Merge branch 'pci/enumeration'

  - Enable PCIe services for host controller drivers that use managed host
    bridge alloc (Jean-Philippe Brucker)

  - Add quirk to clear PCIe Retrain Link bit to work around Pericom bridge
    erratum (Stefan Mätje)

  - Add "external-facing" DT property to identify cases where we require
    IOMMU protection from untrusted devices (Jean-Philippe Brucker)

  - Support fixed bus numbers from bridge Enhanced Allocation capabilities
    (Subbaraya Sundeep)

* pci/enumeration:
  PCI: Assign bus numbers present in EA capability for bridges
  PCI: OF: Support "external-facing" property
  dt-bindings: Add "external-facing" PCIe port property
  PCI: Rework pcie_retrain_link() wait loop
  PCI: Work around Pericom PCIe-to-PCI bridge Retrain Link erratum
  PCI: Factor out pcie_retrain_link() function
  PCI: Init PCIe feature bits for managed host bridge alloc

7 files changed, 180 insertions, 33 deletions

diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
index c77981c5dd18..92c01db610df 100644
--- a/Documentation/devicetree/bindings/pci/pci.txt
+++ b/Documentation/devicetree/bindings/pci/pci.txt
@@ -24,3 +24,53 @@ driver implementation may support the following properties:
    unsupported link speed, for instance, trying to do training for
    unsupported link speed, etc.  Must be '4' for gen4, '3' for gen3, '2'
    for gen2, and '1' for gen1. Any other values are invalid.
+
+PCI-PCI Bridge properties
+-------------------------
+
+PCIe root ports and switch ports may be described explicitly in the device
+tree, as children of the host bridge node. Even though those devices are
+discoverable by probing, it might be necessary to describe properties that
+aren't provided by standard PCIe capabilities.
+
+Required properties:
+
+- reg:
+   Identifies the PCI-PCI bridge. As defined in the IEEE Std 1275-1994
+   document, it is a five-cell address encoded as (phys.hi phys.mid
+   phys.lo size.hi size.lo). phys.hi should contain the device's BDF as
+   0b00000000 bbbbbbbb dddddfff 00000000. The other cells should be zero.
+
+   The bus number is defined by firmware, through the standard bridge
+   configuration mechanism. If this port is a switch port, then firmware
+   allocates the bus number and writes it into the Secondary Bus Number
+   register of the bridge directly above this port. Otherwise, the bus
+   number of a root port is the first number in the bus-range property,
+   defaulting to zero.
+
+   If firmware leaves the ARI Forwarding Enable bit set in the bridge
+   above this port, then phys.hi contains the 8-bit function number as
+   0b00000000 bbbbbbbb ffffffff 00000000. Note that the PCIe specification
+   recommends that firmware only leaves ARI enabled when it knows that the
+   OS is ARI-aware.
+
+Optional properties:
+
+- external-facing:
+   When present, the port is external-facing. All bridges and endpoints
+   downstream of this port are external to the machine. The OS can, for
+   example, use this information to identify devices that cannot be
+   trusted with relaxed DMA protection, as users could easily attach
+   malicious devices to this port.
+
+Example:
+
+pcie@10000000 {
+	compatible = "pci-host-ecam-generic";
+	...
+	pcie@0008 {
+		/* Root port 00:01.0 is external-facing */
+		reg = <0x00000800 0 0 0 0>;
+		external-facing;
+	};
+};
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 3d32da15c215..67376cf45880 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -31,10 +31,16 @@ void pci_release_of_node(struct pci_dev *dev)
 
 void pci_set_bus_of_node(struct pci_bus *bus)
 {
-	if (bus->self == NULL)
-		bus->dev.of_node = pcibios_get_phb_of_node(bus);
-	else
-		bus->dev.of_node = of_node_get(bus->self->dev.of_node);
+	struct device_node *node;
+
+	if (bus->self == NULL) {
+		node = pcibios_get_phb_of_node(bus);
+	} else {
+		node = of_node_get(bus->self->dev.of_node);
+		if (node && of_property_read_bool(node, "external-facing"))
+			bus->self->untrusted = true;
+	}
+	bus->dev.of_node = node;
 }
 
 void pci_release_bus_of_node(struct pci_bus *bus)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 727e3c1ef9a4..fd4cb75088f9 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -196,6 +196,36 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist)
 	link->clkpm_capable = (blacklist) ? 0 : capable;
 }
 
+static bool pcie_retrain_link(struct pcie_link_state *link)
+{
+	struct pci_dev *parent = link->pdev;
+	unsigned long end_jiffies;
+	u16 reg16;
+
+	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
+	reg16 |= PCI_EXP_LNKCTL_RL;
+	pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
+	if (parent->clear_retrain_link) {
+		/*
+		 * Due to an erratum in some devices the Retrain Link bit
+		 * needs to be cleared again manually to allow the link
+		 * training to succeed.
+		 */
+		reg16 &= ~PCI_EXP_LNKCTL_RL;
+		pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
+	}
+
+	/* Wait for link training end. Break out after waiting for timeout */
+	end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
+	do {
+		pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &reg16);
+		if (!(reg16 & PCI_EXP_LNKSTA_LT))
+			break;
+		msleep(1);
+	} while (time_before(jiffies, end_jiffies));
+	return !(reg16 & PCI_EXP_LNKSTA_LT);
+}
+
 /*
  * pcie_aspm_configure_common_clock: check if the 2 ends of a link
  *   could use common clock. If they are, configure them to use the
@@ -205,7 +235,6 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 {
 	int same_clock = 1;
 	u16 reg16, parent_reg, child_reg[8];
-	unsigned long start_jiffies;
 	struct pci_dev *child, *parent = link->pdev;
 	struct pci_bus *linkbus = parent->subordinate;
 	/*
@@ -263,21 +292,7 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
 		reg16 &= ~PCI_EXP_LNKCTL_CCC;
 	pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
 
-	/* Retrain link */
-	reg16 |= PCI_EXP_LNKCTL_RL;
-	pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
-
-	/* Wait for link training end. Break out after waiting for timeout */
-	start_jiffies = jiffies;
-	for (;;) {
-		pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &reg16);
-		if (!(reg16 & PCI_EXP_LNKSTA_LT))
-			break;
-		if (time_after(jiffies, start_jiffies + LINK_RETRAIN_TIMEOUT))
-			break;
-		msleep(1);
-	}
-	if (!(reg16 & PCI_EXP_LNKSTA_LT))
+	if (pcie_retrain_link(link))
 		return;
 
 	/* Training failed. Restore common clock configurations */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2ec0df04e0dc..a6874c306908 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -586,16 +586,9 @@ static void pci_release_host_bridge_dev(struct device *dev)
 	kfree(to_pci_host_bridge(dev));
 }
 
-struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
+static void pci_init_host_bridge(struct pci_host_bridge *bridge)
 {
-	struct pci_host_bridge *bridge;
-
-	bridge = kzalloc(sizeof(*bridge) + priv, GFP_KERNEL);
-	if (!bridge)
-		return NULL;
-
 	INIT_LIST_HEAD(&bridge->windows);
-	bridge->dev.release = pci_release_host_bridge_dev;
 
 	/*
 	 * We assume we can manage these PCIe features.  Some systems may
@@ -608,6 +601,18 @@ struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
 	bridge->native_shpc_hotplug = 1;
 	bridge->native_pme = 1;
 	bridge->native_ltr = 1;
+}
+
+struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
+{
+	struct pci_host_bridge *bridge;
+
+	bridge = kzalloc(sizeof(*bridge) + priv, GFP_KERNEL);
+	if (!bridge)
+		return NULL;
+
+	pci_init_host_bridge(bridge);
+	bridge->dev.release = pci_release_host_bridge_dev;
 
 	return bridge;
 }
@@ -622,7 +627,7 @@ struct pci_host_bridge *devm_pci_alloc_host_bridge(struct device *dev,
 	if (!bridge)
 		return NULL;
 
-	INIT_LIST_HEAD(&bridge->windows);
+	pci_init_host_bridge(bridge);
 	bridge->dev.release = devm_pci_release_host_bridge_dev;
 
 	return bridge;
@@ -1081,6 +1086,36 @@ static void pci_enable_crs(struct pci_dev *pdev)
 
 static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus,
 					      unsigned int available_buses);
+/**
+ * pci_ea_fixed_busnrs() - Read fixed Secondary and Subordinate bus
+ * numbers from EA capability.
+ * @dev: Bridge
+ * @sec: updated with secondary bus number from EA
+ * @sub: updated with subordinate bus number from EA
+ *
+ * If @dev is a bridge with EA capability, update @sec and @sub with
+ * fixed bus numbers from the capability and return true.  Otherwise,
+ * return false.
+ */
+static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub)
+{
+	int ea, offset;
+	u32 dw;
+
+	if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
+		return false;
+
+	/* find PCI EA capability in list */
+	ea = pci_find_capability(dev, PCI_CAP_ID_EA);
+	if (!ea)
+		return false;
+
+	offset = ea + PCI_EA_FIRST_ENT;
+	pci_read_config_dword(dev, offset, &dw);
+	*sec =  dw & PCI_EA_SEC_BUS_MASK;
+	*sub = (dw & PCI_EA_SUB_BUS_MASK) >> PCI_EA_SUB_BUS_SHIFT;
+	return true;
+}
 
 /*
  * pci_scan_bridge_extend() - Scan buses behind a bridge
@@ -1115,6 +1150,9 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 	u16 bctl;
 	u8 primary, secondary, subordinate;
 	int broken = 0;
+	bool fixed_buses;
+	u8 fixed_sec, fixed_sub;
+	int next_busnr;
 
 	/*
 	 * Make sure the bridge is powered on to be able to access config
@@ -1214,17 +1252,24 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 		/* Clear errors */
 		pci_write_config_word(dev, PCI_STATUS, 0xffff);
 
+		/* Read bus numbers from EA Capability (if present) */
+		fixed_buses = pci_ea_fixed_busnrs(dev, &fixed_sec, &fixed_sub);
+		if (fixed_buses)
+			next_busnr = fixed_sec;
+		else
+			next_busnr = max + 1;
+
 		/*
 		 * Prevent assigning a bus number that already exists.
 		 * This can happen when a bridge is hot-plugged, so in this
 		 * case we only re-scan this bus.
 		 */
-		child = pci_find_bus(pci_domain_nr(bus), max+1);
+		child = pci_find_bus(pci_domain_nr(bus), next_busnr);
 		if (!child) {
-			child = pci_add_new_bus(bus, dev, max+1);
+			child = pci_add_new_bus(bus, dev, next_busnr);
 			if (!child)
 				goto out;
-			pci_bus_insert_busn_res(child, max+1,
+			pci_bus_insert_busn_res(child, next_busnr,
 						bus->busn_res.end);
 		}
 		max++;
@@ -1285,7 +1330,13 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 			max += i;
 		}
 
-		/* Set subordinate bus number to its real value */
+		/*
+		 * Set subordinate bus number to its real value.
+		 * If fixed subordinate bus number exists from EA
+		 * capability then use it.
+		 */
+		if (fixed_buses)
+			max = fixed_sub;
 		pci_bus_update_busn_res_end(child, max);
 		pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
 	}
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index a59ad09ce911..6f34e17c98f4 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2245,6 +2245,23 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x10f1, quirk_disable_aspm_l0s);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x10f4, quirk_disable_aspm_l0s);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x1508, quirk_disable_aspm_l0s);
 
+/*
+ * Some Pericom PCIe-to-PCI bridges in reverse mode need the PCIe Retrain
+ * Link bit cleared after starting the link retrain process to allow this
+ * process to finish.
+ *
+ * Affected devices: PI7C9X110, PI7C9X111SL, PI7C9X130.  See also the
+ * Pericom Errata Sheet PI7C9X111SLB_errata_rev1.2_102711.pdf.
+ */
+static void quirk_enable_clear_retrain_link(struct pci_dev *dev)
+{
+	dev->clear_retrain_link = 1;
+	pci_info(dev, "Enable PCIe Retrain Link quirk\n");
+}
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe110, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe111, quirk_enable_clear_retrain_link);
+DECLARE_PCI_FIXUP_HEADER(0x12d8, 0xe130, quirk_enable_clear_retrain_link);
+
 static void fixup_rev1_53c810(struct pci_dev *dev)
 {
 	u32 class = dev->class;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 77448215ef5b..2c056a7a728a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -348,6 +348,8 @@ struct pci_dev {
 	unsigned int	hotplug_user_indicators:1; /* SlotCtl indicators
 						      controlled exclusively by
 						      user sysfs */
+	unsigned int	clear_retrain_link:1;	/* Need to clear Retrain Link
+						   bit manually */
 	unsigned int	d3_delay;	/* D3->D0 transition time in ms */
 	unsigned int	d3cold_delay;	/* D3cold->D0 transition time in ms */
 
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 5c98133f2c94..c51e0066de8b 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -372,6 +372,12 @@
 #define PCI_EA_FIRST_ENT_BRIDGE	8	/* First EA Entry for Bridges */
 #define  PCI_EA_ES		0x00000007 /* Entry Size */
 #define  PCI_EA_BEI		0x000000f0 /* BAR Equivalent Indicator */
+
+/* EA fixed Secondary and Subordinate bus numbers for Bridge */
+#define PCI_EA_SEC_BUS_MASK	0xff
+#define PCI_EA_SUB_BUS_MASK	0xff00
+#define PCI_EA_SUB_BUS_SHIFT	8
+
 /* 0-5 map to BARs 0-5 respectively */
 #define   PCI_EA_BEI_BAR0		0
 #define   PCI_EA_BEI_BAR5		5