[RFC v3 3/7] PCI: hv: Generify PCI probing

[Boqun Feng]

From: Arnd Bergmann <arnd@xxxxxxxx>

In order to support ARM64 Hyper-V PCI, we need to set up the bridge at
probing time because ARM64 is a PCI_DOMAIN_GENERIC arch and we don't
have pci_config_window (ARM64 sysdata) for a PCI root bus on Hyper-V, so
it's impossible to retrieve the information (e.g. PCI domains, irq
domains) from bus sysdata on ARM64 after creation.

Originally in create_root_hv_pci_bus(), pci_create_root_bus() is used to
create the root bus and the corresponding bridge based on x86 sysdata.
Now we create a bridge first and then call pci_scan_root_bus_bridge(),
which allows us to do the necessary set-ups for the bridge.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
 drivers/pci/controller/pci-hyperv.c | 58 +++++++++++++++--------------
 1 file changed, 30 insertions(+), 28 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 6511648271b2..ee9f8e27e2e8 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -450,6 +450,7 @@ enum hv_pcibus_state {
 
 struct hv_pcibus_device {
 	struct pci_sysdata sysdata;
+	struct pci_host_bridge *bridge;
 	/* Protocol version negotiated with the host */
 	enum pci_protocol_version_t protocol_version;
 	enum hv_pcibus_state state;
@@ -462,13 +463,10 @@ struct hv_pcibus_device {
 	struct resource *high_mmio_res;
 	struct completion *survey_event;
 	struct completion remove_event;
-	struct pci_bus *pci_bus;
 	spinlock_t config_lock;	/* Avoid two threads writing index page */
 	spinlock_t device_list_lock;	/* Protect lists below */
 	void __iomem *cfg_addr;
 
-	struct list_head resources_for_children;
-
 	struct list_head children;
 	struct list_head dr_list;
 
@@ -1803,7 +1801,7 @@ static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
 
 		slot_nr = PCI_SLOT(wslot_to_devfn(hpdev->desc.win_slot.slot));
 		snprintf(name, SLOT_NAME_SIZE, "%u", hpdev->desc.ser);
-		hpdev->pci_slot = pci_create_slot(hbus->pci_bus, slot_nr,
+		hpdev->pci_slot = pci_create_slot(hbus->bridge->bus, slot_nr,
 					  name, NULL);
 		if (IS_ERR(hpdev->pci_slot)) {
 			pr_warn("pci_create slot %s failed\n", name);
@@ -1833,7 +1831,7 @@ static void hv_pci_remove_slots(struct hv_pcibus_device *hbus)
 static void hv_pci_assign_numa_node(struct hv_pcibus_device *hbus)
 {
 	struct pci_dev *dev;
-	struct pci_bus *bus = hbus->pci_bus;
+	struct pci_bus *bus = hbus->bridge->bus;
 	struct hv_pci_dev *hv_dev;
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
@@ -1856,21 +1854,22 @@ static void hv_pci_assign_numa_node(struct hv_pcibus_device *hbus)
  */
 static int create_root_hv_pci_bus(struct hv_pcibus_device *hbus)
 {
-	/* Register the device */
-	hbus->pci_bus = pci_create_root_bus(&hbus->hdev->device,
-					    0, /* bus number is always zero */
-					    &hv_pcifront_ops,
-					    &hbus->sysdata,
-					    &hbus->resources_for_children);
-	if (!hbus->pci_bus)
-		return -ENODEV;
+	int error;
+	struct pci_host_bridge *bridge = hbus->bridge;
+
+	bridge->dev.parent = &hbus->hdev->device;
+	bridge->sysdata = &hbus->sysdata;
+	bridge->ops = &hv_pcifront_ops;
+
+	error = pci_scan_root_bus_bridge(bridge);
+	if (error)
+		return error;
 
 	pci_lock_rescan_remove();
-	pci_scan_child_bus(hbus->pci_bus);
 	hv_pci_assign_numa_node(hbus);
-	pci_bus_assign_resources(hbus->pci_bus);
+	pci_bus_assign_resources(bridge->bus);
 	hv_pci_assign_slots(hbus);
-	pci_bus_add_devices(hbus->pci_bus);
+	pci_bus_add_devices(bridge->bus);
 	pci_unlock_rescan_remove();
 	hbus->state = hv_pcibus_installed;
 	return 0;
@@ -2135,7 +2134,7 @@ static void pci_devices_present_work(struct work_struct *work)
 		 * because there may have been changes.
 		 */
 		pci_lock_rescan_remove();
-		pci_scan_child_bus(hbus->pci_bus);
+		pci_scan_child_bus(hbus->bridge->bus);
 		hv_pci_assign_numa_node(hbus);
 		hv_pci_assign_slots(hbus);
 		pci_unlock_rescan_remove();
@@ -2306,8 +2305,8 @@ static void hv_eject_device_work(struct work_struct *work)
 	/*
 	 * Ejection can come before or after the PCI bus has been set up, so
 	 * attempt to find it and tear down the bus state, if it exists.  This
-	 * must be done without constructs like pci_domain_nr(hbus->pci_bus)
-	 * because hbus->pci_bus may not exist yet.
+	 * must be done without constructs like pci_domain_nr(hbus->bridge->bus)
+	 * because hbus->bridge->bus may not exist yet.
 	 */
 	wslot = wslot_to_devfn(hpdev->desc.win_slot.slot);
 	pdev = pci_get_domain_bus_and_slot(hbus->sysdata.domain, 0, wslot);
@@ -2676,8 +2675,7 @@ static int hv_pci_allocate_bridge_windows(struct hv_pcibus_device *hbus)
 		/* Modify this resource to become a bridge window. */
 		hbus->low_mmio_res->flags |= IORESOURCE_WINDOW;
 		hbus->low_mmio_res->flags &= ~IORESOURCE_BUSY;
-		pci_add_resource(&hbus->resources_for_children,
-				 hbus->low_mmio_res);
+		pci_add_resource(&hbus->bridge->windows, hbus->low_mmio_res);
 	}
 
 	if (hbus->high_mmio_space) {
@@ -2696,8 +2694,7 @@ static int hv_pci_allocate_bridge_windows(struct hv_pcibus_device *hbus)
 		/* Modify this resource to become a bridge window. */
 		hbus->high_mmio_res->flags |= IORESOURCE_WINDOW;
 		hbus->high_mmio_res->flags &= ~IORESOURCE_BUSY;
-		pci_add_resource(&hbus->resources_for_children,
-				 hbus->high_mmio_res);
+		pci_add_resource(&hbus->bridge->windows, hbus->high_mmio_res);
 	}
 
 	return 0;
@@ -3027,6 +3024,7 @@ static void hv_put_dom_num(u16 dom)
 static int hv_pci_probe(struct hv_device *hdev,
 			const struct hv_vmbus_device_id *dev_id)
 {
+	struct pci_host_bridge *bridge;
 	struct hv_pcibus_device *hbus;
 	u16 dom_req, dom;
 	char *name;
@@ -3039,6 +3037,10 @@ static int hv_pci_probe(struct hv_device *hdev,
 	 */
 	BUILD_BUG_ON(sizeof(*hbus) > HV_HYP_PAGE_SIZE);
 
+	bridge = devm_pci_alloc_host_bridge(&hdev->device, 0);
+	if (!bridge)
+		return -ENOMEM;
+
 	/*
 	 * With the recent 59bb47985c1d ("mm, sl[aou]b: guarantee natural
 	 * alignment for kmalloc(power-of-two)"), kzalloc() is able to allocate
@@ -3060,6 +3062,8 @@ static int hv_pci_probe(struct hv_device *hdev,
 	hbus = kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
 	if (!hbus)
 		return -ENOMEM;
+
+	hbus->bridge = bridge;
 	hbus->state = hv_pcibus_init;
 	hbus->wslot_res_allocated = -1;
 
@@ -3097,7 +3101,6 @@ static int hv_pci_probe(struct hv_device *hdev,
 	refcount_set(&hbus->remove_lock, 1);
 	INIT_LIST_HEAD(&hbus->children);
 	INIT_LIST_HEAD(&hbus->dr_list);
-	INIT_LIST_HEAD(&hbus->resources_for_children);
 	spin_lock_init(&hbus->config_lock);
 	spin_lock_init(&hbus->device_list_lock);
 	spin_lock_init(&hbus->retarget_msi_interrupt_lock);
@@ -3303,9 +3306,9 @@ static int hv_pci_remove(struct hv_device *hdev)
 	if (hbus->state == hv_pcibus_installed) {
 		/* Remove the bus from PCI's point of view. */
 		pci_lock_rescan_remove();
-		pci_stop_root_bus(hbus->pci_bus);
+		pci_stop_root_bus(hbus->bridge->bus);
 		hv_pci_remove_slots(hbus);
-		pci_remove_root_bus(hbus->pci_bus);
+		pci_remove_root_bus(hbus->bridge->bus);
 		pci_unlock_rescan_remove();
 		hbus->state = hv_pcibus_removed;
 	}
@@ -3316,7 +3319,6 @@ static int hv_pci_remove(struct hv_device *hdev)
 
 	iounmap(hbus->cfg_addr);
 	hv_free_config_window(hbus);
-	pci_free_resource_list(&hbus->resources_for_children);
 	hv_pci_free_bridge_windows(hbus);
 	irq_domain_remove(hbus->irq_domain);
 	irq_domain_free_fwnode(hbus->sysdata.fwnode);
@@ -3402,7 +3404,7 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
  */
 static void hv_pci_restore_msi_state(struct hv_pcibus_device *hbus)
 {
-	pci_walk_bus(hbus->pci_bus, hv_pci_restore_msi_msg, NULL);
+	pci_walk_bus(hbus->bridge->bus, hv_pci_restore_msi_msg, NULL);
 }
 
 static int hv_pci_resume(struct hv_device *hdev)
-- 
2.30.2