configs/snps_arc700_nsim_defconfig: add ARC700 target for nSIM

Add ARC700 image configuration for nSIM instruction set simulator.

This is a nice starting point for ARC700 in nSIM.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/synopsys/nsim/readme.txt

@@ -0,0 +1,43 @@
+How to build it
+===============
+
+Configure build for the selected nSIM target. For instance, for
+ARC700 nSIM target use the following defauilt configuration:
+$ make snps_arc700_nsim_defconfig
+
+Optionally modify the configuration:
+$ make menuconfig
+
+Build:
+$ make
+
+How to use it
+=============
+
+Resulting image can be booted using ARC nSIM instruction set simulator.
+Free version of nSIM is available for download:
+- https://www.synopsys.com/cgi-bin/dwarcnsim/req1.cgi
+It provides nsimdrv binary for Linux that can be used stand-alone
+or with GDB.
+
+To run ARC700 image use the following command:
+$ nsimdrv \
+	-prop=nsim_mem-dev=uart0,kind=dwuart,base=0xf0000000,irq=24 \
+	-prop=icache=32768,64,2,0 \
+	-prop=dcache=32768,64,4,0 \
+	-prop=nsim_isa_enable_timer_0=1 \
+	-prop=nsim_isa_enable_timer_1=1 \
+	-prop=nsim_isa_host_timer=1 \
+	-prop=nsim_mmu=3 \
+	-prop=nsim_isa_family=a700 \
+	-prop=nsim_isa_atomic_option=1 \
+	-prop=nsim_isa_dpfp=none \
+	-prop=nsim_isa_shift_option=2 \
+	-prop=nsim_isa_swap_option=1 \
+	-prop=nsim_isa_bitscan_option=1 \
+	-prop=nsim_isa_sat=1 \
+	-prop=nsim_isa_mpy32=1 \
+	-prop=isa_counters=1 \
+	-prop=nsim_isa_pct_counters=8 \
+	-prop=nsim_isa_pct_size=48 \
+	output/images/vmlinux