From a4d1a319f6f05ac39defda3748c2f04df2c01ccc Mon Sep 17 00:00:00 2001 From: Jason Lowe-Power Date: Mon, 16 Dec 2019 15:28:07 -0800 Subject: [PATCH] Update CSR to use reset functions for bundles Signed-off-by: Jason Lowe-Power --- src/main/scala/components/csr.scala | 210 ++++++++++++++++++++++------ 1 file changed, 165 insertions(+), 45 deletions(-) diff --git a/src/main/scala/components/csr.scala b/src/main/scala/components/csr.scala index 798f0f0f..294e6b2d 100644 --- a/src/main/scala/components/csr.scala +++ b/src/main/scala/components/csr.scala @@ -54,7 +54,7 @@ object MCSRs { //machine memory protection //DONT NEED - + //machine counter/timers val mcycle = 0xb00 //machine cycle counter val minstret = 0xb02 //machine instructions retured counter @@ -83,28 +83,77 @@ class MStatus extends Bundle{ val mpie = Bool() val wpri3 = Bool() //reserved, zero val spie = Bool() - val upie = Bool() + val upie = Bool() //interrupt enable val mie = Bool() //machine interrupt enable val wpri4 = Bool() //reserved, zero val sie = Bool() //supervisor interrupt enable val uie = Bool() //user interrupt enable + + def reset: MStatus = { + val w = Wire(new MStatus) + w.sd := false.B + w.wpri1 := 0.U + w.tsr := false.B + w.tw := false.B + w.tvm := false.B + w.mxr := false.B + w.sum := false.B + w.mprv := false.B + w.xs := 0.U + w.fs := 0.U + w.mpp := MCSRCmd.MPRV // machine mode + w.wpri2 := 0.U + w.spp := 0.U + w.mpie := false.B + w.wpri3 := false.B + w.spie := false.B + w.upie := false.B + w.mie := true.B // machine mode + w.wpri4 := false.B + w.sie := false.B + w.uie := false.B + w + } } class MISA extends Bundle{ val mxl = UInt(2.W) //rv32, 64 , 128 val wlrl = UInt(4.W) //reserved val extensions = UInt(26.W) //isa extensions + + def reset: MISA = { + val w = Wire(new MISA) + w.mxl := 1.U // 32-bit + w.wlrl := 0.U + w.extensions := (1 << 8).U // I only + w + } } class MVendorID extends Bundle{ val bank = UInt(25.W) val offset = UInt(7.W) + + def reset : MVendorID = { + // Use 0 since this is not a standard design + val w = Wire(new MVendorID) + w.bank := 0.U + w.offset := 0.U + w + } } class MTVec extends Bundle{ val base = UInt(30.W) val mode = UInt(2.W) + + def reset : MTVec = { + val w = Wire(new MTVec) + w.base := 0.U + w.mode := 0.U + w + } } class MIx extends Bundle{ @@ -121,6 +170,24 @@ class MIx extends Bundle{ val wpri4 = UInt(1.W) val ssix = Bool() val usix = Bool() + + def reset : MIx = { + val w = Wire(new MIx) + w.wpri1 := 0.U + w.meix := false.B + w.wpri2 := 0.U + w.seix := false.B + w.ueix := false.B + w.mtix := false.B + w.wpri3 := 0.U + w.stix := false.B + w.utix := false.B + w.msix := false.B + w.wpri4 := 0.U + w.ssix := false.B + w.usix := false.B + w + } } class XCounterEnInhibit extends Bundle{ @@ -156,11 +223,55 @@ class XCounterEnInhibit extends Bundle{ val ir = Bool() val tmzero = Bool() val cy = Bool() + + def reset : XCounterEnInhibit = { + val w = Wire(new XCounterEnInhibit) + w.hpm31 := false.B + w.hpm30 := false.B + w.hpm29 := false.B + w.hpm28 := false.B + w.hpm27 := false.B + w.hpm26 := false.B + w.hpm25 := false.B + w.hpm24 := false.B + w.hpm23 := false.B + w.hpm22 := false.B + w.hpm21 := false.B + w.hpm20 := false.B + w.hpm19 := false.B + w.hpm18 := false.B + w.hpm17 := false.B + w.hpm16 := false.B + w.hpm15 := false.B + w.hpm14 := false.B + w.hpm13 := false.B + w.hpm12 := false.B + w.hpm11 := false.B + w.hpm10 := false.B + w.hpm9 := false.B + w.hpm8 := false.B + w.hpm7 := false.B + w.hpm6 := false.B + w.hpm5 := false.B + w.hpm4 := false.B + w.hpm3 := false.B + w.ir := false.B + w.tmzero := false.B + w.cy := false.B + w + } } class MCause extends Bundle{ val interrupt = Bool() val exceptioncode = UInt(31.W) + + def reset : MCause = { + val w = Wire(new MCause) + w.interrupt := 0.U + w.exceptioncode := 0.U + w + } } object MCSRCmd{ @@ -173,7 +284,7 @@ object MCSRCmd{ val clear = 3.asUInt(size) val interrupt = 4.asUInt(size) val read = 5.asUInt(size) - + val SIZE = 3.W val MSB = 31 val LSB = 20 @@ -184,13 +295,13 @@ object MCSRCmd{ class CSRRegFile extends Module{ //INIT CSR val io = IO(new Bundle{ - val illegal_inst = Input(Bool())//an exception signal for a non existent instruction or bad fields + val illegal_inst = Input(Bool())//an exception signal for a non existent instruction or bad fields val retire_inst = Input(Bool())//asserted if a valid instruction has finished val pc = Input(UInt(32.W)) //current program counter value val read_data = Input(UInt(32.W))//data from reg file used in csr instructions val inst = Input(UInt(32.W)) //full instruction used for decoding csrs internally val immid = Input(UInt(32.W)) //sext immidiate for immidiate csr instructions - + val read_illegal = Output(Bool())//an exception raised interally by a bad csr inst, used to raise illegal inst signal val write_illegal = Output(Bool())//raised interally by a bad csr inst, used to raise illegal inst signal val system_illegal = Output(Bool())//bad syscall instruction raised interally, used to raise illegal inst signal @@ -204,60 +315,69 @@ class CSRRegFile extends Module{ }) io := DontCare - val reset_mstatus = WireInit(0.U.asTypeOf(new MStatus())) - reset_mstatus.mpp := MCSRCmd.MPRV//machine mode - reset_mstatus.mie := true.B//machine mode - //contains info about system interrupts and privlidge mode - val reg_mstatus = RegInit(reset_mstatus) + val reg_mstatus = RegInit((new MStatus).reset) + //exception program counter, set when exception raised val reg_mepc = Reg(UInt(32.W)) + + val reset_mcause = (new MCause).Lit( + _.interrupt -> false.B, + _.exceptioncode -> 0.U + ) //contains cause of exception - val reg_mcause = RegInit(0.U.asTypeOf(new MCause())) + val reg_mcause = RegInit((new MCause).reset) + //register that can hold data to assist with exceptions/traps val reg_mtval = Reg(UInt(32.W)) + //scratch register for trap handler, useful for switching between mode memory spaces val reg_mscratch = Reg(UInt(32.W)) + //register used to set time for when timer interrupt should be raised val reg_mtimecmp = Reg(UInt(64.W)) + //register to indicate if trap handler should go directly to a specifc modes' trap handler //rather than trap to machine mode then swap context to a less privileged mode. used to save //performance, our implementation does not implement hardware to do this. val reg_medeleg = Reg(UInt(32.W)) - //indicates if we have a pending iterrupt for different interrupt types and modes - val reg_mip = RegInit(0.U.asTypeOf(new MIx())) + //indicates if we have a pending interrupt for different interrupt types and modes + val reg_mip = RegInit((new MIx).reset) + //indicates which interrupts are enabled - val reg_mie = RegInit(0.U.asTypeOf(new MIx())) + val reg_mie = RegInit((new MIx).reset) + //used to halt cpu if WFI inst is seen, or can also just do nothing. This cpu doesn't //implement WFI inst....yet val reg_wfi = RegInit(false.B) + //trap vector/address - val reg_mtvec = RegInit(0.U.asTypeOf(new MTVec())) + val reg_mtvec = RegInit((new MTVec).reset) + //current cpu time given in cycles val reg_time = WideCounter(64) //number of instructions that have been completed val reg_instret = WideCounter(64, io.retire_inst) + //performance counters, not implemented - val reg_mcounterinhibit = RegInit(0.U.asTypeOf(new XCounterEnInhibit())) + val reg_mcounterinhibit = RegInit((new XCounterEnInhibit).reset) + //performance counter control - val reg_mcounteren = RegInit(0.U.asTypeOf(new XCounterEnInhibit())) + val reg_mcounteren = RegInit((new XCounterEnInhibit).reset) + //machine status, contains interrupt bits, and priviledge mode val read_mstatus = io.status.asUInt() - val isa_string = "I" - //takes user defined ISA string character by character and calculates ascii number for each, - //aligns the result to be a multiple of 2 then ors the results together to fit into MISA - //this tells the system what extensions are implemented - //val reg_misa = RegInit((BigInt(0) | isa_string.map(x => 1 << (x - 'A')).reduce(_|_)).U.asTypeOf(new MISA())) - //same as above but hardcoded for only I extension - val reg_misa = RegInit(16.U.asTypeOf(new MISA())) + + val reg_misa = RegInit((new MISA).reset) + //if we are a company we can hardcode our implementation info here - val reg_mvendorid = RegInit(0.U.asTypeOf(new MVendorID())) + val reg_mvendorid = RegInit((new MVendorID).reset) //this hashmap associates CSR addresses to the actual register contents //this is done to make decoding and working with csr's easier (avoid manual specification) val read_mapping = collection.mutable.LinkedHashMap[Int,Bits]( - MCSRs.mcounterinhibit -> reg_mcounterinhibit.asUInt, + MCSRs.mcounterinhibit -> reg_mcounterinhibit.asUInt, MCSRs.mcycle -> reg_time.value, MCSRs.minstret -> reg_instret.value, MCSRs.mimpid -> 0.U, @@ -274,13 +394,13 @@ class CSRRegFile extends Module{ MCSRs.mcause -> reg_mcause.asUInt(), MCSRs.mhartid -> 0.U, MCSRs.medeleg -> reg_medeleg, - MCSRs.mcycleh -> 0.U, + MCSRs.mcycleh -> 0.U, MCSRs.minstreth -> 0.U ) - + //CSR DECODE val cmd = WireInit(3.U(3.W)) - + when( io.inst(6, 0) === ("b1110011".U)){ switch(io.inst(14, 12)){ is("b011".U){ @@ -290,7 +410,7 @@ class CSRRegFile extends Module{ is("b111".U){ cmd := MCSRCmd.clear io.reg_write := true.B - } + } is("b010".U){ cmd := MCSRCmd.set io.reg_write := true.B @@ -316,7 +436,7 @@ class CSRRegFile extends Module{ cmd := MCSRCmd.nop io.reg_write := false.B } - + val csr = io.inst(MCSRCmd.MSB, MCSRCmd.LSB) val system_insn = cmd === MCSRCmd.interrupt val cpu_ren = cmd =/= MCSRCmd.nop && !system_insn @@ -340,7 +460,7 @@ class CSRRegFile extends Module{ val insn_wfi = system_insn && opcode(5) && priv_sufficient private def decodeAny(m: LinkedHashMap[Int,Bits]): Bool = m.map( { case(k: Int, _: Bits) => csr === k.U }).reduce(_ || _) - io.read_illegal := 3.U < csr(9,8) || !decodeAny(read_mapping) + io.read_illegal := 3.U < csr(9,8) || !decodeAny(read_mapping) io.write_illegal := csr(11,10).andR io.system_illegal := 3.U < csr(9,8) @@ -355,14 +475,14 @@ class CSRRegFile extends Module{ io.evec := "h80000000".U reg_mepc := io.pc // misaligned memory exceptions not supported... } - + //UNALIGNED MEM ACCESS /* when(io.???){ reg_mcause.interrupt := MCauses.misaligned_fetch & "h80000000".U reg_mcause.exceptioncode := MCauses.misaligned_fetch & "h7fffffff".U io.evec := "h80000000".U - reg_mepc := + reg_mepc := }.elsewhen(io.???){ reg_mcause.interrupt := MCauses.misaligned_load & "h80000000".U reg_mcause.exceptioncode := MCauses.misaligned_load & "h7fffffff".U @@ -411,22 +531,22 @@ class CSRRegFile extends Module{ when (wen) { //MISA IS FIXED IN THIS IMPLEMENATION - + //MVENDORID IS FIXED IN THIS IMPLEMENTATION //MARCHID IS FIXED IN THIS IMPLEMENTATION //MIMPID IS FIXED IN THIS IMPLEMENTATION - + //MHARTID IS FIXED IN THIS IMPLEMENTATION - + //MSTATUS /* Only need to worry about m mode interrupts so no need to worry about setting * mpie, mpp, and mie correctly with respect to other modes. * non implemented modes wired to 0 */ when (decoded_addr(MCSRs.mstatus)) { - val new_mstatus = wdata.asTypeOf(new MStatus()) + val new_mstatus = wdata.asTypeOf(new MStatus) reg_mstatus.mie := new_mstatus.mie reg_mstatus.mpie := new_mstatus.mpie //unused bits in mstatus m-mode only specified by spec @@ -443,14 +563,14 @@ class CSRRegFile extends Module{ reg_mstatus.xs := 0.U reg_mstatus.sd := 0.U } - + //MTVEC IS FIXED IN THIS IMPLEMENTATION //MDELEG DOES NOT EXIST IN M-MODE IMPLEMENTATION - + //MIDELEG DOES NOT EXIST IN M-MODE IMPLEMENTATION - + //MIP /* mtip read only, cleared on timercmp write * meip read only, set by external interrupt controller @@ -484,7 +604,7 @@ class CSRRegFile extends Module{ } //MCOUNTEREB IS FIXED IN THIS IMPLEMENTATION BECAUSE NO S | U MODE - + //MCOUNTINHIBIT /* stops counting cycles and retired instructions if need be * @@ -499,10 +619,10 @@ class CSRRegFile extends Module{ writeCounter(MCSRs.minstret, reg_instret, wdata) } } - + //MSCRATCH when (decoded_addr(MCSRs.mscratch)) { reg_mscratch := wdata } - + //MEPC /* hardcoded to be 32 bit aligned because no compressed isa last 2 bits 0 */ @@ -511,7 +631,7 @@ class CSRRegFile extends Module{ /* Only write to on interrupt for hardware. software can write whenever * masks msb and 5 lsb from wdata */ - when (decoded_addr(MCSRs.mcause)) { + when (decoded_addr(MCSRs.mcause)) { reg_mcause.interrupt := (wdata & ((BigInt(1) << (32-1)) + 31).U) & "h80000000".U /* only implement 5 LSBs and MSB */ reg_mcause.exceptioncode := (wdata & ((BigInt(1) << (32-1)) + 31).U) & "h7fffffff".U /* only implement 5 LSBs and MSB */