1 files changed, 246 insertions, 57 deletions

diff --git a/arch/powerpc/lib/dma-noncoherent.c b/arch/powerpc/lib/dma-noncoherent.c
index 005a28d380af..b7dc4c19f582 100644
--- a/arch/powerpc/lib/dma-noncoherent.c
+++ b/arch/powerpc/lib/dma-noncoherent.c
@@ -29,11 +29,121 @@
 #include <linux/types.h>
 #include <linux/highmem.h>
 #include <linux/dma-mapping.h>
-#include <linux/vmalloc.h>
 
 #include <asm/tlbflush.h>
 
 /*
+ * This address range defaults to a value that is safe for all
+ * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
+ * can be further configured for specific applications under
+ * the "Advanced Setup" menu. -Matt
+ */
+#define CONSISTENT_BASE (CONFIG_CONSISTENT_START)
+#define CONSISTENT_END  (CONFIG_CONSISTENT_START + CONFIG_CONSISTENT_SIZE)
+#define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
+
+/*
+ * This is the page table (2MB) covering uncached, DMA consistent allocations
+ */
+static pte_t *consistent_pte;
+static DEFINE_SPINLOCK(consistent_lock);
+
+/*
+ * VM region handling support.
+ *
+ * This should become something generic, handling VM region allocations for
+ * vmalloc and similar (ioremap, module space, etc).
+ *
+ * I envisage vmalloc()'s supporting vm_struct becoming:
+ *
+ *  struct vm_struct {
+ *    struct vm_region  region;
+ *    unsigned long     flags;
+ *    struct page       **pages;
+ *    unsigned int      nr_pages;
+ *    unsigned long     phys_addr;
+ *  };
+ *
+ * get_vm_area() would then call vm_region_alloc with an appropriate
+ * struct vm_region head (eg):
+ *
+ *  struct vm_region vmalloc_head = {
+ *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
+ *      .vm_start       = VMALLOC_START,
+ *      .vm_end         = VMALLOC_END,
+ *  };
+ *
+ * However, vmalloc_head.vm_start is variable (typically, it is dependent on
+ * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
+ * would have to initialise this each time prior to calling vm_region_alloc().
+ */
+struct ppc_vm_region {
+        struct list_head        vm_list;
+        unsigned long           vm_start;
+        unsigned long           vm_end;
+};
+
+static struct ppc_vm_region consistent_head = {
+        .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
+        .vm_start       = CONSISTENT_BASE,
+        .vm_end         = CONSISTENT_END,
+};
+
+static struct ppc_vm_region *
+ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
+{
+        unsigned long addr = head->vm_start, end = head->vm_end - size;
+        unsigned long flags;
+        struct ppc_vm_region *c, *new;
+
+        new = kmalloc(sizeof(struct ppc_vm_region), gfp);
+        if (!new)
+                goto out;
+
+        spin_lock_irqsave(&consistent_lock, flags);
+
+        list_for_each_entry(c, &head->vm_list, vm_list) {
+                if ((addr + size) < addr)
+                        goto nospc;
+                if ((addr + size) <= c->vm_start)
+                        goto found;
+                addr = c->vm_end;
+                if (addr > end)
+                        goto nospc;
+        }
+
+ found:
+        /*
+         * Insert this entry _before_ the one we found.
+         */
+        list_add_tail(&new->vm_list, &c->vm_list);
+        new->vm_start = addr;
+        new->vm_end = addr + size;
+
+        spin_unlock_irqrestore(&consistent_lock, flags);
+        return new;
+
+ nospc:
+        spin_unlock_irqrestore(&consistent_lock, flags);
+        kfree(new);
+ out:
+        return NULL;
+}
+
+static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
+{
+        struct ppc_vm_region *c;
+
+        list_for_each_entry(c, &head->vm_list, vm_list) {
+                if (c->vm_start == addr)
+                        goto out;
+        }
+        c = NULL;
+ out:
+        return c;
+}
+
+/*
  * Allocate DMA-coherent memory space and return both the kernel remapped
  * virtual and bus address for that space.
  */
@@ -41,21 +151,21 @@ void *
 __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
 {
         struct page *page;
+        struct ppc_vm_region *c;
         unsigned long order;
-        int i;
-        unsigned int nr_pages = PAGE_ALIGN(size)>>PAGE_SHIFT;
-        unsigned int array_size = nr_pages * sizeof(struct page *);
-        struct page **pages;
-        struct page *end;
         u64 mask = 0x00ffffff, limit; /* ISA default */
-        struct vm_struct *area;
 
-        BUG_ON(!mem_init_done);
+        if (!consistent_pte) {
+                printk(KERN_ERR "%s: not initialised\n", __func__);
+                dump_stack();
+                return NULL;
+        }
+
         size = PAGE_ALIGN(size);
         limit = (mask + 1) & ~mask;
-        if (limit && size >= limit) {
-                printk(KERN_WARNING "coherent allocation too big (requested "
-                                "%#x mask %#Lx)\n", size, mask);
+        if ((limit && size >= limit) || size >= (CONSISTENT_END - CONSISTENT_BASE)) {
+                printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
+                       size, mask);
                 return NULL;
         }
 
@@ -68,8 +178,6 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
         if (!page)
                 goto no_page;
 
-        end = page + (1 << order);
-
         /*
          * Invalidate any data that might be lurking in the
          * kernel direct-mapped region for device DMA.
@@ -80,59 +188,48 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
                 flush_dcache_range(kaddr, kaddr + size);
         }
 
-        split_page(page, order);
-
         /*
-         * Set the "dma handle"
+         * Allocate a virtual address in the consistent mapping region.
          */
-        *handle = page_to_phys(page);
-
-        area = get_vm_area_caller(size, VM_IOREMAP,
-                        __builtin_return_address(1));
-        if (!area)
-                goto out_free_pages;
-
-        if (array_size > PAGE_SIZE) {
-                pages = vmalloc(array_size);
-                area->flags |= VM_VPAGES;
-        } else {
-                pages = kmalloc(array_size, GFP_KERNEL);
-        }
-        if (!pages)
-                goto out_free_area;
+        c = ppc_vm_region_alloc(&consistent_head, size,
+                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
+        if (c) {
+                unsigned long vaddr = c->vm_start;
+                pte_t *pte = consistent_pte + CONSISTENT_OFFSET(vaddr);
+                struct page *end = page + (1 << order);
 
-        area->pages = pages;
-        area->nr_pages = nr_pages;
+                split_page(page, order);
 
-        for (i = 0; i < nr_pages; i++)
-                pages[i] = page + i;
+                /*
+                 * Set the "dma handle"
+                 */
+                *handle = page_to_phys(page);
 
-        if (map_vm_area(area, pgprot_noncached(PAGE_KERNEL), &pages))
-                goto out_unmap;
+                do {
+                        BUG_ON(!pte_none(*pte));
 
-        /*
-         * Free the otherwise unused pages.
-         */
-        page += nr_pages;
-        while (page < end) {
-                __free_page(page);
-                page++;
+                        SetPageReserved(page);
+                        set_pte_at(&init_mm, vaddr,
+                                   pte, mk_pte(page, pgprot_noncached(PAGE_KERNEL)));
+                        page++;
+                        pte++;
+                        vaddr += PAGE_SIZE;
+                } while (size -= PAGE_SIZE);
+
+                /*
+                 * Free the otherwise unused pages.
+                 */
+                while (page < end) {
+                        __free_page(page);
+                        page++;
+                }
+
+                return (void *)c->vm_start;
         }
 
-        return area->addr;
-out_unmap:
-        vunmap(area->addr);
-        if (array_size > PAGE_SIZE)
-                vfree(pages);
-        else
-                kfree(pages);
-        goto out_free_pages;
-out_free_area:
-        free_vm_area(area);
-out_free_pages:
         if (page)
                 __free_pages(page, order);
-no_page:
+ no_page:
         return NULL;
 }
 EXPORT_SYMBOL(__dma_alloc_coherent);
@@ -142,12 +239,104 @@ EXPORT_SYMBOL(__dma_alloc_coherent);
  */
 void __dma_free_coherent(size_t size, void *vaddr)
 {
-        vfree(vaddr);
+        struct ppc_vm_region *c;
+        unsigned long flags, addr;
+        pte_t *ptep;
+
+        size = PAGE_ALIGN(size);
+
+        spin_lock_irqsave(&consistent_lock, flags);
+
+        c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
+        if (!c)
+                goto no_area;
+
+        if ((c->vm_end - c->vm_start) != size) {
+                printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
+                       __func__, c->vm_end - c->vm_start, size);
+                dump_stack();
+                size = c->vm_end - c->vm_start;
+        }
+
+        ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
+        addr = c->vm_start;
+        do {
+                pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
+                unsigned long pfn;
+
+                ptep++;
+                addr += PAGE_SIZE;
 
+                if (!pte_none(pte) && pte_present(pte)) {
+                        pfn = pte_pfn(pte);
+
+                        if (pfn_valid(pfn)) {
+                                struct page *page = pfn_to_page(pfn);
+                                ClearPageReserved(page);
+
+                                __free_page(page);
+                                continue;
+                        }
+                }
+
+                printk(KERN_CRIT "%s: bad page in kernel page table\n",
+                       __func__);
+        } while (size -= PAGE_SIZE);
+
+        flush_tlb_kernel_range(c->vm_start, c->vm_end);
+
+        list_del(&c->vm_list);
+
+        spin_unlock_irqrestore(&consistent_lock, flags);
+
+        kfree(c);
+        return;
+
+ no_area:
+        spin_unlock_irqrestore(&consistent_lock, flags);
+        printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
+               __func__, vaddr);
+        dump_stack();
 }
 EXPORT_SYMBOL(__dma_free_coherent);
 
 /*
+ * Initialise the consistent memory allocation.
+ */
+static int __init dma_alloc_init(void)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+        int ret = 0;
+
+        do {
+                pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
+                pud = pud_alloc(&init_mm, pgd, CONSISTENT_BASE);
+                pmd = pmd_alloc(&init_mm, pud, CONSISTENT_BASE);
+                if (!pmd) {
+                        printk(KERN_ERR "%s: no pmd tables\n", __func__);
+                        ret = -ENOMEM;
+                        break;
+                }
+
+                pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
+                if (!pte) {
+                        printk(KERN_ERR "%s: no pte tables\n", __func__);
+                        ret = -ENOMEM;
+                        break;
+                }
+
+                consistent_pte = pte;
+        } while (0);
+
+        return ret;
+}
+
+core_initcall(dma_alloc_init);
+
+/*
  * make an area consistent.
  */
 void __dma_sync(void *vaddr, size_t size, int direction)