sh: Build PMB entry links for existing contiguous multi-page mappings.

This plugs in entry sizing support for existing mappings and then builds
on top of that for linking together entries that are mapping contiguous
areas. This will ultimately permit us to coalesce mappings and promote
head pages while reclaiming PMB slots for dynamic remapping.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/mmu.h

@@ -59,14 +59,14 @@ struct pmb_entry {
 	unsigned long vpn;
 	unsigned long ppn;
 	unsigned long flags;
+	unsigned long size;
 
 	/*
 	 * 0 .. NR_PMB_ENTRIES for specific entry selection, or
 	 * PMB_NO_ENTRY to search for a free one
 	 */
 	int entry;
 
-	struct pmb_entry *next;
 	/* Adjacent entry link for contiguous multi-entry mappings */
 	struct pmb_entry *link;
 };

arch/sh/mm/pmb.c

@@ -90,20 +90,15 @@ static struct pmb_entry *pmb_alloc(unsigned long vpn, unsigned long ppn,
 	pmbe->ppn	= ppn;
 	pmbe->flags	= flags;
 	pmbe->entry	= pos;
+	pmbe->size	= 0;
 
 	return pmbe;
 }
 
 static void pmb_free(struct pmb_entry *pmbe)
 {
-	int pos = pmbe->entry;
-
-	pmbe->vpn	= 0;
-	pmbe->ppn	= 0;
-	pmbe->flags	= 0;
-	pmbe->entry	= 0;
-
-	clear_bit(pos, pmb_map);
+	clear_bit(pmbe->entry, pmb_map);
+	pmbe->entry = PMB_NO_ENTRY;
 }
 
 /*
@@ -198,6 +193,8 @@ long pmb_remap(unsigned long vaddr, unsigned long phys,
 		vaddr	+= pmb_sizes[i].size;
 		size	-= pmb_sizes[i].size;
 
+		pmbe->size = pmb_sizes[i].size;
+
 		/*
 		 * Link adjacent entries that span multiple PMB entries
 		 * for easier tear-down.
@@ -273,33 +270,16 @@ static void pmb_unmap_entry(struct pmb_entry *pmbe)
 	} while (pmbe);
 }
 
-static inline void
-pmb_log_mapping(unsigned long data_val, unsigned long vpn, unsigned long ppn)
-{
-	unsigned int size;
-	const char *sz_str;
-
-	size = data_val & PMB_SZ_MASK;
-
-	sz_str = (size == PMB_SZ_16M)  ? " 16MB":
-		 (size == PMB_SZ_64M)  ? " 64MB":
-		 (size == PMB_SZ_128M) ? "128MB":
-					 "512MB";
-
-	pr_info("\t0x%08lx -> 0x%08lx [ %s %scached ]\n",
-		vpn >> PAGE_SHIFT, ppn >> PAGE_SHIFT, sz_str,
-		(data_val & PMB_C) ? "" : "un");
-}
-
-static inline unsigned int pmb_ppn_in_range(unsigned long ppn)
+static __always_inline unsigned int pmb_ppn_in_range(unsigned long ppn)
 {
 	return ppn >= __pa(memory_start) && ppn < __pa(memory_end);
 }
 
 static int pmb_synchronize_mappings(void)
 {
 	unsigned int applied = 0;
-	int i;
+	struct pmb_entry *pmbp = NULL;
+	int i, j;
 
 	pr_info("PMB: boot mappings:\n");
 
@@ -323,6 +303,7 @@ static int pmb_synchronize_mappings(void)
 		unsigned long addr, data;
 		unsigned long addr_val, data_val;
 		unsigned long ppn, vpn, flags;
+		unsigned int size;
 		struct pmb_entry *pmbe;
 
 		addr = mk_pmb_addr(i);
@@ -366,15 +347,33 @@ static int pmb_synchronize_mappings(void)
 			__raw_writel(data_val, data);
 		}
 
-		flags = data_val & (PMB_SZ_MASK | PMB_CACHE_MASK);
+		size = data_val & PMB_SZ_MASK;
+		flags = size | (data_val & PMB_CACHE_MASK);
 
 		pmbe = pmb_alloc(vpn, ppn, flags, i);
 		if (IS_ERR(pmbe)) {
 			WARN_ON_ONCE(1);
 			continue;
 		}
 
-		pmb_log_mapping(data_val, vpn, ppn);
+		for (j = 0; j < ARRAY_SIZE(pmb_sizes); j++)
+			if (pmb_sizes[j].flag == size)
+				pmbe->size = pmb_sizes[j].size;
+
+		/*
+		 * Compare the previous entry against the current one to
+		 * see if the entries span a contiguous mapping. If so,
+		 * setup the entry links accordingly.
+		 */
+		if (pmbp && ((pmbe->vpn == (pmbp->vpn + pmbp->size)) &&
+			     (pmbe->ppn == (pmbp->ppn + pmbp->size))))
+			pmbp->link = pmbe;
+
+		pmbp = pmbe;
+
+		pr_info("\t0x%08lx -> 0x%08lx [ %ldMB %scached ]\n",
+			vpn >> PAGE_SHIFT, ppn >> PAGE_SHIFT, pmbe->size >> 20,
+			(data_val & PMB_C) ? "" : "un");
 
 		applied++;
 	}