x86: mpspec: Allow platform to determine how PIRQ is connected to I/O APIC

Currently during writing MP table I/O interrupt assignment entry, we
assume the PIRQ is directly mapped to I/O APIC INTPIN#16-23, which
however is not always the case on some platforms.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
index efa9231..ad8eba9 100644
--- a/arch/x86/include/asm/mpspec.h
+++ b/arch/x86/include/asm/mpspec.h
@@ -432,6 +432,23 @@
 u32 mptable_finalize(struct mp_config_table *mc);
 
 /**
+ * mp_determine_pci_dstirq() - Determine PCI device's int pin on the I/O APIC
+ *
+ * This determines a PCI device's interrupt pin number on the I/O APIC.
+ *
+ * This can be implemented by platform codes to handle specifal cases, which
+ * do not conform to the normal chipset/board design where PIRQ[A-H] are mapped
+ * directly to I/O APIC INTPIN#16-23.
+ *
+ * @bus:	bus number of the pci device
+ * @dev:	device number of the pci device
+ * @func:	function number of the pci device
+ * @pirq:	PIRQ number the PCI device's interrupt pin is routed to
+ * @return:	interrupt pin number on the I/O APIC
+ */
+int mp_determine_pci_dstirq(int bus, int dev, int func, int pirq);
+
+/**
  * write_mp_table() - Write MP table
  *
  * This writes MP table at a given address.