[PATCH v5 2/3] pci, pci-thunder-pem: Add PCIe host driver for ThunderX processors.

[David Daney]

From: David Daney <david.daney@xxxxxxxxxx>

The root complexes used to access off-chip PCIe devices (called PEM
units in the hardware manuals) on some Cavium ThunderX processors
require quirky access methods for the config space of the PCIe bridge.
Add a driver to provide these config space accessor functions.  The
pci-host-common code is used to configure the PCI machinery.

Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 .../devicetree/bindings/pci/pci-thunder-pem.txt    |  43 +++
 MAINTAINERS                                        |   8 +
 drivers/pci/host/Kconfig                           |   7 +
 drivers/pci/host/Makefile                          |   1 +
 drivers/pci/host/pci-thunder-pem.c                 | 332 +++++++++++++++++++++
 5 files changed, 391 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pci/pci-thunder-pem.txt
 create mode 100644 drivers/pci/host/pci-thunder-pem.c

diff --git a/Documentation/devicetree/bindings/pci/pci-thunder-pem.txt b/Documentation/devicetree/bindings/pci/pci-thunder-pem.txt
new file mode 100644
index 0000000..f131fae
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/pci-thunder-pem.txt
@@ -0,0 +1,43 @@
+* ThunderX PEM PCIe host controller
+
+Firmware-initialized PCI host controller found on some Cavium
+ThunderX processors.
+
+The properties and their meanings are identical to those described in
+host-generic-pci.txt except as listed below.
+
+Properties of the host controller node that differ from
+host-generic-pci.txt:
+
+- compatible     : Must be "cavium,pci-host-thunder-pem"
+
+- reg            : Two entries: First the configuration space for down
+                   stream devices base address and size, as accessed
+                   from the parent bus. Second, the register bank of
+                   the PEM device PCIe bridge.
+
+Example:
+
+    pci@87e0,c2000000 {
+	compatible = "cavium,pci-host-thunder-pem";
+	device_type = "pci";
+	msi-parent = <&its>;
+	msi-map = <0 &its 0x10000 0x10000>;
+	bus-range = <0x8f 0xc7>;
+	#size-cells = <2>;
+	#address-cells = <3>;
+
+	reg = <0x8880 0x8f000000 0x0 0x39000000>,  /* Configuration space */
+	      <0x87e0 0xc2000000 0x0 0x00010000>; /* PEM space */
+	ranges = <0x01000000 0x00 0x00020000 0x88b0 0x00020000 0x00 0x00010000>, /* I/O */
+		 <0x03000000 0x00 0x10000000 0x8890 0x10000000 0x0f 0xf0000000>, /* mem64 */
+		 <0x43000000 0x10 0x00000000 0x88a0 0x00000000 0x10 0x00000000>, /* mem64-pref */
+		 <0x03000000 0x87e0 0xc2f00000 0x87e0 0xc2000000 0x00 0x00100000>; /* mem64 PEM BAR4 */
+
+	#interrupt-cells = <1>;
+	interrupt-map-mask = <0 0 0 7>;
+	interrupt-map = <0 0 0 1 &gic0 0 0 0 24 4>, /* INTA */
+			<0 0 0 2 &gic0 0 0 0 25 4>, /* INTB */
+			<0 0 0 3 &gic0 0 0 0 26 4>, /* INTC */
+			<0 0 0 4 &gic0 0 0 0 27 4>; /* INTD */
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 9287929..ff5c367 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8413,6 +8413,14 @@ L:     linux-arm-msm@xxxxxxxxxxxxxxx
 S:     Maintained
 F:     drivers/pci/host/*qcom*
 
+PCIE DRIVER FOR CAVIUM THUNDERX
+M:	David Daney <david.daney@xxxxxxxxxx>
+L:	linux-pci@xxxxxxxxxxxxxxx
+L:	linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers)
+S:	Supported
+F:	Documentation/devicetree/bindings/pci/pci-thunder-*
+F:	drivers/pci/host/pci-thunder-*
+
 PCMCIA SUBSYSTEM
 P:	Linux PCMCIA Team
 L:	linux-pcmcia@xxxxxxxxxxxxxxxxxxx
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 65709b4..184df22 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -195,4 +195,11 @@ config PCIE_QCOM
 	  PCIe controller uses the Designware core plus Qualcomm-specific
 	  hardware wrappers.
 
+config PCI_HOST_THUNDER_PEM
+	bool "Cavium Thunder PCIe controller to off-chip devices"
+	depends on OF && ARM64
+	select PCI_HOST_COMMON
+	help
+	  Say Y here if you want PCIe support for CN88XX Cavium Thunder SoCs.
+
 endmenu
diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
index 3b24af8..8903172 100644
--- a/drivers/pci/host/Makefile
+++ b/drivers/pci/host/Makefile
@@ -23,3 +23,4 @@ obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o
 obj-$(CONFIG_PCIE_ALTERA_MSI) += pcie-altera-msi.o
 obj-$(CONFIG_PCI_HISI) += pcie-hisi.o
 obj-$(CONFIG_PCIE_QCOM) += pcie-qcom.o
+obj-$(CONFIG_PCI_HOST_THUNDER_PEM) += pci-thunder-pem.o
diff --git a/drivers/pci/host/pci-thunder-pem.c b/drivers/pci/host/pci-thunder-pem.c
new file mode 100644
index 0000000..e3a6554
--- /dev/null
+++ b/drivers/pci/host/pci-thunder-pem.c
@@ -0,0 +1,332 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (C) 2015 - 2016 Cavium, Inc.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_pci.h>
+#include <linux/platform_device.h>
+
+#include "pci-host-common.h"
+
+#define PEM_CFG_WR 0x28
+#define PEM_CFG_RD 0x30
+
+struct thunder_pem_pci {
+	struct gen_pci	gen_pci;
+	u32		ea_entry[3];
+	void __iomem	*pem_reg_base;
+};
+
+static void __iomem *thunder_pem_map_bus(struct pci_bus *bus,
+					 unsigned int devfn, int where)
+{
+	struct gen_pci *pci = bus->sysdata;
+	resource_size_t idx = bus->number - pci->cfg.bus_range->start;
+
+	return pci->cfg.win[idx] + ((devfn << 16) | where);
+}
+
+static int thunder_pem_config_read(struct pci_bus *bus, unsigned int devfn,
+				   int where, int size, u32 *val)
+{
+	int r;
+	struct thunder_pem_pci *pem_pci;
+	struct gen_pci *pci = bus->sysdata;
+
+	pem_pci = container_of(pci, struct thunder_pem_pci, gen_pci);
+
+	/*
+	 * The first device on the bus in the PEM PCIe bridge.
+	 * Special case its config access.
+	 */
+	if (bus->number == pci->cfg.bus_range->start) {
+		u64 read_val;
+
+		if (devfn != 0 || where >= 2048) {
+			*val = ~0;
+			return PCIBIOS_DEVICE_NOT_FOUND;
+		}
+
+		/*
+		 * 32-bit accesses only.  Write the address to the low
+		 * order bits of PEM_CFG_RD, then trigger the read by
+		 * reading back.  The config data lands in the upper
+		 * 32-bits of PEM_CFG_RD.
+		 */
+		read_val = where & ~3ull;
+		writeq(read_val, pem_pci->pem_reg_base + PEM_CFG_RD);
+		read_val = readq(pem_pci->pem_reg_base + PEM_CFG_RD);
+		read_val >>= 32;
+
+		/*
+		 * The config space contains some garbage, fix it up.
+		 * Also synthesize an EA capability for the BAR used
+		 * by MSI-X.
+		 */
+		switch (where & ~3u) {
+		case 0x40:
+			read_val &= 0xffff00ff;
+			read_val |= 0x00007000; /* Skip MSI CAP */
+			break;
+		case 0x70: /* Express Cap */
+			/* PME interrupt on vector 2*/
+			read_val |= (2u << 25);
+			break;
+		case 0xb0: /* MSI-X Cap */
+			/* TableSize=4, Next Cap is EA */
+			read_val &= 0xc00000ff;
+			read_val |= 0x0003bc00;
+			break;
+		case 0xb4:
+			/* Table offset=0, BIR=0 */
+			read_val = 0x00000000;
+			break;
+		case 0xb8:
+			/* BPA offset=0xf0000, BIR=0 */
+			read_val = 0x000f0000;
+			break;
+		case 0xbc:
+			/* EA, 1 entry, no next Cap */
+			read_val = 0x00010014;
+			break;
+		case 0xc0:
+			/* DW2 for type-1 */
+			read_val = 0x00000000;
+			break;
+		case 0xc4:
+			/* Entry BEI=0, PP=0x00, SP=0xff, ES=3 */
+			read_val = 0x80ff0003;
+			break;
+		case 0xc8:
+			read_val = pem_pci->ea_entry[0];
+			break;
+		case 0xcc:
+			read_val = pem_pci->ea_entry[1];
+			break;
+		case 0xd0:
+			read_val = pem_pci->ea_entry[2];
+			break;
+		default:
+			break;
+		}
+		read_val >>= (8 * (where & 3));
+		switch (size) {
+		case 1:
+			read_val &= 0xff;
+			break;
+		case 2:
+			read_val &= 0xffff;
+			break;
+		default:
+			break;
+		}
+		*val = read_val;
+		return PCIBIOS_SUCCESSFUL;
+	}
+	if (bus->number < pci->cfg.bus_range->start ||
+	    bus->number > pci->cfg.bus_range->end)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	r = pci_generic_config_read(bus, devfn, where, size, val);
+	return r;
+}
+
+static int thunder_pem_config_write(struct pci_bus *bus, unsigned int devfn,
+				    int where, int size, u32 val)
+{
+	struct gen_pci *pci = bus->sysdata;
+	struct thunder_pem_pci *pem_pci;
+
+	pem_pci = container_of(pci, struct thunder_pem_pci, gen_pci);
+
+	/*
+	 * The first device on the bus in the PEM PCIe bridge.
+	 * Special case its config access.
+	 */
+	if (bus->number == pci->cfg.bus_range->start) {
+		u64 write_val, read_val;
+		u32 mask = 0;
+
+		if (devfn != 0 || where >= 2048)
+			return PCIBIOS_DEVICE_NOT_FOUND;
+
+		/*
+		 * 32-bit accesses only.  If the write is for a size
+		 * smaller than 32-bits, we must first read the 32-bit
+		 * value and merge in the desired bits and then write
+		 * the whole 32-bits back out.
+		 */
+		switch (size) {
+		case 1:
+			read_val = where & ~3ull;
+			writeq(read_val, pem_pci->pem_reg_base + PEM_CFG_RD);
+			read_val = readq(pem_pci->pem_reg_base + PEM_CFG_RD);
+			read_val >>= 32;
+			mask = ~(0xff << (8 * (where & 3)));
+			read_val &= mask;
+			val = (val & 0xff) << (8 * (where & 3));
+			val |= (u32)read_val;
+			break;
+		case 2:
+			read_val = where & ~3ull;
+			writeq(read_val, pem_pci->pem_reg_base + PEM_CFG_RD);
+			read_val = readq(pem_pci->pem_reg_base + PEM_CFG_RD);
+			read_val >>= 32;
+			mask = ~(0xffff << (8 * (where & 3)));
+			read_val &= mask;
+			val = (val & 0xffff) << (8 * (where & 3));
+			val |= (u32)read_val;
+			break;
+		default:
+			break;
+
+		}
+
+		if (mask) {
+			/*
+			 * By expanding the write width to 32 bits, we
+			 * may inadvertently hit some W1C bits that
+			 * were not intended to be written.  Mask
+			 * these out.
+			 *
+			 * Some of the w1c_bits below also include
+			 * read-only or non-writable reserved bits,
+			 * this makes the code simpler and is OK as
+			 * the bits are not affected by writing zeros
+			 * to them.
+			 */
+			u32 w1c_bits = 0;
+
+			switch (where & 3) {
+			case 0x04: /* Command/Status */
+			case 0x1c: /* Base and I/O Limit/Secondary Status */
+				w1c_bits = 0xff000000;
+				break;
+			case 0x44: /* Power Management Control and Status */
+				w1c_bits = 0xfffffe00;
+				break;
+			case 0x78: /* Device Control/Device Status */
+			case 0x80: /* Link Control/Link Status */
+			case 0x88: /* Slot Control/Slot Status */
+			case 0x90: /* Root Status */
+			case 0xa0: /* Link Control 2 Registers/Link Status 2 */
+				w1c_bits = 0xffff0000;
+				break;
+			case 0x104: /* Uncorrectable Error Status */
+			case 0x110: /* Correctable Error Status */
+			case 0x130: /* Error Status */
+			case 0x160: /* Link Control 4 */
+				w1c_bits = 0xffffffff;
+				break;
+			default:
+				break;
+
+			}
+			if (w1c_bits) {
+				mask &= w1c_bits;
+				val &= ~mask;
+			}
+		}
+
+		/*
+		 * Low order bits are the config address, the high
+		 * order 32 bits are the data to be written.
+		 */
+		write_val = where & ~3ull;
+		write_val |= (((u64)val) << 32);
+		writeq(write_val, pem_pci->pem_reg_base + PEM_CFG_WR);
+		return PCIBIOS_SUCCESSFUL;
+	}
+	if (bus->number < pci->cfg.bus_range->start ||
+	    bus->number > pci->cfg.bus_range->end)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	return pci_generic_config_write(bus, devfn, where, size, val);
+}
+
+static struct gen_pci_cfg_bus_ops thunder_pem_bus_ops = {
+	.bus_shift	= 24,
+	.ops		= {
+		.map_bus	= thunder_pem_map_bus,
+		.read		= thunder_pem_config_read,
+		.write		= thunder_pem_config_write,
+	}
+};
+
+static const struct of_device_id thunder_pem_of_match[] = {
+	{ .compatible = "cavium,pci-host-thunder-pem",
+	  .data = &thunder_pem_bus_ops },
+
+	{ },
+};
+MODULE_DEVICE_TABLE(of, thunder_pem_of_match);
+
+static int thunder_pem_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *of_id;
+	resource_size_t bar4_start;
+	struct resource *res_pem;
+	struct thunder_pem_pci *pem_pci;
+
+	pem_pci = devm_kzalloc(dev, sizeof(*pem_pci), GFP_KERNEL);
+	if (!pem_pci)
+		return -ENOMEM;
+
+	of_id = of_match_node(thunder_pem_of_match, dev->of_node);
+	pem_pci->gen_pci.cfg.ops = (struct gen_pci_cfg_bus_ops *)of_id->data;
+
+	/*
+	 * The second register range is the PEM bridge to the PCIe
+	 * bus.  It has a different config access method than those
+	 * devices behind the bridge.
+	 */
+	res_pem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res_pem) {
+		dev_err(dev, "missing \"reg[1]\"property\n");
+		return -EINVAL;
+	}
+
+	pem_pci->pem_reg_base = devm_ioremap(dev, res_pem->start, 0x10000);
+	if (!pem_pci->pem_reg_base)
+		return -ENOMEM;
+
+	/*
+	 * The MSI-X BAR for the PEM and AER interrupts is located at
+	 * a fixed offset from the PEM register base.  Generate a
+	 * fragment of the synthesized Enhanced Allocation capability
+	 * structure here for the BAR.
+	 */
+	bar4_start = res_pem->start + 0xf00000;
+	pem_pci->ea_entry[0] = (u32)bar4_start | 2;
+	pem_pci->ea_entry[1] = (u32)(res_pem->end - bar4_start) & ~3u;
+	pem_pci->ea_entry[2] = (u32)(bar4_start >> 32);
+
+	return pci_host_common_probe(pdev, &pem_pci->gen_pci);
+}
+
+static struct platform_driver thunder_pem_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = thunder_pem_of_match,
+	},
+	.probe = thunder_pem_probe,
+};
+module_platform_driver(thunder_pem_driver);
+
+MODULE_DESCRIPTION("Thunder PEM PCIe host driver");
+MODULE_LICENSE("GPL v2");
-- 
1.8.3.1