Enable support of IOAPIC hotplug by:
1) reintroducing ACPI based IOAPIC driver
2) enhance pci_root driver to hook hotplug events

The ACPI IOAPIC driver is always enabled if system supports all of
ACPI, PCI and IOAPIC.

Signed-off-by: Jiang Liu <jiang....@linux.intel.com>
---
 drivers/acpi/Kconfig    |    6 ++
 drivers/acpi/Makefile   |    1 +
 drivers/acpi/internal.h |    7 ++
 drivers/acpi/ioapic.c   |  231 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/pci_root.c |    3 +
 5 files changed, 248 insertions(+)
 create mode 100644 drivers/acpi/ioapic.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index ab686b310100..2d0ed9da6fea 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -292,6 +292,12 @@ config ACPI_HOTPLUG_MEMORY
          To compile this driver as a module, choose M here:
          the module will be called acpi_memhotplug.
 
+config ACPI_HOTPLUG_IOAPIC
+       bool
+       depends on PCI
+       depends on X86_IO_APIC
+       default y
+
 config ACPI_SBS
        tristate "Smart Battery System"
        depends on X86
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index d922febd9164..b85b226a7f49 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_ACPI_PROCESSOR)  += processor.o
 obj-$(CONFIG_ACPI_CONTAINER)   += container.o
 obj-$(CONFIG_ACPI_THERMAL)     += thermal.o
 obj-$(CONFIG_ACPI_HOTPLUG_MEMORY) += acpi_memhotplug.o
+obj-$(CONFIG_ACPI_HOTPLUG_IOAPIC) += ioapic.o
 obj-$(CONFIG_ACPI_BATTERY)     += battery.o
 obj-$(CONFIG_ACPI_SBS)         += sbshc.o
 obj-$(CONFIG_ACPI_SBS)         += sbs.o
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 957391306cbf..e8023cd81da3 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -52,6 +52,13 @@ void acpi_memory_hotplug_init(void);
 #else
 static inline void acpi_memory_hotplug_init(void) {}
 #endif
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+int acpi_ioapic_add(struct acpi_pci_root *root);
+int acpi_ioapic_remove(struct acpi_pci_root *root);
+#else
+static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
+static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
+#endif
 #ifdef CONFIG_X86
 void acpi_cmos_rtc_init(void);
 #else
diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
new file mode 100644
index 000000000000..3c9442899782
--- /dev/null
+++ b/drivers/acpi/ioapic.c
@@ -0,0 +1,231 @@
+/*
+ * IOAPIC/IOxAPIC/IOSAPIC driver
+ *
+ * Copyright (C) 2009 Fujitsu Limited.
+ * (c) Copyright 2009 Hewlett-Packard Development Company, L.P.
+ *
+ * Copyright (C) 2014 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Based on original drivers/pci/ioapic.c
+ *     Yinghai Lu <ying...@kernel.org>
+ *     Jiang Liu <jiang....@intel.com>
+ */
+
+/*
+ * This driver manages I/O APICs added by hotplug after boot.
+ * We try to claim all I/O APIC devices, but those present at boot were
+ * registered when we parsed the ACPI MADT, so we'll fail when we try to
+ * re-register them.
+ */
+
+#define pr_fmt(fmt) "ACPI : IOAPIC: " fmt
+
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/pci.h>
+#include <acpi/acpi.h>
+
+struct acpi_pci_ioapic {
+       acpi_handle     root_handle;
+       acpi_handle     handle;
+       u32             gsi_base;
+       struct resource res;
+       struct pci_dev  *pdev;
+       struct list_head list;
+};
+
+static LIST_HEAD(ioapic_list);
+static DEFINE_MUTEX(ioapic_list_lock);
+
+static acpi_status setup_res(struct acpi_resource *acpi_res, void *data)
+{
+       struct resource *res = data;
+       struct acpi_resource_address64 addr;
+       acpi_status status;
+
+       status = acpi_mem_addr_resource_to_address64(acpi_res, &addr);
+       if (!ACPI_SUCCESS(status))
+               return AE_OK;
+
+       if (addr.resource_type != ACPI_MEMORY_RANGE ||
+           addr.info.mem.caching == ACPI_PREFETCHABLE_MEMORY)
+               return AE_OK;
+
+       res->flags = IORESOURCE_MEM;
+       res->start = addr.minimum + addr.translation_offset;
+       res->end = addr.maximum + addr.translation_offset;
+
+       return AE_OK;
+}
+
+static bool acpi_is_ioapic(acpi_handle handle, char **type)
+{
+       acpi_status status;
+       struct acpi_device_info *info;
+       char *hid = NULL;
+       bool match = false;
+
+       if (!acpi_has_method(handle, "_GSB"))
+               return false;
+
+       status = acpi_get_object_info(handle, &info);
+       if (ACPI_SUCCESS(status)) {
+               if (info->valid & ACPI_VALID_HID)
+                       hid = info->hardware_id.string;
+               if (hid) {
+                       if (strcmp(hid, "ACPI0009") == 0) {
+                               *type = "IOxAPIC";
+                               match = true;
+                       } else if (strcmp(hid, "ACPI000A") == 0) {
+                               *type = "IOAPIC";
+                               match = true;
+                       }
+               }
+               kfree(info);
+       }
+
+       return match;
+}
+
+static acpi_status handle_ioapic_add(acpi_handle handle, u32 lvl,
+                                    void *context, void **rv)
+{
+       acpi_status status;
+       unsigned long long gsi_base;
+       struct acpi_pci_ioapic *ioapic;
+       struct pci_dev *dev = NULL;
+       struct resource *res = NULL;
+       char *type = NULL;
+
+       if (!acpi_is_ioapic(handle, &type))
+               return AE_OK;
+
+       mutex_lock(&ioapic_list_lock);
+       list_for_each_entry(ioapic, &ioapic_list, list)
+               if (ioapic->handle == handle) {
+                       mutex_unlock(&ioapic_list_lock);
+                       return AE_OK;
+               }
+
+       status = acpi_evaluate_integer(handle, "_GSB", NULL, &gsi_base);
+       if (ACPI_FAILURE(status)) {
+               acpi_handle_warn(handle, "failed to evaluate _GSB method\n");
+               goto exit;
+       }
+
+       ioapic = kzalloc(sizeof(*ioapic), GFP_KERNEL);
+       if (!ioapic) {
+               pr_err("cannot allocate memory for new IOAPIC\n");
+               goto exit;
+       } else {
+               ioapic->root_handle = (acpi_handle)context;
+               ioapic->handle = handle;
+               ioapic->gsi_base = (u32)gsi_base;
+               ioapic->res.flags = IORESOURCE_UNSET;
+       }
+
+       if (acpi_ioapic_registered(handle, (u32)gsi_base))
+               goto done;
+
+       dev = acpi_get_pci_dev(handle);
+       if (dev && pci_resource_len(dev, 0)) {
+               if (pci_enable_device(dev) < 0)
+                       goto exit_put;
+               pci_set_master(dev);
+               if (pci_request_region(dev, 0, type))
+                       goto exit_disable;
+               res = &dev->resource[0];
+               ioapic->pdev = dev;
+       } else {
+               pci_dev_put(dev);
+               dev = NULL;
+
+               res = &ioapic->res;
+               acpi_walk_resources(handle, METHOD_NAME__CRS, setup_res, res);
+               if (res->flags == IORESOURCE_UNSET) {
+                       acpi_handle_warn(handle, "failed to get resource\n");
+                       goto exit_free;
+               } else if (request_resource(&iomem_resource, res)) {
+                       acpi_handle_warn(handle, "failed to insert resource\n");
+                       goto exit_free;
+               }
+       }
+
+       if (acpi_register_ioapic(handle, res->start, (u32)gsi_base)) {
+               acpi_handle_warn(handle, "failed to register IOAPIC\n");
+               goto exit_release;
+       }
+done:
+       list_add(&ioapic->list, &ioapic_list);
+       mutex_unlock(&ioapic_list_lock);
+
+       if (dev)
+               dev_info(&dev->dev, "%s at %pR, GSI %u\n",
+                        type, res, (u32)gsi_base);
+       else
+               acpi_handle_info(handle, "%s at %pR, GSI %u\n",
+                                type, res, (u32)gsi_base);
+
+       return AE_OK;
+
+exit_release:
+       if (dev)
+               pci_release_region(dev, 0);
+       else
+               release_resource(res);
+exit_disable:
+       if (dev)
+               pci_disable_device(dev);
+exit_put:
+       if (dev)
+               pci_dev_put(dev);
+exit_free:
+       kfree(ioapic);
+exit:
+       mutex_unlock(&ioapic_list_lock);
+       *(acpi_status *)rv = AE_ERROR;
+       return AE_OK;
+}
+
+int acpi_ioapic_add(struct acpi_pci_root *root)
+{
+       acpi_status status, retval = AE_OK;
+
+       status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
+                                    UINT_MAX, handle_ioapic_add, NULL,
+                                    root->device->handle, (void **)&retval);
+
+       return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
+}
+
+int acpi_ioapic_remove(struct acpi_pci_root *root)
+{
+       int retval = 0;
+       struct acpi_pci_ioapic *ioapic, *tmp;
+
+       mutex_lock(&ioapic_list_lock);
+       list_for_each_entry_safe(ioapic, tmp, &ioapic_list, list) {
+               if (root->device->handle != ioapic->root_handle)
+                       continue;
+
+               if (acpi_unregister_ioapic(ioapic->handle, ioapic->gsi_base))
+                       retval = -EBUSY;
+
+               if (ioapic->pdev) {
+                       pci_release_region(ioapic->pdev, 0);
+                       pci_disable_device(ioapic->pdev);
+                       pci_dev_put(ioapic->pdev);
+               } else if (ioapic->res.flags != IORESOURCE_UNSET) {
+                       release_resource(&ioapic->res);
+               }
+               list_del(&ioapic->list);
+               kfree(ioapic);
+       }
+       mutex_unlock(&ioapic_list_lock);
+
+       return retval;
+}
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index d388f13d48b4..e1223fac65ce 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -600,6 +600,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
        if (system_state != SYSTEM_BOOTING) {
                pcibios_resource_survey_bus(root->bus);
                pci_assign_unassigned_root_bus_resources(root->bus);
+               acpi_ioapic_add(root);
        }
 
        pci_lock_rescan_remove();
@@ -620,6 +621,8 @@ static void acpi_pci_root_remove(struct acpi_device *device)
 
        pci_stop_root_bus(root->bus);
 
+       WARN_ON(acpi_ioapic_remove(root));
+
        device_set_run_wake(root->bus->bridge, false);
        pci_acpi_remove_bus_pm_notifier(device);
 
-- 
1.7.10.4

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