[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>

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;
 
@@ -129,37 +130,45 @@ remap_area_pages(unsigned long start, unsigned long phys_addr,
  * 'flags' are the extra L_PTE_ flags that you want to specify for this
  * 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);
 

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 @@ check_signature(void __iomem *io_addr, const unsigned char *signature,
  *
  * ioremap takes a PCI memory address, as specified in
  * Documentation/IO-mapping.txt.
+ *
  */
 #ifndef __arch_ioremap
 #define ioremap(cookie,size)		__ioremap(cookie,size,0)

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);

include/asm-arm/memory.h

@@ -57,6 +57,12 @@
 #define __phys_to_virt(x)	((x) - PHYS_OFFSET + PAGE_OFFSET)
 #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.