update docs and add quota formal test

tb/formal/PMU_quota_sby/PMU_quota.gtkw

+[*]
+[*] GTKWave Analyzer v3.3.86 (w)1999-2017 BSI
+[*] Wed Apr 15 14:07:42 2020
+[*]
+[dumpfile] "/home/bscuser/BSC/grlib-gpl-2019-4-b4246-kc705/lib/bsc/ahb_pmu/bsc_pmu/tb/formal/PMU_quota_sby/PMU_quota_cover/engine_0/trace2.vcd"
+[dumpfile_mtime] "Wed Apr 15 13:53:13 2020"
+[dumpfile_size] 23904
+[savefile] "/home/bscuser/BSC/grlib-gpl-2019-4-b4246-kc705/lib/bsc/ahb_pmu/bsc_pmu/tb/formal/PMU_quota_sby/PMU_quota.gtkw"
+[timestart] 0
+[size] 1559 972
+[pos] 50 50
+*-6.707499 216 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
+[sst_width] 228
+[signals_width] 402
+[sst_expanded] 1
+[sst_vpaned_height] 276
+@28
+PMU_quota.clk_i
+@22
+PMU_quota.counter_value_i[287:0]
+@28
+PMU_quota.f_past_valid
+@22
+PMU_quota.i[31:0]
+PMU_quota.i_2[31:0]
+@28
+PMU_quota.intr_quota_o
+@22
+PMU_quota.masked_counter_value_int<0>[31:0]
+PMU_quota.masked_counter_value_int<1>[31:0]
+PMU_quota.masked_counter_value_int<2>[31:0]
+PMU_quota.masked_counter_value_int<3>[31:0]
+PMU_quota.masked_counter_value_int<4>[31:0]
+PMU_quota.masked_counter_value_int<5>[31:0]
+PMU_quota.masked_counter_value_int<6>[31:0]
+PMU_quota.masked_counter_value_int<7>[31:0]
+PMU_quota.masked_counter_value_int<8>[31:0]
+@28
+PMU_quota.new_mask
+@22
+PMU_quota.old_mask[8:0]
+PMU_quota.quota_limit_i[31:0]
+PMU_quota.quota_mask_i[8:0]
+@28
+PMU_quota.rstn_i
+PMU_quota.softrst_i
+@22
+PMU_quota.suma_int[31:0]
+@23
+PMU_quota.state_int[3:0]
+[pattern_trace] 1
+[pattern_trace] 0

tb/formal/PMU_quota_sby/PMU_quota.sby

+[tasks]
+bmc
+cover
+
+[options]
+bmc: 
+    mode bmc
+--
+cover:
+    mode cover
+    depth 40
+    append 2 
+--
+
+[engines]
+#smtbmc boolector
+smtbmc
+#abc bmc3
+
+#SystemVerilog
+[script]
+verific -vlog-define FORMAL
+verific -sv PMU_quota.sv
+verific -import -extnets -all PMU_quota
+prep -top PMU_quota
+
+#Verilog
+#[script]
+#read_verilog -formal PMU_quota.sv
+#prep -top PMU_quota
+#opt -share_all
+
+[files]
+../../../submodules/quota/PMU_quota.sv 
+

tb/formal/PMU_quota_sby/run.sh

+#Check that the formal properties pass
+sby -f PMU_quota.sby | \
+   GREP_COLORS='mt=01;31' egrep --color=always 'Unreached|Unreached cover statement at|Assert failed in|' | \
+   GREP_COLORS='mt=01;31' egrep -i --color=always 'FAIL|FAILED|ERROR|syntax|' | \
+   GREP_COLORS='mt=01;34' egrep --color=always 'Reached cover statement at|BMC|' | \
+   GREP_COLORS='mt=01;32' egrep -i --color=always 'PASS|PASSED|' | \
+   GREP_COLORS='mt=01;33' egrep -i --color=always 'WARNING|' | \
+   GREP_COLORS='mt=01;36' egrep -i --color=always 'Writing trace to VCD file:|counterexample trace:|'
+#Run a particular case
+#sby -f PMU_quota_cover.sby
+#Show the trace of the cover
+#gtkwave ./PMU_quota/engine_0/trace.vcd PMU_quota.gtkw