PCI hotplug: move IOAPIC support from acpiphp to ioapic driver

This patch moves PCI I/O APIC support from acpiphp to a separate driver.

Like pciehp and shpchp, acpiphp handles PCI hotplug, i.e., addition and
removal of PCI adapters.  But in addition, acpiphp handles some ACPI
hotplug, such as the addition of new host bridges, and the I/O APIC
support was tangled up with that.

I don't think the I/O APIC support needs to be in acpiphp; PCI I/O APICs
usually appear as a function on a PCI host bridge, and we'll enumerate the
APIC before any of the devices behind the bridge that use it.

As far as I know, nobody actually uses I/O APIC hotplug.  It depends on
acpi_register_ioapic(), which is only implemented for ia64, and I don't
think any vendors have supported I/O chassis hotplug yet.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
CC: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
CC: MUNEDA Takahiro <muneda.takahiro@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 127 insertions, 0 deletions

diff --git a/drivers/pci/ioapic.c b/drivers/pci/ioapic.c
new file mode 100644
index 000000000000..3e0d7b5dd1b9
--- /dev/null
+++ b/drivers/pci/ioapic.c
@@ -0,0 +1,127 @@
+/*
+ * IOAPIC/IOxAPIC/IOSAPIC driver
+ *
+ * Copyright (C) 2009 Fujitsu Limited.
+ * (c) Copyright 2009 Hewlett-Packard Development Company, L.P.
+ *
+ * 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.
+ */
+
+/*
+ * This driver manages PCI I/O APICs added by hotplug after boot.  We try to
+ * claim all I/O APIC PCI 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.
+ */
+
+#include <linux/pci.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
+
+struct ioapic {
+        acpi_handle     handle;
+        u32             gsi_base;
+};
+
+static int ioapic_probe(struct pci_dev *dev, const struct pci_device_id *ent)
+{
+        acpi_handle handle;
+        acpi_status status;
+        unsigned long long gsb;
+        struct ioapic *ioapic;
+        u64 addr;
+        int ret;
+        char *type;
+
+        handle = DEVICE_ACPI_HANDLE(&dev->dev);
+        if (!handle)
+                return -EINVAL;
+
+        status = acpi_evaluate_integer(handle, "_GSB", NULL, &gsb);
+        if (ACPI_FAILURE(status))
+                return -EINVAL;
+
+        /*
+         * The previous code in acpiphp evaluated _MAT if _GSB failed, but
+         * ACPI spec 4.0 sec 6.2.2 requires _GSB for hot-pluggable I/O APICs.
+         */
+
+        ioapic = kzalloc(sizeof(*ioapic), GFP_KERNEL);
+        if (!ioapic)
+                return -ENOMEM;
+
+        ioapic->handle = handle;
+        ioapic->gsi_base = (u32) gsb;
+
+        if (dev->class == PCI_CLASS_SYSTEM_PIC_IOAPIC)
+                type = "IOAPIC";
+        else
+                type = "IOxAPIC";
+
+        ret = pci_enable_device(dev);
+        if (ret < 0)
+                goto exit_free;
+
+        pci_set_master(dev);
+
+        if (pci_request_region(dev, 0, type))
+                goto exit_disable;
+
+        addr = pci_resource_start(dev, 0);
+        if (acpi_register_ioapic(ioapic->handle, addr, ioapic->gsi_base))
+                goto exit_release;
+
+        pci_set_drvdata(dev, ioapic);
+        dev_info(&dev->dev, "%s at %#llx, GSI %u\n", type, addr,
+                 ioapic->gsi_base);
+        return 0;
+
+exit_release:
+        pci_release_region(dev, 0);
+exit_disable:
+        pci_disable_device(dev);
+exit_free:
+        kfree(ioapic);
+        return -ENODEV;
+}
+
+static void ioapic_remove(struct pci_dev *dev)
+{
+        struct ioapic *ioapic = pci_get_drvdata(dev);
+
+        acpi_unregister_ioapic(ioapic->handle, ioapic->gsi_base);
+        pci_release_region(dev, 0);
+        pci_disable_device(dev);
+        kfree(ioapic);
+}
+
+
+static struct pci_device_id ioapic_devices[] = {
+        { PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+          PCI_CLASS_SYSTEM_PIC_IOAPIC << 8, 0xffff00, },
+        { PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+          PCI_CLASS_SYSTEM_PIC_IOXAPIC << 8, 0xffff00, },
+        { }
+};
+
+static struct pci_driver ioapic_driver = {
+        .name           = "ioapic",
+        .id_table       = ioapic_devices,
+        .probe          = ioapic_probe,
+        .remove         = __devexit_p(ioapic_remove),
+};
+
+static int __init ioapic_init(void)
+{
+        return pci_register_driver(&ioapic_driver);
+}
+
+static void __exit ioapic_exit(void)
+{
+        pci_unregister_driver(&ioapic_driver);
+}
+
+module_init(ioapic_init);
+module_exit(ioapic_exit);