PCI: pciehp: add ACPI based slot detection

There is a problem that some non hot-pluggable PCIe slots are detected
as hot-pluggable by pciehp on some platforms. The immediate cause of
this problem is that hot-plug capable bit in the Slot Capabilities
register is set even for non hot-pluggable slots on those platforms.
It seems a BIOS/hardware problem, but we need workaround about that.

Some of those platforms define hot-pluggable PCIe slots on ACPI
namespace properly, while hot-plug capable bit in the Slot
Capabilities register is set improperly. So using ACPI namespace
information in pciehp to detect PCIe hot-pluggable slots would be a
workaround.

This patch adds 'pciehp_detect_mode' module option. When 'acpi' is
specified, pciehp uses ACPI namespace information to detect PCIe
hot-pluggable slots.

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

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index b2801a7ee37..27fd18f019f 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -220,11 +220,23 @@ struct hpc_ops {
 #include <acpi/actypes.h>
 #include <linux/pci-acpi.h>
 
+extern void __init pciehp_acpi_slot_detection_init(void);
+extern int pciehp_acpi_slot_detection_check(struct pci_dev *dev);
+
+static inline void pciehp_firmware_init(void)
+{
+        pciehp_acpi_slot_detection_init();
+}
+
 static inline int pciehp_get_hp_hw_control_from_firmware(struct pci_dev *dev)
 {
+        int retval;
         u32 flags = (OSC_PCI_EXPRESS_NATIVE_HP_CONTROL |
                      OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
-        return acpi_get_hp_hw_control_from_firmware(dev, flags);
+        retval = acpi_get_hp_hw_control_from_firmware(dev, flags);
+        if (retval)
+                return retval;
+        return pciehp_acpi_slot_detection_check(dev);
 }
 
 static inline int pciehp_get_hp_params_from_firmware(struct pci_dev *dev,
@@ -235,6 +247,7 @@ static inline int pciehp_get_hp_params_from_firmware(struct pci_dev *dev,
         return 0;
 }
 #else
+#define pciehp_firmware_init()                          do {} while (0)
 #define pciehp_get_hp_hw_control_from_firmware(dev)     0
 #define pciehp_get_hp_params_from_firmware(dev, hpp)    (-ENODEV)
 #endif                          /* CONFIG_ACPI */