From: Yinghai Lu <ying...@kernel.org>

For ioapic hotplug, we need to parse apic id for ioapic registration.

We could check _MAT and MADT to get io apic id, just like cpu hotplug
path to get apic id.

Signed-off-by: Yinghai Lu <ying...@kernel.org>
Signed-off-by: Jiang Liu <jiang....@linux.intel.com>
---
 drivers/acpi/apic_id.c |   97 +++++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/acpi.h   |    3 ++
 2 files changed, 98 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/apic_id.c b/drivers/acpi/apic_id.c
index ac3b10a9f92d..a74a3fcd8362 100644
--- a/drivers/acpi/apic_id.c
+++ b/drivers/acpi/apic_id.c
@@ -2,6 +2,10 @@
  * Copyright (C) 2005 Intel Corporation
  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
  *     All routines dealing with CPU APIC ID are moved from processor_core.c
+ *
+ * I/O APIC hotplug support
+ *     Yinghai Lu <ying...@kernel.org>
+ *     Jiang Liu <jiang....@intel.com>
  */
 #include <linux/export.h>
 #include <linux/slab.h>
@@ -9,6 +13,9 @@
 
 #include "internal.h"
 
+static struct acpi_table_madt *madt;
+static int read_madt;
+
 static int map_lapic_id(struct acpi_subtable_header *entry,
                 u32 acpi_id, int *apic_id)
 {
@@ -64,8 +71,6 @@ static int map_lsapic_id(struct acpi_subtable_header *entry,
 static int map_madt_entry(int type, u32 acpi_id)
 {
        unsigned long madt_end, entry;
-       static struct acpi_table_madt *madt;
-       static int read_madt;
        int apic_id = -1;
 
        if (!read_madt) {
@@ -200,3 +205,91 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 
acpi_id)
        return acpi_map_cpuid(apic_id, acpi_id);
 }
 EXPORT_SYMBOL_GPL(acpi_get_cpuid);
+
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+static int map_ioapic_id(struct acpi_subtable_header *entry, u32 gsi_base,
+                        u64 *phys_addr, int *ioapic_id)
+{
+       struct acpi_madt_io_apic *ioapic = (struct acpi_madt_io_apic *)entry;
+
+       if (ioapic->global_irq_base != gsi_base)
+               return 0;
+
+       *phys_addr = ioapic->address;
+       *ioapic_id = ioapic->id;
+       return 1;
+}
+
+static int map_madt_ioapic_entry(u32 gsi_base, u64 *phys_addr)
+{
+       struct acpi_subtable_header *hdr;
+       unsigned long madt_end, entry;
+       int apic_id = -1;
+
+       if (!read_madt) {
+               if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0,
+                                       (struct acpi_table_header **)&madt)))
+                       madt = NULL;
+               read_madt++;
+       }
+
+       if (!madt)
+               return apic_id;
+
+       entry = (unsigned long)madt;
+       madt_end = entry + madt->header.length;
+
+       /* Parse all entries looking for a match. */
+       entry += sizeof(struct acpi_table_madt);
+       while (entry + sizeof(struct acpi_subtable_header) < madt_end) {
+               hdr = (struct acpi_subtable_header *)entry;
+               if (hdr->type == ACPI_MADT_TYPE_IO_APIC &&
+                   map_ioapic_id(hdr, gsi_base, phys_addr, &apic_id))
+                       break;
+               else
+                       entry += hdr->length;
+       }
+
+       return apic_id;
+}
+
+static int map_mat_ioapic_entry(acpi_handle handle, u32 gsi_base,
+                               u64 *phys_addr)
+{
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+       union acpi_object *obj;
+       struct acpi_subtable_header *header;
+       int apic_id = -1;
+
+       if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
+               goto exit;
+
+       if (!buffer.length || !buffer.pointer)
+               goto exit;
+
+       obj = buffer.pointer;
+       if (obj->type != ACPI_TYPE_BUFFER ||
+           obj->buffer.length < sizeof(struct acpi_subtable_header)) {
+               goto exit;
+       }
+
+       header = (struct acpi_subtable_header *)obj->buffer.pointer;
+       if (header->type == ACPI_MADT_TYPE_IO_APIC)
+               map_ioapic_id(header, gsi_base, phys_addr, &apic_id);
+
+exit:
+       kfree(buffer.pointer);
+       return apic_id;
+}
+
+int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr)
+{
+       int apic_id;
+
+       apic_id = map_mat_ioapic_entry(handle, gsi_base, phys_addr);
+       if (apic_id == -1)
+               apic_id = map_madt_ioapic_entry(gsi_base, phys_addr);
+
+       return apic_id;
+}
+#endif /* CONFIG_ACPI_HOTPLUG_IOAPIC */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 5c432e842921..f478af87f575 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -148,6 +148,9 @@ int acpi_unmap_lsapic(int cpu);
 int acpi_get_apicid(acpi_handle, int type, u32 acpi_id);
 int acpi_map_cpuid(int apic_id, u32 acpi_id);
 int acpi_get_cpuid(acpi_handle, int type, u32 acpi_id);
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
+#endif
 
 int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
 int acpi_unregister_ioapic(acpi_handle handle, u32 gsi_base);
-- 
1.7.10.4

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