wii: use both mem1 and mem2 as ram

The Nintendo Wii video game console has two discontiguous RAM regions:
- MEM1: 24MB @ 0x00000000
- MEM2: 64MB @ 0x10000000

Unfortunately, the kernel currently does not support discontiguous RAM
memory regions on 32-bit PowerPC platforms.

This patch adds a series of workarounds to allow the use of the second
memory region (MEM2) as RAM by the kernel.
Basically, a single range of memory from the beginning of MEM1 to the
end of MEM2 is reported to the kernel, and a memory reservation is
created for the hole between MEM1 and MEM2.

With this patch the system is able to use all the available RAM and not
just ~27% of it.

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>

1 files changed, 28 insertions, 4 deletions

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index cb96cb2e17c..b55bbe87acb 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -283,18 +283,18 @@ int map_page(unsigned long va, phys_addr_t pa, int flags)
 }
 
 /*
- * Map in a big chunk of physical memory starting at PAGE_OFFSET.
+ * Map in a chunk of physical memory starting at start.
  */
-void __init mapin_ram(void)
+void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
 {
 	unsigned long v, s, f;
 	phys_addr_t p;
 	int ktext;
 
-	s = mmu_mapin_ram();
+	s = offset;
 	v = PAGE_OFFSET + s;
 	p = memstart_addr + s;
-	for (; s < total_lowmem; s += PAGE_SIZE) {
+	for (; s < top; s += PAGE_SIZE) {
 		ktext = ((char *) v >= _stext && (char *) v < etext);
 		f = ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL;
 		map_page(v, p, f);
@@ -307,6 +307,30 @@ void __init mapin_ram(void)
 	}
 }
 
+void __init mapin_ram(void)
+{
+	unsigned long s, top;
+
+#ifndef CONFIG_WII
+	top = total_lowmem;
+	s = mmu_mapin_ram(top);
+	__mapin_ram_chunk(s, top);
+#else
+	if (!wii_hole_size) {
+		s = mmu_mapin_ram(total_lowmem);
+		__mapin_ram_chunk(s, total_lowmem);
+	} else {
+		top = wii_hole_start;
+		s = mmu_mapin_ram(top);
+		__mapin_ram_chunk(s, top);
+
+		top = lmb_end_of_DRAM();
+		s = wii_mmu_mapin_mem2(top);
+		__mapin_ram_chunk(s, top);
+	}
+#endif
+}
+
 /* Scan the real Linux page tables and return a PTE pointer for
  * a virtual address in a context.
  * Returns true (1) if PTE was found, zero otherwise.  The pointer to