1 files changed, 74 insertions, 0 deletions
diff --git a/mm/ioremap.c b/mm/ioremap.c
new file mode 100644
index 000000000..3e049dfb2
--- /dev/null
+++ b/mm/ioremap.c
@@ -0,0 +1,74 @@
+// 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>
+#include <linux/ioremap.h>
+
+void __iomem *generic_ioremap_prot(phys_addr_t phys_addr, size_t size,
+				   pgprot_t prot)
+{
+	unsigned long offset, vaddr;
+	phys_addr_t last_addr;
+	struct vm_struct *area;
+
+	/* An early platform driver might end up here */
+	if (WARN_ON_ONCE(!slab_is_available()))
+		return NULL;
+
+	/* 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);
+
+	area = __get_vm_area_caller(size, VM_IOREMAP, IOREMAP_START,
+				    IOREMAP_END, __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, prot)) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return (void __iomem *)(vaddr + offset);
+}
+
+#ifndef ioremap_prot
+void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
+			   unsigned long prot)
+{
+	return generic_ioremap_prot(phys_addr, size, __pgprot(prot));
+}
+EXPORT_SYMBOL(ioremap_prot);
+#endif
+
+void generic_iounmap(volatile void __iomem *addr)
+{
+	void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
+
+	if (is_ioremap_addr(vaddr))
+		vunmap(vaddr);
+}
+
+#ifndef iounmap
+void iounmap(volatile void __iomem *addr)
+{
+	generic_iounmap(addr);
+}
+EXPORT_SYMBOL(iounmap);
+#endif