sd: Hide the qdev-but-not-quite thing created by sd_init()

Commit 260bc9d8aa "hw/sd/sd.c: QOMify" QOMified only the device
itself, not its users.  It kept sd_init() around for non-QOMified
users.

More than four years later, three such users remain: omap1 (machines
cheetah, sx1, sx1-v1) and omap2 (machines n800, n810) are not
QOMified, and pl181 (machines integratorcp, realview-eb,
realview-eb-mpcore, realview-pb-a8 realview-pbx-a9, versatileab,
versatilepb, vexpress-a15, vexpress-a9) is not QOMified properly.

The issue I presently have with this: an "sd-card" device should plug
into an "sd-bus" (its DeviceClass member bus_type says so), but
sd_init() leaves it unplugged.  This is normally a bug (I just fixed
some instances), and I'd like to assert proper pluggedness to prevent
regressions.  However, the qdev-but-not-quite thing returned by
sd_init() would fail the assertion.  Meh.

Make sd_init() hide it from QOM/qdev.  Visible in "info qom-tree",
here's the change for cheetah:

     /machine (cheetah-machine)
       [...]
       /unattached (container)
         [...]
         /device[5] (serial-mm)
           /serial (serial)
           /serial[0] (qemu:memory-region)
    -    /device[6] (sd-card)
    -    /device[7] (omap-gpio)
    +    /device[6] (omap-gpio)
         [rest of device[*] renumbered...]

Cc: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200609122339.937862-24-armbru@redhat.com>

hw/sd/sd.c

@@ -83,6 +83,10 @@ enum SDCardStates {
 struct SDState {
     DeviceState parent_obj;
 
+    /* If true, created by sd_init() for a non-qdevified caller */
+    /* TODO purge them with fire */
+    bool me_no_qdev_me_kill_mammoth_with_rocks;
+
     /* SD Memory Card Registers */
     uint32_t ocr;
     uint8_t scr[8];
@@ -129,6 +133,8 @@ struct SDState {
     bool cmd_line;
 };
 
+static void sd_realize(DeviceState *dev, Error **errp);
+
 static const char *sd_state_name(enum SDCardStates state)
 {
     static const char *state_name[] = {
@@ -590,7 +596,7 @@ static void sd_cardchange(void *opaque, bool load, Error **errp)
 {
     SDState *sd = opaque;
     DeviceState *dev = DEVICE(sd);
-    SDBus *sdbus = SD_BUS(qdev_get_parent_bus(dev));
+    SDBus *sdbus;
     bool inserted = sd_get_inserted(sd);
     bool readonly = sd_get_readonly(sd);
 
@@ -601,19 +607,17 @@ static void sd_cardchange(void *opaque, bool load, Error **errp)
         trace_sdcard_ejected();
     }
 
-    /* The IRQ notification is for legacy non-QOM SD controller devices;
+    if (sd->me_no_qdev_me_kill_mammoth_with_rocks) {
-     * QOMified controllers use the SDBus APIs.
-     */
-    if (sdbus) {
-        sdbus_set_inserted(sdbus, inserted);
-        if (inserted) {
-            sdbus_set_readonly(sdbus, readonly);
-        }
-    } else {
         qemu_set_irq(sd->inserted_cb, inserted);
         if (inserted) {
             qemu_set_irq(sd->readonly_cb, readonly);
         }
+    } else {
+        sdbus = SD_BUS(qdev_get_parent_bus(dev));
+        sdbus_set_inserted(sdbus, inserted);
+        if (inserted) {
+            sdbus_set_readonly(sdbus, readonly);
+        }
     }
 }
 
@@ -697,6 +701,7 @@ SDState *sd_init(BlockBackend *blk, bool is_spi)
 {
     Object *obj;
     DeviceState *dev;
+    SDState *sd;
     Error *err = NULL;
 
     obj = object_new(TYPE_SD_CARD);
@@ -707,13 +712,24 @@ SDState *sd_init(BlockBackend *blk, bool is_spi)
         return NULL;
     }
     qdev_prop_set_bit(dev, "spi", is_spi);
-    object_property_set_bool(obj, true, "realized", &err);
+
+    /*
+     * Realizing the device properly would put it into the QOM
+     * composition tree even though it is not plugged into an
+     * appropriate bus.  That's a no-no.  Hide the device from
+     * QOM/qdev, and call its qdev realize callback directly.
+     */
+    object_ref(obj);
+    object_unparent(obj);
+    sd_realize(dev, &err);
     if (err) {
         error_reportf_err(err, "sd_init failed: ");
         return NULL;
     }
 
-    return SD_CARD(dev);
+    sd = SD_CARD(dev);
+    sd->me_no_qdev_me_kill_mammoth_with_rocks = true;
+    return sd;
 }
 
 void sd_set_cb(SDState *sd, qemu_irq readonly, qemu_irq insert)