[Blackfin] arch: detect the memory available in the system on the fly by default

detect the memory available in the system on the fly by default
rather than forcing people to set this manually in the kconfig

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 44 insertions, 1 deletions

diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index c2f3e73ba25a..d6668328be72 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -649,6 +649,49 @@ static __init void setup_bootmem_allocator(void)
                 BOOTMEM_DEFAULT);
 }
 
+#define EBSZ_TO_MEG(ebsz) \
+({ \
+        int meg = 0; \
+        switch (ebsz & 0xf) { \
+                case 0x1: meg =  16; break; \
+                case 0x3: meg =  32; break; \
+                case 0x5: meg =  64; break; \
+                case 0x7: meg = 128; break; \
+                case 0x9: meg = 256; break; \
+                case 0xb: meg = 512; break; \
+        } \
+        meg; \
+})
+static inline int __init get_mem_size(void)
+{
+#ifdef CONFIG_MEM_SIZE
+        return CONFIG_MEM_SIZE;
+#else
+# if defined(EBIU_SDBCTL)
+#  if defined(BF561_FAMILY)
+        int ret = 0;
+        u32 sdbctl = bfin_read_EBIU_SDBCTL();
+        ret += EBSZ_TO_MEG(sdbctl >>  0);
+        ret += EBSZ_TO_MEG(sdbctl >>  8);
+        ret += EBSZ_TO_MEG(sdbctl >> 16);
+        ret += EBSZ_TO_MEG(sdbctl >> 24);
+        return ret;
+#  else
+        return EBSZ_TO_MEG(bfin_read_EBIU_SDBCTL());
+#  endif
+# elif defined(EBIU_DDRCTL1)
+        switch (bfin_read_EBIU_DDRCTL1() & 0xc0000) {
+                case DEVSZ_64:  return 64;
+                case DEVSZ_128: return 128;
+                case DEVSZ_256: return 256;
+                case DEVSZ_512: return 512;
+                default:        return 0;
+        }
+# endif
+#endif
+        BUG();
+}
+
 void __init setup_arch(char **cmdline_p)
 {
         unsigned long sclk, cclk;
@@ -669,7 +712,7 @@ void __init setup_arch(char **cmdline_p)
 
         /* setup memory defaults from the user config */
         physical_mem_end = 0;
-        _ramend = CONFIG_MEM_SIZE * 1024 * 1024;
+        _ramend = get_mem_size() * 1024 * 1024;
 
         memset(&bfin_memmap, 0, sizeof(bfin_memmap));