ARM: 8547/1: dma-mapping: store buffer information

Keep a list of allocated DMA buffers so that we can store metadata in
alloc() which we later need in free().

Signed-off-by: Rabin Vincent <rabin.vincent@axis.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 9f996a3..696f6ee 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -42,6 +42,31 @@
 #include "dma.h"
 #include "mm.h"
 
+struct arm_dma_buffer {
+       struct list_head list;
+       void *virt;
+};
+
+static LIST_HEAD(arm_dma_bufs);
+static DEFINE_SPINLOCK(arm_dma_bufs_lock);
+
+static struct arm_dma_buffer *arm_dma_buffer_find(void *virt)
+{
+       struct arm_dma_buffer *buf, *found = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&arm_dma_bufs_lock, flags);
+       list_for_each_entry(buf, &arm_dma_bufs, list) {
+               if (buf->virt == virt) {
+                       list_del(&buf->list);
+                       found = buf;
+                       break;
+               }
+       }
+       spin_unlock_irqrestore(&arm_dma_bufs_lock, flags);
+       return found;
+}
+
 /*
  * The DMA API is built upon the notion of "buffer ownership".  A buffer
  * is either exclusively owned by the CPU (and therefore may be accessed
@@ -620,6 +645,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
        struct page *page = NULL;
        void *addr;
        bool want_vaddr;
+       struct arm_dma_buffer *buf;
 
 #ifdef CONFIG_DMA_API_DEBUG
        u64 limit = (mask + 1) & ~mask;
@@ -633,6 +659,10 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
        if (!mask)
                return NULL;
 
+       buf = kzalloc(sizeof(*buf), gfp);
+       if (!buf)
+               return NULL;
+
        if (mask < 0xffffffffULL)
                gfp |= GFP_DMA;
 
@@ -662,8 +692,18 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
                addr = __alloc_remap_buffer(dev, size, gfp, prot, &page,
                                            caller, want_vaddr);
 
-       if (page)
+       if (page) {
+               unsigned long flags;
+
                *handle = pfn_to_dma(dev, page_to_pfn(page));
+               buf->virt = want_vaddr ? addr : page;
+
+               spin_lock_irqsave(&arm_dma_bufs_lock, flags);
+               list_add(&buf->list, &arm_dma_bufs);
+               spin_unlock_irqrestore(&arm_dma_bufs_lock, flags);
+       } else {
+               kfree(buf);
+       }
 
        return want_vaddr ? addr : page;
 }
@@ -742,6 +782,11 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
 {
        struct page *page = pfn_to_page(dma_to_pfn(dev, handle));
        bool want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs);
+       struct arm_dma_buffer *buf;
+
+       buf = arm_dma_buffer_find(cpu_addr);
+       if (WARN(!buf, "Freeing invalid buffer %p\n", cpu_addr))
+               return;
 
        size = PAGE_ALIGN(size);
 
@@ -760,6 +805,8 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
                WARN_ON(irqs_disabled());
                __free_from_contiguous(dev, page, cpu_addr, size, want_vaddr);
        }
+
+       kfree(buf);
 }
 
 void arm_dma_free(struct device *dev, size_t size, void *cpu_addr,