MIPS: add kmap_noncoherent to wire a cached non-coherent TLB entry

This is identical to kmap_coherent apart from the cache coherency
attribute used for the TLB entry, so kmap_coherent is abstracted to
kmap_prot which is then called for both kmap_coherent &
kmap_noncoherent. This will be used by a subsequent patch.

Suggested-by: Leonid Yegoshin <[e-mail]>
Signed-off-by: Paul Burton <[e-mail]>

arch/mips/include/asm/cacheflush.h

···
 
 extern void *kmap_coherent(struct page *page, unsigned long addr);
 extern void kunmap_coherent(void);
+extern void *kmap_noncoherent(struct page *page, unsigned long addr);
+
+static inline void kunmap_noncoherent(void)
+{
+	kunmap_coherent();
+}
 
 #define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
 static inline void flush_kernel_dcache_page(struct page *page)

arch/mips/include/asm/pgtable.h

···
 				 _page_cachable_default)
 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
 				 _PAGE_GLOBAL | _page_cachable_default)
+#define PAGE_KERNEL_NC	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
+				 _PAGE_GLOBAL | _CACHE_CACHABLE_NONCOHERENT)
 #define PAGE_USERIO	__pgprot(_PAGE_PRESENT | (cpu_has_rixi ? 0 : _PAGE_READ) | _PAGE_WRITE | \
 				 _page_cachable_default)
 #define PAGE_KERNEL_UNCACHED __pgprot(_PAGE_PRESENT | __READABLE | \

arch/mips/mm/init.c

···
 static inline void kmap_coherent_init(void) {}
 #endif
 
-void *kmap_coherent(struct page *page, unsigned long addr)
+static void *__kmap_pgprot(struct page *page, unsigned long addr, pgprot_t prot)
 {
 	enum fixed_addresses idx;
 	unsigned long vaddr, flags, entrylo;
···
 	idx += in_interrupt() ? FIX_N_COLOURS : 0;
 #endif
 	vaddr = __fix_to_virt(FIX_CMAP_END - idx);
-	pte = mk_pte(page, PAGE_KERNEL);
+	pte = mk_pte(page, prot);
 #if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
 	entrylo = pte.pte_high;
 #else
···
 	EXIT_CRITICAL(flags);
 
 	return (void*) vaddr;
+}
+
+void *kmap_coherent(struct page *page, unsigned long addr)
+{
+	return __kmap_pgprot(page, addr, PAGE_KERNEL);
+}
+
+void *kmap_noncoherent(struct page *page, unsigned long addr)
+{
+	return __kmap_pgprot(page, addr, PAGE_KERNEL_NC);
 }
 
 void kunmap_coherent(void)