powerpc: allow ioremap within reserved memory regions

Add a flag to let a platform ioremap memory regions marked as reserved.

This flag will be used later by the Nintendo Wii support code to allow
ioremapping the I/O region sitting between MEM1 and MEM2 and marked
as reserved RAM in the patch "wii: use both mem1 and mem2 as ram".

This will no longer be needed when proper discontig memory support
for 32-bit PowerPC is added to the kernel.
Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/powerpc/mm/init_32.c

@@ -82,6 +82,11 @@ extern struct task_struct *current_set[NR_CPUS];
 int __map_without_bats;
 int __map_without_ltlbs;
 
+/*
+ * This tells the system to allow ioremapping memory marked as reserved.
+ */
+int __allow_ioremap_reserved;
+
 /* max amount of low RAM to map in */
 unsigned long __max_low_memory = MAX_LOW_MEM;
 

arch/powerpc/mm/mmu_decl.h

@@ -115,6 +115,7 @@ extern void settlbcam(int index, unsigned long virt, phys_addr_t phys,
 extern void invalidate_tlbcam_entry(int index);
 
 extern int __map_without_bats;
+extern int __allow_ioremap_reserved;
 extern unsigned long ioremap_base;
 extern unsigned int rtas_data, rtas_size;
 

arch/powerpc/mm/pgtable_32.c

@@ -26,6 +26,7 @@
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
+#include <linux/lmb.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -191,7 +192,8 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, unsigned long flags,
 	 * Don't allow anybody to remap normal RAM that we're using.
 	 * mem_init() sets high_memory so only do the check after that.
 	 */
-	if (mem_init_done && (p < virt_to_phys(high_memory))) {
+	if (mem_init_done && (p < virt_to_phys(high_memory)) &&
+	    !(__allow_ioremap_reserved && lmb_is_region_reserved(p, size))) {
 		printk("__ioremap(): phys addr 0x%llx is RAM lr %p\n",
 		       (unsigned long long)p, __builtin_return_address(0));
 		return NULL;

include/linux/lmb.h

@@ -54,6 +54,7 @@ extern u64 __init lmb_phys_mem_size(void);
 extern u64 lmb_end_of_DRAM(void);
 extern void __init lmb_enforce_memory_limit(u64 memory_limit);
 extern int __init lmb_is_reserved(u64 addr);
+extern int lmb_is_region_reserved(u64 base, u64 size);
 extern int lmb_find(struct lmb_property *res);
 
 extern void lmb_dump_all(void);

lib/lmb.c

@@ -263,7 +263,7 @@ long __init lmb_reserve(u64 base, u64 size)
 	return lmb_add_region(_rgn, base, size);
 }
 
-long __init lmb_overlaps_region(struct lmb_region *rgn, u64 base, u64 size)
+long lmb_overlaps_region(struct lmb_region *rgn, u64 base, u64 size)
 {
 	unsigned long i;
 
@@ -493,6 +493,11 @@ int __init lmb_is_reserved(u64 addr)
 	return 0;
 }
 
+int lmb_is_region_reserved(u64 base, u64 size)
+{
+	return lmb_overlaps_region(&lmb.reserved, base, size);
+}
+
 /*
  * Given a <base, len>, find which memory regions belong to this range.
  * Adjust the request and return a contiguous chunk.