PCI: Add PCIE_MSG_CODE_ASSERT_INTx message macros

Add "Message Routing" and "INTx Mechanism Messages" macros to enable
a PCIe driver to send messages for INTx Interrupt Signaling.

Values from PCIe r6.1, sec 2.2.8 and 2.2.8.1.

Link: https://lore.kernel.org/linux-pci/20240418-pme_msg-v8-1-a54265c39742@nxp.com
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>

Author: shimoday

drivers/pci/pci.h

@@ -22,6 +22,24 @@
  */
 #define PCIE_PME_TO_L2_TIMEOUT_US	10000
 
+/* Message Routing (r[2:0]); PCIe r6.0, sec 2.2.8 */
+#define PCIE_MSG_TYPE_R_RC	0
+#define PCIE_MSG_TYPE_R_ADDR	1
+#define PCIE_MSG_TYPE_R_ID	2
+#define PCIE_MSG_TYPE_R_BC	3
+#define PCIE_MSG_TYPE_R_LOCAL	4
+#define PCIE_MSG_TYPE_R_GATHER	5
+
+/* INTx Mechanism Messages; PCIe r6.0, sec 2.2.8.1 */
+#define PCIE_MSG_CODE_ASSERT_INTA	0x20
+#define PCIE_MSG_CODE_ASSERT_INTB	0x21
+#define PCIE_MSG_CODE_ASSERT_INTC	0x22
+#define PCIE_MSG_CODE_ASSERT_INTD	0x23
+#define PCIE_MSG_CODE_DEASSERT_INTA	0x24
+#define PCIE_MSG_CODE_DEASSERT_INTB	0x25
+#define PCIE_MSG_CODE_DEASSERT_INTC	0x26
+#define PCIE_MSG_CODE_DEASSERT_INTD	0x27
+
 extern const unsigned char pcie_link_speed[];
 extern bool pci_early_dump;