1 files changed, 88 insertions, 0 deletions
diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
new file mode 100644
index 000000000000..a15c393ea4e5
--- /dev/null
+++ b/kernel/dma/remap.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014 The Linux Foundation
+ */
+#include <linux/dma-mapping.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+static struct vm_struct *__dma_common_pages_remap(struct page **pages,
+			size_t size, unsigned long vm_flags, pgprot_t prot,
+			const void *caller)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area_caller(size, vm_flags, caller);
+	if (!area)
+		return NULL;
+
+	if (map_vm_area(area, prot, pages)) {
+		vunmap(area->addr);
+		return NULL;
+	}
+
+	return area;
+}
+
+/*
+ * 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,
+			unsigned long vm_flags, pgprot_t prot,
+			const void *caller)
+{
+	struct vm_struct *area;
+
+	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+	if (!area)
+		return NULL;
+
+	area->pages = pages;
+
+	return area->addr;
+}
+
+/*
+ * 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,
+			unsigned long vm_flags,
+			pgprot_t prot, const void *caller)
+{
+	int i;
+	struct page **pages;
+	struct vm_struct *area;
+
+	pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
+	if (!pages)
+		return NULL;
+
+	for (i = 0; i < (size >> PAGE_SHIFT); i++)
+		pages[i] = nth_page(page, i);
+
+	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+
+	kfree(pages);
+
+	if (!area)
+		return NULL;
+	return area->addr;
+}
+
+/*
+ * Unmaps a range previously mapped by dma_common_*_remap
+ */
+void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
+{
+	struct vm_struct *area = find_vm_area(cpu_addr);
+
+	if (!area || (area->flags & vm_flags) != vm_flags) {
+		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);
+}