm_ops;
        vma->vm_private_data = dma;
        vma->vm_file = file;
        vma->vm_flags |= VM_RESERVED | VM_ALWAYSDUMP;

        return 0;
}

#else                           /* CONFIG_MMU */

int dma_region_mmap(struct dma_region *dma, struct file *file,
                    struct vm_area_struct *vma)
{
        return -EINVAL;
}

#endif                          /* CONFIG_MMU */