drivers: dma-coherent: support coherent memory declaration with no kernel mapping

Add DMA_MEMORY_NOMAP flag to avoid creation of kernel virtual mapping
during the declaration of DMA coherent memory.
This would allow managing carveout memories via dma-coherent API with no
impact on kernel VMALLOC space.

bug 898152

Change-Id: I700fbfc83716516d15a97f1e18ad0b1a8154a0a9
Signed-off-by: Vandana Salve <vsalve@nvidia.com>
Reviewed-on: http://git-master/r/267938
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index bc256b64102710039e208ec82c513e97b223a290..7e4d53183b4aa93b3ad81e315515be67b1e2c8b6 100644 (file)
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -23,7 +23,8 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
        int pages = size >> PAGE_SHIFT;
        int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 
-       if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
+       if ((flags &
+               (DMA_MEMORY_MAP | DMA_MEMORY_IO | DMA_MEMORY_NOMAP)) == 0)
                goto out;
        if (!size)
                goto out;
@@ -32,10 +33,6 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
 
        /* 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;
@@ -43,7 +40,15 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
        if (!dev->dma_mem->bitmap)
                goto free1_out;
 
+       if (flags & DMA_MEMORY_NOMAP)
+               goto skip_mapping;
+
+       mem_base = ioremap(bus_addr, size);
+       if (!mem_base)
+               goto out;
        dev->dma_mem->virt_base = mem_base;
+
+skip_mapping:
        dev->dma_mem->device_base = device_addr;
        dev->dma_mem->pfn_base = PFN_DOWN(bus_addr);
        dev->dma_mem->size = pages;
@@ -52,6 +57,9 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
        if (flags & DMA_MEMORY_MAP)
                return DMA_MEMORY_MAP;
 
+       if (flags & DMA_MEMORY_NOMAP)
+               return DMA_MEMORY_NOMAP;
+
        return DMA_MEMORY_IO;
 
  free1_out:
@@ -70,7 +78,10 @@ void dma_release_declared_memory(struct device *dev)
        if (!mem)
                return;
        dev->dma_mem = NULL;
-       iounmap(mem->virt_base);
+
+       if (!(mem->flags & DMA_MEMORY_NOMAP))
+               iounmap(mem->virt_base);
+
        kfree(mem->bitmap);
        kfree(mem);
 }
@@ -136,8 +147,10 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
         * Memory was found in the per-device area.
         */
        *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
-       *ret = mem->virt_base + (pageno << PAGE_SHIFT);
-       memset(*ret, 0, size);
+       if (!(mem->flags & DMA_MEMORY_NOMAP)) {
+               *ret = mem->virt_base + (pageno << PAGE_SHIFT);
+               memset(*ret, 0, size);
+       }
 
        return 1;
 
@@ -167,11 +180,20 @@ EXPORT_SYMBOL(dma_alloc_from_coherent);
 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 {
        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+       void *mem_addr;
+
+       if (!mem)
+               return 0;
 
-       if (mem && vaddr >= mem->virt_base && vaddr <
-                  (mem->virt_base + (mem->size << PAGE_SHIFT))) {
-               int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+       if (mem->flags & DMA_MEMORY_NOMAP)
+               mem_addr =  (void *)mem->device_base;
+       else
+               mem_addr =  mem->virt_base;
 
+       if (mem && vaddr >= mem_addr && vaddr <
+                  (mem_addr + (mem->size << PAGE_SHIFT))) {
+
+               int page = (vaddr - mem_addr) >> PAGE_SHIFT;
                bitmap_release_region(mem->bitmap, page, order);
                return 1;
        }
@@ -198,11 +220,20 @@ int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
                           void *vaddr, size_t size, int *ret)
 {
        struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+       void *mem_addr;
+
+       if (!mem)
+               return 0;
+
+       if (mem->flags & DMA_MEMORY_NOMAP)
+               mem_addr =  (void *)mem->device_base;
+       else
+               mem_addr =  mem->virt_base;
 
-       if (mem && vaddr >= mem->virt_base && vaddr + size <=
-                  (mem->virt_base + (mem->size << PAGE_SHIFT))) {
+       if (mem && vaddr >= mem_addr && vaddr + size <=
+                  (mem_addr + (mem->size << PAGE_SHIFT))) {
                unsigned long off = vma->vm_pgoff;
-               int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+               int start = (vaddr - mem_addr) >> PAGE_SHIFT;
                int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
                int count = size >> PAGE_SHIFT;
 

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 69b360847d404ccc2ee6bdd48485e122b328d5f0..30f84df5be9bebafc5457cc06d50a1b9111076d3 100644 (file)
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -172,6 +172,7 @@ static inline int dma_get_cache_alignment(void)
 #define DMA_MEMORY_IO                  0x02
 #define DMA_MEMORY_INCLUDES_CHILDREN   0x04
 #define DMA_MEMORY_EXCLUSIVE           0x08
+#define DMA_MEMORY_NOMAP               0x10
 
 #ifndef ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY
 static inline int