platform-bus-device: use device plug callback instead of machine_done notifier

platform-bus were using machine_done notifier to get and map
(assign irq/mmio resources) dynamically added sysbus devices
after all '-device' options had been processed.
That however creates non obvious dependencies on ordering of
machine_done notifiers and requires carefull line juggling
to keep it working. For example see comment above
create_platform_bus() and 'straitforward' arm_load_kernel()
had to converted to machine_done notifier and that lead to
yet another machine_done notifier to keep it working
arm_register_platform_bus_fdt_creator().

Instead of hiding resource assignment in platform-bus-device
to magically initialize sysbus devices, use device plug
callback and assign resources explicitly at board level
at the moment each -device option is being processed.

That adds a bunch of machine declaration boiler plate to
e500plat board, similar to ARM/x86 but gets rid of hidden
machine_done notifier and would allow to remove the dependent
notifiers in ARM code simplifying it and making code flow
easier to follow.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-id: 1525691524-32265-3-git-send-email-imammedo@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 53 insertions, 21 deletions

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index 748a8d213b..826053edc8 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -222,16 +222,15 @@ static void sysbus_device_create_devtree(SysBusDevice *sbdev, void *opaque)
     }
 }
 
-static void platform_bus_create_devtree(const PPCE500MachineClass *pmc,
+static void platform_bus_create_devtree(PPCE500MachineState *pms,
                                         void *fdt, const char *mpic)
 {
+    const PPCE500MachineClass *pmc = PPCE500_MACHINE_GET_CLASS(pms);
     gchar *node = g_strdup_printf("/platform@%"PRIx64, pmc->platform_bus_base);
     const char platcomp[] = "qemu,platform\0simple-bus";
     uint64_t addr = pmc->platform_bus_base;
     uint64_t size = pmc->platform_bus_size;
     int irq_start = pmc->platform_bus_first_irq;
-    PlatformBusDevice *pbus;
-    DeviceState *dev;
 
     /* Create a /platform node that we can put all devices into */
 
@@ -246,22 +245,17 @@ static void platform_bus_create_devtree(const PPCE500MachineClass *pmc,
 
     qemu_fdt_setprop_phandle(fdt, node, "interrupt-parent", mpic);
 
-    dev = qdev_find_recursive(sysbus_get_default(), TYPE_PLATFORM_BUS_DEVICE);
-    pbus = PLATFORM_BUS_DEVICE(dev);
-
-    /* We can only create dt nodes for dynamic devices when they're ready */
-    if (pbus->done_gathering) {
-        PlatformDevtreeData data = {
-            .fdt = fdt,
-            .mpic = mpic,
-            .irq_start = irq_start,
-            .node = node,
-            .pbus = pbus,
-        };
+    /* Create dt nodes for dynamic devices */
+    PlatformDevtreeData data = {
+        .fdt = fdt,
+        .mpic = mpic,
+        .irq_start = irq_start,
+        .node = node,
+        .pbus = pms->pbus_dev,
+    };
 
-        /* Loop through all dynamic sysbus devices and create nodes for them */
-        foreach_dynamic_sysbus_device(sysbus_device_create_devtree, &data);
-    }
+    /* Loop through all dynamic sysbus devices and create nodes for them */
+    foreach_dynamic_sysbus_device(sysbus_device_create_devtree, &data);
 
     g_free(node);
 }
@@ -533,8 +527,8 @@ static int ppce500_load_device_tree(PPCE500MachineState *pms,
     }
     g_free(soc);
 
-    if (pmc->has_platform_bus) {
-        platform_bus_create_devtree(pmc, fdt, mpic);
+    if (pms->pbus_dev) {
+        platform_bus_create_devtree(pms, fdt, mpic);
     }
     g_free(mpic);
 
@@ -953,8 +947,9 @@ void ppce500_init(MachineState *machine)
         qdev_prop_set_uint32(dev, "num_irqs", pmc->platform_bus_num_irqs);
         qdev_prop_set_uint32(dev, "mmio_size", pmc->platform_bus_size);
         qdev_init_nofail(dev);
-        s = SYS_BUS_DEVICE(dev);
+        pms->pbus_dev = PLATFORM_BUS_DEVICE(dev);
 
+        s = SYS_BUS_DEVICE(pms->pbus_dev);
         for (i = 0; i < pmc->platform_bus_num_irqs; i++) {
             int irqn = pmc->platform_bus_first_irq + i;
             sysbus_connect_irq(s, i, qdev_get_gpio_in(mpicdev, irqn));
@@ -1097,6 +1092,7 @@ static const TypeInfo ppce500_info = {
     .name          = TYPE_PPCE500_MACHINE,
     .parent        = TYPE_MACHINE,
     .abstract      = true,
+    .instance_size = sizeof(PPCE500MachineState),
     .class_size    = sizeof(PPCE500MachineClass),
 };
 
diff --git a/hw/ppc/e500.h b/hw/ppc/e500.h
index 621403bd24..3fd9f825ca 100644
--- a/hw/ppc/e500.h
+++ b/hw/ppc/e500.h
@@ -2,11 +2,16 @@
 #define PPCE500_H
 
 #include "hw/boards.h"
+#include "hw/platform-bus.h"
 
 typedef struct PPCE500MachineState {
     /*< private >*/
     MachineState parent_obj;
 
+    /* points to instance of TYPE_PLATFORM_BUS_DEVICE if
+     * board supports dynamic sysbus devices
+     */
+    PlatformBusDevice *pbus_dev;
 } PPCE500MachineState;
 
 typedef struct PPCE500MachineClass {
diff --git a/hw/ppc/e500plat.c b/hw/ppc/e500plat.c
index f69aadb666..1a469ba69f 100644
--- a/hw/ppc/e500plat.c
+++ b/hw/ppc/e500plat.c
@@ -43,13 +43,40 @@ static void e500plat_init(MachineState *machine)
     ppce500_init(machine);
 }
 
+static void e500plat_machine_device_plug_cb(HotplugHandler *hotplug_dev,
+                                            DeviceState *dev, Error **errp)
+{
+    PPCE500MachineState *pms = PPCE500_MACHINE(hotplug_dev);
+
+    if (pms->pbus_dev) {
+        if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
+            platform_bus_link_device(pms->pbus_dev, SYS_BUS_DEVICE(dev));
+        }
+    }
+}
+
+static
+HotplugHandler *e500plat_machine_get_hotpug_handler(MachineState *machine,
+                                                    DeviceState *dev)
+{
+    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
+        return HOTPLUG_HANDLER(machine);
+    }
+
+    return NULL;
+}
+
 #define TYPE_E500PLAT_MACHINE  MACHINE_TYPE_NAME("ppce500")
 
 static void e500plat_machine_class_init(ObjectClass *oc, void *data)
 {
     PPCE500MachineClass *pmc = PPCE500_MACHINE_CLASS(oc);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
     MachineClass *mc = MACHINE_CLASS(oc);
 
+    mc->get_hotplug_handler = e500plat_machine_get_hotpug_handler;
+    hc->plug = e500plat_machine_device_plug_cb;
+
     pmc->pci_first_slot = 0x1;
     pmc->pci_nr_slots = PCI_SLOT_MAX - 1;
     pmc->fixup_devtree = e500plat_fixup_devtree;
@@ -77,6 +104,10 @@ static const TypeInfo e500plat_info = {
     .name          = TYPE_E500PLAT_MACHINE,
     .parent        = TYPE_PPCE500_MACHINE,
     .class_init    = e500plat_machine_class_init,
+    .interfaces    = (InterfaceInfo[]) {
+         { TYPE_HOTPLUG_HANDLER },
+         { }
+    }
 };
 
 static void e500plat_register_types(void)