[PATCH v3] PCI: pci-bridge-emul: Set position of PCI capabilities to real HW value

["Pali Rohár" <pali@kernel.org>]

mvebu and aardvark HW have PCIe capabilities on different offset in PCI
config space. Extend pci-bridge-emul.c code to allow setting custom driver
custom value where PCIe capabilities starts.

With this change PCIe capabilities of both drivers are reported at the same
location as where they are reported by U-Boot - in their real HW offset.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
Changes in v3:
* Correctly initialize pcie_conf.next pointer for SSID capability (if it is
  after the PCIe capability)

Changes in v2:
* Rebase on top of v6.0-rc1, fix usage of PCIE_CAP_PCIEXP
---
 drivers/pci/controller/pci-aardvark.c |  1 +
 drivers/pci/controller/pci-mvebu.c    |  1 +
 drivers/pci/pci-bridge-emul.c         | 48 +++++++++++++++++----------
 drivers/pci/pci-bridge-emul.h         |  2 ++
 4 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 966c8b48bd96..4834198cc86b 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -1078,6 +1078,7 @@ static int advk_sw_pci_bridge_init(struct advk_pcie *pcie)
 	bridge->pcie_conf.rootcap = cpu_to_le16(PCI_EXP_RTCAP_CRSVIS);
 
 	bridge->has_pcie = true;
+	bridge->pcie_start = PCIE_CORE_PCIEXP_CAP;
 	bridge->data = pcie;
 	bridge->ops = &advk_pci_bridge_emul_ops;
 
diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index af915c951f06..0fdbb5585fec 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -946,6 +946,7 @@ static int mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 	bridge->subsystem_vendor_id = ssdev_id & 0xffff;
 	bridge->subsystem_id = ssdev_id >> 16;
 	bridge->has_pcie = true;
+	bridge->pcie_start = PCIE_CAP_PCIEXP;
 	bridge->data = port;
 	bridge->ops = &mvebu_pci_bridge_emul_ops;
 
diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 9c2ca28e3ecf..9334b2dd4764 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -22,11 +22,7 @@
 
 #define PCI_BRIDGE_CONF_END	PCI_STD_HEADER_SIZEOF
 #define PCI_CAP_SSID_SIZEOF	(PCI_SSVID_DEVICE_ID + 2)
-#define PCI_CAP_SSID_START	PCI_BRIDGE_CONF_END
-#define PCI_CAP_SSID_END	(PCI_CAP_SSID_START + PCI_CAP_SSID_SIZEOF)
 #define PCI_CAP_PCIE_SIZEOF	(PCI_EXP_SLTSTA2 + 2)
-#define PCI_CAP_PCIE_START	PCI_CAP_SSID_END
-#define PCI_CAP_PCIE_END	(PCI_CAP_PCIE_START + PCI_CAP_PCIE_SIZEOF)
 
 /**
  * struct pci_bridge_reg_behavior - register bits behaviors
@@ -324,7 +320,7 @@ pci_bridge_emul_read_ssid(struct pci_bridge_emul *bridge, int reg, u32 *value)
 	switch (reg) {
 	case PCI_CAP_LIST_ID:
 		*value = PCI_CAP_ID_SSVID |
-			(bridge->has_pcie ? (PCI_CAP_PCIE_START << 8) : 0);
+			((bridge->pcie_start > bridge->ssid_start) ? (bridge->pcie_start << 8) : 0);
 		return PCI_BRIDGE_EMUL_HANDLED;
 
 	case PCI_SSVID_VENDOR_ID:
@@ -365,18 +361,33 @@ int pci_bridge_emul_init(struct pci_bridge_emul *bridge,
 	if (!bridge->pci_regs_behavior)
 		return -ENOMEM;
 
-	if (bridge->subsystem_vendor_id)
-		bridge->conf.capabilities_pointer = PCI_CAP_SSID_START;
-	else if (bridge->has_pcie)
-		bridge->conf.capabilities_pointer = PCI_CAP_PCIE_START;
-	else
-		bridge->conf.capabilities_pointer = 0;
+	/* If ssid_start and pcie_start were not specified then choose the lowest possible value. */
+	if (!bridge->ssid_start && !bridge->pcie_start) {
+		if (bridge->subsystem_vendor_id)
+			bridge->ssid_start = PCI_BRIDGE_CONF_END;
+		if (bridge->has_pcie)
+			bridge->pcie_start = bridge->ssid_start + PCI_CAP_SSID_SIZEOF;
+	} else if (!bridge->ssid_start && bridge->subsystem_vendor_id) {
+		if (bridge->pcie_start - PCI_BRIDGE_CONF_END >= PCI_CAP_SSID_SIZEOF)
+			bridge->ssid_start = PCI_BRIDGE_CONF_END;
+		else
+			bridge->ssid_start = bridge->pcie_start + PCI_CAP_PCIE_SIZEOF;
+	} else if (!bridge->pcie_start && bridge->has_pcie) {
+		if (bridge->ssid_start - PCI_BRIDGE_CONF_END >= PCI_CAP_PCIE_SIZEOF)
+			bridge->pcie_start = PCI_BRIDGE_CONF_END;
+		else
+			bridge->pcie_start = bridge->ssid_start + PCI_CAP_SSID_SIZEOF;
+	}
+
+	bridge->conf.capabilities_pointer = min(bridge->ssid_start, bridge->pcie_start);
 
 	if (bridge->conf.capabilities_pointer)
 		bridge->conf.status |= cpu_to_le16(PCI_STATUS_CAP_LIST);
 
 	if (bridge->has_pcie) {
 		bridge->pcie_conf.cap_id = PCI_CAP_ID_EXP;
+		bridge->pcie_conf.next = (bridge->ssid_start > bridge->pcie_start) ?
+					 bridge->ssid_start : 0;
 		bridge->pcie_conf.cap |= cpu_to_le16(PCI_EXP_TYPE_ROOT_PORT << 4);
 		bridge->pcie_cap_regs_behavior =
 			kmemdup(pcie_cap_regs_behavior,
@@ -459,15 +470,17 @@ int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
 		read_op = bridge->ops->read_base;
 		cfgspace = (__le32 *) &bridge->conf;
 		behavior = bridge->pci_regs_behavior;
-	} else if (reg >= PCI_CAP_SSID_START && reg < PCI_CAP_SSID_END && bridge->subsystem_vendor_id) {
+	} else if (reg >= bridge->ssid_start && reg < bridge->ssid_start + PCI_CAP_SSID_SIZEOF &&
+		   bridge->subsystem_vendor_id) {
 		/* Emulated PCI Bridge Subsystem Vendor ID capability */
-		reg -= PCI_CAP_SSID_START;
+		reg -= bridge->ssid_start;
 		read_op = pci_bridge_emul_read_ssid;
 		cfgspace = NULL;
 		behavior = NULL;
-	} else if (reg >= PCI_CAP_PCIE_START && reg < PCI_CAP_PCIE_END && bridge->has_pcie) {
+	} else if (reg >= bridge->pcie_start && reg < bridge->pcie_start + PCI_CAP_PCIE_SIZEOF &&
+		   bridge->has_pcie) {
 		/* Our emulated PCIe capability */
-		reg -= PCI_CAP_PCIE_START;
+		reg -= bridge->pcie_start;
 		read_op = bridge->ops->read_pcie;
 		cfgspace = (__le32 *) &bridge->pcie_conf;
 		behavior = bridge->pcie_cap_regs_behavior;
@@ -538,9 +551,10 @@ int pci_bridge_emul_conf_write(struct pci_bridge_emul *bridge, int where,
 		write_op = bridge->ops->write_base;
 		cfgspace = (__le32 *) &bridge->conf;
 		behavior = bridge->pci_regs_behavior;
-	} else if (reg >= PCI_CAP_PCIE_START && reg < PCI_CAP_PCIE_END && bridge->has_pcie) {
+	} else if (reg >= bridge->pcie_start && reg < bridge->pcie_start + PCI_CAP_PCIE_SIZEOF &&
+		   bridge->has_pcie) {
 		/* Our emulated PCIe capability */
-		reg -= PCI_CAP_PCIE_START;
+		reg -= bridge->pcie_start;
 		write_op = bridge->ops->write_pcie;
 		cfgspace = (__le32 *) &bridge->pcie_conf;
 		behavior = bridge->pcie_cap_regs_behavior;
diff --git a/drivers/pci/pci-bridge-emul.h b/drivers/pci/pci-bridge-emul.h
index 71392b67471d..2a0e59c7f0d9 100644
--- a/drivers/pci/pci-bridge-emul.h
+++ b/drivers/pci/pci-bridge-emul.h
@@ -131,6 +131,8 @@ struct pci_bridge_emul {
 	struct pci_bridge_reg_behavior *pci_regs_behavior;
 	struct pci_bridge_reg_behavior *pcie_cap_regs_behavior;
 	void *data;
+	u8 pcie_start;
+	u8 ssid_start;
 	bool has_pcie;
 	u16 subsystem_vendor_id;
 	u16 subsystem_id;
-- 
2.20.1