MIPS: add initial infrastructure for Broadcom MIPS SoCs

CFE checks CPU Thread in a different way (using register $22):
mfc0	t1, C0_BCM_CONFIG, 3 # $22
li	t2, CP0_CMT_TPID # (1 << 31)
and	t1, t2
bnez	t1, 2f	# if we are running on thread 1, skip init
nop

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/mips/mach-bmips/Kconfig b/arch/mips/mach-bmips/Kconfig
new file mode 100644
index 0000000..4f4d351
--- /dev/null
+++ b/arch/mips/mach-bmips/Kconfig
@@ -0,0 +1,23 @@
+menu "Broadcom MIPS platforms"
+	depends on ARCH_BMIPS
+
+config SYS_SOC
+	default "none"
+
+choice
+	prompt "Boot mode"
+
+config BMIPS_BOOT_RAM
+	bool "RAM boot"
+	depends on BMIPS_SUPPORTS_BOOT_RAM
+	help
+	  This builds an image that is linked to a RAM address. It can be used
+	  for booting from CFE via TFTP using an ELF image, but it can also be
+	  booted from RAM by other bootloaders using a BIN image.
+
+endchoice
+
+config BMIPS_SUPPORTS_BOOT_RAM
+	bool
+
+endmenu