tcl/target/atheros_ar9331: add DDR2 helper

this helper works on many different boards, so it is
good to have it in target config

Change-Id: I068deac36fdd73dbbcedffc87865cc5b9d992c1d
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-on: http://openocd.zylin.com/4422
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

tcl/target/atheros_ar9331.cfg

@@ -48,3 +48,46 @@ proc ar9331_ddr1_init {} {
 	mww 0xb8000018 0xff	;# DDR read and capture bit mask.
 				;# Each bit represents a cycle of valid data.
 }
+
+proc ar9331_ddr2_init {} {
+	mww 0xb8000000 0x7fbc8cd0	;# DDR_CONFIG - lots of DRAM confs
+	mww 0xb8000004 0x9dd0e6a8	;# DDR_CONFIG2 - more DRAM confs
+
+	mww 0xb800008c 0x00000a59
+	mww 0xb8000010 0x00000008	;# PRECHARGE ALL cycle
+
+	mww 0xb8000090 0x00000000
+	mww 0xb8000010 0x00000010	;# EMR2S update cycle
+
+	mww 0xb8000094 0x00000000
+	mww 0xb8000010 0x00000020	;# EMR3S update cycle
+
+	mww 0xb800000c 0x00000000
+	mww 0xb8000010 0x00000002	;# EMRS update cycle
+
+	mww 0xb8000008 0x00000100
+	mww 0xb8000010 0x00000001	;# MRS update cycle
+
+	mww 0xb8000010 0x00000008	;# PRECHARGE ALL cycle
+
+	mww 0xb8000010 0x00000004
+	mww 0xb8000010 0x00000004	;# AUTO REFRESH cycle
+
+	mww 0xb8000008 0x00000a33
+	mww 0xb8000010 0x00000001	;# MRS update cycle
+
+	mww 0xb800000c 0x00000382
+	mww 0xb8000010 0x00000002	;# EMRS update cycle
+
+	mww 0xb800000c 0x00000402
+	mww 0xb8000010 0x00000002	;# EMRS update cycle
+
+	mww 0xb8000014 0x00004186	;# DDR_REFRESH
+	mww 0xb800001c 0x00000008	;# DDR_TAP_CTRL0
+	mww 0xb8000020 0x00000009	;# DDR_TAP_CTRL1
+
+	;# DDR read and capture bit mask.
+	;# Each bit represents a cycle of valid data.
+	;# 0xff: use 16-bit DDR
+	mww 0xb8000018 0x000000ff
+}