[PATCH v9 2/3] PCI: Add tango PCIe host bridge support

Marc Gonzalez
2017-06-20T08:21:09Z

This driver is required to work around several hardware bugs
in the PCIe controller.

NB: Revision 1 does not support legacy interrupts, or IO space.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
---
drivers/pci/host/Kconfig | 8 +++
drivers/pci/host/Makefile | 1 +
drivers/pci/host/pcie-tango.c | 164 ++++++++++++++++++++++++++++++++++++++++++
include/linux/pci_ids.h | 2 +
4 files changed, 175 insertions(+)
create mode 100644 drivers/pci/host/pcie-tango.c

diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index d7e7c0a827c3..5183d9095c3a 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -285,6 +285,14 @@ config PCIE_ROCKCHIP
There is 1 internal PCIe port available to support GEN2 with
4 slots.

+config PCIE_TANGO
+ bool "Tango PCIe controller"
+ depends on ARCH_TANGO && PCI_MSI && OF
+ select PCI_HOST_COMMON
+ help
+ Say Y here to enable PCIe controller support for Sigma Designs
+ Tango systems, such as SMP8759 and later chips.
+
config VMD
depends on PCI_MSI && X86_64
tristate "Intel Volume Management Device Driver"
diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
index 084cb4983645..fc7ea90196f3 100644
--- a/drivers/pci/host/Makefile
+++ b/drivers/pci/host/Makefile
@@ -32,4 +32,5 @@ obj-$(CONFIG_PCI_HOST_THUNDER_PEM) += pci-thunder-pem.o
obj-$(CONFIG_PCIE_ARMADA_8K) += pcie-armada8k.o
obj-$(CONFIG_PCIE_ARTPEC6) += pcie-artpec6.o
obj-$(CONFIG_PCIE_ROCKCHIP) += pcie-rockchip.o
+obj-$(CONFIG_PCIE_TANGO) += pcie-tango.o
obj-$(CONFIG_VMD) += vmd.o
diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c
new file mode 100644
index 000000000000..67aaadcc1c5e
--- /dev/null
+++ b/drivers/pci/host/pcie-tango.c
@@ -0,0 +1,164 @@
+#include <linux/pci-ecam.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+
+#define MSI_MAX 256
+
+#define SMP8759_MUX 0x48
+#define SMP8759_TEST_OUT 0x74
+
+struct tango_pcie {
+ void __iomem *mux;
+};
+
+/*** HOST BRIDGE SUPPORT ***/
+
+static int smp8759_config_read(struct pci_bus *bus,
+ unsigned int devfn, int where, int size, u32 *val)
+{
+ int ret;
+ struct pci_config_window *cfg = bus->sysdata;
+ struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
+
+ /*
+ * QUIRK #1
+ * Reads in configuration space outside devfn 0 return garbage.
+ */
+ if (devfn != 0)
+ return PCIBIOS_FUNC_NOT_SUPPORTED;
+
+ /*
+ * QUIRK #2
+ * Unfortunately, config and mem spaces are muxed.
+ * Linux does not support such a setting, since drivers are free
+ * to access mem space directly, at any time.
+ * Therefore, we can only PRAY that config and mem space accesses
+ * NEVER occur concurrently.
+ */
+ writel_relaxed(1, pcie->mux);
+ ret = pci_generic_config_read(bus, devfn, where, size, val);
+ writel_relaxed(0, pcie->mux);
+
+ return ret;
+}
+
+static int smp8759_config_write(struct pci_bus *bus,
+ unsigned int devfn, int where, int size, u32 val)
+{
+ int ret;
+ struct pci_config_window *cfg = bus->sysdata;
+ struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
+
+ writel_relaxed(1, pcie->mux);
+ ret = pci_generic_config_write(bus, devfn, where, size, val);
+ writel_relaxed(0, pcie->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 const struct of_device_id tango_pcie_ids[] = {
+ { .compatible = "sigma,smp8759-pcie" },
+ { /* sentinel */ },
+};
+
+static int tango_check_pcie_link(void __iomem *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 0;
+ usleep_range(3000, 4000);
+ }
+
+ return -ENODEV;
+}
+
+static int smp8759_init(struct tango_pcie *pcie, void __iomem *base)
+{
+ pcie->mux = base + SMP8759_MUX;
+
+ return tango_check_pcie_link(base + SMP8759_TEST_OUT);
+}
+
+static int tango_pcie_probe(struct platform_device *pdev)
+{
+ int ret = -EINVAL;
+ void __iomem *base;
+ struct resource *res;
+ struct tango_pcie *pcie;
+ struct device *dev = &pdev->dev;
+
+ pr_err("MAJOR ISSUE: PCIe config and mem spaces are muxed\n");
+ pr_err("Tainting kernel... Use driver at your own risk\n");
+ add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+
+ pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+ if (!pcie)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, pcie);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ if (of_device_is_compatible(dev->of_node, "sigma,smp8759-pcie"))
+ ret = smp8759_init(pcie, base);
+
+ if (ret)
+ return ret;
+
+ return pci_host_common_probe(pdev, &smp8759_ecam_ops);
+}
+
+static struct platform_driver tango_pcie_driver = {
+ .probe = tango_pcie_probe,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = tango_pcie_ids,
+ },
+};
+
+builtin_platform_driver(tango_pcie_driver);
+
+/*
+ * QUIRK #3
+ * The root complex advertizes 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, 0x24, tango_fixup_class);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x28, tango_fixup_class);
+
+/*
+ * QUIRK #4
+ * 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, 0x24, tango_fixup_bar);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x28, tango_fixup_bar);
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index f020ab4079d3..b577dbe46f8f 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -1369,6 +1369,8 @@
#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
--
2.11.0