dma-alloc.c

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/* dma-alloc.c: consistent DMA memory allocation
 *
 * Derived from arch/ppc/mm/cachemap.c
 *
 *  PowerPC version derived from arch/arm/mm/consistent.c
 *    Copyright (C) 2001 Dan Malek ([email protected])
 *
 *  linux/arch/arm/mm/consistent.c
 *
 *  Copyright (C) 2000 Russell King
 *
 * Consistent memory allocators.  Used for DMA devices that want to
 * share uncached memory with the processor core.  The function return
 * is the virtual address and 'dma_handle' is the physical address.
 * Mostly stolen from the ARM port, with some changes for PowerPC.
 *                      -- Dan
 * Modified for 36-bit support.  -Matt
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/hardirq.h>
#include <linux/gfp.h>

#include <asm/pgalloc.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/uaccess.h>
#include <asm/smp.h>

static int map_page(unsigned long va, unsigned long pa, pgprot_t prot)
{
    pgd_t *pge;
    pud_t *pue;
    pmd_t *pme;
    pte_t *pte;
    int err = -ENOMEM;

    /* Use upper 10 bits of VA to index the first level map */
    pge = pgd_offset_k(va);
    pue = pud_offset(pge, va);
    pme = pmd_offset(pue, va);

    /* Use middle 10 bits of VA to index the second-level map */
    pte = pte_alloc_kernel(pme, va);
    if (pte != 0) {
        err = 0;
        set_pte(pte, mk_pte_phys(pa & PAGE_MASK, prot));
    }

    return err;
}

/*
 * This function will allocate the requested contiguous pages and
 * map them into the kernel's vmalloc() space.  This is done so we
 * get unique mapping for these pages, outside of the kernel's 1:1
 * virtual:physical mapping.  This is necessary so we can cover large
 * portions of the kernel with single large page TLB entries, and
 * still get unique uncached pages for consistent DMA.
 */
void *consistent_alloc(gfp_t gfp, size_t size, dma_addr_t *dma_handle)
{
    struct vm_struct *area;
    unsigned long page, va, pa;
    void *ret;
    int order, err, i;

    if (in_interrupt())
        BUG();

    /* only allocate page size areas */
    size = PAGE_ALIGN(size);
    order = get_order(size);

    page = __get_free_pages(gfp, order);
    if (!page) {
        BUG();
        return NULL;
    }

    /* allocate some common virtual space to map the new pages */
    area = get_vm_area(size, VM_ALLOC);
    if (area == 0) {
        free_pages(page, order);
        return NULL;
    }
    va = VMALLOC_VMADDR(area->addr);
    ret = (void *) va;

    /* this gives us the real physical address of the first page */
    *dma_handle = pa = virt_to_bus((void *) page);

    /* set refcount=1 on all pages in an order>0 allocation so that vfree() will actually free
     * all pages that were allocated.
     */
    if (order > 0) {
        struct page *rpage = virt_to_page(page);
        split_page(rpage, order);
    }

    err = 0;
    for (i = 0; i < size && err == 0; i += PAGE_SIZE)
        err = map_page(va + i, pa + i, PAGE_KERNEL_NOCACHE);

    if (err) {
        vfree((void *) va);
        return NULL;
    }

    /* we need to ensure that there are no cachelines in use, or worse dirty in this area
     * - can't do until after virtual address mappings are created
     */
    frv_cache_invalidate(va, va + size);

    return ret;
}

/*
 * free page(s) as defined by the above mapping.
 */
void consistent_free(void *vaddr)
{
    if (in_interrupt())
        BUG();
    vfree(vaddr);
}

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

    switch (direction) {
    case PCI_DMA_NONE:
        BUG();
    case PCI_DMA_FROMDEVICE:    /* invalidate only */
        frv_cache_invalidate(start, end);
        break;
    case PCI_DMA_TODEVICE:      /* writeback only */
        frv_dcache_writeback(start, end);
        break;
    case PCI_DMA_BIDIRECTIONAL: /* writeback and invalidate */
        frv_dcache_writeback(start, end);
        break;
    }
}

/*
 * consistent_sync_page make a page are consistent. identical
 * to consistent_sync, but takes a struct page instead of a virtual address
 */

void consistent_sync_page(struct page *page, unsigned long offset,
              size_t size, int direction)
{
    void *start;

    start = page_address(page) + offset;
    consistent_sync(start, size, direction);
}