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-rw-r--r--include/asm-sh/page.h50
1 files changed, 37 insertions, 13 deletions
diff --git a/include/asm-sh/page.h b/include/asm-sh/page.h
index bff635a..002e64a 100644
--- a/include/asm-sh/page.h
+++ b/include/asm-sh/page.h
@@ -5,6 +5,8 @@
* Copyright (C) 1999 Niibe Yutaka
*/
+#include <linux/const.h>
+
#ifdef __KERNEL__
/* PAGE_SHIFT determines the page size */
@@ -18,15 +20,13 @@
# error "Bogus kernel page size?"
#endif
-#ifdef __ASSEMBLY__
-#define PAGE_SIZE (1 << PAGE_SHIFT)
-#else
-#define PAGE_SIZE (1UL << PAGE_SHIFT)
-#endif
-
+#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#define PTE_MASK PAGE_MASK
+/* to align the pointer to the (next) page boundary */
+#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
+
#if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
#define HPAGE_SHIFT 16
#elif defined(CONFIG_HUGETLB_PAGE_SIZE_256K)
@@ -104,20 +104,44 @@ typedef struct { unsigned long pgd; } pgd_t;
#endif /* !__ASSEMBLY__ */
-/* to align the pointer to the (next) page boundary */
-#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
-
+/*
+ * __MEMORY_START and SIZE are the physical addresses and size of RAM.
+ */
#define __MEMORY_START CONFIG_MEMORY_START
#define __MEMORY_SIZE CONFIG_MEMORY_SIZE
+/*
+ * PAGE_OFFSET is the virtual address of the start of kernel address
+ * space.
+ */
#define PAGE_OFFSET CONFIG_PAGE_OFFSET
-#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
-#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
-#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
+/*
+ * Virtual to physical RAM address translation.
+ *
+ * In 29 bit mode, the physical offset of RAM from address 0 is visible in
+ * the kernel virtual address space, and thus we don't have to take
+ * this into account when translating. However in 32 bit mode this offset
+ * is not visible (it is part of the PMB mapping) and so needs to be
+ * added or subtracted as required.
+ */
+#ifdef CONFIG_32BIT
+#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET+__MEMORY_START)
+#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET-__MEMORY_START))
+#else
+#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
+#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
+#endif
+
+#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
-/* PFN start number, because of __MEMORY_START */
+/*
+ * PFN = physical frame number (ie PFN 0 == physical address 0)
+ * PFN_START is the PFN of the first page of RAM. By defining this we
+ * don't have struct page entries for the portion of address space
+ * between physical address 0 and the start of RAM.
+ */
#define PFN_START (__MEMORY_START >> PAGE_SHIFT)
#define ARCH_PFN_OFFSET (PFN_START)
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
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