ARM: tegra: support large RAM sizes

[karo-tx-uboot.git] / arch / arm / mach-tegra / board.c

diff --git a/arch/arm/mach-tegra/board.c b/arch/arm/mach-tegra/board.c
index f16fe68a66492cfc3f9e605cdfa5789b0b8f1ef2..87511a31df180526225b14efa9288e80013f6f77 100644 (file)
--- a/arch/arm/mach-tegra/board.c
+++ b/arch/arm/mach-tegra/board.c
@@ -40,7 +40,27 @@ unsigned int query_sdram_size(void)
        size_bytes = get_ram_size((void *)PHYS_SDRAM_1, emem_cfg * 1024);
 #else
        debug("mc->mc_emem_cfg (MEM_SIZE_MB) = 0x%08x\n", emem_cfg);
-       size_bytes = get_ram_size((void *)PHYS_SDRAM_1, emem_cfg * 1024 * 1024);
+       /*
+        * If >=4GB RAM is present, the byte RAM size won't fit into 32-bits
+        * and will wrap. Clip the reported size to the maximum that a 32-bit
+        * variable can represent (rounded to a page).
+        */
+       if (emem_cfg >= 4096) {
+               size_bytes = U32_MAX & ~(0x1000 - 1);
+       } else {
+               /* RAM size EMC is programmed to. */
+               size_bytes = emem_cfg * 1024 * 1024;
+               /*
+                * If all RAM fits within 32-bits, it can be accessed without
+                * LPAE, so go test the RAM size. Otherwise, we can't access
+                * all the RAM, and get_ram_size() would get confused, so
+                * avoid using it. There's no reason we should need this
+                * validation step anyway.
+                */
+               if (emem_cfg <= (0 - PHYS_SDRAM_1) / (1024 * 1024))
+                       size_bytes = get_ram_size((void *)PHYS_SDRAM_1,
+                                                 size_bytes);
+       }
 #endif
 
 #if defined(CONFIG_TEGRA30) || defined(CONFIG_TEGRA114)