PCI: tegra: Add Tegra194 MCFG quirks for ECAM errata

The PCIe controller in Tegra194 SoC is not ECAM-compliant.  With the
current hardware design, ECAM can be enabled only for one controller (the
C5 controller) 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.

This issue is specific to Tegra194 and it would be fixed in the future
generations of Tegra SoCs.

Link: https://lore.kernel.org/r/20210416134537.19474-1-vidyas@nvidia.com
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.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/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 +313,104 @@ struct tegra_pcie_dw_of_data {
 	enum dw_pcie_device_mode mode;
 };
 
+#if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
+struct tegra194_pcie_ecam  {
+	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_ecam *pcie_ecam;
+
+	pcie_ecam = devm_kzalloc(dev, sizeof(*pcie_ecam), GFP_KERNEL);
+	if (!pcie_ecam)
+		return -ENOMEM;
+
+	pcie_ecam->config_base = cfg->win;
+	pcie_ecam->iatu_base = cfg->win + SZ_256K;
+	pcie_ecam->dbi_base = cfg->win + SZ_512K;
+	cfg->priv = pcie_ecam;
+
+	return 0;
+}
+
+static void atu_reg_write(struct tegra194_pcie_ecam *pcie_ecam, int index,
+			  u32 val, u32 reg)
+{
+	u32 offset = PCIE_GET_ATU_OUTB_UNR_REG_OFFSET(index);
+
+	writel(val, pcie_ecam->iatu_base + offset + reg);
+}
+
+static void program_outbound_atu(struct tegra194_pcie_ecam *pcie_ecam,
+				 int index, int type, u64 cpu_addr,
+				 u64 pci_addr, u64 size)
+{
+	atu_reg_write(pcie_ecam, index, lower_32_bits(cpu_addr),
+		      PCIE_ATU_LOWER_BASE);
+	atu_reg_write(pcie_ecam, index, upper_32_bits(cpu_addr),
+		      PCIE_ATU_UPPER_BASE);
+	atu_reg_write(pcie_ecam, index, lower_32_bits(pci_addr),
+		      PCIE_ATU_LOWER_TARGET);
+	atu_reg_write(pcie_ecam, index, lower_32_bits(cpu_addr + size - 1),
+		      PCIE_ATU_LIMIT);
+	atu_reg_write(pcie_ecam, index, upper_32_bits(pci_addr),
+		      PCIE_ATU_UPPER_TARGET);
+	atu_reg_write(pcie_ecam, index, type, PCIE_ATU_CR1);
+	atu_reg_write(pcie_ecam, 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_ecam *pcie_ecam = 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_ecam->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_ecam, 0, type, cfg->res.start, busdev,
+			     SZ_256K);
+
+	return pcie_ecam->config_base + where;
+}
+
+const struct pci_ecam_ops tegra194_pcie_ops = {
+	.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 +2411,5 @@ 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)