ARM: 7805/1: mm: change max*pfn to include the physical offset of memory

Most of the kernel code assumes that max*pfn is maximum pfns because
the physical start of memory is expected to be PFN0. Since this
assumption is not true on ARM architectures, the meaning of max*pfn
is number of memory pages. This is done to keep drivers happy which
are making use of of these variable to calculate the dma bounce limit
using dma_mask.

Now since we have a architecture override possibility for DMAable
maximum pfns, lets make meaning of max*pfns as maximum pnfs on ARM
as well.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 12 insertions, 6 deletions

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 5b579b951503..863cd84eb1a2 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -64,6 +64,7 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 {
         return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
 }
+
 #else
 static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
 {
@@ -86,6 +87,13 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 }
 #endif
 
+/* The ARM override for dma_max_pfn() */
+static inline unsigned long dma_max_pfn(struct device *dev)
+{
+        return PHYS_PFN_OFFSET + dma_to_pfn(dev, *dev->dma_mask);
+}
+#define dma_max_pfn(dev) dma_max_pfn(dev)
+
 /*
  * DMA errors are defined by all-bits-set in the DMA address.
  */
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 8aab24f35a5e..d50533c2b409 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -426,12 +426,10 @@ void __init bootmem_init(void)
          * This doesn't seem to be used by the Linux memory manager any
          * more, but is used by ll_rw_block.  If we can get rid of it, we
          * also get rid of some of the stuff above as well.
-         *
-         * Note: max_low_pfn and max_pfn reflect the number of _pages_ in
-         * the system, not the maximum PFN.
          */
-        max_low_pfn = max_low - PHYS_PFN_OFFSET;
-        max_pfn = max_high - PHYS_PFN_OFFSET;
+        min_low_pfn = min;
+        max_low_pfn = max_low;
+        max_pfn = max_high;
 }
 
 /*
@@ -537,7 +535,7 @@ static inline void free_area_high(unsigned long pfn, unsigned long end)
 static void __init free_highpages(void)
 {
 #ifdef CONFIG_HIGHMEM
-        unsigned long max_low = max_low_pfn + PHYS_PFN_OFFSET;
+        unsigned long max_low = max_low_pfn;
         struct memblock_region *mem, *res;
 
         /* set highmem page free */