+/*
+ * IO-APIC versions below 0x20 don't support EOI register.
+ * For the record, here is the information about various versions:
+ * 0Xh 82489DX
+ * 1Xh I/OAPIC or I/O(x)APIC which are not PCI 2.2 Compliant
+ * 2Xh I/O(x)APIC which is PCI 2.2 Compliant
+ * 30h-FFh Reserved
+ *
+ * Some of the Intel ICH Specs (ICH2 to ICH5) documents the io-apic
+ * version as 0x2. This is an error with documentation and these ICH chips
+ * use io-apic's of version 0x20.
+ *
+ * For IO-APIC's with EOI register, we use that to do an explicit EOI.
+ * Otherwise, we simulate the EOI message manually by changing the trigger
+ * mode to edge and then back to level, with RTE being masked during this.
+ */
+static void __eoi_ioapic_pin(int apic, int pin, int vector, struct irq_cfg *cfg)
+{
+ if (mpc_ioapic_ver(apic) >= 0x20) {
+ /*
+ * Intr-remapping uses pin number as the virtual vector
+ * in the RTE. Actual vector is programmed in
+ * intr-remapping table entry. Hence for the io-apic
+ * EOI we use the pin number.
+ */
+ if (cfg && irq_remapped(cfg))
+ io_apic_eoi(apic, pin);
+ else
+ io_apic_eoi(apic, vector);
+ } else {
+ struct IO_APIC_route_entry entry, entry1;
+
+ entry = entry1 = __ioapic_read_entry(apic, pin);
+
+ /*
+ * Mask the entry and change the trigger mode to edge.
+ */
+ entry1.mask = 1;
+ entry1.trigger = IOAPIC_EDGE;
+
+ __ioapic_write_entry(apic, pin, entry1);
+
+ /*
+ * Restore the previous level triggered entry.
+ */
+ __ioapic_write_entry(apic, pin, entry);
+ }
+}
+
+static void eoi_ioapic_irq(unsigned int irq, struct irq_cfg *cfg)
+{
+ struct irq_pin_list *entry;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&ioapic_lock, flags);
+ for_each_irq_pin(entry, cfg->irq_2_pin)
+ __eoi_ioapic_pin(entry->apic, entry->pin, cfg->vector, cfg);
+ raw_spin_unlock_irqrestore(&ioapic_lock, flags);
+}
+