Add bit more logic to decide when to switch to multilane CSR documentation.

Now we only generate multilane bitfield documentation when the CSR has
fields, and the smallest field is less than 8bit long. As this is when
we start running into space problems with the field names.

diff --git a/litex/soc/doc/csr.py b/litex/soc/doc/csr.py
index 0b0670daa5246c07e1e6a3e6bb96c2f2f92b496c..cfc17bf6d8741a8126a618b37dea9254104a2a30 100644 (file)
--- a/litex/soc/doc/csr.py
+++ b/litex/soc/doc/csr.py
@@ -235,7 +235,9 @@ class DocumentedCSRRegion:
         print("", file=stream)
         print("        {", file=stream)
         print("            \"reg\": [", file=stream)
+        multilane = False
         if len(reg.fields) > 0:
+            min_field_size = self.csr_data_width
             bit_offset = 0
             for field in reg.fields:
                 field_name = field.name
@@ -254,6 +256,9 @@ class DocumentedCSRRegion:
                     term=""
                 print("                {\"name\": \"" + field_name + "\",  " + type_str + attr_str + "\"bits\": " + str(field.size) + "}" + term, file=stream)
                 bit_offset = field.offset + field.size
+                min_field_size = min(min_field_size, field.size)
+                if min_field_size < 8:
+                    multilane = True
             if bit_offset != self.busword:
                 print("                {\"bits\": " + str(self.busword - bit_offset) + "}", file=stream)
         else:
@@ -265,8 +270,12 @@ class DocumentedCSRRegion:
                 attr_str = "\"attr\": 'reset: " + str(reg.reset_value) + "', "
             print("                {\"name\": \"" + reg.short_name.lower() + self.bit_range(reg.offset, reg.offset + reg.size, empty_if_zero=True) + "\", " + attr_str + "\"bits\": " + str(reg.size) + "}" + term, file=stream)
             if reg.size != self.csr_data_width:
+                multilane = True
                 print("                {\"bits\": " + str(self.csr_data_width - reg.size) + "},", file=stream)
-        lanes = self.busword / 8
+        if multilane:
+            lanes = self.busword / 8
+        else:
+            lanes = 1
         print("            ], \"config\": {\"hspace\": 400, \"bits\": " + str(self.busword) + ", \"lanes\": " + str(lanes) + " }, \"options\": {\"hspace\": 400, \"bits\": " + str(self.busword) + ", \"lanes\": " + str(lanes) + "}", file=stream)
         print("        }", file=stream)
         print("", file=stream)