package Top { import Chisel._; import Node._; import Constants._; import scala.math._; // interface between I$ and pipeline/ITLB (32 bits wide) class ioImem(view: List[String] = null) extends Bundle (view) { val invalidate = Bool('input); val itlb_miss = Bool('input); val req_val = Bool('input); val req_rdy = Bool('output); val req_idx = Bits(PGIDX_BITS, 'input); val req_ppn = Bits(PPN_BITS, 'input); val resp_data = Bits(32, 'output); val resp_val = Bool('output); } // interface between I$ and memory (128 bits wide) class ioIcache(view: List[String] = null) extends Bundle (view) { val req_addr = UFix(PADDR_BITS, 'input); val req_val = Bool('input); val req_rdy = Bool('output); val resp_data = Bits(128, 'output); val resp_val = Bool('output); } class ioICacheDM extends Bundle() { val cpu = new ioImem(); val mem = new ioIcache().flip(); } // basic direct mapped instruction cache // 32 bit wide cpu port, 128 bit wide memory port, 64 byte cachelines // parameters : // lines = # cache lines class rocketICacheDM(lines: Int) extends Component { val io = new ioICacheDM(); val addrbits = PADDR_BITS; val indexbits = ceil(log10(lines)/log10(2)).toInt; val offsetbits = 6; val tagmsb = addrbits - 1; val taglsb = indexbits+offsetbits; val tagbits = addrbits-taglsb; val indexmsb = taglsb-1; val indexlsb = offsetbits; val offsetmsb = indexlsb-1; val offsetlsb = 2; val databits = 32; val s_reset :: s_ready :: s_request :: s_refill_wait :: s_refill :: s_resolve_miss :: Nil = Enum(6) { UFix() }; val state = Reg(resetVal = s_reset); val r_cpu_req_idx = Reg(resetVal = Bits(0, PGIDX_BITS)); val r_cpu_req_ppn = Reg(resetVal = Bits(0, PPN_BITS)); val r_cpu_req_val = Reg(resetVal = Bool(false)); when (io.cpu.req_val && io.cpu.req_rdy) { r_cpu_req_idx <== io.cpu.req_idx; } when (state === s_ready && r_cpu_req_val && !io.cpu.itlb_miss) { r_cpu_req_ppn <== io.cpu.req_ppn; } when (io.cpu.req_rdy) { r_cpu_req_val <== io.cpu.req_val; } otherwise { r_cpu_req_val <== Bool(false); } // refill counter val refill_count = Reg(resetVal = UFix(0,2)); when (io.mem.resp_val) { refill_count <== refill_count + UFix(1); } val tag_addr = Mux((state === s_refill_wait), r_cpu_req_idx(PGIDX_BITS-1,offsetbits), io.cpu.req_idx(PGIDX_BITS-1,offsetbits)).toUFix; val tag_we = (state === s_refill_wait) && io.mem.resp_val; val tag_array = Mem4(lines, r_cpu_req_ppn); tag_array.setReadLatency(SRAM_READ_LATENCY); // tag_array.setTarget('inst); val tag_rdata = tag_array.rw(tag_addr, r_cpu_req_ppn, tag_we); // valid bit array val vb_array = Reg(resetVal = Bits(0, lines)); when (io.cpu.invalidate) { vb_array <== Bits(0,lines); } when (tag_we) { vb_array <== vb_array.bitSet(r_cpu_req_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(1,1)); } val tag_valid = Reg(vb_array(tag_addr)).toBool; val tag_match = (tag_rdata === io.cpu.req_ppn); // data array val data_addr = Mux((state === s_refill_wait) || (state === s_refill), Cat(r_cpu_req_idx(PGIDX_BITS-1, offsetbits), refill_count), io.cpu.req_idx(PGIDX_BITS-1, offsetmsb-1)).toUFix; val data_array = Mem4(lines*4, io.mem.resp_data); data_array.setReadLatency(SRAM_READ_LATENCY); // data_array.setTarget('inst); val data_array_rdata = data_array.rw(data_addr, io.mem.resp_data, io.mem.resp_val); // output signals io.cpu.resp_val := !io.cpu.itlb_miss && (state === s_ready) && r_cpu_req_val && tag_valid && tag_match; io.cpu.req_rdy := !io.cpu.itlb_miss && (state === s_ready) && (!r_cpu_req_val || (tag_valid && tag_match)); io.cpu.resp_data := MuxLookup(r_cpu_req_idx(offsetmsb-2, offsetlsb).toUFix, data_array_rdata(127, 96), Array(UFix(2) -> data_array_rdata(95,64), UFix(1) -> data_array_rdata(63,32), UFix(0) -> data_array_rdata(31,0))); io.mem.req_val := (state === s_request); io.mem.req_addr := Cat(r_cpu_req_ppn, r_cpu_req_idx(PGIDX_BITS-1, offsetbits), Bits(0,2)).toUFix; // control state machine switch (state) { is (s_reset) { state <== s_ready; } is (s_ready) { when (io.cpu.itlb_miss) { state <== s_ready; } when (r_cpu_req_val && !(tag_valid && tag_match)) { state <== s_request; } } is (s_request) { when (io.mem.req_rdy) { state <== s_refill_wait; } } is (s_refill_wait) { when (io.mem.resp_val) { state <== s_refill; } } is (s_refill) { when (io.mem.resp_val && (refill_count === UFix(3,2))) { state <== s_resolve_miss; } } is (s_resolve_miss) { state <== s_ready; } } } }