[otbn,rtl] Add helper types to efficiently access integrity and data bits of GPRs/CSR/WDR/WSRs

This adds two signal types to easily access the integrity or data bits of the base registers and
wide registers. The wide registers are constructed of 8 base registers (integrity is
computed per 32 bits).
The 3rd type allows an easy assignment of bits from URND to a WSR, especially useful for secure wipe
assignments.

Signed-off-by: Pascal Etterli <pascal.etterli@lowrisc.org>

Author: etterli

hw/ip/otbn/rtl/otbn_mai.sv

@@ -82,15 +82,6 @@ module otbn_mai
     logic          busy;
   } ispr_mai_status_t;
 
-  localparam int unsigned MaiEccWidth = BaseIntgWidth - 32'd32;
-
-  typedef struct packed {
-    logic [MaiEccWidth-1:0] intg;
-    logic [31:0]            word;
-  } otbn_base_intg_word_t;
-
-  typedef otbn_base_intg_word_t [BaseWordsPerWLEN-1:0] ispr_mai_t;
-
   typedef struct packed {
     logic out_cnt;
     logic in_cnt;
@@ -117,13 +108,6 @@ module otbn_mai
 
   typedef logic [MaiCntWidth-1:0] mai_cnt_t;
 
-  localparam int unsigned MaiIsprRndRsvdWidth = UrndLen - ExtWLEN;
-
-  typedef struct packed {
-    logic [MaiIsprRndRsvdWidth-1:0] rsvd;
-    logic [ExtWLEN-1:0]             urnd;
-  } mai_ispr_urnd_t;
-
   typedef struct packed {
     logic [MaiCntWidth-1:0] cnt;
     logic [31:0]            mask_1;
@@ -137,27 +121,27 @@ module otbn_mai
   /////////////
 
   // PRNG input
-  mai_ispr_urnd_t mai_ispr_urnd;
-  mai_ma_urnd_t   mai_ma_urnd;
-  logic           unused_urnd;
+  otbn_ispr_urnd_t mai_ispr_urnd;
+  mai_ma_urnd_t    mai_ma_urnd;
+  logic            unused_urnd;
 
   // Error signals
   mai_reg_intg_violation_err_t mai_reg_intg_violation_err;
   logic                        mai_reg_intg_violation_err_masked;
   mai_state_err_t              mai_state_err;
 
   // Masking accelerator signals
-  logic        ma_in_valid_q;
-  logic        ma_in_ready;
-  logic        ma_in_consume;
-  logic        ma_out_ready;
-  logic        ma_busy_q;
-  logic [31:0] ma_in0[32'd2];
-  logic [31:0] ma_in1[32'd2];
-  logic [31:0] ma_remask_rand[32'd2];
-  logic [31:0] ma_result[32'd2];
-  ispr_mai_t   ma_mod;
-  logic [31:0] ma_mod_lsw;
+  logic                 ma_in_valid_q;
+  logic                 ma_in_ready;
+  logic                 ma_in_consume;
+  logic                 ma_out_ready;
+  logic                 ma_busy_q;
+  logic [31:0]          ma_in0[32'd2];
+  logic [31:0]          ma_in1[32'd2];
+  logic [31:0]          ma_remask_rand[32'd2];
+  logic [31:0]          ma_result[32'd2];
+  otbn_wide_intg_word_t ma_mod;
+  logic [31:0]          ma_mod_lsw;
 
   // Counter load values
   mai_cnt_t cnt_load_val;
@@ -199,12 +183,12 @@ module otbn_mai
   ispr_mai_sw_err_t ispr_mai_sw_err;
 
   // WSRs
-  ispr_mai_t ispr_mai_in0_s0_d, ispr_mai_in0_s0_q;
-  ispr_mai_t ispr_mai_in0_s1_d, ispr_mai_in0_s1_q;
-  ispr_mai_t ispr_mai_in1_s0_d, ispr_mai_in1_s0_q;
-  ispr_mai_t ispr_mai_in1_s1_d, ispr_mai_in1_s1_q;
-  ispr_mai_t ispr_mai_res_s0_d, ispr_mai_res_s0_q;
-  ispr_mai_t ispr_mai_res_s1_d, ispr_mai_res_s1_q;
+  otbn_wide_intg_word_t ispr_mai_in0_s0_d, ispr_mai_in0_s0_q;
+  otbn_wide_intg_word_t ispr_mai_in0_s1_d, ispr_mai_in0_s1_q;
+  otbn_wide_intg_word_t ispr_mai_in1_s0_d, ispr_mai_in1_s0_q;
+  otbn_wide_intg_word_t ispr_mai_in1_s1_d, ispr_mai_in1_s1_q;
+  otbn_wide_intg_word_t ispr_mai_res_s0_d, ispr_mai_res_s0_q;
+  otbn_wide_intg_word_t ispr_mai_res_s1_d, ispr_mai_res_s1_q;
 
 
   ////////////

hw/ip/otbn/rtl/otbn_pkg.sv

@@ -24,6 +24,9 @@ package otbn_pkg;
   // Width of base (32b) data path with added integrity bits
   parameter int BaseIntgWidth = 39;
 
+  // Width of the base (32b) integrity part.
+  parameter int BaseEccWidth = BaseIntgWidth - 32;
+
   // Number of 32-bit words per WLEN / HWLEN / QWLEN
   parameter int BaseWordsPerWLEN  = WLEN / 32;
   parameter int BaseWordsPerHWLEN = HWLEN / 32;
@@ -74,6 +77,23 @@ package otbn_pkg;
   // Number of vector chunk processing elements
   parameter int NVecProc = VLEN / VChunkLEN;
 
+  // A type to split a base word into integrity and data bits.
+  typedef struct packed {
+    logic [BaseEccWidth-1:0] intg;
+    logic [31:0]             word;
+  } otbn_base_intg_word_t;
+
+  // A wide register (WDR or WSR) split into base words with integrity and data each.
+  typedef otbn_base_intg_word_t [BaseWordsPerWLEN-1:0] otbn_wide_intg_word_t;
+
+  // A type to select bits from URND to secure wipe a full WSR.
+  localparam int unsigned IsprRndRsvdWidth = UrndLen - ExtWLEN;
+
+  typedef struct packed {
+    logic [IsprRndRsvdWidth-1:0] rsvd;
+    logic [ExtWLEN-1:0]          urnd;
+  } otbn_ispr_urnd_t;
+
   // Toplevel constants ============================================================================
 
   parameter int AlertFatal = 0;