[MIPS] FLATMEM: introduce PHYS_OFFSET.
The old code was assuming that min_low_pfn was always 0. This
means that platforms having a big hole at their memory start
paid the price of wasting some memory for the allocation of
unused entries in mem_map[].
This patch prevents this waste.
It introduces PHYS_OFFSET define which is the start of the
physical memory and uses it wherever needed. Specially when
converting physical/virtual addresses into virtual/physical
ones.
Currently all platforms defines PHYS_OFFSET to 0.
Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/include/asm-mips/page.h b/include/asm-mips/page.h
index 2f9e1a9..d3fbd83 100644
--- a/include/asm-mips/page.h
+++ b/include/asm-mips/page.h
@@ -34,6 +34,20 @@
#ifndef __ASSEMBLY__
+/*
+ * This gives the physical RAM offset.
+ */
+#ifndef PHYS_OFFSET
+#define PHYS_OFFSET 0UL
+#endif
+
+/*
+ * It's normally defined only for FLATMEM config but it's
+ * used in our early mem init code for all memory models.
+ * So always define it.
+ */
+#define ARCH_PFN_OFFSET PFN_UP(PHYS_OFFSET)
+
#include <linux/pfn.h>
#include <asm/io.h>
@@ -132,20 +146,23 @@
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr) + PAGE_SIZE - 1) & PAGE_MASK)
+/*
+ * __pa()/__va() should be used only during mem init.
+ */
#if defined(CONFIG_64BIT) && !defined(CONFIG_BUILD_ELF64)
#define __pa_page_offset(x) ((unsigned long)(x) < CKSEG0 ? PAGE_OFFSET : CKSEG0)
#else
#define __pa_page_offset(x) PAGE_OFFSET
#endif
-#define __pa(x) ((unsigned long)(x) - __pa_page_offset(x))
-#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x),0))
-#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET))
+#define __pa(x) ((unsigned long)(x) - __pa_page_offset(x) + PHYS_OFFSET)
+#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET - PHYS_OFFSET))
+#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x),0))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#ifdef CONFIG_FLATMEM
-#define pfn_valid(pfn) ((pfn) < max_mapnr)
+#define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
#elif defined(CONFIG_SPARSEMEM)
