ppc/pnv: add helpers for pnv-phb user devices

pnv_parent_qom_fixup() and pnv_parent_bus_fixup() are versions of the
helpers that were reverted by commit 9c10d86fee "ppc/pnv: Remove
user-created PHB{3,4,5} devices". They are needed to amend the QOM and
bus hierarchies of user created pnv-phbs, matching them with default
pnv-phbs.

A new helper pnv_phb_user_device_init() is created to handle
user-created devices setup. We're going to call it inside
pnv_phb_realize() in case we're realizing an user created device. This
will centralize all user device realated in a single spot, leaving the
realize functions of the phb3/phb4 backends untouched.

Another helper called pnv_chip_add_phb() was added to handle the
particularities of each chip version when adding a new PHB.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220811163950.578927-5-danielhb413@gmail.com>

hw/pci-host/pnv_phb.c

@@ -18,6 +18,38 @@
 #include "hw/qdev-properties.h"
 #include "qom/object.h"
 
+
+/*
+ * Set the QOM parent of an object child. If the device state
+ * associated with the child has an id, use it as QOM id. Otherwise
+ * use object_typename[index] as QOM id.
+ */
+static void pnv_parent_qom_fixup(Object *parent, Object *child, int index)
+{
+    g_autofree char *default_id =
+        g_strdup_printf("%s[%d]", object_get_typename(child), index);
+    const char *dev_id = DEVICE(child)->id;
+
+    if (child->parent == parent) {
+        return;
+    }
+
+    object_ref(child);
+    object_unparent(child);
+    object_property_add_child(parent, dev_id ? dev_id : default_id, child);
+    object_unref(child);
+}
+
+static void pnv_parent_bus_fixup(DeviceState *parent, DeviceState *child,
+                                 Error **errp)
+{
+    BusState *parent_bus = qdev_get_parent_bus(parent);
+
+    if (!qdev_set_parent_bus(child, parent_bus, errp)) {
+        return;
+    }
+}
+
 /*
  * Attach a root port device.
  *
@@ -41,6 +73,39 @@ static void pnv_phb_attach_root_port(PCIHostState *pci)
     pci_realize_and_unref(root, pci->bus, &error_fatal);
 }
 
+/*
+ * User created devices won't have the initial setup that default
+ * devices have. This setup consists of assigning a parent device
+ * (chip for PHB3, PEC for PHB4/5) that will be the QOM/bus parent
+ * of the PHB.
+ */
+static bool pnv_phb_user_device_init(PnvPHB *phb, Error **errp)
+{
+    PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
+    PnvChip *chip = pnv_get_chip(pnv, phb->chip_id);
+    Object *parent = NULL;
+
+    if (!chip) {
+        error_setg(errp, "invalid chip id: %d", phb->chip_id);
+        return false;
+    }
+
+    parent = pnv_chip_add_phb(chip, phb, errp);
+    if (!parent) {
+        return false;
+    }
+
+    /*
+     * Reparent user created devices to the chip to build
+     * correctly the device tree. pnv_xscom_dt() needs every
+     * PHB to be a child of the chip to build the DT correctly.
+     */
+    pnv_parent_qom_fixup(parent, OBJECT(phb), phb->phb_id);
+    pnv_parent_bus_fixup(DEVICE(chip), DEVICE(phb), errp);
+
+    return true;
+}
+
 static void pnv_phb_realize(DeviceState *dev, Error **errp)
 {
     PnvPHB *phb = PNV_PHB(dev);
@@ -74,6 +139,16 @@ static void pnv_phb_realize(DeviceState *dev, Error **errp)
     object_property_set_uint(phb->backend, "chip-id", phb->chip_id, errp);
     object_property_set_link(phb->backend, "phb-base", OBJECT(phb), errp);
 
+    /*
+     * Handle user created devices. User devices will not have a
+     * pointer to a chip (PHB3) and a PEC (PHB4/5).
+     */
+    if (!phb->chip && !phb->pec) {
+        if (!pnv_phb_user_device_init(phb, errp)) {
+            return;
+        }
+    }
+
     if (phb->version == 3) {
         object_property_set_link(phb->backend, "chip",
                                  OBJECT(phb->chip), errp);

hw/ppc/pnv.c

@@ -281,6 +281,26 @@ static void pnv_dt_icp(PnvChip *chip, void *fdt, uint32_t pir,
     g_free(reg);
 }
 
+/*
+ * Adds a PnvPHB to the chip. Returns the parent obj of the
+ * PHB which varies with each version (phb version 3 is parented
+ * by the chip, version 4 and 5 are parented by the PEC
+ * device).
+ *
+ * TODO: for version 3 we're still parenting the PHB with the
+ * chip. We should parent with a (so far not implemented)
+ * PHB3 PEC device.
+ */
+Object *pnv_chip_add_phb(PnvChip *chip, PnvPHB *phb, Error **errp)
+{
+    if (phb->version == 3) {
+        return OBJECT(chip);
+    } else {
+        /* phb4 support will be added later */
+        return NULL;
+    }
+}
+
 static void pnv_chip_power8_dt_populate(PnvChip *chip, void *fdt)
 {
     static const char compat[] = "ibm,power8-xscom\0ibm,xscom";

include/hw/ppc/pnv.h

@@ -234,6 +234,7 @@ struct PnvMachineState {
 };
 
 PnvChip *pnv_get_chip(PnvMachineState *pnv, uint32_t chip_id);
+Object *pnv_chip_add_phb(PnvChip *chip, PnvPHB *phb, Error **errp);
 
 #define PNV_FDT_ADDR          0x01000000
 #define PNV_TIMEBASE_FREQ     512000000ULL