mmu cleanup

pipelined/src/mmu/mmu.sv

@@ -24,76 +24,56 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-
 `include "wally-config.vh"
 
-module mmu #(parameter TLB_ENTRIES = 8, // number of TLB Entries
+module mmu #(parameter TLB_ENTRIES = 8, IMMU = 0) (
-             parameter IMMU = 0) (
-
   input logic                 clk, reset,
-  // Current value of satp CSR (from privileged unit)
+  input logic [`XLEN-1:0]     SATP_REGW,          // Current value of satp CSR (from privileged unit)
-  input logic [`XLEN-1:0]     SATP_REGW,
+  input logic                 STATUS_MXR, STATUS_SUM, STATUS_MPRV, // Status bits affecting translation
-  input logic                 STATUS_MXR, STATUS_SUM, STATUS_MPRV,
+  input logic [1:0]           STATUS_MPP,         // previous machine privilege level
-  input logic [1:0]           STATUS_MPP,
+  input logic [1:0]           PrivilegeModeW,     // Current privilege level of the processeor
-
+  input logic                 DisableTranslation, // virtual address translation disabled during D$ flush and HPTW walk that use physical addresses
-  // Current privilege level of the processeor
+  input logic [`XLEN+1:0]     VAdr,               // virtual/physical address from IEU or physical address from HPTW
-  input logic [1:0]           PrivilegeModeW,
+  input logic [1:0]           Size,               // access size: 00 = 8 bits, 01 = 16 bits, 10 = 32 bits , 11 = 64 bits
-
+  input logic [`XLEN-1:0]     PTE,                // page table entry
-  // 00 - TLB is not being accessed
+  input logic [1:0]           PageTypeWriteVal,   // page type
-  // 1x - TLB is accessed for a read (or an instruction)
+  input logic                 TLBWrite,           // write TLB entry
-  // x1 - TLB is accessed for a write
+  input logic                 TLBFlush,           // Invalidate all TLB entries
-  // 11 - TLB is accessed for both read and write
+  output logic [`PA_BITS-1:0] PhysicalAddress,    // PAdr when no translation, or translated VAdr (TLBPAdr) when there is translation
-  input logic                 DisableTranslation,
+  output logic                TLBMiss,            // Miss TLB
-
+  output logic                Cacheable,          // PMA indicates memory address is cachable
-  // VAdr is the virtual/physical address from IEU or physical address from HPTW.
+  output logic                Idempotent,         // PMA indicates memory address is idempotent
-  // PhysicalAddress is selected to be PAdr when no translation or the translated VAdr (TLBPAdr)
+  output logic                SelTIM,             // Select a tightly integrated memory
-  // when there is translation.
-  input logic [`XLEN+1:0]     VAdr,
-  input logic [1:0]           Size, // 00 = 8 bits, 01 = 16 bits, 10 = 32 bits , 11 = 64 bits
-
-  // Controls for writing a new entry to the TLB
-  input logic [`XLEN-1:0]     PTE,
-  input logic [1:0]           PageTypeWriteVal,
-  input logic                 TLBWrite,
-
-  // Invalidate all TLB entries
-  input logic                 TLBFlush,
-
-  // Physical address outputs
-  output logic [`PA_BITS-1:0] PhysicalAddress,
-  output logic                TLBMiss,
-  output logic                Cacheable, Idempotent, SelTIM,
-
   // Faults
-  output logic                InstrAccessFaultF, LoadAccessFaultM, StoreAmoAccessFaultM,
+  output logic                InstrAccessFaultF, LoadAccessFaultM, StoreAmoAccessFaultM,  // access fault sources
-  output logic                InstrPageFaultF, LoadPageFaultM, StoreAmoPageFaultM,
+  output logic                InstrPageFaultF, LoadPageFaultM, StoreAmoPageFaultM,        // page fault sources
-  output logic                DAPageFault,
+  output logic                DAPageFault,                                                // page fault due to setting dirty or access bit
-  output logic                LoadMisalignedFaultM, StoreAmoMisalignedFaultM,
+  output logic                LoadMisalignedFaultM, StoreAmoMisalignedFaultM,             // misaligned fault sources
-
   // PMA checker signals
-  input logic                 AtomicAccessM, ExecuteAccessF, WriteAccessM, ReadAccessM,
+  input logic                 AtomicAccessM, ExecuteAccessF, WriteAccessM, ReadAccessM,   // access type
-  input var                   logic [7:0] PMPCFG_ARRAY_REGW[`PMP_ENTRIES-1:0],
+  input var logic [7:0]       PMPCFG_ARRAY_REGW[`PMP_ENTRIES-1:0],                        // PMP configuration
-  input var                   logic [`XLEN-1:0] PMPADDR_ARRAY_REGW [`PMP_ENTRIES-1:0]
+  input var logic [`XLEN-1:0] PMPADDR_ARRAY_REGW[`PMP_ENTRIES-1:0]                        // PMP addresses
 );
 
-  logic [`PA_BITS-1:0] TLBPAdr;
+  logic [`PA_BITS-1:0]        TLBPAdr;                  // physical address for TLB                   
-  // Translation lookaside buffer
+  logic                       PMAInstrAccessFaultF;     // Instruction access fault from PMA
-
+  logic                       PMPInstrAccessFaultF;     // Instruction access fault from PMP
-  logic PMAInstrAccessFaultF, PMPInstrAccessFaultF;
+  logic                       PMALoadAccessFaultM;      // Load access fault from PMA
-  logic PMALoadAccessFaultM, PMPLoadAccessFaultM;
+  logic                       PMPLoadAccessFaultM;      // Load access fault from PMP
-  logic PMAStoreAmoAccessFaultM, PMPStoreAmoAccessFaultM;
+  logic                       PMAStoreAmoAccessFaultM;  // Store or AMO access fault from PMA
-  logic DataMisalignedM;
+  logic                       PMPStoreAmoAccessFaultM;  // Store or AMO access fault from PMP
-  logic Translate;
+  logic                       DataMisalignedM;          // load or store misaligned
-  logic TLBHit;
+  logic                       Translate;                // Translation occurs when virtual memory is active and DisableTranslation is off
-  logic TLBPageFault;
+  logic                       TLBHit;                   // Hit in TLB
+  logic                       TLBPageFault;             // Page fault from TLB
   
   // only instantiate TLB if Virtual Memory is supported
   if (`VIRTMEM_SUPPORTED) begin:tlb
     logic ReadAccess, WriteAccess;
     assign ReadAccess = ExecuteAccessF | ReadAccessM; // execute also acts as a TLB read.  Execute and Read are never active for the same MMU, so safe to mix pipestages
     assign WriteAccess = WriteAccessM;
-    tlb #(.TLB_ENTRIES(TLB_ENTRIES), .ITLB(IMMU)) 
+    tlb #(.TLB_ENTRIES(TLB_ENTRIES), .ITLB(IMMU)) tlb(
-      tlb(.clk, .reset,
+          .clk, .reset,
           .SATP_MODE(SATP_REGW[`XLEN-1:`XLEN-`SVMODE_BITS]),
           .SATP_ASID(SATP_REGW[`ASID_BASE+`ASID_BITS-1:`ASID_BASE]),
           .VAdr(VAdr[`XLEN-1:0]), .STATUS_MXR, .STATUS_SUM, .STATUS_MPRV, .STATUS_MPP,
@@ -111,11 +91,9 @@ module mmu #(parameter TLB_ENTRIES = 8, // number of TLB Entries
   // If translation is occuring, select translated physical address from TLB
   // the lower 12 bits are the page offset. These are never changed from the orginal
   // non translated address.
-  //mux2 #(`PA_BITS) addressmux(PAdr, TLBPAdr, Translate, PhysicalAddress);
   mux2 #(`PA_BITS-12) addressmux(VAdr[`PA_BITS-1:12], TLBPAdr[`PA_BITS-1:12], Translate, PhysicalAddress[`PA_BITS-1:12]);
   assign PhysicalAddress[11:0] = VAdr[11:0];
   
-  
   ///////////////////////////////////////////
   // Check physical memory accesses
   ///////////////////////////////////////////