digilent: implement Init / DeInit

DmgrOpen + DjtgEnable + DjtgSetSpeed at 4 MHz (Adept rounds to the
nearest supported, e.g. 3.75 MHz on SMT2-NC). DeInit does the reverse.

An atexit hook also forces Close on process shutdown — leaving an open
HIF when libdjtg's C++ static destructors run triggers "pure virtual
method called".

modules/drivers/digilent_jtag/digilent_jtag_drv.c

@@ -7,6 +7,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <stdint.h>
 #include <dlfcn.h>
@@ -71,6 +72,21 @@ static struct {
 
 static int g_dj_loaded = 0; /* 0 = not tried, 1 = ok, -1 = failed */
 
+static DJ_HIF g_dj_hif = 0;
+static int    g_dj_open = 0;
+
+static void digilent_atexit_close(void)
+{
+    /* libdjtg/libdmgr are C++ internally — leaving an open HIF when
+     * their static destructors run triggers "pure virtual method called"
+     * during process shutdown. Force a clean Close from atexit. */
+    if (g_dj_open && g_dj.Disable && g_dj.Close) {
+        g_dj.Disable(g_dj_hif);
+        g_dj.Close(g_dj_hif);
+        g_dj_open = 0;
+    }
+}
+
 static int digilent_load(jtag_core *jc)
 {
     if (g_dj_loaded > 0) return 0;
@@ -115,6 +131,8 @@ static int digilent_load(jtag_core *jc)
     RESOLVE(PutTmsTdiBits,  libjtg, DjtgPutTmsTdiBits);
 #undef RESOLVE
 
+    atexit(digilent_atexit_close);
+
     g_dj_loaded = 1;
     return 0;
 
@@ -184,14 +202,67 @@ static int drv_Digilent_Detect(jtag_core *jc)
 
 static int drv_Digilent_Init(jtag_core *jc, int sub_drv, char *params)
 {
-    jtagcore_logs_printf(jc, MSG_ERROR,
+    DJ_DWORD frq_req = 4000000; /* 4 MHz — safe and fast enough for IDCODE/IR */
-        "drv_Digilent_Init : not yet implemented (step 3)\r\n");
+    DJ_DWORD frq_set = 0;
-    return -1;
+
+    (void)params;
+
+    if (g_dj_loaded != 1) {
+        jtagcore_logs_printf(jc, MSG_ERROR,
+            "drv_Digilent_Init : Adept libs not loaded\r\n");
+        return JTAG_CORE_BAD_PARAMETER;
+    }
+    if (sub_drv < 0 || sub_drv >= g_dj_num_probes) {
+        jtagcore_logs_printf(jc, MSG_ERROR,
+            "drv_Digilent_Init : sub_drv %d out of range (have %d)\r\n",
+            sub_drv, g_dj_num_probes);
+        return JTAG_CORE_BAD_PARAMETER;
+    }
+
+    if (g_dj_open) {
+        g_dj.Disable(g_dj_hif);
+        g_dj.Close(g_dj_hif);
+        g_dj_open = 0;
+    }
+
+    if (!g_dj.Open(&g_dj_hif, subdrv_list[sub_drv].drv_id)) {
+        jtagcore_logs_printf(jc, MSG_ERROR,
+            "drv_Digilent_Init : DmgrOpen(\"%s\") failed\r\n",
+            subdrv_list[sub_drv].drv_id);
+        return JTAG_CORE_BAD_PARAMETER;
+    }
+
+    if (!g_dj.Enable(g_dj_hif)) {
+        jtagcore_logs_printf(jc, MSG_ERROR,
+            "drv_Digilent_Init : DjtgEnable failed\r\n");
+        g_dj.Close(g_dj_hif);
+        return JTAG_CORE_BAD_PARAMETER;
+    }
+
+    if (!g_dj.SetSpeed(g_dj_hif, frq_req, &frq_set)) {
+        jtagcore_logs_printf(jc, MSG_WARNING,
+            "drv_Digilent_Init : DjtgSetSpeed failed, keeping default speed\r\n");
+    } else {
+        jtagcore_logs_printf(jc, MSG_INFO_0,
+            "drv_Digilent_Init : JTAG clock = %u Hz (requested %u)\r\n",
+            (unsigned)frq_set, (unsigned)frq_req);
+    }
+
+    g_dj_open = 1;
+    jtagcore_logs_printf(jc, MSG_INFO_0,
+        "drv_Digilent_Init : opened \"%s\"\r\n", subdrv_list[sub_drv].drv_id);
+    return JTAG_CORE_NO_ERROR;
 }
 
 static int drv_Digilent_DeInit(jtag_core *jc)
 {
-    return 0;
+    (void)jc;
+    if (g_dj_open) {
+        g_dj.Disable(g_dj_hif);
+        g_dj.Close(g_dj_hif);
+        g_dj_open = 0;
+    }
+    return JTAG_CORE_NO_ERROR;
 }
 
 static int drv_Digilent_TMS_xfer(jtag_core *jc, unsigned char *str_out, int size)