PCI: pciehp: add auto option to pciehp_detect_mode

ACPI based hot-pluggable PCIe slot detection logic was added to
prevent the problem non hot-pluggable PCIe slot was detected as
hot-pluggable. The slot detection logic can be selected through
'pciehp_detect_mode', but it would be better if it is selected
automatically.

This patch adds 'auto' option for 'pciehp_detect_mode'. When it is
specified, pciehp judges which 'acpi' or 'pcie' should be used. It
seems that the physical slot number is duplicated among some slots on
most of the platforms with the above-mentioned problem. So 'auto' mode
uses this information to judge which 'acpi' or 'pcie' should be
used. That is, if duplicated physical slot numbers are detected,
'acpi' mode is used. This method is not perfect, but it's realistic.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/hotplug/pciehp_acpi.c

@@ -28,15 +28,18 @@
 
 #define PCIEHP_DETECT_PCIE	(0)
 #define PCIEHP_DETECT_ACPI	(1)
-#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_PCIE
+#define PCIEHP_DETECT_AUTO	(2)
+#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_AUTO
 
 static int slot_detection_mode;
 static char *pciehp_detect_mode;
 module_param(pciehp_detect_mode, charp, 0444);
 MODULE_PARM_DESC(pciehp_detect_mode,
-		 "Slot detection mode: pcie, acpi\n"
-		 "  pcie - Use PCIe based slot detection (default)\n"
-		 "  acpi - Use ACPI for slot detection\n");
+	 "Slot detection mode: pcie, acpi, auto\n"
+	 "  pcie          - Use PCIe based slot detection\n"
+	 "  acpi          - Use ACPI for slot detection\n"
+	 "  auto(default) - Auto select mode. Use acpi option if duplicate\n"
+	 "                  slot ids are found. Otherwise, use pcie option\n");
 
 static int is_ejectable(acpi_handle handle)
 {
@@ -103,12 +106,81 @@ static int __init parse_detect_mode(void)
 		return PCIEHP_DETECT_PCIE;
 	if (!strcmp(pciehp_detect_mode, "acpi"))
 		return PCIEHP_DETECT_ACPI;
+	if (!strcmp(pciehp_detect_mode, "auto"))
+		return PCIEHP_DETECT_AUTO;
 	warn("bad specifier '%s' for pciehp_detect_mode. Use default\n",
 	     pciehp_detect_mode);
 	return PCIEHP_DETECT_DEFAULT;
 }
 
+static struct pcie_port_service_id __initdata port_pci_ids[] = {
+	{
+		.vendor = PCI_ANY_ID,
+		.device = PCI_ANY_ID,
+		.port_type = PCIE_ANY_PORT,
+		.service_type = PCIE_PORT_SERVICE_HP,
+		.driver_data =  0,
+        }, { /* end: all zeroes */ }
+};
+
+static int __initdata dup_slot_id;
+static int __initdata acpi_slot_detected;
+static struct list_head __initdata dummy_slots = LIST_HEAD_INIT(dummy_slots);
+
+/* Dummy driver for dumplicate name detection */
+static int __init dummy_probe(struct pcie_device *dev,
+			      const struct pcie_port_service_id *id)
+{
+	int pos;
+	u32 slot_cap;
+	struct slot *slot, *tmp;
+	struct pci_dev *pdev = dev->port;
+	if (!(slot = kzalloc(sizeof(*slot), GFP_KERNEL)))
+		return -ENOMEM;
+	/* Note: pciehp_detect_mode != PCIEHP_DETECT_ACPI here */
+	if (pciehp_get_hp_hw_control_from_firmware(pdev))
+		return -ENODEV;
+	if (!(pos = pci_find_capability(pdev, PCI_CAP_ID_EXP)))
+		return -ENODEV;
+	pci_read_config_dword(pdev, pos + PCI_EXP_SLTCAP, &slot_cap);
+	slot->number = slot_cap >> 19;
+	list_for_each_entry(tmp, &dummy_slots, slot_list) {
+		if (tmp->number == slot->number)
+			dup_slot_id++;
+	}
+	list_add_tail(&slot->slot_list, &dummy_slots);
+	if (!acpi_slot_detected && pciehp_detect_acpi_slot(pdev->subordinate))
+		acpi_slot_detected = 1;
+	return -ENODEV;         /* dummy driver always returns error */
+}
+
+static struct pcie_port_service_driver __initdata dummy_driver = {
+        .name           = "pciehp_dummy",
+        .id_table       = port_pci_ids,
+        .probe          = dummy_probe,
+};
+
+static int __init select_detection_mode(void)
+{
+	struct slot *slot, *tmp;
+	pcie_port_service_register(&dummy_driver);
+	pcie_port_service_unregister(&dummy_driver);
+	list_for_each_entry_safe(slot, tmp, &dummy_slots, slot_list) {
+		list_del(&slot->slot_list);
+		kfree(slot);
+	}
+	if (acpi_slot_detected && dup_slot_id)
+		return PCIEHP_DETECT_ACPI;
+	return PCIEHP_DETECT_PCIE;
+}
+
 void __init pciehp_acpi_slot_detection_init(void)
 {
 	slot_detection_mode = parse_detect_mode();
+	if (slot_detection_mode != PCIEHP_DETECT_AUTO)
+		goto out;
+	slot_detection_mode = select_detection_mode();
+out:
+	if (slot_detection_mode == PCIEHP_DETECT_ACPI)
+		info("Using ACPI for slot detection.\n");
 }