xtensa: add HIGHMEM support

Introduce fixmap area just below the vmalloc region. Use it for atomic
mapping of high memory pages.
High memory on cores with cache aliasing is not supported and is still
to be implemented. Fail build for such configurations for now.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

1 files changed, 44 insertions, 1 deletions

diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index 80be15124697..2653ef5d55f1 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -6,11 +6,54 @@
  * this archive for more details.
  *
  * Copyright (C) 2003 - 2005 Tensilica Inc.
+ * Copyright (C) 2014 Cadence Design Systems Inc.
  */
 
 #ifndef _XTENSA_HIGHMEM_H
 #define _XTENSA_HIGHMEM_H
 
-extern void flush_cache_kmaps(void);
+#include <asm/cacheflush.h>
+#include <asm/fixmap.h>
+#include <asm/kmap_types.h>
+#include <asm/pgtable.h>
+
+#define PKMAP_BASE		(FIXADDR_START - PMD_SIZE)
+#define LAST_PKMAP		PTRS_PER_PTE
+#define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
+#define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)
+#define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))
+
+#define kmap_prot		PAGE_KERNEL
+
+extern pte_t *pkmap_page_table;
+
+void *kmap_high(struct page *page);
+void kunmap_high(struct page *page);
+
+static inline void *kmap(struct page *page)
+{
+	BUG_ON(in_interrupt());
+	if (!PageHighMem(page))
+		return page_address(page);
+	return kmap_high(page);
+}
+
+static inline void kunmap(struct page *page)
+{
+	BUG_ON(in_interrupt());
+	if (!PageHighMem(page))
+		return;
+	kunmap_high(page);
+}
+
+static inline void flush_cache_kmaps(void)
+{
+	flush_cache_all();
+}
+
+void *kmap_atomic(struct page *page);
+void __kunmap_atomic(void *kvaddr);
+
+void kmap_init(void);
 
 #endif