2 files changed, 155 insertions, 0 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 54f69837d35a..4e1d7df7c3e2 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
 obj-$(CONFIG_MARKERS) += marker.o
 obj-$(CONFIG_LATENCYTOP) += latencytop.o
+obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
 obj-$(CONFIG_FTRACE) += trace/
 obj-$(CONFIG_TRACING) += trace/
 obj-$(CONFIG_SMP) += sched_cpupri.o
diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
new file mode 100644
index 000000000000..7517115a8cce
--- /dev/null
+++ b/kernel/dma-coherent.c
@@ -0,0 +1,154 @@
+/*
+ * Coherent per-device memory handling.
+ * Borrowed from i386
+ */
+#include <linux/kernel.h>
+#include <linux/dma-mapping.h>
+
+struct dma_coherent_mem {
+        void            *virt_base;
+        u32             device_base;
+        int             size;
+        int             flags;
+        unsigned long   *bitmap;
+};
+
+int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
+                                dma_addr_t device_addr, size_t size, int flags)
+{
+        void __iomem *mem_base = NULL;
+        int pages = size >> PAGE_SHIFT;
+        int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
+
+        if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
+                goto out;
+        if (!size)
+                goto out;
+        if (dev->dma_mem)
+                goto out;
+
+        /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
+
+        mem_base = ioremap(bus_addr, size);
+        if (!mem_base)
+                goto out;
+
+        dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
+        if (!dev->dma_mem)
+                goto out;
+        dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+        if (!dev->dma_mem->bitmap)
+                goto free1_out;
+
+        dev->dma_mem->virt_base = mem_base;
+        dev->dma_mem->device_base = device_addr;
+        dev->dma_mem->size = pages;
+        dev->dma_mem->flags = flags;
+
+        if (flags & DMA_MEMORY_MAP)
+                return DMA_MEMORY_MAP;
+
+        return DMA_MEMORY_IO;
+
+ free1_out:
+        kfree(dev->dma_mem);
+ out:
+        if (mem_base)
+                iounmap(mem_base);
+        return 0;
+}
+EXPORT_SYMBOL(dma_declare_coherent_memory);
+
+void dma_release_declared_memory(struct device *dev)
+{
+        struct dma_coherent_mem *mem = dev->dma_mem;
+
+        if (!mem)
+                return;
+        dev->dma_mem = NULL;
+        iounmap(mem->virt_base);
+        kfree(mem->bitmap);
+        kfree(mem);
+}
+EXPORT_SYMBOL(dma_release_declared_memory);
+
+void *dma_mark_declared_memory_occupied(struct device *dev,
+                                        dma_addr_t device_addr, size_t size)
+{
+        struct dma_coherent_mem *mem = dev->dma_mem;
+        int pos, err;
+        int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1);
+
+        pages >>= PAGE_SHIFT;
+
+        if (!mem)
+                return ERR_PTR(-EINVAL);
+
+        pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
+        err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
+        if (err != 0)
+                return ERR_PTR(err);
+        return mem->virt_base + (pos << PAGE_SHIFT);
+}
+EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
+
+/**
+ * Try to allocate memory from the per-device coherent area.
+ *
+ * @dev:        device from which we allocate memory
+ * @size:       size of requested memory area
+ * @dma_handle: This will be filled with the correct dma handle
+ * @ret:        This pointer will be filled with the virtual address
+ *              to allocated area.
+ *
+ * This function should be only called from per-arch %dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ *
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * generic memory areas, or !0 if dma_alloc_coherent should return %ret.
+ */
+int dma_alloc_from_coherent(struct device *dev, ssize_t size,
+                                       dma_addr_t *dma_handle, void **ret)
+{
+        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+        int order = get_order(size);
+
+        if (mem) {
+                int page = bitmap_find_free_region(mem->bitmap, mem->size,
+                                                     order);
+                if (page >= 0) {
+                        *dma_handle = mem->device_base + (page << PAGE_SHIFT);
+                        *ret = mem->virt_base + (page << PAGE_SHIFT);
+                        memset(*ret, 0, size);
+                } else if (mem->flags & DMA_MEMORY_EXCLUSIVE)
+                        *ret = NULL;
+        }
+        return (mem != NULL);
+}
+
+/**
+ * Try to free the memory allocated from per-device coherent memory pool.
+ * @dev:        device from which the memory was allocated
+ * @order:      the order of pages allocated
+ * @vaddr:      virtual address of allocated pages
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ *
+ * Returns 1 if we correctly released the memory, or 0 if
+ * %dma_release_coherent() should proceed with releasing memory from
+ * generic pools.
+ */
+int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
+{
+        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+
+        if (mem && vaddr >= mem->virt_base && vaddr <
+                   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
+                int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+
+                bitmap_release_region(mem->bitmap, page, order);
+                return 1;
+        }
+        return 0;
+}