1 files changed, 109 insertions, 0 deletions
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
new file mode 100644
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--- /dev/null
+++ b/include/asm-generic/io.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Generic I/O functions.
+ *
+ * Copyright (c) 2016 Imagination Technologies Ltd.
+ */
+
+#ifndef __ASM_GENERIC_IO_H__
+#define __ASM_GENERIC_IO_H__
+
+/*
+ * This file should be included at the end of each architecture-specific
+ * asm/io.h such that we may provide generic implementations without
+ * conflicting with architecture-specific code.
+ */
+
+#ifndef __ASSEMBLY__
+
+/**
+ * phys_to_virt() - Return a virtual address mapped to a given physical address
+ * @paddr: the physical address
+ *
+ * Returns a virtual address which the CPU can access that maps to the physical
+ * address @paddr. This should only be used where it is known that no dynamic
+ * mapping is required. In general, map_physmem should be used instead.
+ *
+ * Returns: a virtual address which maps to @paddr
+ */
+#ifndef phys_to_virt
+static inline void *phys_to_virt(phys_addr_t paddr)
+{
+	return (void *)(unsigned long)paddr;
+}
+#endif
+
+/**
+ * virt_to_phys() - Return the physical address that a virtual address maps to
+ * @vaddr: the virtual address
+ *
+ * Returns the physical address which the CPU-accessible virtual address @vaddr
+ * maps to.
+ *
+ * Returns: the physical address which @vaddr maps to
+ */
+#ifndef virt_to_phys
+static inline phys_addr_t virt_to_phys(void *vaddr)
+{
+	return (phys_addr_t)((unsigned long)vaddr);
+}
+#endif
+
+/*
+ * Flags for use with map_physmem() & unmap_physmem(). Architectures need not
+ * support all of these, in which case they will be defined as zero here &
+ * ignored. Callers that may run on multiple architectures should therefore
+ * treat them as hints rather than requirements.
+ */
+#ifndef MAP_NOCACHE
+# define MAP_NOCACHE	0	/* Produce an uncached mapping */
+#endif
+#ifndef MAP_WRCOMBINE
+# define MAP_WRCOMBINE	0	/* Allow write-combining on the mapping */
+#endif
+#ifndef MAP_WRBACK
+# define MAP_WRBACK	0	/* Map using write-back caching */
+#endif
+#ifndef MAP_WRTHROUGH
+# define MAP_WRTHROUGH	0	/* Map using write-through caching */
+#endif
+
+/**
+ * map_physmem() - Return a virtual address mapped to a given physical address
+ * @paddr: the physical address
+ * @len: the length of the required mapping
+ * @flags: flags affecting the type of mapping
+ *
+ * Return a virtual address through which the CPU may access the memory at
+ * physical address @paddr. The mapping will be valid for at least @len bytes,
+ * and may be affected by flags passed to the @flags argument. This function
+ * may create new mappings, so should generally be paired with a matching call
+ * to unmap_physmem once the caller is finished with the memory in question.
+ *
+ * Returns: a virtual address suitably mapped to @paddr
+ */
+#ifndef map_physmem
+static inline void *map_physmem(phys_addr_t paddr, unsigned long len,
+				unsigned long flags)
+{
+	return phys_to_virt(paddr);
+}
+#endif
+
+/**
+ * unmap_physmem() - Remove mappings created by a prior call to map_physmem()
+ * @vaddr: the virtual address which map_physmem() previously returned
+ * @flags: flags matching those originally passed to map_physmem()
+ *
+ * Unmap memory which was previously mapped by a call to map_physmem(). If
+ * map_physmem() dynamically created a mapping for the memory in question then
+ * unmap_physmem() will remove that mapping.
+ */
+#ifndef unmap_physmem
+static inline void unmap_physmem(void *vaddr, unsigned long flags)
+{
+}
+#endif
+
+#endif /* !__ASSEMBLY__ */
+#endif /* __ASM_GENERIC_IO_H__ */