[PATCH 3/6] PCI: introduce pci_trim_stale_devices()

[Mika Westerberg <mika.westerberg@linux.intel.com>]

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

The new function stops and removes the device if it doesn't respond.
If the device responds and it's a bus we apply the function to all
subdevices recursively.

It's useful for hotplug bus check case, when you need drop all unplugged
devices before looking for new ones.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/pci/remove.c | 20 ++++++++++++++++++++
 include/linux/pci.h  |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 8fc54b7..77b7a64 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -112,6 +112,26 @@ void pci_stop_and_remove_bus_device(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
 
+/**
+ * pci_trim_stale_devices - remove stale device or any stale child
+ */
+void pci_trim_stale_devices(struct pci_dev *dev)
+{
+	struct pci_bus *bus = dev->subordinate;
+	struct pci_dev *child, *tmp;
+	bool alive;
+	u32 l;
+
+	/* check if the device responds */
+	alive = pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &l, 0);
+	if (!alive)
+		pci_stop_and_remove_bus_device(dev);
+
+	if (alive && bus)
+		list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
+			pci_trim_stale_devices(child);
+}
+
 void pci_stop_root_bus(struct pci_bus *bus)
 {
 	struct pci_dev *child, *tmp;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3a24e4f..8f6e7a0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -754,6 +754,7 @@ struct pci_dev *pci_dev_get(struct pci_dev *dev);
 void pci_dev_put(struct pci_dev *dev);
 void pci_remove_bus(struct pci_bus *b);
 void pci_stop_and_remove_bus_device(struct pci_dev *dev);
+void pci_trim_stale_devices(struct pci_dev *dev);
 void pci_stop_root_bus(struct pci_bus *bus);
 void pci_remove_root_bus(struct pci_bus *bus);
 void pci_setup_cardbus(struct pci_bus *bus);
-- 
1.8.3.1