ACPI: Add interfaces to parse IOAPIC ID for IOAPIC hotplug

We need to parse APIC ID for IOAPIC registration for IOAPIC hotplug.
ACPI _MAT method and MADT table are used to figure out IOAPIC ID, just
like parsing CPU APIC ID for CPU hotplug.

[ tglx: Fixed docbook comment ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/1414387308-27148-8-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 118 insertions, 9 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 02e48394276c..7962651cdbd4 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -4,6 +4,10 @@
  *
  *      Alex Chiang <achiang@hp.com>
  *      - Unified x86/ia64 implementations
+ *
+ * I/O APIC hotplug support
+ *      Yinghai Lu <yinghai@kernel.org>
+ *      Jiang Liu <jiang.liu@intel.com>
  */
 #include <linux/export.h>
 #include <linux/acpi.h>
@@ -12,6 +16,21 @@
 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
 ACPI_MODULE_NAME("processor_core");
 
+static struct acpi_table_madt *get_madt_table(void)
+{
+        static struct acpi_table_madt *madt;
+        static int read_madt;
+
+        if (!read_madt) {
+                if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0,
+                                        (struct acpi_table_header **)&madt)))
+                        madt = NULL;
+                read_madt++;
+        }
+
+        return madt;
+}
+
 static int map_lapic_id(struct acpi_subtable_header *entry,
                  u32 acpi_id, int *apic_id)
 {
@@ -67,17 +86,10 @@ 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 phys_id = -1;       /* CPU hardware ID */
+        struct acpi_table_madt *madt;
 
-        if (!read_madt) {
-                if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0,
-                                        (struct acpi_table_header **)&madt)))
-                        madt = NULL;
-                read_madt++;
-        }
-
+        madt = get_madt_table();
         if (!madt)
                 return phys_id;
 
@@ -203,3 +215,96 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id)
         return acpi_map_cpuid(phys_id, acpi_id);
 }
 EXPORT_SYMBOL_GPL(acpi_get_cpuid);
+
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+static int get_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 parse_madt_ioapic_entry(u32 gsi_base, u64 *phys_addr)
+{
+        struct acpi_subtable_header *hdr;
+        unsigned long madt_end, entry;
+        struct acpi_table_madt *madt;
+        int apic_id = -1;
+
+        madt = get_madt_table();
+        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 &&
+                    get_ioapic_id(hdr, gsi_base, phys_addr, &apic_id))
+                        break;
+                else
+                        entry += hdr->length;
+        }
+
+        return apic_id;
+}
+
+static int parse_mat_ioapic_entry(acpi_handle handle, u32 gsi_base,
+                                  u64 *phys_addr)
+{
+        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+        struct acpi_subtable_header *header;
+        union acpi_object *obj;
+        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)
+                get_ioapic_id(header, gsi_base, phys_addr, &apic_id);
+
+exit:
+        kfree(buffer.pointer);
+        return apic_id;
+}
+
+/**
+ * acpi_get_ioapic_id - Get IOAPIC ID and physical address matching @gsi_base
+ * @handle:     ACPI object for IOAPIC device
+ * @gsi_base:   GSI base to match with
+ * @phys_addr:  Pointer to store physical address of matching IOAPIC record
+ *
+ * Walk resources returned by ACPI_MAT method, then ACPI MADT table, to search
+ * for an ACPI IOAPIC record matching @gsi_base.
+ * Return IOAPIC id and store physical address in @phys_addr if found a match,
+ * otherwise return <0.
+ */
+int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr)
+{
+        int apic_id;
+
+        apic_id = parse_mat_ioapic_entry(handle, gsi_base, phys_addr);
+        if (apic_id == -1)
+                apic_id = parse_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 e53822148b6a..24c7aa8b1d20 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -152,6 +152,10 @@ int acpi_map_cpu(acpi_handle handle, int physid, int *pcpu);
 int acpi_unmap_cpu(int cpu);
 #endif /* CONFIG_ACPI_HOTPLUG_CPU */
 
+#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);
 int acpi_ioapic_registered(acpi_handle handle, u32 gsi_base);