powerpc/32: Add ioremap_wt() and ioremap_coherent()

Other arches have ioremap_wt() to map IO areas write-through.
Implement it on PPC as well in order to avoid drivers using
__ioremap(_PAGE_WRITETHRU)

Also implement ioremap_coherent() to avoid drivers using
__ioremap(_PAGE_COHERENT)

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/io.h

@@ -3,6 +3,9 @@
 #ifdef __KERNEL__
 
 #define ARCH_HAS_IOREMAP_WC
+#ifdef CONFIG_PPC32
+#define ARCH_HAS_IOREMAP_WT
+#endif
 
 /*
  * This program is free software; you can redistribute it and/or
@@ -746,6 +749,10 @@ static inline void iosync(void)
  *
  * * ioremap_wc enables write combining
  *
+ * * ioremap_wt enables write through
+ *
+ * * ioremap_coherent maps coherent cached memory
+ *
  * * iounmap undoes such a mapping and can be hooked
  *
  * * __ioremap_at (and the pending __iounmap_at) are low level functions to
@@ -767,6 +774,8 @@ extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
 extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size,
 				  unsigned long flags);
 extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size);
+void __iomem *ioremap_wt(phys_addr_t address, unsigned long size);
+void __iomem *ioremap_coherent(phys_addr_t address, unsigned long size);
 #define ioremap_nocache(addr, size)	ioremap((addr), (size))
 #define ioremap_uc(addr, size)		ioremap((addr), (size))
 #define ioremap_cache(addr, size) \

arch/powerpc/mm/pgtable_32.c

@@ -89,6 +89,22 @@ ioremap_wc(phys_addr_t addr, unsigned long size)
 }
 EXPORT_SYMBOL(ioremap_wc);
 
+void __iomem *
+ioremap_wt(phys_addr_t addr, unsigned long size)
+{
+	return __ioremap_caller(addr, size, _PAGE_WRITETHRU,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_wt);
+
+void __iomem *
+ioremap_coherent(phys_addr_t addr, unsigned long size)
+{
+	return __ioremap_caller(addr, size, _PAGE_COHERENT,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_coherent);
+
 void __iomem *
 ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
 {

arch/powerpc/mm/pgtable_64.c

@@ -222,6 +222,16 @@ void __iomem * ioremap_wc(phys_addr_t addr, unsigned long size)
 	return __ioremap_caller(addr, size, flags, caller);
 }
 
+void __iomem *ioremap_coherent(phys_addr_t addr, unsigned long size)
+{
+	unsigned long flags = pgprot_val(pgprot_cached(__pgprot(0)));
+	void *caller = __builtin_return_address(0);
+
+	if (ppc_md.ioremap)
+		return ppc_md.ioremap(addr, size, flags, caller);
+	return __ioremap_caller(addr, size, flags, caller);
+}
+
 void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
 			     unsigned long flags)
 {