1 files changed, 65 insertions, 0 deletions
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
new file mode 100644
index 0000000000..9aaa756ddf
--- /dev/null
+++ b/arch/x86/mm/iomap_32.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright © 2008 Ingo Molnar
+ */
+
+#include <asm/iomap.h>
+#include <asm/memtype.h>
+#include <linux/export.h>
+#include <linux/highmem.h>
+
+static int is_io_mapping_possible(resource_size_t base, unsigned long size)
+{
+#if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
+	/* There is no way to map greater than 1 << 32 address without PAE */
+	if (base + size > 0x100000000ULL)
+		return 0;
+#endif
+	return 1;
+}
+
+int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
+{
+	enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
+	int ret;
+
+	if (!is_io_mapping_possible(base, size))
+		return -EINVAL;
+
+	ret = memtype_reserve_io(base, base + size, &pcm);
+	if (ret)
+		return ret;
+
+	*prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
+	/* Filter out unsupported __PAGE_KERNEL* bits: */
+	pgprot_val(*prot) &= __default_kernel_pte_mask;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_create_wc);
+
+void iomap_free(resource_size_t base, unsigned long size)
+{
+	memtype_free_io(base, base + size);
+}
+EXPORT_SYMBOL_GPL(iomap_free);
+
+void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
+{
+	/*
+	 * For non-PAT systems, translate non-WB request to UC- just in
+	 * case the caller set the PWT bit to prot directly without using
+	 * pgprot_writecombine(). UC- translates to uncached if the MTRR
+	 * is UC or WC. UC- gets the real intention, of the user, which is
+	 * "WC if the MTRR is WC, UC if you can't do that."
+	 */
+	if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
+		prot = __pgprot(__PAGE_KERNEL |
+				cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
+
+	/* Filter out unsupported __PAGE_KERNEL* bits: */
+	pgprot_val(prot) &= __default_kernel_pte_mask;
+
+	return (void __force __iomem *)__kmap_local_pfn_prot(pfn, prot);
+}
+EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);