diff --git a/Documentation/devicetree/bindings/pci/tango-pcie.txt b/Documentation/devicetree/bindings/pci/tango-pcie.txt
new file mode 100644
index 0000000000000000000000000000000000000000..244683836a7954656b32c5e09b36a547ede43c1f
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/tango-pcie.txt
@@ -0,0 +1,29 @@
+Sigma Designs Tango PCIe controller
+
+Required properties:
+
+- compatible: "sigma,smp8759-pcie"
+- reg: address/size of PCI configuration space, address/size of register area
+- bus-range: defined by size of PCI configuration space
+- device_type: "pci"
+- #size-cells: <2>
+- #address-cells: <3>
+- msi-controller
+- ranges: translation from system to bus addresses
+- interrupts: spec for misc interrupts, spec for MSI
+
+Example:
+
+ pcie@2e000 {
+ compatible = "sigma,smp8759-pcie";
+ reg = <0x50000000 0x400000>, <0x2e000 0x100>;
+ bus-range = <0 3>;
+ device_type = "pci";
+ #size-cells = <2>;
+ #address-cells = <3>;
+ msi-controller;
+ ranges = <0x02000000 0x0 0x00400000 0x50400000 0x0 0x3c00000>;
+ interrupts =
+ <54 IRQ_TYPE_LEVEL_HIGH>, /* misc interrupts */
+ <55 IRQ_TYPE_LEVEL_HIGH>; /* MSI */
+ };
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 0cd5b30dccb15d1655424faeff8385cd528d48b4..89d61c2cbfaa1c2926e7592a4b1d62b4b45208e2 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -191,6 +191,20 @@ config PCIE_MEDIATEK
MT7623 series SoCs. There is one single root complex with 3 root
ports available. Each port supports Gen2 lane x1.
+config PCIE_TANGO_SMP8759
+ bool "Tango SMP8759 PCIe controller (DANGEROUS)"
+ depends on ARCH_TANGO && PCI_MSI && OF
+ depends on BROKEN
+ select PCI_HOST_COMMON
+ help
+ Say Y here to enable PCIe controller support for Sigma Designs
+ Tango SMP8759-based systems.
+
+ Note: The SMP8759 controller multiplexes PCI config and MMIO
+ accesses, and Linux doesn't provide a way to serialize them.
+ This can lead to data corruption if drivers perform concurrent
+ config and MMIO accesses.
+
config VMD
depends on PCI_MSI && X86_64 && SRCU
tristate "Intel Volume Management Device Driver"
diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
index b10d104c85fdd43e4baa2e06ea418268d8c7c749..12382785e02a652637b64599e1b51c6a7b78206d 100644
--- a/drivers/pci/host/Makefile
+++ b/drivers/pci/host/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o
obj-$(CONFIG_PCIE_ALTERA_MSI) += pcie-altera-msi.o
obj-$(CONFIG_PCIE_ROCKCHIP) += pcie-rockchip.o
obj-$(CONFIG_PCIE_MEDIATEK) += pcie-mediatek.o
+obj-$(CONFIG_PCIE_TANGO_SMP8759) += pcie-tango.o
obj-$(CONFIG_VMD) += vmd.o
# The following drivers are for devices that use the generic ACPI
diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c
new file mode 100644
index 0000000000000000000000000000000000000000..6bbb81f06a53c33bcd6acaee3cbb1bd92ecf7823
--- /dev/null
+++ b/drivers/pci/host/pcie-tango.c
@@ -0,0 +1,141 @@
+#include <linux/pci-ecam.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+
+#define SMP8759_MUX 0x48
+#define SMP8759_TEST_OUT 0x74
+
+struct tango_pcie {
+ void __iomem *base;
+};
+
+static int smp8759_config_read(struct pci_bus *bus, unsigned int devfn,
+ int where, int size, u32 *val)
+{
+ struct pci_config_window *cfg = bus->sysdata;
+ struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
+ int ret;
+
+ /* Reads in configuration space outside devfn 0 return garbage */
+ if (devfn != 0)
+ return PCIBIOS_FUNC_NOT_SUPPORTED;
+
+ /*
+ * PCI config and MMIO accesses are muxed. Linux doesn't have a
+ * mutual exclusion mechanism for config vs. MMIO accesses, so
+ * concurrent accesses may cause corruption.
+ */
+ writel_relaxed(1, pcie->base + SMP8759_MUX);
+ ret = pci_generic_config_read(bus, devfn, where, size, val);
+ writel_relaxed(0, pcie->base + SMP8759_MUX);
+
+ return ret;
+}
+
+static int smp8759_config_write(struct pci_bus *bus, unsigned int devfn,
+ int where, int size, u32 val)
+{
+ struct pci_config_window *cfg = bus->sysdata;
+ struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
+ int ret;
+
+ writel_relaxed(1, pcie->base + SMP8759_MUX);
+ ret = pci_generic_config_write(bus, devfn, where, size, val);
+ writel_relaxed(0, pcie->base + SMP8759_MUX);
+
+ return ret;
+}
+
+static struct pci_ecam_ops smp8759_ecam_ops = {
+ .bus_shift = 20,
+ .pci_ops = {
+ .map_bus = pci_ecam_map_bus,
+ .read = smp8759_config_read,
+ .write = smp8759_config_write,
+ }
+};
+
+static int tango_pcie_link_up(struct tango_pcie *pcie)
+{
+ void __iomem *test_out = pcie->base + SMP8759_TEST_OUT;
+ int i;
+
+ writel_relaxed(16, test_out);
+ for (i = 0; i < 10; ++i) {
+ u32 ltssm_state = readl_relaxed(test_out) >> 8;
+ if ((ltssm_state & 0x1f) == 0xf) /* L0 */
+ return 1;
+ usleep_range(3000, 4000);
+ }
+
+ return 0;
+}
+
+static int tango_pcie_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct tango_pcie *pcie;
+ struct resource *res;
+ int ret;
+
+ dev_warn(dev, "simultaneous PCI config and MMIO accesses may cause data corruption\n");
+ add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);
+
+ pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+ if (!pcie)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ pcie->base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(pcie->base))
+ return PTR_ERR(pcie->base);
+
+ platform_set_drvdata(pdev, pcie);
+
+ if (!tango_pcie_link_up(pcie))
+ return -ENODEV;
+
+ return pci_host_common_probe(pdev, &smp8759_ecam_ops);
+}
+
+static const struct of_device_id tango_pcie_ids[] = {
+ { .compatible = "sigma,smp8759-pcie" },
+ { },
+};
+
+static struct platform_driver tango_pcie_driver = {
+ .probe = tango_pcie_probe,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = tango_pcie_ids,
+ .suppress_bind_attrs = true,
+ },
+};
+builtin_platform_driver(tango_pcie_driver);
+
+/*
+ * The root complex advertises the wrong device class.
+ * Header Type 1 is for PCI-to-PCI bridges.
+ */
+static void tango_fixup_class(struct pci_dev *dev)
+{
+ dev->class = PCI_CLASS_BRIDGE_PCI << 8;
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_class);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_class);
+
+/*
+ * The root complex exposes a "fake" BAR, which is used to filter
+ * bus-to-system accesses. Only accesses within the range defined by this
+ * BAR are forwarded to the host, others are ignored.
+ *
+ * By default, the DMA framework expects an identity mapping, and DRAM0 is
+ * mapped at 0x80000000.
+ */
+static void tango_fixup_bar(struct pci_dev *dev)
+{
+ dev->non_compliant_bars = true;
+ pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, 0x80000000);
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_bar);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_bar);
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 5f6b71d15393a4d6df153589cee33e42d42ebb26..c71e532da4589df0ee73fd0a8c2bb586c5f9f0ca 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -1373,6 +1373,8 @@
#define PCI_DEVICE_ID_TTI_HPT374 0x0008
#define PCI_DEVICE_ID_TTI_HPT372N 0x0009 /* apparently a 372N variant? */
+#define PCI_VENDOR_ID_SIGMA 0x1105
+
#define PCI_VENDOR_ID_VIA 0x1106
#define PCI_DEVICE_ID_VIA_8763_0 0x0198
#define PCI_DEVICE_ID_VIA_8380_0 0x0204