arch/tile: various header improvements for building drivers

This change adds a number of missing headers in asm (fb.h, parport.h,
serial.h, and vga.h) using the minimal generic versions.

It also adds a number of missing interfaces that showed up as build
failures when trying to build various drivers not normally included in the
"tile" distribution: ioremap_wc(), memset_io(), io{read,write}{16,32}be(),
virt_to_bus(), bus_to_virt(), irq_canonicalize(), __pte(), __pgd(),
and __pmd().  I also added a cast in virt_to_page() since not all callers
pass a pointer.

I fixed <asm/stat.h> to properly include a __KERNEL__ guard for the
__ARCH_WANT_STAT64 symbol, and <asm/swab.h> to use __builtin_bswap32()
even for our 64-bit architecture, since the same code is produced.

I added an export for get_cycles(), since it's used in some modules.

And I made <arch/spr_def.h> properly include the __KERNEL__ guard,
even though it's not yet exported, since it likely will be soon.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/include/asm/page.h b/arch/tile/include/asm/page.h
index 3eb5352..7105629 100644
--- a/arch/tile/include/asm/page.h
+++ b/arch/tile/include/asm/page.h
@@ -91,6 +91,10 @@
 /* Must be a macro since it is used to create constants. */
 #define __pgprot(val) hv_pte(val)
 
+/* Rarely-used initializers, typically with a "zero" value. */
+#define __pte(x) hv_pte(x)
+#define __pgd(x) hv_pte(x)
+
 static inline u64 pgprot_val(pgprot_t pgprot)
 {
 	return hv_pte_val(pgprot);
@@ -110,6 +114,8 @@
 
 typedef HV_PTE pmd_t;
 
+#define __pmd(x) hv_pte(x)
+
 static inline u64 pmd_val(pmd_t pmd)
 {
 	return hv_pte_val(pmd);
@@ -318,7 +324,7 @@
 
 /* Provide as macros since these require some other headers included. */
 #define page_to_pa(page) ((phys_addr_t)(page_to_pfn(page)) << PAGE_SHIFT)
-#define virt_to_page(kaddr) pfn_to_page(kaddr_to_pfn(kaddr))
+#define virt_to_page(kaddr) pfn_to_page(kaddr_to_pfn((void *)(kaddr)))
 #define page_to_virt(page) pfn_to_kaddr(page_to_pfn(page))
 
 struct mm_struct;