Revert "[jtag_dmi_reg_frontdoor] Send an extra JTAG read after a DMI …

…request"

This reverts commit c592837.

Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>

hw/dv/sv/jtag_dmi_agent/jtag_dmi_reg_frontdoor.sv

@@ -22,8 +22,9 @@ class jtag_dmi_reg_frontdoor extends uvm_reg_frontdoor;
 
   virtual task body();
     csr_field_t         csr_or_fld;
-    uvm_reg_data_t      wdata = 0;
+    uvm_reg_data_t      wdata = 0, rdata;
     jtag_dtm_reg_block  jtag_dtm_ral = jtag_agent_cfg_h.jtag_dtm_ral;
+    jtag_dmi_op_rsp_e   op_rsp;
 
     // If the JTAG agent is sitting in reset, print a debug message and exit early
     if (jtag_agent_cfg_h.in_reset) begin
@@ -74,9 +75,26 @@ class jtag_dmi_reg_frontdoor extends uvm_reg_frontdoor;
     // soon, it may end up setting the in progress sticky bit, causing more time wasted.
     jtag_agent_cfg_h.vif.wait_tck(10);
 
-    // Poll for completion.
+    // Poll for completion. Reset DMI if the sticky bit 'InProgress' is set.
     `DV_SPINWAIT_EXIT(
-      read_dmi_over_jtag(jtag_dtm_ral, csr_or_fld);,
+      do begin
+        csr_rd(.ptr(jtag_dtm_ral.dmi), .value(rdata), .blocking(1));
+        op_rsp = jtag_dmi_op_rsp_e'(get_field_val(jtag_dtm_ral.dmi.op, rdata));
+        `uvm_info(`gfn, $sformatf("DMI CSR req status: %0s", op_rsp.name()), UVM_HIGH)
+        if (op_rsp == DmiOpInProgress) begin
+          csr_wr(.ptr(jtag_dtm_ral.dtmcs.dmireset), .value(1), .blocking(1), .predict(1));
+        end else begin
+          rw_info.status = op_rsp == DmiOpOk ? UVM_IS_OK : UVM_NOT_OK;
+          if (rw_info.kind == UVM_READ) begin
+            rdata = get_field_val(jtag_dtm_ral.dmi.data, rdata);
+            if (csr_or_fld.field != null) begin
+              rdata = get_field_val(csr_or_fld.field, rdata);
+            end
+            rw_info.value = new[1];
+            rw_info.value[0] = rdata;
+          end
+        end
+      end while (op_rsp == DmiOpInProgress);,
       begin
         fork
           wait(jtag_agent_cfg_h.in_reset);
@@ -90,56 +108,4 @@ class jtag_dmi_reg_frontdoor extends uvm_reg_frontdoor;
     jtag_dtm_ral_sem_h.put();
   endtask
 
-  // Use JTAG to read the contents of the DMI register
-  //
-  // If the underlying operation in rw_info is UVM_READ, this also updates rw_info.value to contain
-  // the requested register contents.
-  //
-  // For either direction (read or write), it waits until the DMI is running an operation.
-  task read_dmi_over_jtag(jtag_dtm_reg_block jtag_dtm_ral, csr_field_t csr_or_fld);
-    uvm_reg_data_t    dmi_data_rdata;
-    jtag_dmi_op_rsp_e op_rsp;
-    int               num_dones_seen = 0;
-
-    // This loop works around a confusing situation where TCK is running much faster than the main
-    // clock and the first JTAG read responds with DmiOpOk just as it discovers (too late) that
-    // there was actually an operation in progress. The next JTAG read correctly responds with
-    // DmiOpInProgress and the operation is done next time we see DmiOpOk (or DmiOpFailed).
-    //
-    // If we see two results other than DmiOpInProgress, we know that the operation is genuinely
-    // finished.
-    while (num_dones_seen < 2) begin
-      uvm_reg_data_t rdata;
-
-      csr_rd(.ptr(jtag_dtm_ral.dmi), .value(rdata), .blocking(1));
-      op_rsp = jtag_dmi_op_rsp_e'(get_field_val(jtag_dtm_ral.dmi.op, rdata));
-
-      // If DMI responds with DmiOpInProgress, it is telling us that an operation was running. That
-      // flag is sticky, so we need to follow up by writing 1 to "dmireset" over JTAG to clear the
-      // flag.
-      if (op_rsp == DmiOpInProgress) begin
-        csr_wr(.ptr(jtag_dtm_ral.dtmcs.dmireset), .value(1), .blocking(1), .predict(1));
-      end else begin
-        if (num_dones_seen == 0) begin
-          dmi_data_rdata = get_field_val(jtag_dtm_ral.dmi.data, rdata);
-        end
-
-        num_dones_seen++;
-      end
-    end
-
-    // At this point, we've seen two reads where op_rsp is not DmiOpInProgress. Use the results of
-    // the second read to populate rw_info. If we are doing a UVM_READ, this includes extracting the
-    // CSR or field from rdata.
-    rw_info.status = op_rsp == DmiOpOk ? UVM_IS_OK : UVM_NOT_OK;
-    if (rw_info.kind == UVM_READ) begin
-      if (csr_or_fld.field != null) begin
-        dmi_data_rdata = get_field_val(csr_or_fld.field, dmi_data_rdata);
-      end
-
-      rw_info.value = new[1];
-      rw_info.value[0] = dmi_data_rdata;
-    end
-  endtask
-
 endclass