modify-floorplan

Modify Floorplan

Generate or modify floorplan.tcl and/or io_floorplan.tcl based on user's natural language description.

Arguments: $ARGUMENTS = natural language description of the desired changes.

Examples:

• "Change core size to 200x100 um with 10um offset"
• "Put all DAC pins on the top edge, clock and control on the right"
• "Increase die size by 20% in both dimensions"

Setup

1. Find the project root by looking for the fc/scripts/fc_setup.tcl file starting from the current directory.
2. Read fc/scripts/fc_setup.tcl to extract DESIGN_NAME and PROJECT_PATH.
3. Read the current fc/scripts/floorplan.tcl and fc/scripts/io_floorplan.tcl to understand existing settings.
4. Read RTL files in hdl/ to get the complete list of ports (input/output/inout with bit widths).

Understanding the Current Floorplan

Parse current floorplan.tcl for:

• initialize_floorplan arguments: core_offset and side_length
• PG ring/mesh configuration
• Routing layer settings

Parse current io_floorplan.tcl for:

• Pin placement commands (place_port, place_pin_group, set_individual_pin_constraints)
• Pin groupings and their edge assignments
• Layer alternation patterns

Modifying Core/Die Size

When the user asks to change the die or core size:

1. Calculate new dimensions:

   • Core size = user-specified side_length {WIDTH HEIGHT}
   • Die size = core size + 2 * core_offset on each side
   • Core offset = user-specified or keep existing

2. Update initialize_floorplan in floorplan.tcl:

   initialize_floorplan -control_type core \
       -core_offset {LEFT BOTTOM RIGHT TOP} \
       -shape R \
       -side_length {WIDTH HEIGHT}
   

3. If die size changes significantly, PG ring/mesh may need adjustment:

   • Mesh pitch should scale with die size
   • Ring offset should remain proportional

Modifying Pin Placement

When the user describes pin arrangements:

1. Parse the RTL to get all port names and widths:

   grep -E '^\s*(input|output|inout)' $PROJECT_PATH/hdl/*.v
   

2. Map user description to pin groups and edges:

   • Side 1 = bottom, Side 2 = top, Side 3 = right, Side 4 = left
   • Group related pins (e.g., all sw_vrefp_a[*] together)

3. Calculate spacing:

   • Minimum pitch for GF130: 0.46 um
   • Default pin width: 0.2-0.3 um
   • Step = pin_width + gap (typically 0.46 um for this process)
   • Verify total pin span fits within the edge length

4. Generate TCL using the helper procs from the existing io_floorplan.tcl:

   proc place_port {name layer side offset width} { ... }
   proc place_pin_group {pins side start step width layers} { ... }
   

5. Layer alternation:

   • Horizontal edges (top/bottom): alternate METAL2/METAL4
   • Vertical edges (left/right): use METAL3
   • This reduces coupling between adjacent pins

Output

Generate new versions of the modified files (do not overwrite directly):

• Write to fc/scripts/floorplan_new.tcl and/or fc/scripts/io_floorplan_new.tcl
• Show a diff against the current files
• Ask the user to confirm before replacing

After confirmation:

# Backup originals
cp $PROJECT_PATH/fc/scripts/floorplan.tcl $PROJECT_PATH/fc/scripts/floorplan_$(date +%Y%m%d_%H%M%S).tcl.bak
cp $PROJECT_PATH/fc/scripts/io_floorplan.tcl $PROJECT_PATH/fc/scripts/io_floorplan_$(date +%Y%m%d_%H%M%S).tcl.bak

# Replace
mv $PROJECT_PATH/fc/scripts/floorplan_new.tcl $PROJECT_PATH/fc/scripts/floorplan.tcl
mv $PROJECT_PATH/fc/scripts/io_floorplan_new.tcl $PROJECT_PATH/fc/scripts/io_floorplan.tcl

Validation

After generating new floorplan scripts, verify:

1. All RTL ports are assigned: Compare port list from RTL against pins in io_floorplan.tcl.
2. No pin overlaps: Check that no two pins occupy the same offset on the same edge.
3. Pins within boundary: All pin offsets must be > 0 and < edge length.
4. Minimum pitch: Step between pins >= 0.46 um.
5. PG ring clearance: Signal pins should not overlap with the PG ring offset region.

Present validation results:

=== Floorplan Validation ===
| Check                    | Status |
|--------------------------|--------|
| All ports assigned       | OK     |
| No pin overlaps          | OK     |
| Pins within boundary     | OK     |
| Minimum pitch satisfied  | OK     |
| PG ring clearance        | OK     |

Safety Rules

• Always show proposed changes and ask for user confirmation before replacing files.
• Always backup original files before overwriting.
• Never modify RTL to match the floorplan -- the floorplan must match the RTL.
• Verify pin names against the actual RTL port list.