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rocket-chip/vsrc/DebugTransportModuleJtag.v

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Add JTAG DTM and test support in simulation Initial cut checkpoint which compiles and runs but there is some off-by-1 in the protocol Debugging the clock crossing logic checkpoint which works Clean up the AsyncMailbox black box
2016-08-19 18:46:43 +02:00
module DebugTransportModuleJtag (
//JTAG Interface
jtag_TDI,
jtag_TDO,
jtag_TCK,
jtag_TMS,
jtag_TRST,
jtag_DRV_TDO,
dtm_req_valid,
dtm_req_ready,
dtm_req_bits,
dtm_resp_valid,
dtm_resp_ready,
dtm_resp_bits
);
//--------------------------------------------------------
// Parameter Declarations
parameter DEBUG_DATA_BITS = 34;
parameter DEBUG_ADDR_BITS = 5; // Spec allows values are 5-7
parameter DEBUG_OP_BITS = 2; // OP and RESP are the same size.
parameter JTAG_VERSION = 4'h1;
parameter JTAG_PART_NUM = 16'h0E31; // E31
parameter JTAG_MANUF_ID = 11'h489; // As Assigned by JEDEC
localparam IR_BITS = 5;
localparam DEBUG_VERSION = 0;
// JTAG State Machine
localparam TEST_LOGIC_RESET = 4'h0;
localparam RUN_TEST_IDLE = 4'h1;
localparam SELECT_DR = 4'h2;
localparam CAPTURE_DR = 4'h3;
localparam SHIFT_DR = 4'h4;
localparam EXIT1_DR = 4'h5;
localparam PAUSE_DR = 4'h6;
localparam EXIT2_DR = 4'h7;
localparam UPDATE_DR = 4'h8;
localparam SELECT_IR = 4'h9;
localparam CAPTURE_IR = 4'hA;
localparam SHIFT_IR = 4'hB;
localparam EXIT1_IR = 4'hC;
localparam PAUSE_IR = 4'hD;
localparam EXIT2_IR = 4'hE;
localparam UPDATE_IR = 4'hF;
//RISCV DTM Registers (see RISC-V Debug Specification)
// All others are treated as 'BYPASS'.
localparam REG_BYPASS = 5'b11111;
localparam REG_IDCODE = 5'b00001;
localparam REG_DEBUG_ACCESS = 5'b10001;
localparam REG_DTM_INFO = 5'b10000;
localparam DBUS_REG_BITS = DEBUG_OP_BITS + DEBUG_ADDR_BITS + DEBUG_DATA_BITS;
localparam DBUS_REQ_BITS = DEBUG_OP_BITS + DEBUG_ADDR_BITS + DEBUG_DATA_BITS;
localparam DBUS_RESP_BITS = DEBUG_OP_BITS + DEBUG_DATA_BITS;
localparam SHIFT_REG_BITS = DBUS_REG_BITS;
//--------------------------------------------------------
// I/O Declarations
//JTAG SIDE
input jtag_TDI;
output reg jtag_TDO;
input jtag_TCK;
input jtag_TMS;
input jtag_TRST;
// To allow tri-state outside of this block.
output reg jtag_DRV_TDO;
// RISC-V Core Side
output dtm_req_valid;
input dtm_req_ready;
output [DBUS_REQ_BITS - 1 :0] dtm_req_bits;
input dtm_resp_valid;
output dtm_resp_ready;
input [DBUS_RESP_BITS - 1 : 0] dtm_resp_bits;
//--------------------------------------------------------
// Reg and Wire Declarations
reg [IR_BITS -1 : 0 ] irReg;
wire [31:0] idcode;
wire [31:0] dtminfo;
reg [DBUS_REG_BITS - 1 : 0] dbusReg;
reg dbusValidReg;
reg [3:0] jtagStateReg;
reg [SHIFT_REG_BITS -1 : 0] shiftReg;
reg doDbusWriteReg;
reg doDbusReadReg;
reg busyReg;
reg skipOpReg; // Skip op because we're busy.
reg downgradeOpReg; // Downgrade op because prev. op failed.
wire busy;
wire nonzeroResp;
wire [SHIFT_REG_BITS -1 : 0] busyResponse;
wire [SHIFT_REG_BITS -1 : 0] nonbusyResponse;
//--------------------------------------------------------
// Combo Logic
assign idcode = {JTAG_VERSION, JTAG_PART_NUM, JTAG_MANUF_ID, 1'h1};
wire [3:0] debugAddrBits = DEBUG_ADDR_BITS;
wire [3:0] debugVersion = DEBUG_VERSION;
assign dtminfo = {24'b0, debugAddrBits, debugVersion};
//busy, dtm_resp* is only valid during CAPTURE_DR,
// so these signals should only be used at that time.
// This assumes there is only one transaction in flight at a time.
assign busy = busyReg & ~dtm_resp_valid;
// This is needed especially for the first request.
assign nonzeroResp = dtm_resp_valid ? |{dtm_resp_bits[DEBUG_OP_BITS-1:0]} : 1'b0;
// Interface to DM.
// Note that this means dtm_resp_bits must only be used during CAPTURE_DR.
assign dtm_resp_ready = (jtagStateReg == CAPTURE_DR) &&
(irReg == REG_DEBUG_ACCESS) &&
dtm_resp_valid;
assign dtm_req_valid = dbusValidReg;
assign dtm_req_bits = dbusReg;
assign busyResponse = {{(DEBUG_ADDR_BITS + DEBUG_DATA_BITS){1'b0}},
{(DEBUG_OP_BITS){1'b1}}}; // Generalizing 'busy' to 'all-1'
assign nonbusyResponse = {dbusReg[(DEBUG_DATA_BITS + DEBUG_OP_BITS) +: DEBUG_ADDR_BITS] , // retain address bits from Req.
dtm_resp_bits[DEBUG_OP_BITS +: DEBUG_DATA_BITS] , // data
dtm_resp_bits[0 +: DEBUG_OP_BITS] // response
};
//--------------------------------------------------------
// Sequential Logic
// JTAG STATE MACHINE
always @(posedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
jtagStateReg <= TEST_LOGIC_RESET;
end else begin
case (jtagStateReg)
TEST_LOGIC_RESET : jtagStateReg <= jtag_TMS ? TEST_LOGIC_RESET : RUN_TEST_IDLE;
RUN_TEST_IDLE : jtagStateReg <= jtag_TMS ? SELECT_DR : RUN_TEST_IDLE;
SELECT_DR : jtagStateReg <= jtag_TMS ? SELECT_IR : CAPTURE_DR;
CAPTURE_DR : jtagStateReg <= jtag_TMS ? EXIT1_DR : SHIFT_DR;
SHIFT_DR : jtagStateReg <= jtag_TMS ? EXIT1_DR : SHIFT_DR;
EXIT1_DR : jtagStateReg <= jtag_TMS ? UPDATE_DR : PAUSE_DR;
PAUSE_DR : jtagStateReg <= jtag_TMS ? EXIT2_DR : PAUSE_DR;
EXIT2_DR : jtagStateReg <= jtag_TMS ? UPDATE_DR : SHIFT_DR;
UPDATE_DR : jtagStateReg <= jtag_TMS ? SELECT_DR : RUN_TEST_IDLE;
SELECT_IR : jtagStateReg <= jtag_TMS ? TEST_LOGIC_RESET : CAPTURE_IR;
CAPTURE_IR : jtagStateReg <= jtag_TMS ? EXIT1_IR : SHIFT_IR;
SHIFT_IR : jtagStateReg <= jtag_TMS ? EXIT1_IR : SHIFT_IR;
EXIT1_IR : jtagStateReg <= jtag_TMS ? UPDATE_IR : PAUSE_IR;
PAUSE_IR : jtagStateReg <= jtag_TMS ? EXIT2_IR : PAUSE_IR;
EXIT2_IR : jtagStateReg <= jtag_TMS ? UPDATE_IR : SHIFT_IR;
UPDATE_IR : jtagStateReg <= jtag_TMS ? SELECT_DR : RUN_TEST_IDLE;
endcase // case (jtagStateReg)
end // else: !if(jtag_TRST)
end // always @ (posedge jtag_TCK or posedge jtag_TRST)
// SHIFT REG
always @(posedge jtag_TCK) begin
case (jtagStateReg)
CAPTURE_IR : shiftReg <= {{(SHIFT_REG_BITS-1){1'b0}}, 1'b1}; //JTAG spec only says must end with 'b01.
SHIFT_IR : shiftReg <= {{(SHIFT_REG_BITS-IR_BITS){1'b0}}, jtag_TDI, shiftReg[IR_BITS-1 : 1]};
CAPTURE_DR : case (irReg)
REG_BYPASS : shiftReg <= {(SHIFT_REG_BITS){1'b0}};
REG_IDCODE : shiftReg <= {{(SHIFT_REG_BITS-32){1'b0}}, idcode};
REG_DTM_INFO : shiftReg <= {{(SHIFT_REG_BITS-32){1'b0}}, dtminfo};
REG_DEBUG_ACCESS : shiftReg <= busy ? busyResponse : nonbusyResponse;
default : //BYPASS
shiftReg <= {(SHIFT_REG_BITS){1'b0}};
endcase
SHIFT_DR : case (irReg)
REG_BYPASS : shiftReg <= {{(SHIFT_REG_BITS- 1){1'b0}}, jtag_TDI};
REG_IDCODE : shiftReg <= {{(SHIFT_REG_BITS-32){1'b0}}, jtag_TDI, shiftReg[31:1]};
REG_DTM_INFO : shiftReg <= {{(SHIFT_REG_BITS-32){1'b0}}, jtag_TDI, shiftReg[31:1]};
REG_DEBUG_ACCESS : shiftReg <= {jtag_TDI, shiftReg[SHIFT_REG_BITS -1 : 1 ]};
default: // BYPASS
shiftReg <= {{(SHIFT_REG_BITS- 1){1'b0}} , jtag_TDI};
endcase // case (irReg)
endcase // case (jtagStateReg)
end
// IR
always @(negedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
irReg <= REG_IDCODE;
end else if (jtagStateReg == TEST_LOGIC_RESET) begin
irReg <= REG_IDCODE;
end else if (jtagStateReg == UPDATE_IR) begin
irReg <= shiftReg[IR_BITS-1:0];
end
end
// Busy. We become busy when we first try to send a request.
// We stop being busy when we accept a response.
// This means that busyReg will still be set when we check it,
// so the logic for checking busy looks ahead.
always @(posedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
busyReg <= 1'b0;
end else if (dtm_req_valid) begin //UPDATE_DR onwards
busyReg <= 1'b1;
end else if (dtm_resp_valid & dtm_resp_ready) begin //only in CAPTURE_DR
busyReg <= 1'b0;
end
end // always @ (posedge jtag_TCK or posedge jtag_TRST)
// Downgrade/Skip. We make the decision to downgrade or skip
// during every CAPTURE_DR, and use the result in UPDATE_DR.
always @(posedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
skipOpReg <= 1'b0;
downgradeOpReg <= 1'b0;
end else if (irReg == REG_DEBUG_ACCESS) begin
case(jtagStateReg)
CAPTURE_DR: begin
skipOpReg <= busy;
downgradeOpReg <= (~busy & nonzeroResp);
end
UPDATE_DR: begin
skipOpReg <= 1'b0;
downgradeOpReg <= 1'b0;
end
endcase // case (jtagStateReg)
end
end // always @ (posedge jtag_TCK or posedge jtag_TRST)
//dbusReg, dbusValidReg.
always @(posedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
dbusReg <= {(DBUS_REG_BITS) {1'b0}};
dbusValidReg <= 1'b0;
end else if (jtagStateReg == UPDATE_DR) begin
if (irReg == REG_DEBUG_ACCESS) begin
if (skipOpReg) begin
// do nothing.
end else if (downgradeOpReg) begin
dbusReg <= {(DBUS_REG_BITS){1'b0}}; // NOP has encoding 2'b00.
dbusValidReg <= 1'b1;
end else begin
dbusReg <= shiftReg[DBUS_REG_BITS-1:0];
dbusValidReg <= 1'b1;
end
end
end else if (dtm_req_ready) begin
dbusValidReg <= 1'b0;
end
end // always @ (negedge jtag_TCK or posedge jtag_TRST)
//TDO
always @(negedge jtag_TCK or posedge jtag_TRST) begin
if (jtag_TRST) begin
jtag_TDO <= 1'b0;
jtag_DRV_TDO <= 1'b0;
end else if (jtagStateReg == SHIFT_IR) begin
jtag_TDO <= shiftReg[0];
jtag_DRV_TDO <= 1'b1;
end else if (jtagStateReg == SHIFT_DR) begin
jtag_TDO <= shiftReg[0];
jtag_DRV_TDO <= 1'b1;
end else begin
jtag_TDO <= 1'b0;
jtag_DRV_TDO <= 1'b0;
end
end // always @ (negedge jtag_TCK or posedge jtag_TRST)
endmodule
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