script: add jtag_close to release the current probe

Lets a session hand a probe back (frees its USB handle) without opening
another, e.g. to flash two FPGAs on different probes in turn:
jtag_close, then jtag_open the next one and jtag_autoinit. Mirrors the
DeInit teardown jtagcore_loaddriver already does when switching drivers.

Also fix the help printer: no-arg commands (whose params slot is "")
printed an empty body because "" was treated as the terminator. Params
are now optional and the description always shows.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README.md

@@ -107,7 +107,7 @@ the full walkthrough (probe → proxy → flash) lives in
 | Category | Commands |
 |----------|----------|
 | Script control | `set`, `print`, `print_env_var`, `if`, `goto`, `call`, `return`, `rand`, `init_array`, `system`, `pause` |
-| Probe / chain | `jtag_probes`, `jtag_open`, `jtag_scan`, `jtag_autoinit`, `jtag_ndev`, `jtag_devices` |
+| Probe / chain | `jtag_probes`, `jtag_open`, `jtag_close`, `jtag_scan`, `jtag_autoinit`, `jtag_ndev`, `jtag_devices` |
 | BSDL / pins | `jtag_bsdl`, `jtag_pins`, `jtag_mode`, `jtag_pin_dir`, `jtag_pin_set`, `jtag_pin_get`, `jtag_push_pop` |
 | I²C / MDIO / SPI over BS pins (EXTEST) | `jtag_i2c_scl`, `jtag_i2c_sda`, `jtag_i2c_rd`, `jtag_i2c_wr`, `jtag_mdio_mdc`, `jtag_mdio_io`, `jtag_mdio_rd`, `jtag_mdio_wr`, `jtag_spi_cs/mosi/miso/clk`, `jtag_spi_xfer` |
 | FPGA registry | `fpga_list`, `fpga_info` |

modules/script/script.c

@@ -1157,19 +1157,20 @@ static int cmd_help(script_ctx *ctx, char *line)
                 not_found = 0;
                 ctx->script_printf(ctx, MSG_NONE, "Documentation of command '%s' :\n", cmdlist[i].command);
                 ctx->script_printf(ctx, MSG_NONE, "---------------------------------------------------\n");
-                j = 0;
+                // help[0] is the parameter list ("" when the command takes
-                while (strcmp(cmdlist[i].help[j], "")) {
+                // none); description lines follow, terminated by "".
-                    if (j == 0) {
+                if (cmdlist[i].help[0][0]) {
                     ctx->script_printf(ctx, MSG_NONE, "Parameters :\n");
-                        ctx->script_printf(ctx, MSG_NONE, "  %s\n", cmdlist[i].help[j]);
+                    ctx->script_printf(ctx, MSG_NONE, "  %s\n", cmdlist[i].help[0]);
-                    } else {
+                }
-                        if (j == 1) {
+                j = 1;
+                if (strcmp(cmdlist[i].help[j], "")) {
                     ctx->script_printf(ctx, MSG_NONE, "Description :\n");
-                        }
+                    while (strcmp(cmdlist[i].help[j], "")) {
                         ctx->script_printf(ctx, MSG_NONE, "  %s\n", cmdlist[i].help[j]);
-                    }
                         j++;
                     }
+                }
                 break;
             }
             i++;
@@ -1855,6 +1856,39 @@ static int cmd_open_probe(script_ctx *ctx, char *line)
     }
 }
 
+const char *cmd_close_probe_help[] = {
+    "",                                  // Arguments "1<arg>(type) ..."
+    "Release the currently open probe, freeing its USB handle.",
+    "Use it to hand the probe to another tool, or before driving a",
+    "second target on a different probe: jtag_close, then jtag_open the",
+    "other one and jtag_autoinit to rescan. (Opening another probe also",
+    "releases the current one, so jtag_close is only needed to fully let",
+    "go without immediately reopening.)",
+    ""
+};
+static int cmd_close_probe(script_ctx *ctx, char *line)
+{
+    jtag_core *jc;
+
+    (void)line;
+    jc = (jtag_core *)ctx->app_ctx;
+
+    if (jc->io_functions.drv_DeInit)
+    {
+        // Same teardown jtagcore_loaddriver does before switching drivers:
+        // call the driver's DeInit, then forget its function table so the
+        // chain looks probe-less until the next jtag_open.
+        jc->io_functions.drv_DeInit(jc);
+        memset(&jc->io_functions, 0, sizeof(jc->io_functions));
+        ctx->script_printf(ctx, MSG_INFO_0, "Probe released.\n");
+    }
+    else
+    {
+        ctx->script_printf(ctx, MSG_INFO_0, "No probe is open.\n");
+    }
+    return JTAG_CORE_NO_ERROR;
+}
+
 const char *cmd_load_bsdl_help[] = {
     "<file>(string) <device>(int)",
     "Load/attach a bsdl file to a device into the chain.",
@@ -3333,6 +3367,7 @@ cmd_list script_commands_list[] =
         {"init_array", cmd_initarray, cmd_initarray_help},
         {"jtag_probes", cmd_print_probes_list, cmd_print_probes_list_help},
         {"jtag_open", cmd_open_probe, cmd_open_probe_help},
+        {"jtag_close", cmd_close_probe, cmd_close_probe_help},
         {"jtag_autoinit", cmd_autoinit, cmd_autoinit_help},
         {"jtag_scan", cmd_init_and_scan, cmd_init_and_scan_help},
         {"jtag_ndev", cmd_print_nb_dev, cmd_print_nb_dev_help},