arc: add more flavours of ARC700 series CPU

Now we may select a particular version of ARC700:
 * ARC750D or
 * ARC770D

It allows more flexible (or more fine tuned) configuration of U-Boot.
Before that change we relied on minimal configuration but now we may
use specific features of each CPU.

Moreover allows us to escape manual selection of options that
exist in both CPUs but may have say different version like MMUv2 in
ARC750D vs MMUv3 in ARC770D.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index c6b1efe..f7d2964 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -8,6 +8,46 @@
 	default "arcv1"
 
 choice
+	prompt "CPU selection"
+	default CPU_ARC770D
+
+config CPU_ARC750D
+	bool "ARC 750D"
+	select ARC_MMU_V2
+	help
+	  Choose this option to build an U-Boot for ARC750D CPU.
+
+config CPU_ARC770D
+	bool "ARC 770D"
+	select ARC_MMU_V3
+	help
+	  Choose this option to build an U-Boot for ARC770D CPU.
+
+endchoice
+
+choice
+	prompt "MMU Version"
+	default ARC_MMU_V3 if CPU_ARC770D
+	default ARC_MMU_V2 if CPU_ARC750D
+
+config ARC_MMU_V2
+	bool "MMU v2"
+	depends on CPU_ARC750D
+	help
+	  Fixed the deficiency of v1 - possible thrashing in memcpy sceanrio
+	  when 2 D-TLB and 1 I-TLB entries index into same 2way set.
+
+config ARC_MMU_V3
+	bool "MMU v3"
+	depends on CPU_ARC770D
+	help
+	  Introduced with ARC700 4.10: New Features
+	  Variable Page size (1k-16k), var JTLB size 128 x (2 or 4)
+	  Shared Address Spaces (SASID)
+
+endchoice
+
+choice
 	prompt "Target select"
 
 config TARGET_TB100