+
+int mp_find_ioapic(u32 gsi)
+{
+ int i = 0;
+
+ /* Find the IOAPIC that manages this GSI. */
+ for (i = 0; i < nr_ioapics; i++) {
+ if ((gsi >= mp_gsi_routing[i].gsi_base)
+ && (gsi <= mp_gsi_routing[i].gsi_end))
+ return i;
+ }
+
+ printk(KERN_ERR "ERROR: Unable to locate IOAPIC for GSI %d\n", gsi);
+ return -1;
+}
+
+int mp_find_ioapic_pin(int ioapic, u32 gsi)
+{
+ if (WARN_ON(ioapic == -1))
+ return -1;
+ if (WARN_ON(gsi > mp_gsi_routing[ioapic].gsi_end))
+ return -1;
+
+ return gsi - mp_gsi_routing[ioapic].gsi_base;
+}
+
+static int bad_ioapic(unsigned long address)
+{
+ if (nr_ioapics >= MAX_IO_APICS) {
+ printk(KERN_WARNING "WARING: Max # of I/O APICs (%d) exceeded "
+ "(found %d), skipping\n", MAX_IO_APICS, nr_ioapics);
+ return 1;
+ }
+ if (!address) {
+ printk(KERN_WARNING "WARNING: Bogus (zero) I/O APIC address"
+ " found in table, skipping!\n");
+ return 1;
+ }
+ return 0;
+}
+
+void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
+{
+ int idx = 0;
+ int entries;
+
+ if (bad_ioapic(address))
+ return;
+
+ idx = nr_ioapics;
+
+ mp_ioapics[idx].type = MP_IOAPIC;
+ mp_ioapics[idx].flags = MPC_APIC_USABLE;
+ mp_ioapics[idx].apicaddr = address;
+
+ set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
+ mp_ioapics[idx].apicid = io_apic_unique_id(id);
+ mp_ioapics[idx].apicver = io_apic_get_version(idx);
+
+ /*
+ * Build basic GSI lookup table to facilitate gsi->io_apic lookups
+ * and to prevent reprogramming of IOAPIC pins (PCI GSIs).
+ */
+ entries = io_apic_get_redir_entries(idx);
+ mp_gsi_routing[idx].gsi_base = gsi_base;
+ mp_gsi_routing[idx].gsi_end = gsi_base + entries - 1;
+
+ /*
+ * The number of IO-APIC IRQ registers (== #pins):
+ */
+ nr_ioapic_registers[idx] = entries;
+
+ if (mp_gsi_routing[idx].gsi_end > gsi_end)
+ gsi_end = mp_gsi_routing[idx].gsi_end;
+
+ printk(KERN_INFO "IOAPIC[%d]: apic_id %d, version %d, address 0x%x, "
+ "GSI %d-%d\n", idx, mp_ioapics[idx].apicid,
+ mp_ioapics[idx].apicver, mp_ioapics[idx].apicaddr,
+ mp_gsi_routing[idx].gsi_base, mp_gsi_routing[idx].gsi_end);
+
+ nr_ioapics++;
+}
+
+/* Enable IOAPIC early just for system timer */
+void __init pre_init_apic_IRQ0(void)
+{
+ struct irq_cfg *cfg;
+ struct irq_desc *desc;
+
+ printk(KERN_INFO "Early APIC setup for system timer0\n");
+#ifndef CONFIG_SMP
+ phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);
+#endif
+ desc = irq_to_desc_alloc_node(0, 0);
+
+ setup_local_APIC();
+
+ cfg = irq_cfg(0);
+ add_pin_to_irq_node(cfg, 0, 0, 0);
+ set_irq_chip_and_handler_name(0, &ioapic_chip, handle_edge_irq, "edge");
+
+ setup_IO_APIC_irq(0, 0, 0, desc, 0, 0);
+}