PCI: aardvark: Fix reporting Slot capabilities on emulated bridge

Slot capabilities are currently not reported because emulated bridge does
not report the PCI_EXP_FLAGS_SLOT flag.

Set PCI_EXP_FLAGS_SLOT to let the kernel know that PCI_EXP_SLT* registers
are supported.

Move setting of PCI_EXP_SLTCTL register from "dynamic" pcie_conf_read
function to static buffer as it is only statically filled the
PCI_EXP_SLTSTA_PDS flag and dynamic read callback is not needed for this
register.

Set Presence State Bit to 1 since there is no support for unplugging the
card and there is currently no platform able to detect presence of a card -
in such a case the bit needs to be set to 1.

Finally correctly set Physical Slot Number to 1 since there is only one
port and zero value is reserved for ports within the same silicon as Root
Port which is not our case for Aardvark HW.

Link: https://lore.kernel.org/r/20220524132827.8837-3-kabel@kernel.orgSigned-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/controller/pci-aardvark.c

@@ -8,6 +8,7 @@
  * Author: Hezi Shahmoon <hezi.shahmoon@marvell.com>
  */
 
+#include <linux/bitfield.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
@@ -858,14 +859,11 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 
 
 	switch (reg) {
-	case PCI_EXP_SLTCTL:
-		*value = PCI_EXP_SLTSTA_PDS << 16;
-		return PCI_BRIDGE_EMUL_HANDLED;
-
 	/*
-	 * PCI_EXP_RTCTL and PCI_EXP_RTSTA are also supported, but do not need
-	 * to be handled here, because their values are stored in emulated
-	 * config space buffer, and we read them from there when needed.
+	 * PCI_EXP_SLTCAP, PCI_EXP_SLTCTL, PCI_EXP_RTCTL and PCI_EXP_RTSTA are
+	 * also supported, but do not need to be handled here, because their
+	 * values are stored in emulated config space buffer, and we read them
+	 * from there when needed.
 	 */
 
 	case PCI_EXP_LNKCAP: {
@@ -1056,8 +1054,25 @@ static int advk_sw_pci_bridge_init(struct advk_pcie *pcie)
 	/* Support interrupt A for MSI feature */
 	bridge->conf.intpin = PCI_INTERRUPT_INTA;
 
-	/* Aardvark HW provides PCIe Capability structure in version 2 */
-	bridge->pcie_conf.cap = cpu_to_le16(2);
+	/*
+	 * Aardvark HW provides PCIe Capability structure in version 2 and
+	 * indicate slot support, which is emulated.
+	 */
+	bridge->pcie_conf.cap = cpu_to_le16(2 | PCI_EXP_FLAGS_SLOT);
+
+	/*
+	 * Set Presence Detect State bit permanently since there is no support
+	 * for unplugging the card nor detecting whether it is plugged. (If a
+	 * platform exists in the future that supports it, via a GPIO for
+	 * example, it should be implemented via this bit.)
+	 *
+	 * Set physical slot number to 1 since there is only one port and zero
+	 * value is reserved for ports within the same silicon as Root Port
+	 * which is not our case.
+	 */
+	bridge->pcie_conf.slotcap = cpu_to_le32(FIELD_PREP(PCI_EXP_SLTCAP_PSN,
+							   1));
+	bridge->pcie_conf.slotsta = cpu_to_le16(PCI_EXP_SLTSTA_PDS);
 
 	/* Indicates supports for Completion Retry Status */
 	bridge->pcie_conf.rootcap = cpu_to_le16(PCI_EXP_RTCAP_CRSVIS);