sh: Fix up dynamically created write-through PMB mappings.

Write-through PMB mappings still require the cache bit to be set, even if
they're to be flagged with a different cache policy and bufferability
bit. To reduce some of the confusion surrounding the flag encoding we
centralize the cache mask based on the system cache policy while we're at
it.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/pmb.c

@@ -101,6 +101,26 @@ static void pmb_free(struct pmb_entry *pmbe)
 	pmbe->entry = PMB_NO_ENTRY;
 }
 
+/*
+ * Ensure that the PMB entries match our cache configuration.
+ *
+ * When we are in 32-bit address extended mode, CCR.CB becomes
+ * invalid, so care must be taken to manually adjust cacheable
+ * translations.
+ */
+static __always_inline unsigned long pmb_cache_flags(void)
+{
+	unsigned long flags = 0;
+
+#if defined(CONFIG_CACHE_WRITETHROUGH)
+	flags |= PMB_C | PMB_WT | PMB_UB;
+#elif defined(CONFIG_CACHE_WRITEBACK)
+	flags |= PMB_C;
+#endif
+
+	return flags;
+}
+
 /*
  * Must be run uncached.
  */
@@ -108,18 +128,10 @@ static void set_pmb_entry(struct pmb_entry *pmbe)
 {
 	jump_to_uncached();
 
-	__raw_writel(pmbe->vpn | PMB_V, mk_pmb_addr(pmbe->entry));
-
-#ifdef CONFIG_CACHE_WRITETHROUGH
-	/*
-	 * When we are in 32-bit address extended mode, CCR.CB becomes
-	 * invalid, so care must be taken to manually adjust cacheable
-	 * translations.
-	 */
-	if (likely(pmbe->flags & PMB_C))
-		pmbe->flags |= PMB_WT;
-#endif
+	pmbe->flags &= ~PMB_CACHE_MASK;
+	pmbe->flags |= pmb_cache_flags();
 
+	__raw_writel(pmbe->vpn | PMB_V, mk_pmb_addr(pmbe->entry));
 	__raw_writel(pmbe->ppn | pmbe->flags | PMB_V, mk_pmb_data(pmbe->entry));
 
 	back_to_cached();
@@ -163,14 +175,15 @@ long pmb_remap(unsigned long vaddr, unsigned long phys,
 
 	flags = pgprot_val(prot);
 
+	pmb_flags = PMB_WT | PMB_UB;
+
 	/* Convert typical pgprot value to the PMB equivalent */
 	if (flags & _PAGE_CACHABLE) {
-		if (flags & _PAGE_WT)
-			pmb_flags = PMB_WT;
-		else
-			pmb_flags = PMB_C;
-	} else
-		pmb_flags = PMB_WT | PMB_UB;
+		pmb_flags |= PMB_C;
+
+		if ((flags & _PAGE_WT) == 0)
+			pmb_flags &= ~(PMB_WT | PMB_UB);
+	}
 
 	pmbp = NULL;
 	wanted = size;
@@ -337,13 +350,8 @@ static int pmb_synchronize_mappings(void)
 		 * Update the caching attributes if necessary
 		 */
 		if (data_val & PMB_C) {
-#if defined(CONFIG_CACHE_WRITETHROUGH)
-			data_val |= PMB_WT;
-#elif defined(CONFIG_CACHE_WRITEBACK)
-			data_val &= ~PMB_WT;
-#else
-			data_val &= ~(PMB_C | PMB_WT);
-#endif
+			data_val &= ~PMB_CACHE_MASK;
+			data_val |= pmb_cache_flags();
 			__raw_writel(data_val, data);
 		}