[PATCH v2 4/4] ACPI: PCI: Add generic PCI host controller

[Jayachandran C]

Add a generic ACPI based PCI host controller, and provide a config
option ACPI_PCI_HOST_GENERIC to enable it.

The implementation selects PCI_GENERIC_ECAM and uses functions from
drivers/pci/ecam.h to create and access ECAM mappings. It also selects
PCI_MMCONFIG and implements the pci_mmcfg_late_init() function to parse
and map entries in the MCFG table.

The implementation of pci_acpi_scan_root() looks up the saved mappings
and sets up a new mapping if needed. Generic PCI functions are used for
accessing config space.

Signed-off-by: Jayachandran C <jchandra@xxxxxxxxxxxx>
---
 drivers/acpi/Kconfig        |   9 ++
 drivers/acpi/Makefile       |   1 +
 drivers/acpi/pci_gen_host.c | 258 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)
 create mode 100644 drivers/acpi/pci_gen_host.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 82b96ee..f178f2e 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -343,6 +343,15 @@ config ACPI_PCI_SLOT
 	  i.e., segment/bus/device/function tuples, with physical slots in
 	  the system.  If you are unsure, say N.
 
+config ACPI_PCI_HOST_GENERIC
+	bool "Generic ACPI based PCI controller"
+	depends on ARM64
+	select PCI_MMCONFIG
+	select PCI_GENERIC_ECAM
+	help
+	  Say Y if you want the generic ACPI based PCI controller
+	  implementation.
+
 config X86_PM_TIMER
 	bool "Power Management Timer Support" if EXPERT
 	depends on X86
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index edeb2d1..eaf429c 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_ACPI_BUTTON)	+= button.o
 obj-$(CONFIG_ACPI_FAN)		+= fan.o
 obj-$(CONFIG_ACPI_VIDEO)	+= video.o
 obj-$(CONFIG_ACPI_PCI_SLOT)	+= pci_slot.o
+obj-$(CONFIG_ACPI_PCI_HOST_GENERIC)	+= pci_gen_host.o
 obj-$(CONFIG_ACPI_PROCESSOR)	+= processor.o
 obj-$(CONFIG_ACPI)		+= container.o
 obj-$(CONFIG_ACPI_THERMAL)	+= thermal.o
diff --git a/drivers/acpi/pci_gen_host.c b/drivers/acpi/pci_gen_host.c
new file mode 100644
index 00000000..bd31faa
--- /dev/null
+++ b/drivers/acpi/pci_gen_host.c
@@ -0,0 +1,258 @@
+/*
+ * Copyright 2016 Broadcom
+ *
+ * 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 (the "GPL").
+ *
+ * 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 version 2 (GPLv2) for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 (GPLv2) along with this source code.
+ */
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/pci-acpi.h>
+#include <linux/sfi_acpi.h>
+#include <linux/slab.h>
+
+#include "../pci/ecam.h"
+
+#define PREFIX	"ACPI: "
+
+/*
+ * Array of config windows from MCFG table, parsed and created by
+ * pci_mmcfg_late_init() at boot
+ */
+struct pci_config_window	**cfgarr;
+
+/* ACPI info for generic ACPI PCI controller */
+struct acpi_pci_generic_root_info {
+	struct acpi_pci_root_info	common;
+	struct pci_config_window	*cfg;	/* config space mapping */
+	bool				mcfg_added;
+};
+
+/* find the entry in cfgarr which contains range bus_start..bus_end */
+static int mcfg_lookup(u16 seg, u8 bus_start, u8 bus_end)
+{
+	struct pci_config_window *cfg;
+	int i;
+
+	if (!cfgarr)
+		return -ENOENT;
+
+	for (i = 0; cfgarr[i]; i++) {
+		cfg = cfgarr[i];
+		if (seg != cfg->domain)
+			continue;
+		if (bus_start >= cfg->bus_start && bus_start <= cfg->bus_end)
+			return (bus_end <= cfg->bus_end) ? i : -EINVAL;
+		else if (bus_end >= cfg->bus_start && bus_end <= cfg->bus_end)
+			return -EINVAL;
+	}
+	return -ENOENT;
+}
+
+/*
+ * create a new mapping
+ */
+static struct pci_config_window *pci_acpi_ecam_create(struct device *dev,
+			phys_addr_t addr, u16 seg, u8 bus_start, u8 bus_end)
+{
+	struct pci_config_window *cfg;
+	int ret;
+
+	cfg = pci_generic_ecam_create(dev, addr, bus_start, bus_end,
+				      &pci_generic_ecam_default_ops);
+	if (IS_ERR(cfg)) {
+		ret = PTR_ERR(cfg);
+		pr_err("%04x:%02x-%02x error %d mapping CAM\n", seg,
+			bus_start, bus_end, ret);
+		return NULL;
+	}
+	cfg->domain = seg;
+	return cfg;
+}
+
+/*
+ * Lookup the bus range for the domain in MCFG, and set up config space
+ * mapping.
+ */
+static int pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root,
+		struct acpi_pci_generic_root_info *ri)
+{
+	struct pci_config_window *cfg;
+	u16 seg = root->segment;
+	u8 bus_start = root->secondary.start;
+	u8 bus_end = root->secondary.end;
+	phys_addr_t addr = root->mcfg_addr;
+	struct acpi_device *adev = root->device;
+	int ret;
+
+	ret = mcfg_lookup(seg, bus_start, bus_end);
+	if (ret == -ENOENT) {
+		if (addr == 0) {
+			pr_err("%04x:%02x-%02x mcfg lookup failed\n", seg,
+				bus_start, bus_end);
+			return ret;
+		}
+		cfg = pci_acpi_ecam_create(&adev->dev, addr, seg, bus_start,
+					   bus_end);
+		if (!cfg)
+			return ret;
+	} else if (ret < 0) {
+		pr_err("%04x:%02x-%02x bus range error (%d)\n", seg, bus_start,
+		       bus_end, ret);
+		return ret;
+	} else {
+		cfg = cfgarr[ret];
+		if (addr == 0)
+			addr = cfg->cfgaddr;
+		if (bus_start != cfg->bus_start) {
+			pr_err("%04x:%02x-%02x bus range mismatch %02x\n",
+			       seg, bus_start, bus_end, cfg->bus_start);
+			return -EINVAL;
+		}
+		if (addr != cfg->cfgaddr) {
+			pr_warn("%04x:%02x-%02x addr mismatch, ignoring MCFG\n",
+				seg, bus_start, bus_end);
+		} else if (bus_end != cfg->bus_end) {
+			pr_warn("%04x:%02x-%02x bus end mismatch using %02x\n",
+				seg, bus_start, bus_end, cfg->bus_end);
+			bus_end = cfg->bus_end;
+		}
+	}
+	ri->cfg = cfg;
+	ri->mcfg_added = (ret >= 0);
+
+	return 0;
+}
+
+/* release_info: free resrouces allocated by init_info */
+static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
+{
+	struct acpi_pci_generic_root_info *ri;
+
+	ri = container_of(ci, struct acpi_pci_generic_root_info, common);
+	if (!ri->mcfg_added)
+		pci_generic_ecam_free(ri->cfg);
+	kfree(ri);
+}
+
+static struct acpi_pci_root_ops acpi_pci_root_ops = {
+	.release_info = pci_acpi_generic_release_info,
+};
+
+/* Interface called from ACPI code to setup PCI host controller */
+struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
+{
+	int node = acpi_get_node(root->device->handle);
+	struct acpi_pci_generic_root_info *ri;
+	struct pci_bus *bus, *child;
+	int err;
+
+	ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
+	if (!ri)
+		return NULL;
+
+	err = pci_acpi_setup_ecam_mapping(root, ri);
+	if (err)
+		return NULL;
+
+	acpi_pci_root_ops.pci_ops = &ri->cfg->ops->ops;
+	bus = acpi_pci_root_create(root, &acpi_pci_root_ops, &ri->common,
+				   ri->cfg);
+	if (!bus)
+		return NULL;
+
+	pci_bus_size_bridges(bus);
+	pci_bus_assign_resources(bus);
+
+	list_for_each_entry(child, &bus->children, node)
+		pcie_bus_configure_settings(child);
+
+	return bus;
+}
+
+/* handle MCFG table entries */
+static __init int handle_mcfg(struct acpi_table_header *header)
+{
+	struct acpi_table_mcfg *mcfg;
+	struct acpi_mcfg_allocation *mptr;
+	struct pci_config_window *cfg;
+	int i, j, n;
+
+	if (!header)
+		return -EINVAL;
+
+	mcfg = (struct acpi_table_mcfg *)header;
+	mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
+	n = (header->length - sizeof(*mcfg)) / sizeof(*mptr);
+	if (n <= 0 || n > 255) {
+		pr_err(PREFIX " MCFG has incorrect entries (%d).\n", n);
+		return -EINVAL;
+	}
+
+	cfgarr = kcalloc(n + 1, sizeof(*cfgarr), GFP_KERNEL);
+	if (!cfgarr)
+		return -ENOMEM;
+
+	for (i = 0, j = 0; i < n; i++) {
+		cfg = pci_acpi_ecam_create(NULL, mptr->address,
+				mptr->pci_segment, mptr->start_bus_number,
+				mptr->end_bus_number);
+		if (!cfg)
+			continue;
+		cfgarr[j++] = cfg;
+	}
+
+	if (j == 0) {
+		kfree(cfgarr);
+		cfgarr = NULL;
+		return -ENOENT;
+	}
+	cfgarr[j] = NULL;
+	return 0;
+}
+
+/* Interface called by ACPI - parse and save MCFG table */
+void __init pci_mmcfg_late_init(void)
+{
+	int i, err;
+
+	err = acpi_sfi_table_parse(ACPI_SIG_MCFG, handle_mcfg);
+	if (err) {
+		pr_err(PREFIX " Failed to parse MCFG (%d)\n", err);
+	} else if (cfgarr == NULL) {
+		pr_err(PREFIX " Failed to parse MCFG, no valid entries.\n");
+	} else {
+		for (i = 0; cfgarr[i]; i++)
+			;
+		pr_info(PREFIX " MCFG table at loaded, %d entries\n", i);
+	}
+}
+
+/* Raw operations, works only for MCFG entries with an associated bus */
+int raw_pci_read(unsigned int domain, unsigned int busn, unsigned int devfn,
+		 int reg, int len, u32 *val)
+{
+	struct pci_bus *bus = pci_find_bus(domain, busn);
+
+	if (!bus)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	return bus->ops->read(bus, devfn, reg, len, val);
+}
+
+int raw_pci_write(unsigned int domain, unsigned int busn, unsigned int devfn,
+		  int reg, int len, u32 val)
+{
+	struct pci_bus *bus = pci_find_bus(domain, busn);
+
+	if (!bus)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	return bus->ops->write(bus, devfn, reg, len, val);
+}
-- 
1.9.1