PCI: Get rid of dev->has_secondary_link flag

In some systems, the Device/Port Type in the PCI Express Capabilities
register incorrectly identifies upstream ports as downstream ports.

d0751b98df ("PCI: Add dev->has_secondary_link to track downstream PCIe
links") addressed this by adding pci_dev.has_secondary_link, which is set
for downstream ports.  But this is confusing because pci_pcie_type()
sometimes gives the wrong answer, and it's not obvious that we should use
pci_dev.has_secondary_link instead.

Reduce the confusion by correcting the type of the port itself so that
pci_pcie_type() returns the actual type regardless of what the Device/Port
Type register claims it is.  Update the users to call pci_pcie_type() and
pcie_downstream_port() accordingly, and remove pci_dev.has_secondary_link
completely.

Link: https://lore.kernel.org/linux-pci/20190703133953.GK128603@google.com/
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20190822085553.62697-2-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/pci/pcie/aspm.c

@@ -913,10 +913,10 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
 
 	/*
 	 * We allocate pcie_link_state for the component on the upstream
-	 * end of a Link, so there's nothing to do unless this device has a
-	 * Link on its secondary side.
+	 * end of a Link, so there's nothing to do unless this device is
+	 * downstream port.
 	 */
-	if (!pdev->has_secondary_link)
+	if (!pcie_downstream_port(pdev))
 		return;
 
 	/* VIA has a strange chipset, root port is under a bridge */
@@ -1070,7 +1070,7 @@ static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
 	if (!pci_is_pcie(pdev))
 		return 0;
 
-	if (pdev->has_secondary_link)
+	if (pcie_downstream_port(pdev))
 		parent = pdev;
 	if (!parent || !parent->link_state)
 		return -EINVAL;

drivers/pci/pcie/err.c

@@ -166,7 +166,7 @@ static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service)
 	driver = pcie_port_find_service(dev, service);
 	if (driver && driver->reset_link) {
 		status = driver->reset_link(dev);
-	} else if (dev->has_secondary_link) {
+	} else if (pcie_downstream_port(dev)) {
 		status = default_reset_link(dev);
 	} else {
 		pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream device %s\n",