PCI: mvebu: Add support for PCI Bridge Subsystem Vendor ID on emulated bridge

Register with Subsystem Device/Vendor ID is at offset 0x2c. Export is via
emulated bridge.

After this change Subsystem ID is visible in lspci output at line:

  Capabilities: [40] Subsystem

Link: https://lore.kernel.org/r/20220222155030.988-7-pali@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Author: pali

drivers/pci/controller/pci-mvebu.c

@@ -32,6 +32,7 @@
 #define PCIE_DEV_REV_OFF	0x0008
 #define PCIE_BAR_LO_OFF(n)	(0x0010 + ((n) << 3))
 #define PCIE_BAR_HI_OFF(n)	(0x0014 + ((n) << 3))
+#define PCIE_SSDEV_ID_OFF	0x002c
 #define PCIE_CAP_PCIEXP		0x0060
 #define PCIE_HEADER_LOG_4_OFF	0x0128
 #define PCIE_BAR_CTRL_OFF(n)	(0x1804 + (((n) - 1) * 4))
@@ -731,6 +732,7 @@ static int mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 	struct pci_bridge_emul *bridge = &port->bridge;
 	u32 dev_id = mvebu_readl(port, PCIE_DEV_ID_OFF);
 	u32 dev_rev = mvebu_readl(port, PCIE_DEV_REV_OFF);
+	u32 ssdev_id = mvebu_readl(port, PCIE_SSDEV_ID_OFF);
 	u32 pcie_cap = mvebu_readl(port, PCIE_CAP_PCIEXP);
 	u8 pcie_cap_ver = ((pcie_cap >> 16) & PCI_EXP_FLAGS_VERS);
 
@@ -752,6 +754,8 @@ static int mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 	 */
 	bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver);
 
+	bridge->subsystem_vendor_id = ssdev_id & 0xffff;
+	bridge->subsystem_id = ssdev_id >> 16;
 	bridge->has_pcie = true;
 	bridge->data = port;
 	bridge->ops = &mvebu_pci_bridge_emul_ops;