1 files changed, 451 insertions, 0 deletions

diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
new file mode 100644
index 000000000000..26356ce4da54
--- /dev/null
+++ b/arch/arm/mm/consistent.c
@@ -0,0 +1,451 @@
+/*
+ *  linux/arch/arm/mm/consistent.c
+ *
+ *  Copyright (C) 2000-2004 Russell King
+ *
+ * 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.
+ *
+ *  DMA uncached mapping support.
+ */
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/cacheflush.h>
+#include <asm/io.h>
+#include <asm/tlbflush.h>
+
+#define CONSISTENT_BASE (0xffc00000)
+#define CONSISTENT_END  (0xffe00000)
+#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 vm_region {
+        struct list_head        vm_list;
+        unsigned long           vm_start;
+        unsigned long           vm_end;
+        struct page             *vm_pages;
+};
+
+static struct vm_region consistent_head = {
+        .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
+        .vm_start       = CONSISTENT_BASE,
+        .vm_end         = CONSISTENT_END,
+};
+
+static struct vm_region *
+vm_region_alloc(struct vm_region *head, size_t size, int gfp)
+{
+        unsigned long addr = head->vm_start, end = head->vm_end - size;
+        unsigned long flags;
+        struct vm_region *c, *new;
+
+        new = kmalloc(sizeof(struct 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 vm_region *vm_region_find(struct vm_region *head, unsigned long addr)
+{
+        struct 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;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+#error ARM Coherent DMA allocator does not (yet) support huge TLB
+#endif
+
+static void *
+__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, int gfp,
+            pgprot_t prot)
+{
+        struct page *page;
+        struct vm_region *c;
+        unsigned long order;
+        u64 mask = ISA_DMA_THRESHOLD, limit;
+
+        if (!consistent_pte) {
+                printk(KERN_ERR "%s: not initialised\n", __func__);
+                dump_stack();
+                return NULL;
+        }
+
+        if (dev) {
+                mask = dev->coherent_dma_mask;
+
+                /*
+                 * Sanity check the DMA mask - it must be non-zero, and
+                 * must be able to be satisfied by a DMA allocation.
+                 */
+                if (mask == 0) {
+                        dev_warn(dev, "coherent DMA mask is unset\n");
+                        goto no_page;
+                }
+
+                if ((~mask) & ISA_DMA_THRESHOLD) {
+                        dev_warn(dev, "coherent DMA mask %#llx is smaller "
+                                 "than system GFP_DMA mask %#llx\n",
+                                 mask, (unsigned long long)ISA_DMA_THRESHOLD);
+                        goto no_page;
+                }
+        }
+
+        /*
+         * Sanity check the allocation size.
+         */
+        size = PAGE_ALIGN(size);
+        limit = (mask + 1) & ~mask;
+        if ((limit && size >= limit) ||
+            size >= (CONSISTENT_END - CONSISTENT_BASE)) {
+                printk(KERN_WARNING "coherent allocation too big "
+                       "(requested %#x mask %#llx)\n", size, mask);
+                goto no_page;
+        }
+
+        order = get_order(size);
+
+        if (mask != 0xffffffff)
+                gfp |= GFP_DMA;
+
+        page = alloc_pages(gfp, order);
+        if (!page)
+                goto no_page;
+
+        /*
+         * Invalidate any data that might be lurking in the
+         * kernel direct-mapped region for device DMA.
+         */
+        {
+                unsigned long kaddr = (unsigned long)page_address(page);
+                memset(page_address(page), 0, size);
+                dmac_flush_range(kaddr, kaddr + size);
+        }
+
+        /*
+         * Allocate a virtual address in the consistent mapping region.
+         */
+        c = vm_region_alloc(&consistent_head, size,
+                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
+        if (c) {
+                pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
+                struct page *end = page + (1 << order);
+
+                c->vm_pages = page;
+
+                /*
+                 * Set the "dma handle"
+                 */
+                *handle = page_to_dma(dev, page);
+
+                do {
+                        BUG_ON(!pte_none(*pte));
+
+                        set_page_count(page, 1);
+                        /*
+                         * x86 does not mark the pages reserved...
+                         */
+                        SetPageReserved(page);
+                        set_pte(pte, mk_pte(page, prot));
+                        page++;
+                        pte++;
+                } while (size -= PAGE_SIZE);
+
+                /*
+                 * Free the otherwise unused pages.
+                 */
+                while (page < end) {
+                        set_page_count(page, 1);
+                        __free_page(page);
+                        page++;
+                }
+
+                return (void *)c->vm_start;
+        }
+
+        if (page)
+                __free_pages(page, order);
+ no_page:
+        *handle = ~0;
+        return NULL;
+}
+
+/*
+ * Allocate DMA-coherent memory space and return both the kernel remapped
+ * virtual and bus address for that space.
+ */
+void *
+dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, int gfp)
+{
+        return __dma_alloc(dev, size, handle, gfp,
+                           pgprot_noncached(pgprot_kernel));
+}
+EXPORT_SYMBOL(dma_alloc_coherent);
+
+/*
+ * Allocate a writecombining region, in much the same way as
+ * dma_alloc_coherent above.
+ */
+void *
+dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, int gfp)
+{
+        return __dma_alloc(dev, size, handle, gfp,
+                           pgprot_writecombine(pgprot_kernel));
+}
+EXPORT_SYMBOL(dma_alloc_writecombine);
+
+static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
+                    void *cpu_addr, dma_addr_t dma_addr, size_t size)
+{
+        unsigned long flags, user_size, kern_size;
+        struct vm_region *c;
+        int ret = -ENXIO;
+
+        user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+
+        spin_lock_irqsave(&consistent_lock, flags);
+        c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
+        spin_unlock_irqrestore(&consistent_lock, flags);
+
+        if (c) {
+                unsigned long off = vma->vm_pgoff;
+
+                kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
+
+                if (off < kern_size &&
+                    user_size <= (kern_size - off)) {
+                        vma->vm_flags |= VM_RESERVED;
+                        ret = remap_pfn_range(vma, vma->vm_start,
+                                              page_to_pfn(c->vm_pages) + off,
+                                              user_size << PAGE_SHIFT,
+                                              vma->vm_page_prot);
+                }
+        }
+
+        return ret;
+}
+
+int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
+                      void *cpu_addr, dma_addr_t dma_addr, size_t size)
+{
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+        return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
+}
+EXPORT_SYMBOL(dma_mmap_coherent);
+
+int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
+                          void *cpu_addr, dma_addr_t dma_addr, size_t size)
+{
+        vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+        return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
+}
+EXPORT_SYMBOL(dma_mmap_writecombine);
+
+/*
+ * free a page as defined by the above mapping.
+ */
+void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
+{
+        struct vm_region *c;
+        unsigned long flags, addr;
+        pte_t *ptep;
+
+        size = PAGE_ALIGN(size);
+
+        spin_lock_irqsave(&consistent_lock, flags);
+
+        c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
+        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);
+
+                                /*
+                                 * x86 does not mark the pages reserved...
+                                 */
+                                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__, cpu_addr);
+        dump_stack();
+}
+EXPORT_SYMBOL(dma_free_coherent);
+
+/*
+ * Initialise the consistent memory allocation.
+ */
+static int __init consistent_init(void)
+{
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        int ret = 0;
+
+        spin_lock(&init_mm.page_table_lock);
+
+        do {
+                pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
+                pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
+                if (!pmd) {
+                        printk(KERN_ERR "%s: no pmd tables\n", __func__);
+                        ret = -ENOMEM;
+                        break;
+                }
+                WARN_ON(!pmd_none(*pmd));
+
+                pte = pte_alloc_kernel(&init_mm, pmd, CONSISTENT_BASE);
+                if (!pte) {
+                        printk(KERN_ERR "%s: no pte tables\n", __func__);
+                        ret = -ENOMEM;
+                        break;
+                }
+
+                consistent_pte = pte;
+        } while (0);
+
+        spin_unlock(&init_mm.page_table_lock);
+
+        return ret;
+}
+
+core_initcall(consistent_init);
+
+/*
+ * Make an area consistent for devices.
+ */
+void consistent_sync(void *vaddr, size_t size, int direction)
+{
+        unsigned long start = (unsigned long)vaddr;
+        unsigned long end   = start + size;
+
+        switch (direction) {
+        case DMA_FROM_DEVICE:           /* invalidate only */
+                dmac_inv_range(start, end);
+                break;
+        case DMA_TO_DEVICE:             /* writeback only */
+                dmac_clean_range(start, end);
+                break;
+        case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
+                dmac_flush_range(start, end);
+                break;
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(consistent_sync);