mx51evk: Update environment in order to allow booting a dt kernel

Update the environment as done in other imx boards to allow easy switching
between booting a non-dt kernel and a dt kernel.

Change CONFIG_LOADADDR to 0x92000000, so that we can have the:

- uImage at 0x92000000
- imx51-babbage.dtb at 0x91000000

,which are adequate locations in RAM to avoid overlapping.

Boot tested the following kernels:

- 2.6.35 from FSL (11.09 branch)
- 3.9-rc7 non-dt
- 3.9-rc7 dt

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>

include/configs/mx51evk.h

@@ -149,11 +149,15 @@
 
 #define CONFIG_ETHPRIME		"FEC0"
 
-#define CONFIG_LOADADDR		0x90800000	/* loadaddr env var */
+#define CONFIG_LOADADDR		0x92000000	/* loadaddr env var */
 
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"script=boot.scr\0" \
 	"uimage=uImage\0" \
+	"fdt_file=imx51-babbage.dtb\0" \
+	"fdt_addr=0x91000000\0" \
+	"boot_fdt=try\0" \
+	"ip_dyn=yes\0" \
 	"mmcdev=0\0" \
 	"mmcpart=2\0" \
 	"mmcroot=/dev/mmcblk0p3 rw\0" \
@@ -166,15 +170,47 @@
 	"bootscript=echo Running bootscript from mmc ...; " \
 		"source\0" \
 	"loaduimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${uimage}\0" \
+	"loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}\0" \
 	"mmcboot=echo Booting from mmc ...; " \
 		"run mmcargs; " \
-		"bootm\0" \
+		"if test ${boot_fdt} = yes || test ${boot_fdt} = try; then " \
+			"if run loadfdt; then " \
+				"bootm ${loadaddr} - ${fdt_addr}; " \
+			"else " \
+				"if test ${boot_fdt} = try; then " \
+					"bootm; " \
+				"else " \
+					"echo WARN: Cannot load the DT; " \
+				"fi; " \
+			"fi; " \
+		"else " \
+			"bootm; " \
+		"fi;\0" \
 	"netargs=setenv bootargs console=ttymxc0,${baudrate} " \
 		"root=/dev/nfs " \
 		"ip=dhcp nfsroot=${serverip}:${nfsroot},v3,tcp\0" \
 	"netboot=echo Booting from net ...; " \
 		"run netargs; " \
-		"dhcp ${uimage}; bootm\0" \
+		"if test ${ip_dyn} = yes; then " \
+			"setenv get_cmd dhcp; " \
+		"else " \
+			"setenv get_cmd tftp; " \
+		"fi; " \
+		"${get_cmd} ${uimage}; " \
+		"if test ${boot_fdt} = yes ||  test ${boot_fdt} = try; then " \
+			"if ${get_cmd} ${fdt_addr} ${fdt_file}; then " \
+				"bootm ${loadaddr} - ${fdt_addr}; " \
+			"else " \
+				"if test ${boot_fdt} = try; then " \
+					"bootm; " \
+				"else " \
+					"echo ERROR: Cannot load the DT; " \
+					"exit; " \
+				"fi; " \
+			"fi; " \
+		"else " \
+			"bootm; " \
+		"fi;\0"
 
 #define CONFIG_BOOTCOMMAND \
 	"mmc dev ${mmcdev}; if mmc rescan; then " \