PCI: thunder: Add driver for ThunderX-pass{1,2} on-chip devices

The cavium,pci-thunder-ecam devices are exactly ECAM-based PCI root
complexes.  These root complexes (loosely referred to as ECAM units in the
hardware manuals) are used to access the Thunder on-chip devices.  They
are special in that all the BARs on devices behind these root complexes are
at fixed addresses.

Add a driver for these devices that synthesizes Enhanced Allocation (EA)
capability entries for each BAR.

Since this EA synthesis is needed for exactly two chip models, we can hard-
code some assumptions about the device topology and the layout of the
config space of specific DEVFNs in the driver.

[bhelgaas: changelog, whitespace]
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>

1 files changed, 403 insertions, 0 deletions

diff --git a/drivers/pci/host/pci-thunder-ecam.c b/drivers/pci/host/pci-thunder-ecam.c
new file mode 100644
index 000000000000..d71935cb2678
--- /dev/null
+++ b/drivers/pci/host/pci-thunder-ecam.c
@@ -0,0 +1,403 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2015, 2016 Cavium, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/of_pci.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include "pci-host-common.h"
+
+/* Mapping is standard ECAM */
+static void __iomem *thunder_ecam_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 << 12) | where);
+}
+
+static void set_val(u32 v, int where, int size, u32 *val)
+{
+	int shift = (where & 3) * 8;
+
+	pr_debug("set_val %04x: %08x\n", (unsigned)(where & ~3), v);
+	v >>= shift;
+	if (size == 1)
+		v &= 0xff;
+	else if (size == 2)
+		v &= 0xffff;
+	*val = v;
+}
+
+static int handle_ea_bar(u32 e0, int bar, struct pci_bus *bus,
+			 unsigned int devfn, int where, int size, u32 *val)
+{
+	void __iomem *addr;
+	u32 v;
+
+	/* Entries are 16-byte aligned; bits[2,3] select word in entry */
+	int where_a = where & 0xc;
+
+	if (where_a == 0) {
+		set_val(e0, where, size, val);
+		return PCIBIOS_SUCCESSFUL;
+	}
+	if (where_a == 0x4) {
+		addr = bus->ops->map_bus(bus, devfn, bar); /* BAR 0 */
+		if (!addr) {
+			*val = ~0;
+			return PCIBIOS_DEVICE_NOT_FOUND;
+		}
+		v = readl(addr);
+		v &= ~0xf;
+		v |= 2; /* EA entry-1. Base-L */
+		set_val(v, where, size, val);
+		return PCIBIOS_SUCCESSFUL;
+	}
+	if (where_a == 0x8) {
+		u32 barl_orig;
+		u32 barl_rb;
+
+		addr = bus->ops->map_bus(bus, devfn, bar); /* BAR 0 */
+		if (!addr) {
+			*val = ~0;
+			return PCIBIOS_DEVICE_NOT_FOUND;
+		}
+		barl_orig = readl(addr + 0);
+		writel(0xffffffff, addr + 0);
+		barl_rb = readl(addr + 0);
+		writel(barl_orig, addr + 0);
+		/* zeros in unsettable bits */
+		v = ~barl_rb & ~3;
+		v |= 0xc; /* EA entry-2. Offset-L */
+		set_val(v, where, size, val);
+		return PCIBIOS_SUCCESSFUL;
+	}
+	if (where_a == 0xc) {
+		addr = bus->ops->map_bus(bus, devfn, bar + 4); /* BAR 1 */
+		if (!addr) {
+			*val = ~0;
+			return PCIBIOS_DEVICE_NOT_FOUND;
+		}
+		v = readl(addr); /* EA entry-3. Base-H */
+		set_val(v, where, size, val);
+		return PCIBIOS_SUCCESSFUL;
+	}
+	return PCIBIOS_DEVICE_NOT_FOUND;
+}
+
+static int thunder_ecam_p2_config_read(struct pci_bus *bus, unsigned int devfn,
+				       int where, int size, u32 *val)
+{
+	struct gen_pci *pci = bus->sysdata;
+	int where_a = where & ~3;
+	void __iomem *addr;
+	u32 node_bits;
+	u32 v;
+
+	/* EA Base[63:32] may be missing some bits ... */
+	switch (where_a) {
+	case 0xa8:
+	case 0xbc:
+	case 0xd0:
+	case 0xe4:
+		break;
+	default:
+		return pci_generic_config_read(bus, devfn, where, size, val);
+	}
+
+	addr = bus->ops->map_bus(bus, devfn, where_a);
+	if (!addr) {
+		*val = ~0;
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	}
+
+	v = readl(addr);
+
+	/*
+	 * Bit 44 of the 64-bit Base must match the same bit in
+	 * the config space access window.  Since we are working with
+	 * the high-order 32 bits, shift everything down by 32 bits.
+	 */
+	node_bits = (pci->cfg.res.start >> 32) & (1 << 12);
+
+	v |= node_bits;
+	set_val(v, where, size, val);
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
+				    int where, int size, u32 *val)
+{
+	u32 v;
+	u32 vendor_device;
+	u32 class_rev;
+	void __iomem *addr;
+	int cfg_type;
+	int where_a = where & ~3;
+
+	addr = bus->ops->map_bus(bus, devfn, 0xc);
+	if (!addr) {
+		*val = ~0;
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	}
+
+	v = readl(addr);
+
+	/* Check for non type-00 header */
+	cfg_type = (v >> 16) & 0x7f;
+
+	addr = bus->ops->map_bus(bus, devfn, 8);
+	if (!addr) {
+		*val = ~0;
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	}
+
+	class_rev = readl(addr);
+	if (class_rev == 0xffffffff)
+		goto no_emulation;
+
+	if ((class_rev & 0xff) >= 8) {
+		/* Pass-2 handling */
+		if (cfg_type)
+			goto no_emulation;
+		return thunder_ecam_p2_config_read(bus, devfn, where,
+						   size, val);
+	}
+
+	/*
+	 * All BARs have fixed addresses specified by the EA
+	 * capability; they must return zero on read.
+	 */
+	if (cfg_type == 0 &&
+	    ((where >= 0x10 && where < 0x2c) ||
+	     (where >= 0x1a4 && where < 0x1bc))) {
+		/* BAR or SR-IOV BAR */
+		*val = 0;
+		return PCIBIOS_SUCCESSFUL;
+	}
+
+	addr = bus->ops->map_bus(bus, devfn, 0);
+	if (!addr) {
+		*val = ~0;
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	}
+
+	vendor_device = readl(addr);
+	if (vendor_device == 0xffffffff)
+		goto no_emulation;
+
+	pr_debug("%04x:%04x - Fix pass#: %08x, where: %03x, devfn: %03x\n",
+		 vendor_device & 0xffff, vendor_device >> 16, class_rev,
+		 (unsigned) where, devfn);
+
+	/* Check for non type-00 header */
+	if (cfg_type == 0) {
+		bool has_msix;
+		bool is_nic = (vendor_device == 0xa01e177d);
+		bool is_tns = (vendor_device == 0xa01f177d);
+
+		addr = bus->ops->map_bus(bus, devfn, 0x70);
+		if (!addr) {
+			*val = ~0;
+			return PCIBIOS_DEVICE_NOT_FOUND;
+		}
+		/* E_CAP */
+		v = readl(addr);
+		has_msix = (v & 0xff00) != 0;
+
+		if (!has_msix && where_a == 0x70) {
+			v |= 0xbc00; /* next capability is EA at 0xbc */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xb0) {
+			addr = bus->ops->map_bus(bus, devfn, where_a);
+			if (!addr) {
+				*val = ~0;
+				return PCIBIOS_DEVICE_NOT_FOUND;
+			}
+			v = readl(addr);
+			if (v & 0xff00)
+				pr_err("Bad MSIX cap header: %08x\n", v);
+			v |= 0xbc00; /* next capability is EA at 0xbc */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xbc) {
+			if (is_nic)
+				v = 0x40014; /* EA last in chain, 4 entries */
+			else if (is_tns)
+				v = 0x30014; /* EA last in chain, 3 entries */
+			else if (has_msix)
+				v = 0x20014; /* EA last in chain, 2 entries */
+			else
+				v = 0x10014; /* EA last in chain, 1 entry */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a >= 0xc0 && where_a < 0xd0)
+			/* EA entry-0. PP=0, BAR0 Size:3 */
+			return handle_ea_bar(0x80ff0003,
+					     0x10, bus, devfn, where,
+					     size, val);
+		if (where_a >= 0xd0 && where_a < 0xe0 && has_msix)
+			 /* EA entry-1. PP=0, BAR4 Size:3 */
+			return handle_ea_bar(0x80ff0043,
+					     0x20, bus, devfn, where,
+					     size, val);
+		if (where_a >= 0xe0 && where_a < 0xf0 && is_tns)
+			/* EA entry-2. PP=0, BAR2, Size:3 */
+			return handle_ea_bar(0x80ff0023,
+					     0x18, bus, devfn, where,
+					     size, val);
+		if (where_a >= 0xe0 && where_a < 0xf0 && is_nic)
+			/* EA entry-2. PP=4, VF_BAR0 (9), Size:3 */
+			return handle_ea_bar(0x80ff0493,
+					     0x1a4, bus, devfn, where,
+					     size, val);
+		if (where_a >= 0xf0 && where_a < 0x100 && is_nic)
+			/* EA entry-3. PP=4, VF_BAR4 (d), Size:3 */
+			return handle_ea_bar(0x80ff04d3,
+					     0x1b4, bus, devfn, where,
+					     size, val);
+	} else if (cfg_type == 1) {
+		bool is_rsl_bridge = devfn == 0x08;
+		bool is_rad_bridge = devfn == 0xa0;
+		bool is_zip_bridge = devfn == 0xa8;
+		bool is_dfa_bridge = devfn == 0xb0;
+		bool is_nic_bridge = devfn == 0x10;
+
+		if (where_a == 0x70) {
+			addr = bus->ops->map_bus(bus, devfn, where_a);
+			if (!addr) {
+				*val = ~0;
+				return PCIBIOS_DEVICE_NOT_FOUND;
+			}
+			v = readl(addr);
+			if (v & 0xff00)
+				pr_err("Bad PCIe cap header: %08x\n", v);
+			v |= 0xbc00; /* next capability is EA at 0xbc */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xbc) {
+			if (is_nic_bridge)
+				v = 0x10014; /* EA last in chain, 1 entry */
+			else
+				v = 0x00014; /* EA last in chain, no entries */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xc0) {
+			if (is_rsl_bridge || is_nic_bridge)
+				v = 0x0101; /* subordinate:secondary = 1:1 */
+			else if (is_rad_bridge)
+				v = 0x0202; /* subordinate:secondary = 2:2 */
+			else if (is_zip_bridge)
+				v = 0x0303; /* subordinate:secondary = 3:3 */
+			else if (is_dfa_bridge)
+				v = 0x0404; /* subordinate:secondary = 4:4 */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xc4 && is_nic_bridge) {
+			/* Enabled, not-Write, SP=ff, PP=05, BEI=6, ES=4 */
+			v = 0x80ff0564;
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xc8 && is_nic_bridge) {
+			v = 0x00000002; /* Base-L 64-bit */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xcc && is_nic_bridge) {
+			v = 0xfffffffe; /* MaxOffset-L 64-bit */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xd0 && is_nic_bridge) {
+			v = 0x00008430; /* NIC Base-H */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+		if (where_a == 0xd4 && is_nic_bridge) {
+			v = 0x0000000f; /* MaxOffset-H */
+			set_val(v, where, size, val);
+			return PCIBIOS_SUCCESSFUL;
+		}
+	}
+no_emulation:
+	return pci_generic_config_read(bus, devfn, where, size, val);
+}
+
+static int thunder_ecam_config_write(struct pci_bus *bus, unsigned int devfn,
+				     int where, int size, u32 val)
+{
+	/*
+	 * All BARs have fixed addresses; ignore BAR writes so they
+	 * don't get corrupted.
+	 */
+	if ((where >= 0x10 && where < 0x2c) ||
+	    (where >= 0x1a4 && where < 0x1bc))
+		/* BAR or SR-IOV BAR */
+		return PCIBIOS_SUCCESSFUL;
+
+	return pci_generic_config_write(bus, devfn, where, size, val);
+}
+
+static struct gen_pci_cfg_bus_ops thunder_ecam_bus_ops = {
+	.bus_shift	= 20,
+	.ops		= {
+		.map_bus        = thunder_ecam_map_bus,
+		.read           = thunder_ecam_config_read,
+		.write          = thunder_ecam_config_write,
+	}
+};
+
+static const struct of_device_id thunder_ecam_of_match[] = {
+	{ .compatible = "cavium,pci-host-thunder-ecam",
+	  .data = &thunder_ecam_bus_ops },
+
+	{ },
+};
+MODULE_DEVICE_TABLE(of, thunder_ecam_of_match);
+
+static int thunder_ecam_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *of_id;
+	struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
+
+	if (!pci)
+		return -ENOMEM;
+
+	of_id = of_match_node(thunder_ecam_of_match, dev->of_node);
+	pci->cfg.ops = (struct gen_pci_cfg_bus_ops *)of_id->data;
+
+	return pci_host_common_probe(pdev, pci);
+}
+
+static struct platform_driver thunder_ecam_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = thunder_ecam_of_match,
+	},
+	.probe = thunder_ecam_probe,
+};
+module_platform_driver(thunder_ecam_driver);
+
+MODULE_DESCRIPTION("Thunder ECAM PCI host driver");
+MODULE_LICENSE("GPL v2");