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-rw-r--r--kernel/dma/remap.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
new file mode 100644
index 000000000..5bff06199
--- /dev/null
+++ b/kernel/dma/remap.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014 The Linux Foundation
+ */
+#include <linux/dma-map-ops.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+struct page **dma_common_find_pages(void *cpu_addr)
+{
+ struct vm_struct *area = find_vm_area(cpu_addr);
+
+ if (!area || area->flags != VM_DMA_COHERENT)
+ return NULL;
+ return area->pages;
+}
+
+/*
+ * Remaps an array of PAGE_SIZE pages into another vm_area.
+ * Cannot be used in non-sleeping contexts
+ */
+void *dma_common_pages_remap(struct page **pages, size_t size,
+ pgprot_t prot, const void *caller)
+{
+ void *vaddr;
+
+ vaddr = vmap(pages, PAGE_ALIGN(size) >> PAGE_SHIFT,
+ VM_DMA_COHERENT, prot);
+ if (vaddr)
+ find_vm_area(vaddr)->pages = pages;
+ return vaddr;
+}
+
+/*
+ * Remaps an allocated contiguous region into another vm_area.
+ * Cannot be used in non-sleeping contexts
+ */
+void *dma_common_contiguous_remap(struct page *page, size_t size,
+ pgprot_t prot, const void *caller)
+{
+ int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ struct page **pages;
+ void *vaddr;
+ int i;
+
+ pages = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
+ if (!pages)
+ return NULL;
+ for (i = 0; i < count; i++)
+ pages[i] = nth_page(page, i);
+ vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
+ kvfree(pages);
+
+ return vaddr;
+}
+
+/*
+ * Unmaps a range previously mapped by dma_common_*_remap
+ */
+void dma_common_free_remap(void *cpu_addr, size_t size)
+{
+ struct vm_struct *area = find_vm_area(cpu_addr);
+
+ if (!area || area->flags != VM_DMA_COHERENT) {
+ WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
+ return;
+ }
+
+ unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
+ vunmap(cpu_addr);
+}