openroad: improve parasitics estimation, add RCX

Author: phsauter

openroad/run_backend.sh

@@ -96,6 +96,15 @@ open_openroad_script() {
         2>&1 | TZ=UTC gawk '{ print strftime(\"[%H:%M %Z]\"), \$0 }'"
 }
 
+download_rcx_file() {
+    local ihp_rcx_url="https://raw.githubusercontent.com/The-OpenROAD-Project/OpenROAD-flow-scripts/7747f88f70daaeb63f43ce36e71829707b7e3fa7/flow/platforms/ihp-sg13g2/IHP_rcx_patterns.rules"
+    local ihp_rcx_file="IHP_rcx_patterns.rules"
+
+    if [ ! -f "${ihp_rcx_file}" ]; then
+        run_cmd "curl -L -o ${ihp_rcx_file} ${ihp_rcx_url}"
+    fi
+}
+
 
 ####################
 # Parse Arguments
@@ -164,6 +173,10 @@ while [[ $# -gt 0 ]]; do
             open_openroad_script "$2"
             shift 2
             ;;
+        --download-rcx)
+            download_rcx_file
+            shift
+            ;;
         # Error handling
         *)
             echo "[ERROR] Unknown option: $1 (use --help for usage)" >&2

openroad/scripts/05_finishing.tcl

@@ -58,11 +58,11 @@ write_sdc                      ${out_dir}/${proj_name}.sdc
 
 ## WARNING: Currently the extract_parasitics command removes metal patches (eg for min area)
 ## So if you want to use it, do so at the very end after writing out the def and odb files
-# define_process_corner -ext_model_index 0 X
-# extract_parasitics -ext_model_file IHP_rcx_patterns.rules
-# write_spef ${out_dir}/${proj_name}.spef
-# read_spef  ${out_dir}/${proj_name}.spef; # readback parasitics for OpenSTA
-# report_metrics "${step_nr}_${proj_name}.extract"
+define_process_corner -ext_model_index 0 X
+extract_parasitics -ext_model_file IHP_rcx_patterns.rules
+write_spef ${out_dir}/${proj_name}.spef
+read_spef  ${out_dir}/${proj_name}.spef; # readback parasitics for OpenSTA
+report_metrics "05_${proj_name}.extract"
 
 utl::report "###############################################################################"
 utl::report "# Stage 05 complete: Final outputs written to ${out_dir}/"

openroad/scripts/init_tech.tcl

@@ -54,20 +54,36 @@ foreach file [glob -directory $pdk_sram_lib RM_IHPSG13*_fast_1p32V_m55C.lib] {
 }
 
 puts "Init tech-lef"
-read_lef ${pdk_cells_lef}/ez130_tech.lef
+read_lef -tech ${pdk_cells_lef}/ez130_tech.lef
 
 puts "Init cell-lef"
-read_lef ${pdk_cells_lef}/ez130_8t.lef
-read_lef ${pdk_io_lef}/sg13g2_io.lef
-read_lef ${pdk_pad_lef}/bondpad_70x70.lef
+read_lef -library ${pdk_cells_lef}/ez130_8t.lef
+read_lef -library ${pdk_io_lef}/sg13g2_io.lef
+read_lef -library ${pdk_pad_lef}/bondpad_70x70.lef
 
 foreach file [glob -directory $pdk_sram_lef RM_IHPSG13*.lef] {
-	read_lef "$file"
+	read_lef -library "$file"
 }
 
 # Set layers used for estimate_parasitics
 proc setDefaultParasitics {} {
-	set_wire_rc -clock -layer Metal3
+	# derived from https://github.com/The-OpenROAD-Project/OpenROAD-flow-scripts/blob/master/flow/platforms/ihp-sg13g2/setRC.tcl
+	# and process spec by IHP, simplified since its only for estimation
+	# units: kohm/um and pF/um of standard-width wire on each layer
+	set_layer_rc -layer Metal1 -resistance 5.2E-04 -capacitance 1e-10
+	set_layer_rc -layer Metal2 -resistance 5.2E-04 -capacitance 1.85E-04
+	set_layer_rc -layer Metal3 -resistance 5.2E-04 -capacitance 1.85E-04
+	set_layer_rc -layer Metal4 -resistance 5.2E-04 -capacitance 1.85E-04
+	set_layer_rc -layer Metal5 -resistance 5.2E-04 -capacitance 8.6E-05
+
+	set_layer_rc -via Via1 -resistance 2.0E-3
+	set_layer_rc -via Via2 -resistance 2.0E-3
+	set_layer_rc -via Via3 -resistance 2.0E-3
+	set_layer_rc -via Via4 -resistance 2.0E-3
+	set_layer_rc -via TopVia1 -resistance 4.0E-4
+	set_layer_rc -via TopVia2 -resistance 2.0E-4
+
+	set_wire_rc -clock  -layer Metal3
 	set_wire_rc -signal -layer Metal3
 }
 

openroad/src/constraints.sdc

@@ -17,20 +17,26 @@ source src/instances.tcl
 #############################
 ## Driving Cells and Loads ##
 #############################
-
 # As a default, drive multiple GPIO pads and be driven by one.
 # accomodate for driving up to 2 74HC pads plus a 5pF trace
 set_load [expr 2 * 5.0 + 5.0] [all_outputs]
 set_driving_cell [all_inputs] -lib_cell sg13g2_IOPadOut16mA -pin pad
 
 
+###################
+## Global Limits ##
+###################
+# Limit fanout to ease routing and keep loads reasonable
+set_max_fanout 32 [current_design]
+set_max_transition 0.5 [current_design]
+
 ##################
 ## Input Clocks ##
 ##################
 puts "Clocks..."
 
-# We target 100 MHz
-set TCK_SYS 10.0
+# We target 90 MHz
+set TCK_SYS 11.2
 create_clock -name clk_sys -period $TCK_SYS [get_ports clk_i]
 
 set TCK_JTG 25.0