ARM: tegra: use standard variables to define load addresses

Currently, Tegra's default environment uses non-standard variables to define
where boot scripts should load the kernel, FDT, and initrd. This change both
changes the variable names to match those described in U-Boot's README, and
shuffles their values around a little so that the values make a little more
sense; see comments in the patch for rationale behind the values chosen.

Note that this patch does remove the old non-standard variable "fdt_load" from
the default environment, so this patch requires people to change their boot
scripts.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

include/configs/tegra-common-post.h

@@ -95,8 +95,6 @@
 #endif
 
 #define BOOTCMDS_COMMON \
-	"scriptaddr=0x400000\0" \
-	\
 	"rootpart=1\0" \
 	\
 	"script_boot="                                                    \
@@ -140,9 +138,36 @@
 
 #endif
 
+/*
+ * Memory layout for where various images get loaded by boot scripts:
+ *
+ * scriptaddr can be pretty much anywhere that doesn't conflict with something
+ *   else. Put it above BOOTMAPSZ to eliminate conflicts.
+ *
+ * kernel_addr_r must be within the first 128M of RAM in order for the
+ *   kernel's CONFIG_AUTO_ZRELADDR option to work. Since the kernel will
+ *   decompress itself to 0x8000 after the start of RAM, kernel_addr_r
+ *   should not overlap that area, or the kernel will have to copy itself
+ *   somewhere else before decompression. Similarly, the address of any other
+ *   data passed to the kernel shouldn't overlap the start of RAM. Pushing
+ *   this up to 16M allows for a sizable kernel to be decompressed below the
+ *   compressed load address.
+ *
+ * fdt_addr_r simply shouldn't overlap anything else. Choosing 32M allows for
+ *   the compressed kernel to be up to 16M too.
+ *
+ * ramdisk_addr_r simply shouldn't overlap anything else. Choosing 33M allows
+ *   for the FDT/DTB to be up to 1M, which is hopefully plenty.
+ */
+#define MEM_LAYOUT_ENV_SETTINGS \
+	"scriptaddr=0x10000000\0" \
+	"kernel_addr_r=0x01000000\0" \
+	"fdt_addr_r=0x02000000\0" \
+	"ramdisk_addr_r=0x02100000\0" \
+
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	TEGRA_DEVICE_SETTINGS \
-	"fdt_load=0x01000000\0" \
+	MEM_LAYOUT_ENV_SETTINGS \
 	BOOTCMDS_COMMON
 
 /* overrides for SPL build here */