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dma-alloc.c

/* 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 (dmalek@jlc.net)
 *
 *  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 <asm/pgalloc.h>
#include <asm/io.h>
#include <asm/hardirq.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);
}

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