[PATCH 15/17] ppc/pnv: Introduce user creatable pnv-phb4 devices

[Daniel Henrique Barboza <danielhb413@gmail.com>]

This patch introduces pnv-phb4 user creatable devices that are created
in a similar manner as pnv-phb3 devices, allowing the user to interact
with the PHBs directly instead of creating PCI Express Controllers that
will create a certain amount of PHBs per controller index.

First thing we need is to discover which stack will host the created
PHB, which is done by the new pnv_phb4_get_stack() function. During
pnv_phb4_realize() we'll inspect phb->stack to see if we're dealing with
an user creatable device or not. When using default settings, the
automatically created PHB4 devices will be realized with phb->stack
already assigned beforehand during PEC realize. In case we're dealing
with an user device, find its stack, set the PHB attributes based on the
stack it belongs and assign the PHB to the stack.

The xscom stack initialization takes place in pnv_pec_stk_realize() when
using default settings, but at that point we aren't aware of any user
PHB4 devices that will belong to the stack. In that case we'll postpone
xscom stack init until the the end of pnv_phb4_realize(), after all the
memory mappings of the PHB are done.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/pci-host/pnv_phb4.c     | 84 +++++++++++++++++++++++++++++++++++++-
 hw/pci-host/pnv_phb4_pec.c | 12 +++---
 hw/ppc/pnv.c               |  2 +
 3 files changed, 90 insertions(+), 8 deletions(-)

diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c
index 5b2f644662..7b53c12b7c 100644
--- a/hw/pci-host/pnv_phb4.c
+++ b/hw/pci-host/pnv_phb4.c
@@ -1244,6 +1244,41 @@ static void pnv_phb4_instance_init(Object *obj)
     object_initialize_child(obj, "source", &phb->xsrc, TYPE_XIVE_SOURCE);
 }
 
+static PnvPhb4PecStack *pnv_phb4_get_stack(PnvChip *chip, PnvPHB4 *phb,
+                                           Error **errp)
+{
+    Pnv9Chip *chip9 = NULL;
+    int chip_id = phb->chip_id;
+    int index = phb->phb_id;
+    int i, j;
+
+    if (chip->num_pecs == 0) {
+        /* Something weird happened. Bail out */
+        error_setg(errp, "chip id %d has no PCIE controllers", chip_id);
+        return NULL;
+    }
+
+    chip9 = PNV9_CHIP(chip);
+
+    for (i = 0; i < chip->num_pecs; i++) {
+        /*
+         * For each PEC, check the amount of stacks it supports
+         * and see if the given phb4 index matches a stack.
+         */
+        PnvPhb4PecState *pec = &chip9->pecs[i];
+
+        for (j = 0; j < pec->num_stacks; j++) {
+            if (index == pnv_pec_get_phb_id(pec, j)) {
+                return &pec->stacks[j];
+            }
+        }
+    }
+
+    error_setg(errp, "pnv-phb4 index %d didn't match any existing PEC",
+               chip_id);
+    return NULL;
+}
+
 static void pnv_phb4_realize(DeviceState *dev, Error **errp)
 {
     PnvPHB4 *phb = PNV_PHB4(dev);
@@ -1251,8 +1286,49 @@ static void pnv_phb4_realize(DeviceState *dev, Error **errp)
     XiveSource *xsrc = &phb->xsrc;
     int nr_irqs;
     char name[32];
+    PnvPhb4PecStack *stack = NULL;
+    bool stack_init_xscom = false;
+    Error *local_err = NULL;
 
-    assert(phb->stack);
+    /* User created PHB */
+    if (!phb->stack) {
+        PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
+        PnvChip *chip = pnv_get_chip(pnv, phb->chip_id);
+        BusState *s;
+
+        if (!chip) {
+            error_setg(errp, "invalid chip id: %d", phb->chip_id);
+            return;
+        }
+
+        stack = pnv_phb4_get_stack(chip, phb, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        object_property_set_int(OBJECT(phb), "index",
+                                phb->phb_id, &error_abort);
+
+        pnv_phb4_set_stack_phb_props(stack, phb);
+
+        /* Assign the phb to the stack */
+        stack->phb = phb;
+
+        /*
+         * Reparent user created devices to the chip to build
+         * correctly the device tree.
+         */
+        pnv_chip_parent_fixup(chip, OBJECT(phb), phb->phb_id);
+
+        s = qdev_get_parent_bus(DEVICE(chip));
+        if (!qdev_set_parent_bus(DEVICE(phb), s, &local_err)) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        stack_init_xscom = true;
+    }
 
     /* Set the "big_phb" flag */
     phb->big_phb = phb->phb_id == 0 || phb->phb_id == 3;
@@ -1305,6 +1381,10 @@ static void pnv_phb4_realize(DeviceState *dev, Error **errp)
         pnv_phb_attach_root_port(PCI_HOST_BRIDGE(phb),
                                  TYPE_PNV_PHB4_ROOT_PORT);
     }
+
+    if (stack_init_xscom) {
+        pnv_pec_init_stack_xscom(stack);
+    }
 }
 
 static const char *pnv_phb4_root_bus_path(PCIHostState *host_bridge,
@@ -1416,7 +1496,7 @@ static void pnv_phb4_class_init(ObjectClass *klass, void *data)
     dc->realize         = pnv_phb4_realize;
     device_class_set_props(dc, pnv_phb4_properties);
     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
-    dc->user_creatable  = false;
+    dc->user_creatable  = true;
 
     xfc->notify         = pnv_phb4_xive_notify;
 }
diff --git a/hw/pci-host/pnv_phb4_pec.c b/hw/pci-host/pnv_phb4_pec.c
index aa93ad3f10..27973779c5 100644
--- a/hw/pci-host/pnv_phb4_pec.c
+++ b/hw/pci-host/pnv_phb4_pec.c
@@ -574,13 +574,13 @@ static void pnv_pec_stk_realize(DeviceState *dev, Error **errp)
                           &pnv_pec_stk_pci_xscom_ops, stack, name,
                           PHB4_PEC_PCI_STK_REGS_COUNT);
 
-    /* PHB pass-through */
-    pnv_phb4_set_stack_phb_props(stack, stack->phb);
-    if (!sysbus_realize(SYS_BUS_DEVICE(&stack->phb), errp)) {
-        return;
+    /*
+     * There is no guarantee that stack->phb will be available
+     * at this point.
+     */
+    if (stack->phb) {
+        pnv_pec_init_stack_xscom(stack);
     }
-
-    pnv_pec_init_stack_xscom(stack);
 }
 
 static Property pnv_pec_stk_properties[] = {
diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index bf2607446a..e93e77cb2e 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -2270,6 +2270,8 @@ static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
                                   pnv_machine_get_endian, pnv_machine_set_endian);
     object_class_property_set_description(oc, "endianness",
                               "Change CPU initial endianness (default is big)");
+
+    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB4);
 }
 
 static void pnv_machine_power10_class_init(ObjectClass *oc, void *data)
-- 
2.33.1