PCI: pci-bridge-emul: Correctly set PCIe capabilities

Older mvebu hardware provides PCIe Capability structure only in version 1.
New mvebu and aardvark hardware provides it in version 2. So do not force
version to 2 in pci_bridge_emul_init() and rather allow drivers to set
correct version. Drivers need to set version in pcie_conf.cap field without
overwriting PCI_CAP_LIST_ID register. Both drivers (mvebu and aardvark) do
not provide slot support yet, so do not set PCI_EXP_FLAGS_SLOT flag.

Link: https://lore.kernel.org/r/20211124155944.1290-6-pali@kernel.org
Fixes: 23a5fba4d9 ("PCI: Introduce PCI bridge emulated config space common logic")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org

drivers/pci/controller/pci-aardvark.c

@@ -881,7 +881,6 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 		return PCI_BRIDGE_EMUL_HANDLED;
 	}
 
-	case PCI_CAP_LIST_ID:
 	case PCI_EXP_DEVCAP:
 	case PCI_EXP_DEVCTL:
 		*value = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg);
@@ -962,6 +961,9 @@ static int advk_sw_pci_bridge_init(struct advk_pcie *pcie)
 	/* Support interrupt A for MSI feature */
 	bridge->conf.intpin = PCIE_CORE_INT_A_ASSERT_ENABLE;
 
+	/* Aardvark HW provides PCIe Capability structure in version 2 */
+	bridge->pcie_conf.cap = cpu_to_le16(2);
+
 	/* Indicates supports for Completion Retry Status */
 	bridge->pcie_conf.rootcap = cpu_to_le16(PCI_EXP_RTCAP_CRSVIS);
 

drivers/pci/controller/pci-mvebu.c

@@ -573,6 +573,8 @@ static struct pci_bridge_emul_ops mvebu_pci_bridge_emul_ops = {
 static void mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 {
 	struct pci_bridge_emul *bridge = &port->bridge;
+	u32 pcie_cap = mvebu_readl(port, PCIE_CAP_PCIEXP);
+	u8 pcie_cap_ver = ((pcie_cap >> 16) & PCI_EXP_FLAGS_VERS);
 
 	bridge->conf.vendor = PCI_VENDOR_ID_MARVELL;
 	bridge->conf.device = mvebu_readl(port, PCIE_DEV_ID_OFF) >> 16;
@@ -585,6 +587,12 @@ static void mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 		bridge->conf.iolimit = PCI_IO_RANGE_TYPE_32;
 	}
 
+	/*
+	 * Older mvebu hardware provides PCIe Capability structure only in
+	 * version 1. New hardware provides it in version 2.
+	 */
+	bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver);
+
 	bridge->has_pcie = true;
 	bridge->data = port;
 	bridge->ops = &mvebu_pci_bridge_emul_ops;

drivers/pci/pci-bridge-emul.c

@@ -297,10 +297,7 @@ int pci_bridge_emul_init(struct pci_bridge_emul *bridge,
 	if (bridge->has_pcie) {
 		bridge->conf.capabilities_pointer = PCI_CAP_PCIE_START;
 		bridge->pcie_conf.cap_id = PCI_CAP_ID_EXP;
-		/* Set PCIe v2, root port, slot support */
-		bridge->pcie_conf.cap =
-			cpu_to_le16(PCI_EXP_TYPE_ROOT_PORT << 4 | 2 |
-				    PCI_EXP_FLAGS_SLOT);
+		bridge->pcie_conf.cap |= cpu_to_le16(PCI_EXP_TYPE_ROOT_PORT << 4);
 		bridge->pcie_cap_regs_behavior =
 			kmemdup(pcie_cap_regs_behavior,
 				sizeof(pcie_cap_regs_behavior),