PCI: Add MCFG quirks for Tegra194 host controllers

The PCIe controller in Tegra194 SoC is not completely ECAM-compliant.
With the current hardware design limitations in place, ECAM can be enabled
only for one controller (C5 controller to be precise) with bus numbers
starting from 160 instead of 0. A different approach is taken to avoid this
abnormal way of enabling ECAM for just one controller but to enable
configuration space access for all the other controllers. In this approach,
ops are added through MCFG quirk mechanism which access the configuration
spaces by dynamically programming iATU (internal AddressTranslation Unit)
to generate respective configuration accesses just like the way it is
done in DesignWare core sub-system.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
[ Updated by jonathanh@nvidia.com only permit building the Tegra194
  PCIe driver into the kernel and not as a module ]
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>

drivers/acpi/pci_mcfg.c

@@ -116,6 +116,13 @@ static struct mcfg_fixup mcfg_quirks[] = {
 	THUNDER_ECAM_QUIRK(2, 12),
 	THUNDER_ECAM_QUIRK(2, 13),
 
+	{ "NVIDIA", "TEGRA194", 1, 0, MCFG_BUS_ANY, &tegra194_pcie_ops},
+	{ "NVIDIA", "TEGRA194", 1, 1, MCFG_BUS_ANY, &tegra194_pcie_ops},
+	{ "NVIDIA", "TEGRA194", 1, 2, MCFG_BUS_ANY, &tegra194_pcie_ops},
+	{ "NVIDIA", "TEGRA194", 1, 3, MCFG_BUS_ANY, &tegra194_pcie_ops},
+	{ "NVIDIA", "TEGRA194", 1, 4, MCFG_BUS_ANY, &tegra194_pcie_ops},
+	{ "NVIDIA", "TEGRA194", 1, 5, MCFG_BUS_ANY, &tegra194_pcie_ops},
+
 #define XGENE_V1_ECAM_MCFG(rev, seg) \
 	{"APM   ", "XGENE   ", rev, seg, MCFG_BUS_ANY, \
 		&xgene_v1_pcie_ecam_ops }

drivers/pci/controller/dwc/Kconfig

@@ -254,25 +254,27 @@ config PCI_MESON
 	  implement the driver.
 
 config PCIE_TEGRA194
-	tristate
+	bool
 
 config PCIE_TEGRA194_HOST
-	tristate "NVIDIA Tegra194 (and later) PCIe controller - Host Mode"
+	bool "NVIDIA Tegra194 (and later) PCIe controller - Host Mode"
 	depends on ARCH_TEGRA_194_SOC || COMPILE_TEST
 	depends on PCI_MSI_IRQ_DOMAIN
 	select PCIE_DW_HOST
 	select PHY_TEGRA194_P2U
 	select PCIE_TEGRA194
+	default y if ARCH_TEGRA_194_SOC
 	help
 	  Enables support for the PCIe controller in the NVIDIA Tegra194 SoC to
 	  work in host mode. There are two instances of PCIe controllers in
 	  Tegra194. This controller can work either as EP or RC. In order to
 	  enable host-specific features PCIE_TEGRA194_HOST must be selected and
 	  in order to enable device-specific features PCIE_TEGRA194_EP must be
-	  selected. This uses the DesignWare core.
+	  selected. This uses the DesignWare core. ACPI platforms with Tegra194
+	  don't need to enable this.
 
 config PCIE_TEGRA194_EP
-	tristate "NVIDIA Tegra194 (and later) PCIe controller - Endpoint Mode"
+	bool "NVIDIA Tegra194 (and later) PCIe controller - Endpoint Mode"
 	depends on ARCH_TEGRA_194_SOC || COMPILE_TEST
 	depends on PCI_ENDPOINT
 	select PCIE_DW_EP

drivers/pci/controller/dwc/Makefile

@@ -17,7 +17,6 @@ obj-$(CONFIG_PCIE_INTEL_GW) += pcie-intel-gw.o
 obj-$(CONFIG_PCIE_KIRIN) += pcie-kirin.o
 obj-$(CONFIG_PCIE_HISI_STB) += pcie-histb.o
 obj-$(CONFIG_PCI_MESON) += pci-meson.o
-obj-$(CONFIG_PCIE_TEGRA194) += pcie-tegra194.o
 obj-$(CONFIG_PCIE_UNIPHIER) += pcie-uniphier.o
 obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
 
@@ -34,4 +33,5 @@ obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
 ifdef CONFIG_PCI
 obj-$(CONFIG_ARM64) += pcie-al.o
 obj-$(CONFIG_ARM64) += pcie-hisi.o
+obj-$(CONFIG_ARM64) += pcie-tegra194.o
 endif

drivers/pci/controller/dwc/pcie-tegra194.c

@@ -22,6 +22,8 @@
 #include <linux/of_irq.h>
 #include <linux/of_pci.h>
 #include <linux/pci.h>
+#include <linux/pci-acpi.h>
+#include <linux/pci-ecam.h>
 #include <linux/phy/phy.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
@@ -311,6 +313,103 @@ struct tegra_pcie_dw_of_data {
 	enum dw_pcie_device_mode mode;
 };
 
+#if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
+struct tegra194_pcie_acpi  {
+	void __iomem *config_base;
+	void __iomem *iatu_base;
+	void __iomem *dbi_base;
+};
+
+static int tegra194_acpi_init(struct pci_config_window *cfg)
+{
+	struct device *dev = cfg->parent;
+	struct tegra194_pcie_acpi *pcie;
+
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	pcie->config_base = cfg->win;
+	pcie->iatu_base = cfg->win + SZ_256K;
+	pcie->dbi_base = cfg->win + SZ_512K;
+	cfg->priv = pcie;
+
+	return 0;
+}
+
+static inline void atu_reg_write(struct tegra194_pcie_acpi *pcie, int index,
+				 u32 val, u32 reg)
+{
+	u32 offset = PCIE_GET_ATU_OUTB_UNR_REG_OFFSET(index);
+
+	writel(val, pcie->iatu_base + offset + reg);
+}
+
+static void program_outbound_atu(struct tegra194_pcie_acpi *pcie, int index,
+				 int type, u64 cpu_addr, u64 pci_addr, u64 size)
+{
+	atu_reg_write(pcie, index, lower_32_bits(cpu_addr),
+		      PCIE_ATU_LOWER_BASE);
+	atu_reg_write(pcie, index, upper_32_bits(cpu_addr),
+		      PCIE_ATU_UPPER_BASE);
+	atu_reg_write(pcie, index, lower_32_bits(pci_addr),
+		      PCIE_ATU_LOWER_TARGET);
+	atu_reg_write(pcie, index, lower_32_bits(cpu_addr + size - 1),
+		      PCIE_ATU_LIMIT);
+	atu_reg_write(pcie, index, upper_32_bits(pci_addr),
+		      PCIE_ATU_UPPER_TARGET);
+	atu_reg_write(pcie, index, type, PCIE_ATU_CR1);
+	atu_reg_write(pcie, index, PCIE_ATU_ENABLE, PCIE_ATU_CR2);
+}
+
+static void __iomem *tegra194_map_bus(struct pci_bus *bus,
+				      unsigned int devfn, int where)
+{
+	struct pci_config_window *cfg = bus->sysdata;
+	struct tegra194_pcie_acpi *pcie = cfg->priv;
+	u32 busdev;
+	int type;
+
+	if (bus->number < cfg->busr.start || bus->number > cfg->busr.end)
+		return NULL;
+
+	if (bus->number == cfg->busr.start) {
+		if (PCI_SLOT(devfn) == 0)
+			return pcie->dbi_base + where;
+		else
+			return NULL;
+	}
+
+	busdev = PCIE_ATU_BUS(bus->number) | PCIE_ATU_DEV(PCI_SLOT(devfn)) |
+		 PCIE_ATU_FUNC(PCI_FUNC(devfn));
+
+	if (bus->parent->number == cfg->busr.start) {
+		if (PCI_SLOT(devfn) == 0)
+			type = PCIE_ATU_TYPE_CFG0;
+		else
+			return NULL;
+	} else {
+		type = PCIE_ATU_TYPE_CFG1;
+	}
+
+	program_outbound_atu(pcie, 0, type, cfg->res.start, busdev, SZ_256K);
+
+	return (void __iomem *)(pcie->config_base + where);
+}
+
+const struct pci_ecam_ops tegra194_pcie_ops = {
+	.bus_shift	= 20,
+	.init		= tegra194_acpi_init,
+	.pci_ops	= {
+		.map_bus	= tegra194_map_bus,
+		.read		= pci_generic_config_read,
+		.write		= pci_generic_config_write,
+	}
+};
+#endif /* defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) */
+
+#ifdef CONFIG_PCIE_TEGRA194
+
 static inline struct tegra_pcie_dw *to_tegra_pcie(struct dw_pcie *pci)
 {
 	return container_of(pci, struct tegra_pcie_dw, pci);
@@ -2311,3 +2410,6 @@ MODULE_DEVICE_TABLE(of, tegra_pcie_dw_of_match);
 MODULE_AUTHOR("Vidya Sagar <vidyas@nvidia.com>");
 MODULE_DESCRIPTION("NVIDIA PCIe host controller driver");
 MODULE_LICENSE("GPL v2");
+
+#endif /* CONFIG_PCIE_TEGRA194 */
+

include/linux/pci-ecam.h

@@ -85,6 +85,7 @@ extern const struct pci_ecam_ops pci_thunder_ecam_ops; /* Cavium ThunderX 1.x */
 extern const struct pci_ecam_ops xgene_v1_pcie_ecam_ops; /* APM X-Gene PCIe v1 */
 extern const struct pci_ecam_ops xgene_v2_pcie_ecam_ops; /* APM X-Gene PCIe v2.x */
 extern const struct pci_ecam_ops al_pcie_ops;	/* Amazon Annapurna Labs PCIe */
+extern const struct pci_ecam_ops tegra194_pcie_ops; /* Tegra194 PCIe */
 #endif
 
 #if IS_ENABLED(CONFIG_PCI_HOST_COMMON)