mm: change ioremap to set up huge I/O mappings

ioremap_pud_range() and ioremap_pmd_range() are changed to create huge I/O
mappings when their capability is enabled, and a request meets required
conditions -- both virtual & physical addresses are aligned by their huge
page size, and a requested range fufills their huge page size.  When
pud_set_huge() or pmd_set_huge() returns zero, i.e.  no-operation is
performed, the code simply falls back to the next level.

The changes are only enabled when CONFIG_HAVE_ARCH_HUGE_VMAP is defined on
the architecture.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Robert Elliott <Elliott@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-generic/pgtable.h

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 1f9f5da..9fb7dc7c 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -6,6 +6,7 @@
 
 #include <linux/mm_types.h>
 #include <linux/bug.h>
+#include <linux/errno.h>
 
 #if 4 - defined(__PAGETABLE_PUD_FOLDED) - defined(__PAGETABLE_PMD_FOLDED) != \
 	CONFIG_PGTABLE_LEVELS
@@ -696,6 +697,20 @@
 
 #endif /* CONFIG_MMU */
 
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
+int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
+#else	/* !CONFIG_HAVE_ARCH_HUGE_VMAP */
+static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
+
 #endif /* !__ASSEMBLY__ */
 
 #ifndef io_remap_pfn_range

lib/ioremap.c

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 2008652..be24906 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -80,6 +80,14 @@
 		return -ENOMEM;
 	do {
 		next = pmd_addr_end(addr, end);
+
+		if (ioremap_pmd_enabled() &&
+		    ((next - addr) == PMD_SIZE) &&
+		    IS_ALIGNED(phys_addr + addr, PMD_SIZE)) {
+			if (pmd_set_huge(pmd, phys_addr + addr, prot))
+				continue;
+		}
+
 		if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
 			return -ENOMEM;
 	} while (pmd++, addr = next, addr != end);
@@ -98,6 +106,14 @@
 		return -ENOMEM;
 	do {
 		next = pud_addr_end(addr, end);
+
+		if (ioremap_pud_enabled() &&
+		    ((next - addr) == PUD_SIZE) &&
+		    IS_ALIGNED(phys_addr + addr, PUD_SIZE)) {
+			if (pud_set_huge(pud, phys_addr + addr, prot))
+				continue;
+		}
+
 		if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
 			return -ENOMEM;
 	} while (pud++, addr = next, addr != end);