Keep bit-manipulation extension control option as localparam (#55)

Signed-off-by: Szymon Bieganski <szymon.bieganski@oss.nxp.com> Co-authored-by: Szymon Bieganski <szymon.bieganski@oss.nxp.com>
openhwgroup · Feb 14, 2023 · 2aa3bf8 · 2aa3bf8
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Showing 3 changed files with 9 additions and 13 deletions.
diff --git a/doc/02_user/integration.rst b/doc/02_user/integration.rst
@@ -19,7 +19,6 @@ Instantiation Template
       .MHPMCounterWidth ( 40                               ),
       .RV32E            ( 0                                ),
       .RV32M            ( cve2_pkg::RV32MFast              ),
-      .RV32B            ( cve2_pkg::RV32BNone              ),
       .RegFile          ( cve2_pkg::RegFileFF              ),
       .ICache           ( 0                                ),
       .ICacheECC        ( 0                                ),
@@ -101,12 +100,6 @@ Parameters
 |                              |                     |            | "cve2_pkg::RV32MFast": 3-4 cycle multiplier, iterative divider        |
 |                              |                     |            | "cve2_pkg::RV32MSingleCycle": 1-2 cycle multiplier, iterative divider |
 +------------------------------+---------------------+------------+-----------------------------------------------------------------------+
-| ``RV32B``                    | cve2_pkg::rv32b_e   | RV32BNone  | B(itmanipulation) extension select:                                   |
-|                              |                     |            | "cve2_pkg::RV32BNone": No B-extension                                 |
-|                              |                     |            | "cve2_pkg::RV32BBalanced": Sub-extensions Zba, Zbb, Zbs, Zbf and Zbt  |
-|                              |                     |            | "cve2_pkg::RV32BOTEarlGrey": All sub-extensions except Zbe            |
-|                              |                     |            | "cve2_pkg::RV32BFull": All sub-extensions                             |
-+------------------------------+---------------------+------------+-----------------------------------------------------------------------+
 | ``RegFile``                  | cve2_pkg::regfile_e | RegFileFF  | Register file implementation select:                                  |
 |                              |                     |            | "cve2_pkg::RegFileFF": Generic flip-flop-based register file          |
 |                              |                     |            | "cve2_pkg::RegFileFPGA": Register file for FPGA targets               |
@@ -143,7 +136,7 @@ Parameters
 
 Any parameter marked *EXPERIMENTAL* when enabled is not verified to the same standard as the rest of the Ibex core.
 
-Note that Ibex uses SystemVerilog enum parameters e.g. for ``RV32M`` and ``RV32B``.
+Note that Ibex uses SystemVerilog enum parameters e.g. for ``RV32M``.
 This is well supported by most tools but some care is needed when overriding these parameters at the top level:
 
 * Synopsys VCS does not support overriding enum and string parameters at the top level via command line.

diff --git a/doc/03_reference/instruction_decode_execute.rst b/doc/03_reference/instruction_decode_execute.rst
@@ -66,15 +66,16 @@ Other blocks use the ALU for the following tasks:
 
 Bit-Manipulation Extension
   Support for the `RISC-V Bit-Manipulation Extension version 1.0.0 <https://github.com/riscv/riscv-bitmanip/releases/download/1.0.0/bitmanip-1.0.0-38-g865e7a7.pdf>`_ and `draft version 0.93 from January 10, 2021 <https://github.com/riscv/riscv-bitmanip/blob/master/bitmanip-0.93.pdf>`_ is optional. [#B_draft]_
-  It can be enabled via the enumerated parameter ``RV32B`` defined in :file:`rtl/cve2_pkg.sv`.
+  It can be enabled via the enumerated local parameter ``RV32B`` defined in :file:`rtl/cve2_pkg.sv`.
   By default, this parameter is set to "cve2_pkg::RV32BNone" to disable the bit-manipulation extension.
+  RVB is currently not maintained and activation should be done at the users responsibility.
 
   There are three versions of the bit-manipulation extension available:
   The balanced version comprises a set of sub-extensions aiming for good benefits at a reasonable area overhead.
-  It can be selected by setting the ``RV32B`` parameter to "cve2_pkg::RV32BBalanced".
+  It can be selected by setting the ``RV32B`` local parameter to "cve2_pkg::RV32BBalanced".
   The OTEarlGrey version comprises all sub-extensions except for the Zbe.
-  This version can be selected by setting the ``RV32B`` parameter to "cve2_pkg::RV32BOTEarlGrey".
-  The full version comprises all sub-extensions and can be selected by setting the ``RV32B`` parameter to "cve2_pkg::RV32BFull".
+  This version can be selected by setting the ``RV32B`` local parameter to "cve2_pkg::RV32BOTEarlGrey".
+  The full version comprises all sub-extensions and can be selected by setting the ``RV32B`` local parameter to "cve2_pkg::RV32BFull".
   The following table gives an overview of which sub-extensions are implemented in each version and of which instructions are implemented as multi-cycle instructions.
   Multi-cycle instructions are completed in 2 cycles.
   All remaining instructions complete in a single cycle.

diff --git a/rtl/cve2_top.sv b/rtl/cve2_top.sv
@@ -17,7 +17,6 @@ module cve2_top import cve2_pkg::*; #(
   parameter int unsigned MHPMCounterWidth = 40,
   parameter bit          RV32E            = 1'b0,
   parameter rv32m_e      RV32M            = RV32MFast,
-  parameter rv32b_e      RV32B            = RV32BNone,
   parameter regfile_e    RegFile          = RegFileFF,
   parameter bit          WritebackStage   = 1'b0,
   parameter bit          ICache           = 1'b0,
@@ -148,6 +147,9 @@ module cve2_top import cve2_pkg::*; #(
   localparam bit          DbgTriggerEn     = 1'b1;
   localparam int unsigned DbgHwBreakNum    = 1;
 
+  // Bit manipulation extension
+  localparam rv32b_e      RV32B            = RV32BNone;
+
   // Clock signals
   logic                        clk;
   logic                        core_busy_d, core_busy_q;