[1/4] monitor: add device info infrastructure

diff --git a/monitor.c b/monitor.c
index a1ebc5d..9bb1a30 100644
--- a/monitor.c
+++ b/monitor.c
@@ -129,6 +129,13 @@  typedef struct MonitorControl {
     int command_mode;
 } MonitorControl;

+/* Callback for device info command */
+struct MonDevInfoEntry {
+    const struct MonDevInfo *dev_info;
+    void *dev_opaque;
+    QLIST_ENTRY(MonDevInfoEntry) next;
+};
+
 struct Monitor {
     CharDriverState *chr;
     int mux_out;
@@ -147,6 +154,7 @@  struct Monitor {
 #endif
     QError *error;
     QLIST_HEAD(,mon_fd_t) fds;
+    QLIST_HEAD(,MonDevInfoEntry) dev_infos;
     QLIST_ENTRY(Monitor) entry;
 };

@@ -2494,6 +2502,21 @@  int monitor_get_fd(Monitor *mon, const char *fdname)
     return -1;
 }

+static void do_info_device(Monitor *mon, const QDict *qdict)
+{
+    struct MonDevInfoEntry *entry;
+    const char *name;
+
+    name = qdict_get_str(qdict, "devname");
+
+    QLIST_FOREACH(entry, &mon->dev_infos, next) {
+        if (strcmp(entry->dev_info->dev_name, name) != 0) {
+            continue;
+        }
+        entry->dev_info->dev_info_cb(mon, entry->dev_opaque);
+    }
+}
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },
@@ -4166,6 +4189,13 @@  static void monitor_find_completion(const char *cmdline)
                 for (cmd = mon_cmds; cmd->name != NULL; cmd++) {
                     cmd_completion(str, cmd->name);
                 }
+            } else if (!strcmp(cmd->name, "dev_info")) {
+                struct MonDevInfoEntry *entry;
+
+                readline_set_completion_index(cur_mon->rs, strlen(str));
+                QLIST_FOREACH(entry, &cur_mon->dev_infos, next) {
+                    cmd_completion(str, entry->dev_info->dev_name);
+                }
             }
             break;
         default:
@@ -4680,3 +4710,14 @@  int monitor_read_bdrv_key_start(Monitor *mon,
BlockDriverState *bs,

     return err;
 }
+
+void monitor_register_device_info(const struct MonDevInfo *dev_info,
+                                  void *dev_opaque)
+{
+    struct MonDevInfoEntry *entry;
+
+    entry = qemu_malloc(sizeof(*entry));
+    entry->dev_info = dev_info;
+    entry->dev_opaque = dev_opaque;
+    QLIST_INSERT_HEAD(&cur_mon->dev_infos, entry, next);
+}
diff --git a/monitor.h b/monitor.h
index ea15469..472f367 100644
--- a/monitor.h
+++ b/monitor.h
@@ -43,6 +43,16 @@  int monitor_read_bdrv_key_start(Monitor *mon,
BlockDriverState *bs,
                                 BlockDriverCompletionFunc *completion_cb,
                                 void *opaque);

+typedef void DeviceInfoFunc(Monitor *mon, void *opaque);
+
+struct MonDevInfo {
+    const char *dev_name;
+    DeviceInfoFunc *dev_info_cb;
+};
+
+void monitor_register_device_info(const struct MonDevInfo *dev_info,
+                                  void *dev_opaque);
+
 int monitor_get_fd(Monitor *mon, const char *fdname);

 void monitor_vprintf(Monitor *mon, const char *fmt, va_list ap);
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index a8f194c..596025f 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -1182,6 +1182,19 @@  STEXI
 Enable the specified QMP capabilities
 ETEXI

+    {
+        .name       = "dev_info",
+        .args_type  = "devname:s",
+        .params     = "device name",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd = do_info_device,
+        .help       = "show device information",
+    },
+STEXI
+@item device @var{devicename}
+Show information about a device.
+ETEXI
+
 STEXI
 @end table
 ETEXI