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>

4 files changed, 132 insertions, 1 deletions

diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
index 9bdbe1a6688f..e31fb91652ce 100644
--- a/drivers/pci/hotplug/Makefile
+++ b/drivers/pci/hotplug/Makefile
@@ -55,6 +55,9 @@ pciehp-objs		:=	pciehp_core.o	\
                                 pciehp_ctrl.o   \
                                 pciehp_pci.o    \
                                 pciehp_hpc.o
+ifdef CONFIG_ACPI
+pciehp-objs             +=      pciehp_acpi.o
+endif
 
 shpchp-objs             :=      shpchp_core.o   \
                                 shpchp_ctrl.o   \
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index b2801a7ee37f..27fd18f019f8 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 */
diff --git a/drivers/pci/hotplug/pciehp_acpi.c b/drivers/pci/hotplug/pciehp_acpi.c
new file mode 100644
index 000000000000..0cd49b728045
--- /dev/null
+++ b/drivers/pci/hotplug/pciehp_acpi.c
@@ -0,0 +1,114 @@
+/*
+ * ACPI related functions for PCI Express Hot Plug driver.
+ *
+ * Copyright (C) 2008 Kenji Kaneshige
+ * Copyright (C) 2008 Fujitsu Limited.
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/acpi.h>
+#include "pciehp.h"
+
+#define PCIEHP_DETECT_PCIE      (0)
+#define PCIEHP_DETECT_ACPI      (1)
+#define PCIEHP_DETECT_DEFAULT   PCIEHP_DETECT_PCIE
+
+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");
+
+static int is_ejectable(acpi_handle handle)
+{
+        acpi_status status;
+        acpi_handle tmp;
+        unsigned long long removable;
+        status = acpi_get_handle(handle, "_ADR", &tmp);
+        if (ACPI_FAILURE(status))
+                return 0;
+        status = acpi_get_handle(handle, "_EJ0", &tmp);
+        if (ACPI_SUCCESS(status))
+                return 1;
+        status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
+        if (ACPI_SUCCESS(status) && removable)
+                return 1;
+        return 0;
+}
+
+static acpi_status
+check_hotplug(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+        int *found = (int *)context;
+        if (is_ejectable(handle)) {
+                *found = 1;
+                return AE_CTRL_TERMINATE;
+        }
+        return AE_OK;
+}
+
+static int pciehp_detect_acpi_slot(struct pci_bus *pbus)
+{
+        acpi_handle handle;
+        struct pci_dev *pdev = pbus->self;
+        int found = 0;
+
+        if (!pdev){
+                int seg = pci_domain_nr(pbus), busnr = pbus->number;
+                handle = acpi_get_pci_rootbridge_handle(seg, busnr);
+        } else
+                handle = DEVICE_ACPI_HANDLE(&(pdev->dev));
+
+        if (!handle)
+                return 0;
+
+        acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
+                            check_hotplug, (void *)&found, NULL);
+        return found;
+}
+
+int pciehp_acpi_slot_detection_check(struct pci_dev *dev)
+{
+        if (slot_detection_mode != PCIEHP_DETECT_ACPI)
+                return 0;
+        if (pciehp_detect_acpi_slot(dev->subordinate))
+                return 0;
+        return -ENODEV;
+}
+
+static int __init parse_detect_mode(void)
+{
+        if (!pciehp_detect_mode)
+                return PCIEHP_DETECT_DEFAULT;
+        if (!strcmp(pciehp_detect_mode, "pcie"))
+                return PCIEHP_DETECT_PCIE;
+        if (!strcmp(pciehp_detect_mode, "acpi"))
+                return PCIEHP_DETECT_ACPI;
+        warn("bad specifier '%s' for pciehp_detect_mode. Use default\n",
+             pciehp_detect_mode);
+        return PCIEHP_DETECT_DEFAULT;
+}
+
+void __init pciehp_acpi_slot_detection_init(void)
+{
+        slot_detection_mode = parse_detect_mode();
+}
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 39cf248d24e3..5482d4ed8256 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -522,6 +522,7 @@ static int __init pcied_init(void)
 {
         int retval = 0;
 
+        pciehp_firmware_init();
         retval = pcie_port_service_register(&hpdriver_portdrv);
         dbg("pcie_port_service_register = %d\n", retval);
         info(DRIVER_DESC " version: " DRIVER_VERSION "\n");