nommu: Add noMMU support to the DMA API

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 510c179..b30925f 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -36,7 +36,34 @@
 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
 #define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)
 
+static u64 get_coherent_dma_mask(struct device *dev)
+{
+       u64 mask = ISA_DMA_THRESHOLD;
+
+       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");
+                       return 0;
+               }
+
+               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);
+                       return 0;
+               }
+       }
 
+       return mask;
+}
+
+#ifdef CONFIG_MMU
 /*
  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
  */
@@ -152,7 +179,8 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
        struct page *page;
        struct arm_vm_region *c;
        unsigned long order;
-       u64 mask = ISA_DMA_THRESHOLD, limit;
+       u64 mask = get_coherent_dma_mask(dev);
+       u64 limit;
 
        if (!consistent_pte[0]) {
                printk(KERN_ERR "%s: not initialised\n", __func__);
@@ -160,25 +188,8 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
                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;
-               }
-       }
+       if (!mask)
+               goto no_page;
 
        /*
         * Sanity check the allocation size.
@@ -267,6 +278,31 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
        *handle = ~0;
        return NULL;
 }
+#else  /* !CONFIG_MMU */
+static void *
+__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
+           pgprot_t prot)
+{
+       void *virt;
+       u64 mask = get_coherent_dma_mask(dev);
+
+       if (!mask)
+               goto error;
+
+       if (mask != 0xffffffff)
+               gfp |= GFP_DMA;
+       virt = kmalloc(size, gfp);
+       if (!virt)
+               goto error;
+
+       *handle =  virt_to_dma(dev, virt);
+       return virt;
+
+error:
+       *handle = ~0;
+       return NULL;
+}
+#endif /* CONFIG_MMU */
 
 /*
  * Allocate DMA-coherent memory space and return both the kernel remapped
@@ -311,9 +347,10 @@ 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)
 {
+       int ret = -ENXIO;
+#ifdef CONFIG_MMU
        unsigned long flags, user_size, kern_size;
        struct arm_vm_region *c;
-       int ret = -ENXIO;
 
        user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 
@@ -334,6 +371,7 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
                                              vma->vm_page_prot);
                }
        }
+#endif /* CONFIG_MMU */
 
        return ret;
 }
@@ -358,6 +396,7 @@ EXPORT_SYMBOL(dma_mmap_writecombine);
  * free a page as defined by the above mapping.
  * Must not be called with IRQs disabled.
  */
+#ifdef CONFIG_MMU
 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 {
        struct arm_vm_region *c;
@@ -444,6 +483,14 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr
               __func__, cpu_addr);
        dump_stack();
 }
+#else  /* !CONFIG_MMU */
+void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
+{
+       if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
+               return;
+       kfree(cpu_addr);
+}
+#endif /* CONFIG_MMU */
 EXPORT_SYMBOL(dma_free_coherent);
 
 /*
@@ -451,10 +498,12 @@ EXPORT_SYMBOL(dma_free_coherent);
  */
 static int __init consistent_init(void)
 {
+       int ret = 0;
+#ifdef CONFIG_MMU
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte;
-       int ret = 0, i = 0;
+       int i = 0;
        u32 base = CONSISTENT_BASE;
 
        do {
@@ -477,6 +526,7 @@ static int __init consistent_init(void)
                consistent_pte[i++] = pte;
                base += (1 << PGDIR_SHIFT);
        } while (base < CONSISTENT_END);
+#endif /* !CONFIG_MMU */
 
        return ret;
 }