[ARM] 3070/2: Add __ioremap_pfn() API

Patch from Deepak Saxena

In working on adding 36-bit addressed supersection support to ioremap(),
I came to the conclusion that it would be far simpler to do so by just
splitting __ioremap() into a main external interface and adding an
__ioremap_pfn() function that takes a pfn + offset into the page that
__ioremap() can call. This way existing callers of __ioremap() won't have
to change their code and 36-bit systems will just call __ioremap_pfn()
and we will not have to deal with unsigned long long variables.

Note that __ioremap_pfn() should _NOT_ be called directly by drivers
but is reserved for use by arch_ioremap() implementations that map
32-bit resource regions into the real 36-bit address and then call
this new function.

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

4 files changed, 41 insertions, 23 deletions

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 10901398e4a2..de3ce1eec2ec 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -86,11 +86,12 @@ remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
 }
 
 static int
-remap_area_pages(unsigned long start, unsigned long phys_addr,
+remap_area_pages(unsigned long start, unsigned long pfn,
                  unsigned long size, unsigned long flags)
 {
         unsigned long address = start;
         unsigned long end = start + size;
+        unsigned long phys_addr = __pfn_to_phys(pfn);
         int err = 0;
         pgd_t * dir;
 
@@ -130,36 +131,44 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
  * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
  */
 void __iomem *
+__ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
+              unsigned long flags)
+{
+        unsigned long addr;
+        struct vm_struct * area;
+
+        area = get_vm_area(size, VM_IOREMAP);
+        if (!area)
+                return NULL;
+        addr = (unsigned long)area->addr;
+        if (remap_area_pages(addr, pfn, size, flags)) {
+                vfree(addr);
+                return NULL;
+        }
+        return (void __iomem *) (offset + (char *)addr);
+}
+EXPORT_SYMBOL(__ioremap_pfn);
+
+void __iomem *
 __ioremap(unsigned long phys_addr, size_t size, unsigned long flags)
 {
-        void * addr;
-        struct vm_struct * area;
-        unsigned long offset, last_addr;
+        unsigned long last_addr;
+        unsigned long offset = phys_addr & ~PAGE_MASK;
+        unsigned long pfn = __phys_to_pfn(phys_addr);
 
-        /* Don't allow wraparound or zero size */
+        /*
+         * Don't allow wraparound or zero size
+         */
         last_addr = phys_addr + size - 1;
         if (!size || last_addr < phys_addr)
                 return NULL;
 
         /*
-         * Mappings have to be page-aligned
+         * Page align the mapping size
          */
-        offset = phys_addr & ~PAGE_MASK;
-        phys_addr &= PAGE_MASK;
         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 
-        /*
-         * Ok, go for it..
-         */
-        area = get_vm_area(size, VM_IOREMAP);
-        if (!area)
-                return NULL;
-        addr = area->addr;
-        if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
-                vfree(addr);
-                return NULL;
-        }
-        return (void __iomem *) (offset + (char *)addr);
+        return __ioremap_pfn(pfn, offset, size, flags);
 }
 EXPORT_SYMBOL(__ioremap);
 
diff --git a/include/asm-arm/io.h b/include/asm-arm/io.h
index 0cf4d4f99600..fd0147e52dbb 100644
--- a/include/asm-arm/io.h
+++ b/include/asm-arm/io.h
@@ -56,7 +56,12 @@ extern void __raw_readsl(const void __iomem *addr, void *data, int longlen);
 
 /*
  * Architecture ioremap implementation.
+ *
+ * __ioremap takes CPU physical address.
+ *
+ * __ioremap_pfn takes a Page Frame Number and an offset into that page
  */
+extern void __iomem * __ioremap_pfn(unsigned long, unsigned long, size_t, unsigned long);
 extern void __iomem * __ioremap(unsigned long, size_t, unsigned long);
 extern void __iounmap(void __iomem *addr);
 
@@ -261,6 +266,7 @@ out:
  *
  * ioremap takes a PCI memory address, as specified in
  * Documentation/IO-mapping.txt.
+ *
  */
 #ifndef __arch_ioremap
 #define ioremap(cookie,size)            __ioremap(cookie,size,0)
diff --git a/include/asm-arm/mach/map.h b/include/asm-arm/mach/map.h
index b338936bde4f..3351b77fab36 100644
--- a/include/asm-arm/mach/map.h
+++ b/include/asm-arm/mach/map.h
@@ -27,9 +27,6 @@ struct meminfo;
 #define MT_ROM                  6
 #define MT_IXP2000_DEVICE       7
 
-#define __phys_to_pfn(paddr)    ((paddr) >> PAGE_SHIFT)
-#define __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)
-
 extern void create_memmap_holes(struct meminfo *);
 extern void memtable_init(struct meminfo *);
 extern void iotable_init(struct map_desc *, int);
diff --git a/include/asm-arm/memory.h b/include/asm-arm/memory.h
index 3e572364ee73..3d7f08bd9030 100644
--- a/include/asm-arm/memory.h
+++ b/include/asm-arm/memory.h
@@ -58,6 +58,12 @@
 #endif
 
 /*
+ * Convert a physical address to a Page Frame Number and back
+ */
+#define __phys_to_pfn(paddr)    ((paddr) >> PAGE_SHIFT)
+#define __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)
+
+/*
  * The module space lives between the addresses given by TASK_SIZE
  * and PAGE_OFFSET - it must be within 32MB of the kernel text.
  */