efabless ring IO template + hooks (#792)

* efabless ring IO template + hooks

* consolidate docs

* add sky130_fd_io library from open_pdks, fix template IO file

* fix corner cell, make met5 stripes like caravel

* met5 rings now connected to clamped3 pads

* add set_dont_touch on tie_hi/lo_esd output pins

* Update IO file instructions

* typos, move section

* More clarity

* fix IO filler placement to prevent them from being rotated

Without setting the fillers' place status to `fixed`, Innovus resets the
orientation of all fillers at some point during placement.

* Sky130: snap die to mfg grid for top-level

MPW/ChipIgnite die sizes are not on the placement grid (the default grid
snap); set the snap grid to the manufacturing grid for top-level modules
so that the die size can be set correctly.

* Update core size + docs surrounding core

Larger margins required to keep the entire core in low-tap-density
region.

* Sky130: add docs for IO cells during synthesis

IO cells (or at minimum, the HV tie nets) must be `dont_touch`ed during
synthesis to avoid Genus replacing HV tie connections with constant tie
cells.

* Reformat TCL & Markdown

Use fenced code blocks with proper language in Markdown, dedent TCL
snippets.

* Add patches to spacer cells and note about supplies

* Sky130: Add connect slices to example configuration

Change example hook to use connect filler slices and add critical
regular filler slices to template IO file.

---------

Co-authored-by: Ethan Wu <[email protected]>

hammer/technology/sky130/README.md

@@ -47,6 +47,62 @@ Note that the various configurations of the SRAMs available are encoded in the f
 To modify this file to include different configurations, or switch to using the OpenRAM SRAMs,
 navigate to ``./extra/[sram22|openram]`` and run the script ``./sram-cache-gen.py`` for usage information.
 
+IO Library
+----------
+
+The IO ring required by efabless for MPW/ChipIgnite can be created in Innovus using the `sky130_fd_io` and `sky130_ef_io `IO cell libraries. Here are the steps to use them:
+
+1. `extra/efabless_template.io` is a template IO file. You should modify this by replacing the `<inst_path>`s with the netlist paths to your GPIO & analog pads. **DO NOT MODIFY ANY POSITIONS OR REPLACE CLAMP CELLS WITH IO CELLS**.
+
+    a. For pad assignment: the ordering in the instance lists are from left to right (for top/bottom edges) and **bottom to top (for left/right edges)**.
+
+    b. Refer to [this documentation](https://skywater-pdk.readthedocs.io/en/main/contents/libraries/sky130_fd_io/docs/user_guide.html) for how to configure the pins of the IO cells (not exhaustive).
+
+    c. Your chip reset signal must go thru the `xres4v2` cell. Since this is in your netlist, you must remove the `cell=...` instantiation from your IO file (it is only in the template for clarity) and update the inst name. Otherwise a separate instance will be placed instead.
+
+    d. The `ENABLE_INP_H` pin must be hard-tied to `TIE_HI_ESD` or `TIE_LO_ESD`. Since this is at a higher voltage, verify that this is routed as a wire only (no buffers can be inserted).
+
+    e. `ENABLE_H` must be low at chip startup before going high. Absent using the power detector cell from the NDA IO library, you may elect to connect this to a reset signal.
+
+    f. This template file does not contain dedicated clamps for the `VSWITCH` or `VCCHIB` supplies (following Caravel). EFabless provides a `sky130_ef_io__connect_vcchib_vccd_and_vswitch_vddio_slice_20um` slice in `open_pdks` that replaces a standard 20um spacer with a slice that connects `VCCHIB` and `VCCD` together, and `VSWITCH` and `VDDIO` together. Note that this slice cannot be placed immediately to the right (in the R0 orientation) of a `*_clamped3_pad` cell, because otherwise they *will* create a supply short. The template IO file contains normal 20um spacer slices explicitly placed at these critical locations, and the provided hook instantiates the `connect` slice in place of the standard 20um spacer. This can be modified if desired. Caravel distributes the `*connect*` slices across the bottom edge of the padframe.
+
+2. Then, in your design YAML file, specify your IO file with the following. The top-level constraint must be exactly as below:
+
+    ```yaml
+    technology.sky130.io_file: <path/to/ring.io>
+    technology.sky130.io_file_meta: prependlocal
+
+    path: Top
+    type: toplevel
+    x: 0
+    y: 0
+    width: 3588
+    height: 5188
+    margins:
+      left: 249.78
+      right: 249.78
+      top: 252.08
+      bottom: 252.08
+    ```
+
+3. In your CLIDriver, you must import the following hook from the tech plugin and insert it as a `post_insertion_hook` after `floorplan_design`.
+
+    ```python
+    from hammer.technology.sky130 import efabless_ring_io
+    ```
+
+    In addition, to ensure ties to `TIE_HI_ESD` / `TIE_LO_ESD` are preserved during synthesis, a `post_insertion_hook` to `init_environment` should be added to `dont_touch` the IO cells
+
+    ```python
+    def donttouch_iocells(x: HammerTool) -> bool:
+        x.append('set_dont_touch [get_db insts -if {.base_cell.name == sky130_ef_io__*}] true')
+        return True
+    ```
+
+4. If you want to use the NDA s8iom0s8 library, you must include the `s8io.yml` file with `-p` on the `hammer-vlsi` command line, and then change the cells to that library in the IO file. Net names in the hook above will need to be lower-cased.
+
+5. DRC requires a rectangle of `areaid.lowTapDensity` (GDS layer 81/14) around the core area to check latchup correctly. Currently, this is not yet implemented in Hammer, and will need to be added manually in a GDS editor after GDS streamout.
+
 NDA Files
 ---------
 The NDA version of the Sky130 PDK is only required for Siemens Calibre to perform DRC/LVS signoff with the commercial VLSI flow.
@@ -63,8 +119,6 @@ We use the Calibre decks in the ``s8`` PDK, version ``V2.0.1``,
 see [here for the DRC deck path](https://github.com/ucb-bar/hammer/blob/612b4b662a774b1cab5cf25e8f41c6a771388e47/hammer/technology/sky130/sky130.tech.json#L16) 
 and [here for the LVS deck path](https://github.com/ucb-bar/hammer/blob/612b4b662a774b1cab5cf25e8f41c6a771388e47/hammer/technology/sky130/sky130.tech.json#L24).
 
-
-
 Resources
 ---------
 The good thing about this process being open-source is that most questions about the process are answerable through a google search. 
@@ -195,5 +249,3 @@ make install
 This generates all the Sky130 PDK files and installs them to `$PDK_ROOT/share/pdk/sky130A`
 
 
-
-

hammer/technology/sky130/__init__.py

@@ -12,7 +12,8 @@
 
 import hammer.tech
 from hammer.tech import HammerTechnology
-from hammer.vlsi import HammerTool, HammerPlaceAndRouteTool, TCLTool, HammerDRCTool, HammerLVSTool, HammerToolHookAction
+from hammer.vlsi import HammerTool, HammerPlaceAndRouteTool, TCLTool, HammerDRCTool, HammerLVSTool, \
+    HammerToolHookAction, HierarchicalMode
 
 import hammer.tech.specialcells as specialcells
 from hammer.tech.specialcells import CellType, SpecialCell
@@ -31,6 +32,7 @@ def post_install_script(self) -> None:
         self.setup_verilog()
         self.setup_techlef()
         self.setup_lvs_deck()
+        self.setup_io_lefs()
         print('Loaded Sky130 Tech')
 
 
@@ -160,6 +162,41 @@ def setup_lvs_deck(self) -> None:
                     df.write(matcher.sub("", sf.read()))
                     df.write(LVS_DECK_INSERT_LINES)
 
+    # Power pins for clamps must be CLASS CORE
+    # connect/disconnect spacers must be CLASS PAD SPACER, not AREAIO
+    def setup_io_lefs(self) -> None:
+        sky130A_path = Path(self.get_setting('technology.sky130.sky130A'))
+        source_path = sky130A_path / 'libs.ref' / 'sky130_fd_io' / 'lef' / 'sky130_ef_io.lef'
+        if not source_path.exists():
+            raise FileNotFoundError(f"IO LEF not found: {source_path}")
+
+        cache_tech_dir_path = Path(self.cache_dir)
+        os.makedirs(cache_tech_dir_path, exist_ok=True)
+        dest_path = cache_tech_dir_path / 'sky130_ef_io.lef'
+
+        with open(source_path, 'r') as sf:
+            with open(dest_path, 'w') as df:
+                self.logger.info("Modifying IO LEF: {} -> {}".format
+                    (source_path, dest_path))
+                sl = sf.readlines()
+                for net in ['VCCD1', 'VSSD1']:
+                    start = [idx for idx,line in enumerate(sl) if 'PIN ' + net in line]
+                    end = [idx for idx,line in enumerate(sl) if 'END ' + net in line]
+                    intervals = zip(start, end)
+                    for intv in intervals:
+                        port_idx = [idx for idx,line in enumerate(sl[intv[0]:intv[1]]) if 'PORT' in line]
+                        for idx in port_idx:
+                            sl[intv[0]+idx]=sl[intv[0]+idx].replace('PORT', 'PORT\n      CLASS CORE ;')
+                for cell in [
+                    'sky130_ef_io__connect_vcchib_vccd_and_vswitch_vddio_slice_20um',
+                    'sky130_ef_io__disconnect_vccd_slice_5um',
+                    'sky130_ef_io__disconnect_vdda_slice_5um',
+                ]:
+                    # force class to spacer
+                    start = [idx for idx, line in enumerate(sl) if f'MACRO {cell}' in line]
+                    sl[start[0] + 1] = sl[start[0] + 1].replace('AREAIO', 'SPACER')
+                df.writelines(sl)
+
     def get_tech_par_hooks(self, tool_name: str) -> List[HammerToolHookAction]:
         hooks = {
             "innovus": [
@@ -285,6 +322,13 @@ def sky130_innovus_settings(ht: HammerTool) -> bool:
 set_db route_design_detail_use_multi_cut_via_effort medium
     '''
     )
+    if ht.hierarchical_mode in {HierarchicalMode.Top, HierarchicalMode.Flat}:
+        ht.append(
+            '''
+# For top module: snap die to manufacturing grid, not placement grid
+set_db floorplan_snap_die_grid manufacturing
+        '''
+        )
     return True
 
 def sky130_connect_nets(ht: HammerTool) -> bool:
@@ -319,6 +363,49 @@ def sky130_add_endcaps(ht: HammerTool) -> bool:
     )
     return True
 
+def efabless_ring_io(ht: HammerTool) -> bool:
+    assert isinstance(ht, HammerPlaceAndRouteTool), "IO ring instantiation only for par"
+    assert isinstance(ht, TCLTool), "IO ring instantiation can only run on TCL tools"
+    io_file = ht.get_setting("technology.sky130.io_file")
+    ht.append(f"read_io_file {io_file} -no_die_size_adjust")
+    p_nets = list(map(lambda s: s.name, ht.get_independent_power_nets()))
+    g_nets = list(map(lambda s: s.name, ht.get_independent_ground_nets()))
+    ht.append(f'''
+# Global net connections
+connect_global_net VDDA -type pg_pin -pin_base_name VDDA -verbose
+connect_global_net VDDIO -type pg_pin -pin_base_name VDDIO* -verbose
+connect_global_net {p_nets[0]} -type pg_pin -pin_base_name VCCD* -verbose
+connect_global_net {p_nets[0]} -type pg_pin -pin_base_name VCCHIB -verbose
+connect_global_net {p_nets[0]} -type pg_pin -pin_base_name VSWITCH -verbose
+connect_global_net {g_nets[0]} -type pg_pin -pin_base_name VSSA -verbose
+connect_global_net {g_nets[0]} -type pg_pin -pin_base_name VSSIO* -verbose
+connect_global_net {g_nets[0]} -type pg_pin -pin_base_name VSSD* -verbose
+    ''')
+    ht.append('''
+# IO fillers
+set io_fillers {sky130_ef_io__connect_vcchib_vccd_and_vswitch_vddio_slice_20um sky130_ef_io__com_bus_slice_10um sky130_ef_io__com_bus_slice_5um sky130_ef_io__com_bus_slice_1um}
+add_io_fillers -prefix IO_FILLER -io_ring 1 -cells $io_fillers -side top -filler_orient r0
+add_io_fillers -prefix IO_FILLER -io_ring 1 -cells $io_fillers -side right -filler_orient r270
+add_io_fillers -prefix IO_FILLER -io_ring 1 -cells $io_fillers -side bottom -filler_orient r180
+add_io_fillers -prefix IO_FILLER -io_ring 1 -cells $io_fillers -side left -filler_orient r90
+# Fix placement
+set io_filler_insts [get_db insts IO_FILLER_*]
+set_db $io_filler_insts .place_status fixed
+    ''')
+    # An offset of 40um is used to place the core ring inside the core area. It
+    # can be decreased down to 5um as desired, but will require additional
+    # routing / settings to connect the core power stripes to the ring.
+    ht.append(f'''
+# Core ring
+add_rings -follow io -layer met5 -nets {{ {p_nets[0]} {g_nets[0]} }} -offset 40 -width 13 -spacing 3
+route_special -connect pad_pin -nets {{ {p_nets[0]} {g_nets[0]} }} -detailed_log
+    ''')
+    ht.append('''
+# Prevent buffering on TIE_LO_ESD and TIE_HI_ESD
+set_dont_touch [get_db [get_db pins -if {.name == *TIE*ESD}] .net]
+    ''')
+    return True
+
 def drc_blackbox_srams(ht: HammerTool) -> bool:
     assert isinstance(ht, HammerDRCTool), "Exlude SRAMs only in DRC"
     drc_box = ''

hammer/technology/sky130/defaults.yml

@@ -26,6 +26,9 @@ technology.sky130:
 
   drc_blackbox_srams: false
   lvs_blackbox_srams: false
+
+  io_file: "extra/efabless_template.io"  # IO ring - take this template and modify for your own use
+  io_file_meta: prependlocal
 
 
 mentor.extra_env_vars_meta: lazydeepsubst # Mentor environment variables

hammer/technology/sky130/defaults_types.yml

@@ -20,3 +20,6 @@ technology.sky130:
   # Shouldn't need to change these
   pdk_home: Optional[str]
   lvs_deck_sources: Optional[list[str]]
+
+  # Path to IO file
+  io_file: str

hammer/technology/sky130/extra/efabless_template.io

@@ -0,0 +1,124 @@
+
+(globals
+    version = 3
+    io_order = default
+)
+(row_margin
+    (top
+    (io_row ring_number = 1 margin = 0)
+    )
+    (right
+    (io_row ring_number = 1 margin = 0)
+    )
+    (bottom
+    (io_row ring_number = 1 margin = 0)
+    )
+    (left
+    (io_row ring_number = 1 margin = 0)
+    )
+)
+(iopad
+    (topleft
+    (locals ring_number = 1)
+        (inst name = "corner_topleft"   orientation=R90 cell="sky130_ef_io__corner_pad")
+    )
+
+    (top
+    (locals ring_number = 1)
+        (inst name = "<pad_inst>"   orientation=R0  offset=381)
+        (inst name = "<pad_inst>"   orientation=R0  offset=638)
+        (inst name = "<pad_inst>"   orientation=R0  offset=895)
+        (inst name = "<pad_inst>"   orientation=R0  offset=1152)
+        (inst name = "<pad_inst>"   orientation=R0  offset=1410)
+        (inst name = "clamp_0"      orientation=R0  cell="sky130_ef_io__vssio_hvc_clamped_pad"  offset=1667)
+        (inst name = "<pad_inst>"   orientation=R0  offset=1919)
+        (inst name = "<pad_inst>"   orientation=R0  offset=2364)
+        (inst name = "<pad_inst>"   orientation=R0  offset=2621)
+        (inst name = "clamp_1"      orientation=R0  cell="sky130_ef_io__vssa_hvc_clamped_pad"  offset=2878)
+        (inst name = "<pad_inst>"   orientation=R0  offset=3130)
+    )
+
+    (topright
+    (locals ring_number = 1)
+        (inst name = "corner_topright"   orientation=R0 cell="sky130_ef_io__corner_pad")
+    )
+
+    (right
+    (locals ring_number = 1)
+        (inst name = "<pad_inst>"   orientation=R270    offset=580)
+        (inst name = "<pad_inst>"   orientation=R270    offset=806)
+        (inst name = "<pad_inst>"   orientation=R270    offset=1031)
+        (inst name = "<pad_inst>"   orientation=R270    offset=1257)
+        (inst name = "<pad_inst>"   orientation=R270    offset=1482)
+        (inst name = "<pad_inst>"   orientation=R270    offset=1707)
+        (inst name = "<pad_inst>"   orientation=R270    offset=1933)
+        (inst name = "clamp_2"      orientation=R270    cell="sky130_ef_io__vssa_hvc_clamped_pad"  offset=2153)
+        (inst name = "clamp_3"      orientation=R270    cell="sky130_ef_io__vssd_lvc_clamped3_pad"  offset=2374)
+        (inst name = "clamp_4"      orientation=R270    cell="sky130_ef_io__vdda_hvc_clamped_pad"  offset=2594)
+        (inst name = "<pad_inst>"   orientation=R270    offset=2819)
+        (inst name = "<pad_inst>"   orientation=R270    offset=3045)
+        (inst name = "<pad_inst>"   orientation=R270    offset=3270)
+        (inst name = "<pad_inst>"   orientation=R270    offset=3496)
+        (inst name = "<pad_inst>"   orientation=R270    offset=3721)
+        (inst name = "<pad_inst>"   orientation=R270    offset=3946)
+        (inst name = "clamp_5"      orientation=R270    cell="sky130_ef_io__vdda_hvc_clamped_pad"  offset=4167)
+        (inst name = "<pad_inst>"   orientation=R270    offset=4392)
+        (inst name = "clamp_6"      orientation=R270    cell="sky130_ef_io__vccd_lvc_clamped3_pad"  offset=4613)
+        (inst name = "<pad_inst>"   orientation=R270    offset=4838)
+        (inst name = "IO_FILLER_MANUAL_E_1" orientation = R270 offset = 4593 cell = "sky130_ef_io__com_bus_slice_20um")
+        (inst name = "IO_FILLER_MANUAL_E_2" orientation = R270 offset = 2354 cell = "sky130_ef_io__com_bus_slice_20um")
+    )
+
+    (bottomright
+    (locals ring_number = 1)
+        (inst name = "corner_bottomright"   orientation=R270 cell="sky130_ef_io__corner_pad")
+    )
+
+    (bottom
+    (locals ring_number = 1)
+        (inst name = "clamp_7"      orientation=R180    cell="sky130_ef_io__vssa_hvc_clamped_pad"   offset=469)
+        (inst name = "reset"        orientation=R180    cell="sky130_fd_io__top_xres4v2"   offset=738)
+        (inst name = "<pad_inst>"   orientation=R180    offset=1012)
+        (inst name = "clamp_8"      orientation=R180    cell="sky130_ef_io__vssd_lvc_clamped_pad"   offset=1281)
+        (inst name = "<pad_inst>"   orientation=R180    offset=1555)
+        (inst name = "<pad_inst>"   orientation=R180    offset=1829)
+        (inst name = "<pad_inst>"   orientation=R180    offset=2103)
+        (inst name = "<pad_inst>"   orientation=R180    offset=2377)
+        (inst name = "<pad_inst>"   orientation=R180    offset=2651)
+        (inst name = "clamp_9"      orientation=R180    cell="sky130_ef_io__vssio_hvc_clamped_pad"   offset=2920)
+        (inst name = "clamp_10"      orientation=R180    cell="sky130_ef_io__vdda_hvc_clamped_pad"   offset=3189)
+    )
+
+    (bottomleft
+    (locals ring_number = 1)
+        (inst name = "corner_bottomleft"   orientation=R180 cell="sky130_ef_io__corner_pad")
+    )
+
+    (left
+    (locals ring_number = 1)
+        (inst name = "clamp_11"     orientation=R90     cell="sky130_ef_io__vccd_lvc_clamped_pad"   offset=340)
+        (inst name = "clamp_12"     orientation=R90     cell="sky130_ef_io__vddio_hvc_clamped_pad"   offset=551)
+        (inst name = "<pad_inst>"   orientation=R90     offset=908)
+        (inst name = "<pad_inst>"   orientation=R90     offset=1124)
+        (inst name = "<pad_inst>"   orientation=R90     offset=1340)
+        (inst name = "<pad_inst>"   orientation=R90     offset=1556)
+        (inst name = "<pad_inst>"   orientation=R90     offset=1772)
+        (inst name = "<pad_inst>"   orientation=R90     offset=1988)
+        (inst name = "clamp_13"     orientation=R90     cell="sky130_ef_io__vssd_lvc_clamped3_pad"   offset=2204)
+        (inst name = "clamp_14"     orientation=R90     cell="sky130_ef_io__vdda_hvc_clamped_pad"   offset=2415)
+        (inst name = "<pad_inst>"   orientation=R90     offset=2626)
+        (inst name = "<pad_inst>"   orientation=R90     offset=2842)
+        (inst name = "<pad_inst>"   orientation=R90     offset=3058)
+        (inst name = "<pad_inst>"   orientation=R90     offset=3274)
+        (inst name = "<pad_inst>"   orientation=R90     offset=3490)
+        (inst name = "<pad_inst>"   orientation=R90     offset=3706)
+        (inst name = "<pad_inst>"   orientation=R90     offset=3922)
+        (inst name = "clamp_15"     orientation=R90     cell="sky130_ef_io__vssa_hvc_clamped_pad"   offset=4138)
+        (inst name = "clamp_16"     orientation=R90     cell="sky130_ef_io__vddio_hvc_clamped_pad"   offset=4349)
+        (inst name = "clamp_17"     orientation=R90     cell="sky130_ef_io__vccd_lvc_clamped3_pad"   offset=4560)
+        (inst name = "<pad_inst>"   orientation=R90     offset=4771)
+        (inst name = "IO_FILLER_MANUAL_W_1" orientation = R90 offset = 415 cell = "sky130_ef_io__com_bus_slice_20um")
+        (inst name = "IO_FILLER_MANUAL_W_2" orientation = R90 offset = 2279 cell = "sky130_ef_io__com_bus_slice_20um")
+        (inst name = "IO_FILLER_MANUAL_W_3" orientation = R90 offset = 4635 cell = "sky130_ef_io__com_bus_slice_20um")
+    )
+)