1 files changed, 61 insertions, 0 deletions
diff --git a/mm/ioremap.c b/mm/ioremap.c
new file mode 100644
index 000000000..865242628
--- /dev/null
+++ b/mm/ioremap.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Re-map IO memory to kernel address space so that we can access it.
+ * This is needed for high PCI addresses that aren't mapped in the
+ * 640k-1MB IO memory area on PC's
+ *
+ * (C) Copyright 1995 1996 Linus Torvalds
+ */
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/io.h>
+#include <linux/export.h>
+
+void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
+			   unsigned long prot)
+{
+	unsigned long offset, vaddr;
+	phys_addr_t last_addr;
+	struct vm_struct *area;
+
+	/* Disallow wrap-around or zero size */
+	last_addr = phys_addr + size - 1;
+	if (!size || last_addr < phys_addr)
+		return NULL;
+
+	/* Page-align mappings */
+	offset = phys_addr & (~PAGE_MASK);
+	phys_addr -= offset;
+	size = PAGE_ALIGN(size + offset);
+
+	if (!ioremap_allowed(phys_addr, size, prot))
+		return NULL;
+
+	area = get_vm_area_caller(size, VM_IOREMAP,
+			__builtin_return_address(0));
+	if (!area)
+		return NULL;
+	vaddr = (unsigned long)area->addr;
+	area->phys_addr = phys_addr;
+
+	if (ioremap_page_range(vaddr, vaddr + size, phys_addr,
+			       __pgprot(prot))) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return (void __iomem *)(vaddr + offset);
+}
+EXPORT_SYMBOL(ioremap_prot);
+
+void iounmap(volatile void __iomem *addr)
+{
+	void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
+
+	if (!iounmap_allowed(vaddr))
+		return;
+
+	if (is_vmalloc_addr(vaddr))
+		vunmap(vaddr);
+}
+EXPORT_SYMBOL(iounmap);