/* 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 <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);
  }