hw: Add native bootrom (#168)

---------

Co-authored-by: Thierry Dubochet <[email protected]>
Co-authored-by: Milos Hirsl <[email protected]>
Co-authored-by: Luca Colagrande <[email protected]>

Bender.yml

@@ -159,6 +159,7 @@ sources:
       - hw/snitch_cluster/src/snitch_fpu.sv
       - hw/snitch_cluster/src/snitch_sequencer.sv
       - hw/snitch_cluster/src/snitch_tcdm_interconnect.sv
+      - target/snitch_cluster/test/snitch_bootrom.sv
       # Level 1
       - hw/snitch_cluster/src/snitch_barrier.sv
       - hw/snitch_cluster/src/snitch_fp_ss.sv
@@ -189,4 +190,5 @@ sources:
       - target/snitch_cluster/generated/snitch_cluster_wrapper.sv
   - target: all(snitch_cluster, any(simulation, verilator))
     files:
+      - target/snitch_cluster/test/vip_snitch_cluster.sv
       - target/snitch_cluster/test/testharness.sv

hw/snitch/src/snitch_pkg.sv

@@ -139,7 +139,8 @@ package snitch_pkg;
   typedef enum int unsigned {
     TCDMDMA    = 0,
     SoCDMAOut  = 1,
-    ZeroMemory = 2
+    ZeroMemory = 2,
+    BootRom    = 3
   } cluster_slave_dma_e;
 
   typedef enum int unsigned {

hw/snitch_cluster/src/snitch_cluster.sv

@@ -37,7 +37,8 @@ module snitch_cluster
   parameter int unsigned NarrowUserWidth    = 1,
   /// AXI: dma user width.
   parameter int unsigned WideUserWidth      = 1,
-  /// Address from which to fetch the first instructions.
+  /// Boot Address from which to fetch the first instructions.
+  /// Used if `AliasRegionEnable` or `IntBootromEnable` is not set.
   parameter logic [31:0] BootAddr           = 32'h0,
   /// Number of Hives. Each Hive can hold 1-many cores.
   parameter int unsigned NrHives            = 1,
@@ -47,6 +48,8 @@ module snitch_cluster
   parameter int unsigned TCDMDepth          = 1024,
   /// Zero memory address region size (in kB).
   parameter int unsigned ZeroMemorySize     = 64,
+  /// Bootrom memory address region size (in kB).
+  parameter int unsigned BootRomSize        = 4,
   /// Cluster peripheral address region size (in kB).
   parameter int unsigned ClusterPeriphSize  = 64,
   /// Number of TCDM Banks. It is recommended to have twice the number of banks
@@ -195,7 +198,9 @@ module snitch_cluster
   parameter bit          DebugSupport = 1,
   /// Optional fixed cluster alias region.
   parameter bit          AliasRegionEnable  = 1'b0,
-  parameter logic [PhysicalAddrWidth-1:0] AliasRegionBase    = '0
+  parameter logic [PhysicalAddrWidth-1:0] AliasRegionBase    = '0,
+  /// Instantiate internal bootrom.
+  parameter bit          IntBootromEnable   = 1'b1
 ) (
   /// System clock. If `IsoCrossing` is enabled this port is the _fast_ clock.
   /// The slower, half-frequency clock, is derived internally.
@@ -276,11 +281,12 @@ module snitch_cluster
   localparam int unsigned NrRuleIdcs = NrSlaves - 1;
   localparam int unsigned NrRules = (1 + AliasRegionEnable) * NrRuleIdcs;
 
-  // SoC Request, DMA Channels, `n` instruction caches.
+  // DMA X-BAR configuration
+  // SoC in Request, DMA Channels, `n` instruction caches.
   localparam int unsigned NrWideMasters = 1 + DMANumChannels + NrHives;
   localparam int unsigned WideIdWidthOut = $clog2(NrWideMasters) + WideIdWidthIn;
-  // DMA X-BAR configuration
-  localparam int unsigned NrWideSlaves = 3;
+  // TCDM, SoC out, ZeroMemory, (Bootrom)
+  localparam int unsigned NrWideSlaves = 3 + IntBootromEnable;
   localparam int unsigned NrWideRuleIdcs = NrWideSlaves - 1;
   localparam int unsigned NrWideRules = (1 + AliasRegionEnable) * NrWideRuleIdcs;
 
@@ -459,9 +465,13 @@ module snitch_cluster
   assign tcdm_start_address = (cluster_base_addr_i & TCDMMask);
   assign tcdm_end_address   = (tcdm_start_address + TCDMSize) & TCDMMask;
 
+  addr_t bootrom_start_address, bootrom_end_address;
+  assign bootrom_start_address = tcdm_end_address;
+  assign bootrom_end_address   = tcdm_end_address + BootRomSize * 1024;
+
   addr_t cluster_periph_start_address, cluster_periph_end_address;
-  assign cluster_periph_start_address = tcdm_end_address;
-  assign cluster_periph_end_address   = tcdm_end_address + ClusterPeriphSize * 1024;
+  assign cluster_periph_start_address = IntBootromEnable ? bootrom_end_address : tcdm_end_address;
+  assign cluster_periph_end_address   = cluster_periph_start_address + ClusterPeriphSize * 1024;
 
   addr_t zero_mem_start_address, zero_mem_end_address;
   assign zero_mem_start_address = cluster_periph_end_address;
@@ -470,8 +480,11 @@ module snitch_cluster
   localparam addr_t TCDMAliasStart = AliasRegionBase & TCDMMask;
   localparam addr_t TCDMAliasEnd   = (TCDMAliasStart + TCDMSize) & TCDMMask;
 
-  localparam addr_t PeriphAliasStart = TCDMAliasEnd;
-  localparam addr_t PeriphAliasEnd   = TCDMAliasEnd + ClusterPeriphSize * 1024;
+  localparam addr_t BootRomAliasStart = TCDMAliasEnd;
+  localparam addr_t BootRomAliasEnd   = BootRomAliasStart + BootRomSize * 1024;
+
+  localparam addr_t PeriphAliasStart = IntBootromEnable ? BootRomAliasEnd : TCDMAliasEnd;
+  localparam addr_t PeriphAliasEnd   = PeriphAliasStart + ClusterPeriphSize * 1024;
 
   localparam addr_t ZeroMemAliasStart = PeriphAliasEnd;
   localparam addr_t ZeroMemAliasEnd   = PeriphAliasEnd + ZeroMemorySize * 1024;
@@ -572,34 +585,30 @@ module snitch_cluster
   );
 
   logic [DmaXbarCfg.NoSlvPorts-1:0][$clog2(DmaXbarCfg.NoMstPorts)-1:0] dma_xbar_default_port;
-  xbar_rule_t [DmaXbarCfg.NoAddrRules-1:0] dma_xbar_rule;
-
   assign dma_xbar_default_port = '{default: SoCDMAOut};
-  assign dma_xbar_rule[NrWideRuleIdcs-1:0] = '{
-    '{
-      idx:        TCDMDMA,
-      start_addr: tcdm_start_address,
-      end_addr:   tcdm_end_address
-    },
-    '{
-      idx:        ZeroMemory,
-      start_addr: zero_mem_start_address,
-      end_addr:   zero_mem_end_address
-    }
+
+  xbar_rule_t [5:0] dma_xbar_rules;
+  xbar_rule_t [DmaXbarCfg.NoAddrRules-1:0] enabled_dma_xbar_rule;
+
+  assign dma_xbar_rules = '{
+    '{idx: TCDMDMA,    start_addr: tcdm_start_address,     end_addr: tcdm_end_address},
+    '{idx: ZeroMemory, start_addr: zero_mem_start_address, end_addr: zero_mem_end_address},
+    '{idx: BootRom,    start_addr: bootrom_start_address,  end_addr: bootrom_end_address},
+    '{idx: TCDMDMA,    start_addr: TCDMAliasStart,         end_addr: TCDMAliasEnd},
+    '{idx: ZeroMemory, start_addr: ZeroMemAliasStart,      end_addr: ZeroMemAliasEnd},
+    '{idx: BootRom,    start_addr: BootRomAliasStart,      end_addr: BootRomAliasEnd}
   };
-  if (AliasRegionEnable) begin : gen_dma_xbar_alias
-    assign dma_xbar_rule [NrWideRules-1:NrWideRuleIdcs] = '{
-      '{
-        idx:        TCDMDMA,
-        start_addr: TCDMAliasStart,
-        end_addr:   TCDMAliasEnd
-      },
-      '{
-        idx:        ZeroMemory,
-        start_addr: ZeroMemAliasStart,
-        end_addr:   ZeroMemAliasEnd
-      }
-    };
+
+  always_comb begin
+    automatic int unsigned i = 0;
+    enabled_dma_xbar_rule[i] = dma_xbar_rules[0]; i++; // TCDM
+    enabled_dma_xbar_rule[i] = dma_xbar_rules[1]; i++; // ZeroMemory
+    if (IntBootromEnable) enabled_dma_xbar_rule[i] = dma_xbar_rules[2]; i++; // Bootrom
+    if (AliasRegionEnable) begin
+      enabled_dma_xbar_rule[i] = dma_xbar_rules[3]; i++; // TCDM Alias
+      enabled_dma_xbar_rule[i] = dma_xbar_rules[4]; i++; // ZeroMemory Alias
+      if (IntBootromEnable) enabled_dma_xbar_rule[i] = dma_xbar_rules[5]; // Bootrom Alias
+    end
   end
 
   localparam bit [DmaXbarCfg.NoSlvPorts-1:0] DMAEnableDefaultMstPort = '1;
@@ -628,7 +637,7 @@ module snitch_cluster
     .slv_ports_resp_o (wide_axi_mst_rsp),
     .mst_ports_req_o (wide_axi_slv_req),
     .mst_ports_resp_i (wide_axi_slv_rsp),
-    .addr_map_i (dma_xbar_rule),
+    .addr_map_i (enabled_dma_xbar_rule),
     .en_default_mst_port_i (DMAEnableDefaultMstPort),
     .default_mst_port_i (dma_xbar_default_port)
   );
@@ -857,6 +866,9 @@ module snitch_cluster
 
       tcdm_req_t [TcdmPorts-1:0] tcdm_req_wo_user;
 
+      parameter logic [31:0] BootAddrInternal = (AliasRegionEnable & IntBootromEnable) ?
+                                                 BootRomAliasStart : BootAddr;
+
       snitch_cc #(
         .AddrWidth (PhysicalAddrWidth),
         .DataWidth (NarrowDataWidth),
@@ -881,7 +893,7 @@ module snitch_cluster
         .acc_req_t (acc_req_t),
         .acc_resp_t (acc_resp_t),
         .dma_events_t (dma_events_t),
-        .BootAddr (BootAddr),
+        .BootAddr (BootAddrInternal),
         .RVE (RVE[i]),
         .RVF (RVF[i]),
         .RVD (RVD[i]),
@@ -1236,6 +1248,51 @@ module snitch_cluster
     .reg_rsp_i (reg_rsp)
   );
 
+  if (IntBootromEnable) begin : gen_bootrom
+
+    addr_t bootrom_addr;
+    data_dma_t bootrom_data, bootrom_data_q;
+    logic bootrom_req,  bootrom_req_q;
+
+    `FF(bootrom_data_q, bootrom_data, '0, clk_i, rst_ni)
+    `FF(bootrom_req_q,  bootrom_req,  '0, clk_i, rst_ni)
+
+    axi_to_mem #(
+      .axi_req_t (axi_slv_dma_req_t),
+      .axi_resp_t (axi_slv_dma_resp_t),
+      .AddrWidth (PhysicalAddrWidth),
+      .DataWidth (WideDataWidth),
+      .IdWidth (WideIdWidthOut),
+      .NumBanks (1)
+    ) i_axi_to_mem (
+      .clk_i (clk_i),
+      .rst_ni (rst_ni),
+      .busy_o (),
+      .axi_req_i (wide_axi_slv_req[BootRom]),
+      .axi_resp_o (wide_axi_slv_rsp[BootRom]),
+      .mem_req_o (bootrom_req),
+      .mem_gnt_i (bootrom_req),
+      .mem_addr_o (bootrom_addr),
+      .mem_wdata_o (),
+      .mem_strb_o (),
+      .mem_atop_o (),
+      .mem_we_o (),
+      .mem_rvalid_i (bootrom_req_q),
+      .mem_rdata_i (bootrom_data_q)
+    );
+
+    snitch_bootrom #(
+      .AddrWidth (PhysicalAddrWidth),
+      .DataWidth (WideDataWidth),
+      .BootromSize (BootRomSize * 1024)
+    ) i_bootrom (
+      .clk_i (clk_i),
+      .rst_ni (rst_ni),
+      .addr_i (bootrom_addr),
+      .data_o (bootrom_data)
+    );
+  end
+
   snitch_cluster_peripheral #(
     .reg_req_t (reg_req_t),
     .reg_rsp_t (reg_rsp_t),

hw/snitch_cluster/src/snitch_cluster_peripheral/snitch_cluster_peripheral_reg.hjson

@@ -4,10 +4,17 @@
 // Licensed under Solderpad Hardware License, Version 0.51, see LICENSE for details.
 {
     param_list: [
-        { name: "NumPerfCounters",
-        desc: "Number of performance counters",
-        type: "int",
-        default: "16"
+        {
+            name: "NumPerfCounters",
+            desc: "Number of performance counters",
+            type: "int",
+            default: "16"
+        },
+        {
+            name: "NumCtrlScratch",
+            desc: "Number of scratch registers",
+            type: "int",
+            default: "4"
         },
     ],
     name: "snitch_cluster_peripheral",
@@ -303,6 +310,22 @@
             }]
         }
     },
+    {
+        multireg: {
+            name: "SCRATCH",
+            desc: '''Scratch registers. Used in the bootrom for various purposes.'''
+            swaccess: "rw",
+            hwaccess: "none",
+            count: "NumCtrlScratch",
+            cname: "ctrl_scratch",
+            compact: "false",
+            fields: [{
+                bits: "31:0",
+                name: "SCRATCH",
+                desc: "Scratch register"
+            }]
+        }
+    },
     {
         name: "CL_CLINT_SET",
         desc: '''

hw/snitch_cluster/src/snitch_cluster_peripheral/snitch_cluster_peripheral_reg_pkg.sv

@@ -8,6 +8,7 @@ package snitch_cluster_peripheral_reg_pkg;
 
   // Param list
   parameter int NumPerfCounters = 16;
+  parameter int NumCtrlScratch = 4;
 
   // Address widths within the block
   parameter int BlockAw = 9;
@@ -128,9 +129,13 @@ package snitch_cluster_peripheral_reg_pkg;
   parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_13_OFFSET = 9'h 168;
   parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_14_OFFSET = 9'h 170;
   parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_15_OFFSET = 9'h 178;
-  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_SET_OFFSET = 9'h 180;
-  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_CLEAR_OFFSET = 9'h 188;
-  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_ICACHE_PREFETCH_ENABLE_OFFSET = 9'h 190;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_0_OFFSET = 9'h 180;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_1_OFFSET = 9'h 188;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_2_OFFSET = 9'h 190;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_3_OFFSET = 9'h 198;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_SET_OFFSET = 9'h 1a0;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_CLEAR_OFFSET = 9'h 1a8;
+  parameter logic [BlockAw-1:0] SNITCH_CLUSTER_PERIPHERAL_ICACHE_PREFETCH_ENABLE_OFFSET = 9'h 1b0;
 
   // Reset values for hwext registers and their fields
   parameter logic [31:0] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_SEL_0_RESVAL = 32'h 0;
@@ -218,13 +223,17 @@ package snitch_cluster_peripheral_reg_pkg;
     SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_13,
     SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_14,
     SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_15,
+    SNITCH_CLUSTER_PERIPHERAL_SCRATCH_0,
+    SNITCH_CLUSTER_PERIPHERAL_SCRATCH_1,
+    SNITCH_CLUSTER_PERIPHERAL_SCRATCH_2,
+    SNITCH_CLUSTER_PERIPHERAL_SCRATCH_3,
     SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_SET,
     SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_CLEAR,
     SNITCH_CLUSTER_PERIPHERAL_ICACHE_PREFETCH_ENABLE
   } snitch_cluster_peripheral_id_e;
 
   // Register width information to check illegal writes
-  parameter logic [3:0] SNITCH_CLUSTER_PERIPHERAL_PERMIT [51] = '{
+  parameter logic [3:0] SNITCH_CLUSTER_PERIPHERAL_PERMIT [55] = '{
     4'b 0001, // index[ 0] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_EN_0
     4'b 0001, // index[ 1] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_EN_1
     4'b 0001, // index[ 2] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_EN_2
@@ -273,9 +282,13 @@ package snitch_cluster_peripheral_reg_pkg;
     4'b 1111, // index[45] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_13
     4'b 1111, // index[46] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_14
     4'b 1111, // index[47] SNITCH_CLUSTER_PERIPHERAL_PERF_CNT_15
-    4'b 1111, // index[48] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_SET
-    4'b 1111, // index[49] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_CLEAR
-    4'b 0001  // index[50] SNITCH_CLUSTER_PERIPHERAL_ICACHE_PREFETCH_ENABLE
+    4'b 1111, // index[48] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_0
+    4'b 1111, // index[49] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_1
+    4'b 1111, // index[50] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_2
+    4'b 1111, // index[51] SNITCH_CLUSTER_PERIPHERAL_SCRATCH_3
+    4'b 1111, // index[52] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_SET
+    4'b 1111, // index[53] SNITCH_CLUSTER_PERIPHERAL_CL_CLINT_CLEAR
+    4'b 0001  // index[54] SNITCH_CLUSTER_PERIPHERAL_ICACHE_PREFETCH_ENABLE
   };
 
 endpackage