cxl/core/port.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
#include <linux/platform_device.h>
#include <linux/memregion.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/node.h>
#include <cxl/einj.h>
#include <cxlmem.h>
#include <cxlpci.h>
#include <cxl.h>
#include "core.h"

/**
 * DOC: cxl core
 *
 * The CXL core provides a set of interfaces that can be consumed by CXL aware
 * drivers. The interfaces allow for creation, modification, and destruction of
 * regions, memory devices, ports, and decoders. CXL aware drivers must register
 * with the CXL core via these interfaces in order to be able to participate in
 * cross-device interleave coordination. The CXL core also establishes and
 * maintains the bridge to the nvdimm subsystem.
 *
 * CXL core introduces sysfs hierarchy to control the devices that are
 * instantiated by the core.
 */

static DEFINE_IDA(cxl_port_ida);
static DEFINE_XARRAY(cxl_root_buses);

/*
 * The terminal device in PCI is NULL and @platform_bus
 * for platform devices (for cxl_test)
 */
static bool is_cxl_host_bridge(struct device *dev)
{
	return (!dev || dev == &platform_bus);
}

int cxl_num_decoders_committed(struct cxl_port *port)
{
	lockdep_assert_held(&cxl_rwsem.region);

	return port->commit_end + 1;
}

static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
			    char *buf)
{
	return sysfs_emit(buf, "%s\n", dev->type->name);
}
static DEVICE_ATTR_RO(devtype);

static int cxl_device_id(const struct device *dev)
{
	if (dev->type == &cxl_nvdimm_bridge_type)
		return CXL_DEVICE_NVDIMM_BRIDGE;
	if (dev->type == &cxl_nvdimm_type)
		return CXL_DEVICE_NVDIMM;
	if (dev->type == CXL_PMEM_REGION_TYPE())
		return CXL_DEVICE_PMEM_REGION;
	if (dev->type == CXL_DAX_REGION_TYPE())
		return CXL_DEVICE_DAX_REGION;
	if (is_cxl_port(dev)) {
		if (is_cxl_root(to_cxl_port(dev)))
			return CXL_DEVICE_ROOT;
		return CXL_DEVICE_PORT;
	}
	if (is_cxl_memdev(dev))
		return CXL_DEVICE_MEMORY_EXPANDER;
	if (dev->type == CXL_REGION_TYPE())
		return CXL_DEVICE_REGION;
	if (dev->type == &cxl_pmu_type)
		return CXL_DEVICE_PMU;
	return 0;
}

static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	return sysfs_emit(buf, CXL_MODALIAS_FMT "\n", cxl_device_id(dev));
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *cxl_base_attributes[] = {
	&dev_attr_devtype.attr,
	&dev_attr_modalias.attr,
	NULL,
};

struct attribute_group cxl_base_attribute_group = {
	.attrs = cxl_base_attributes,
};

static ssize_t start_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct cxl_decoder *cxld = to_cxl_decoder(dev);

	return sysfs_emit(buf, "%#llx\n", cxld->hpa_range.start);
}
static DEVICE_ATTR_ADMIN_RO(start);

static ssize_t size_show(struct device *dev, struct device_attribute *attr,
			char *buf)
{
	struct cxl_decoder *cxld = to_cxl_decoder(dev);

	return sysfs_emit(buf, "%#llx\n", range_len(&cxld->hpa_range));
}
static DEVICE_ATTR_RO(size);

#define CXL_DECODER_FLAG_ATTR(name, flag)                            \
static ssize_t name##_show(struct device *dev,                       \
			   struct device_attribute *attr, char *buf) \
{                                                                    \
	struct cxl_decoder *cxld = to_cxl_decoder(dev);              \
                                                                     \
	return sysfs_emit(buf, "%s\n",                               \
			  (cxld->flags & (flag)) ? "1" : "0");       \
}                                                                    \
static DEVICE_ATTR_RO(name)

CXL_DECODER_FLAG_ATTR(cap_pmem, CXL_DECODER_F_PMEM);
CXL_DECODER_FLAG_ATTR(cap_ram, CXL_DECODER_F_RAM);
CXL_DECODER_FLAG_ATTR(cap_type2, CXL_DECODER_F_TYPE2);
CXL_DECODER_FLAG_ATTR(cap_type3, CXL_DECODER_F_TYPE3);
CXL_DECODER_FLAG_ATTR(locked, CXL_DECODER_F_LOCK);

static ssize_t target_type_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct cxl_decoder *cxld = to_cxl_decoder(dev);

	switch (cxld->target_type) {
	case CXL_DECODER_DEVMEM:
		return sysfs_emit(buf, "accelerator\n");
	case CXL_DECODER_HOSTONLYMEM:
		return sysfs_emit(buf, "expander\n");
	}
	return -ENXIO;
}
static DEVICE_ATTR_RO(target_type);

static ssize_t emit_target_list(struct cxl_switch_decoder *cxlsd, char *buf)
{
	struct cxl_decoder *cxld = &cxlsd->cxld;
	ssize_t offset = 0;
	int i, rc = 0;

	for (i = 0; i < cxld->interleave_ways; i++) {
		struct cxl_dport *dport = cxlsd->target[i];
		struct cxl_dport *next = NULL;

		if (!dport)
			break;

		if (i + 1 < cxld->interleave_ways)
			next = cxlsd->target[i + 1];
		rc = sysfs_emit_at(buf, offset, "%d%s", dport->port_id,
				   next ? "," : "");
		if (rc < 0)
			return rc;
		offset += rc;
	}

	return offset;
}

static ssize_t target_list_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct cxl_switch_decoder *cxlsd = to_cxl_switch_decoder(dev);
	ssize_t offset;
	int rc;

	guard(rwsem_read)(&cxl_rwsem.region);
	rc = emit_target_list(cxlsd, buf);
	if (rc < 0)
		return rc;
	offset = rc;

	rc = sysfs_emit_at(buf, offset, "\n");
	if (rc < 0)
		return rc;

	return offset + rc;
}
static DEVICE_ATTR_RO(target_list);

static ssize_t mode_show(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
	struct cxl_dev_state *cxlds = cxlmd->cxlds;
	/* without @cxl_rwsem.dpa, make sure @part is not reloaded */
	int part = READ_ONCE(cxled->part);
	const char *desc;

	if (part < 0)
		desc = "none";
	else
		desc = cxlds->part[part].res.name;

	return sysfs_emit(buf, "%s\n", desc);
}

static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t len)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
	enum cxl_partition_mode mode;
	ssize_t rc;

	if (sysfs_streq(buf, "pmem"))
		mode = CXL_PARTMODE_PMEM;
	else if (sysfs_streq(buf, "ram"))
		mode = CXL_PARTMODE_RAM;
	else
		return -EINVAL;

	rc = cxl_dpa_set_part(cxled, mode);
	if (rc)
		return rc;

	return len;
}
static DEVICE_ATTR_RW(mode);

static ssize_t dpa_resource_show(struct device *dev, struct device_attribute *attr,
			    char *buf)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);

	guard(rwsem_read)(&cxl_rwsem.dpa);
	return sysfs_emit(buf, "%#llx\n", (u64)cxl_dpa_resource_start(cxled));
}
static DEVICE_ATTR_RO(dpa_resource);

static ssize_t dpa_size_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
	resource_size_t size = cxl_dpa_size(cxled);

	return sysfs_emit(buf, "%pa\n", &size);
}

static ssize_t dpa_size_store(struct device *dev, struct device_attribute *attr,
			      const char *buf, size_t len)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);
	unsigned long long size;
	ssize_t rc;

	rc = kstrtoull(buf, 0, &size);
	if (rc)
		return rc;

	if (!IS_ALIGNED(size, SZ_256M))
		return -EINVAL;

	rc = cxl_dpa_free(cxled);
	if (rc)
		return rc;

	if (size == 0)
		return len;

	rc = cxl_dpa_alloc(cxled, size);
	if (rc)
		return rc;

	return len;
}
static DEVICE_ATTR_RW(dpa_size);

static ssize_t interleave_granularity_show(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{
	struct cxl_decoder *cxld = to_cxl_decoder(dev);

	return sysfs_emit(buf, "%d\n", cxld->interleave_granularity);
}

static DEVICE_ATTR_RO(interleave_granularity);

static ssize_t interleave_ways_show(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	struct cxl_decoder *cxld = to_cxl_decoder(dev);

	return sysfs_emit(buf, "%d\n", cxld->interleave_ways);
}

static DEVICE_ATTR_RO(interleave_ways);

static ssize_t qos_class_show(struct device *dev,
			      struct device_attribute *attr, char *buf)
{
	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	return sysfs_emit(buf, "%d\n", cxlrd->qos_class);
}
static DEVICE_ATTR_RO(qos_class);

static struct attribute *cxl_decoder_base_attrs[] = {
	&dev_attr_start.attr,
	&dev_attr_size.attr,
	&dev_attr_locked.attr,
	&dev_attr_interleave_granularity.attr,
	&dev_attr_interleave_ways.attr,
	NULL,
};

static struct attribute_group cxl_decoder_base_attribute_group = {
	.attrs = cxl_decoder_base_attrs,
};

static struct attribute *cxl_decoder_root_attrs[] = {
	&dev_attr_cap_pmem.attr,
	&dev_attr_cap_ram.attr,
	&dev_attr_cap_type2.attr,
	&dev_attr_cap_type3.attr,
	&dev_attr_target_list.attr,
	&dev_attr_qos_class.attr,
	SET_CXL_REGION_ATTR(create_pmem_region)
	SET_CXL_REGION_ATTR(create_ram_region)
	SET_CXL_REGION_ATTR(delete_region)
	NULL,
};

static bool can_create_pmem(struct cxl_root_decoder *cxlrd)
{
	unsigned long flags = CXL_DECODER_F_TYPE3 | CXL_DECODER_F_PMEM;

	return (cxlrd->cxlsd.cxld.flags & flags) == flags;
}

static bool can_create_ram(struct cxl_root_decoder *cxlrd)
{
	unsigned long flags = CXL_DECODER_F_TYPE3 | CXL_DECODER_F_RAM;

	return (cxlrd->cxlsd.cxld.flags & flags) == flags;
}

static umode_t cxl_root_decoder_visible(struct kobject *kobj, struct attribute *a, int n)
{
	struct device *dev = kobj_to_dev(kobj);
	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	if (a == CXL_REGION_ATTR(create_pmem_region) && !can_create_pmem(cxlrd))
		return 0;

	if (a == CXL_REGION_ATTR(create_ram_region) && !can_create_ram(cxlrd))
		return 0;

	if (a == CXL_REGION_ATTR(delete_region) &&
	    !(can_create_pmem(cxlrd) || can_create_ram(cxlrd)))
		return 0;

	return a->mode;
}

static struct attribute_group cxl_decoder_root_attribute_group = {
	.attrs = cxl_decoder_root_attrs,
	.is_visible = cxl_root_decoder_visible,
};

static const struct attribute_group *cxl_decoder_root_attribute_groups[] = {
	&cxl_decoder_root_attribute_group,
	&cxl_decoder_base_attribute_group,
	&cxl_base_attribute_group,
	NULL,
};

static struct attribute *cxl_decoder_switch_attrs[] = {
	&dev_attr_target_type.attr,
	&dev_attr_target_list.attr,
	SET_CXL_REGION_ATTR(region)
	NULL,
};

static struct attribute_group cxl_decoder_switch_attribute_group = {
	.attrs = cxl_decoder_switch_attrs,
};

static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = {
	&cxl_decoder_switch_attribute_group,
	&cxl_decoder_base_attribute_group,
	&cxl_base_attribute_group,
	NULL,
};

static struct attribute *cxl_decoder_endpoint_attrs[] = {
	&dev_attr_target_type.attr,
	&dev_attr_mode.attr,
	&dev_attr_dpa_size.attr,
	&dev_attr_dpa_resource.attr,
	SET_CXL_REGION_ATTR(region)
	NULL,
};

static struct attribute_group cxl_decoder_endpoint_attribute_group = {
	.attrs = cxl_decoder_endpoint_attrs,
};

static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = {
	&cxl_decoder_base_attribute_group,
	&cxl_decoder_endpoint_attribute_group,
	&cxl_base_attribute_group,
	NULL,
};

static void __cxl_decoder_release(struct cxl_decoder *cxld)
{
	struct cxl_port *port = to_cxl_port(cxld->dev.parent);

	ida_free(&port->decoder_ida, cxld->id);
	put_device(&port->dev);
}

static void cxl_endpoint_decoder_release(struct device *dev)
{
	struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(dev);

	__cxl_decoder_release(&cxled->cxld);
	kfree(cxled);
}

static void cxl_switch_decoder_release(struct device *dev)
{
	struct cxl_switch_decoder *cxlsd = to_cxl_switch_decoder(dev);

	__cxl_decoder_release(&cxlsd->cxld);
	kfree(cxlsd);
}

struct cxl_root_decoder *to_cxl_root_decoder(struct device *dev)
{
	if (dev_WARN_ONCE(dev, !is_root_decoder(dev),
			  "not a cxl_root_decoder device\n"))
		return NULL;
	return container_of(dev, struct cxl_root_decoder, cxlsd.cxld.dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_root_decoder, "CXL");

static void cxl_root_decoder_release(struct device *dev)
{
	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);

	if (atomic_read(&cxlrd->region_id) >= 0)
		memregion_free(atomic_read(&cxlrd->region_id));
	__cxl_decoder_release(&cxlrd->cxlsd.cxld);
	kfree(cxlrd);
}

static const struct device_type cxl_decoder_endpoint_type = {
	.name = "cxl_decoder_endpoint",
	.release = cxl_endpoint_decoder_release,
	.groups = cxl_decoder_endpoint_attribute_groups,
};

static const struct device_type cxl_decoder_switch_type = {
	.name = "cxl_decoder_switch",
	.release = cxl_switch_decoder_release,
	.groups = cxl_decoder_switch_attribute_groups,
};

static const struct device_type cxl_decoder_root_type = {
	.name = "cxl_decoder_root",
	.release = cxl_root_decoder_release,
	.groups = cxl_decoder_root_attribute_groups,
};

bool is_endpoint_decoder(struct device *dev)
{
	return dev->type == &cxl_decoder_endpoint_type;
}
EXPORT_SYMBOL_NS_GPL(is_endpoint_decoder, "CXL");

bool is_root_decoder(struct device *dev)
{
	return dev->type == &cxl_decoder_root_type;
}
EXPORT_SYMBOL_NS_GPL(is_root_decoder, "CXL");

bool is_switch_decoder(struct device *dev)
{
	return is_root_decoder(dev) || dev->type == &cxl_decoder_switch_type;
}
EXPORT_SYMBOL_NS_GPL(is_switch_decoder, "CXL");

struct cxl_decoder *to_cxl_decoder(struct device *dev)
{
	if (dev_WARN_ONCE(dev,
			  !is_switch_decoder(dev) && !is_endpoint_decoder(dev),
			  "not a cxl_decoder device\n"))
		return NULL;
	return container_of(dev, struct cxl_decoder, dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_decoder, "CXL");

struct cxl_endpoint_decoder *to_cxl_endpoint_decoder(struct device *dev)
{
	if (dev_WARN_ONCE(dev, !is_endpoint_decoder(dev),
			  "not a cxl_endpoint_decoder device\n"))
		return NULL;
	return container_of(dev, struct cxl_endpoint_decoder, cxld.dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_endpoint_decoder, "CXL");

struct cxl_switch_decoder *to_cxl_switch_decoder(struct device *dev)
{
	if (dev_WARN_ONCE(dev, !is_switch_decoder(dev),
			  "not a cxl_switch_decoder device\n"))
		return NULL;
	return container_of(dev, struct cxl_switch_decoder, cxld.dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_switch_decoder, "CXL");

static void cxl_ep_release(struct cxl_ep *ep)
{
	put_device(ep->ep);
	kfree(ep);
}

static void cxl_ep_remove(struct cxl_port *port, struct cxl_ep *ep)
{
	if (!ep)
		return;
	xa_erase(&port->endpoints, (unsigned long) ep->ep);
	cxl_ep_release(ep);
}

static void cxl_port_release(struct device *dev)
{
	struct cxl_port *port = to_cxl_port(dev);
	unsigned long index;
	struct cxl_ep *ep;

	xa_for_each(&port->endpoints, index, ep)
		cxl_ep_remove(port, ep);
	xa_destroy(&port->endpoints);
	xa_destroy(&port->dports);
	xa_destroy(&port->regions);
	ida_free(&cxl_port_ida, port->id);

	if (is_cxl_root(port)) {
		kfree(to_cxl_root(port));
	} else {
		put_device(dev->parent);
		kfree(port);
	}
}

static ssize_t decoders_committed_show(struct device *dev,
				       struct device_attribute *attr, char *buf)
{
	struct cxl_port *port = to_cxl_port(dev);

	guard(rwsem_read)(&cxl_rwsem.region);
	return sysfs_emit(buf, "%d\n", cxl_num_decoders_committed(port));
}

static DEVICE_ATTR_RO(decoders_committed);

static struct attribute *cxl_port_attrs[] = {
	&dev_attr_decoders_committed.attr,
	NULL,
};

static struct attribute_group cxl_port_attribute_group = {
	.attrs = cxl_port_attrs,
};

static const struct attribute_group *cxl_port_attribute_groups[] = {
	&cxl_base_attribute_group,
	&cxl_port_attribute_group,
	NULL,
};

static const struct device_type cxl_port_type = {
	.name = "cxl_port",
	.release = cxl_port_release,
	.groups = cxl_port_attribute_groups,
};

bool is_cxl_port(const struct device *dev)
{
	return dev->type == &cxl_port_type;
}
EXPORT_SYMBOL_NS_GPL(is_cxl_port, "CXL");

struct cxl_port *to_cxl_port(const struct device *dev)
{
	if (dev_WARN_ONCE(dev, dev->type != &cxl_port_type,
			  "not a cxl_port device\n"))
		return NULL;
	return container_of(dev, struct cxl_port, dev);
}
EXPORT_SYMBOL_NS_GPL(to_cxl_port, "CXL");

struct cxl_port *parent_port_of(struct cxl_port *port)
{
	if (!port || !port->parent_dport)
		return NULL;
	return port->parent_dport->port;
}

static void unregister_port(void *_port)
{
	struct cxl_port *port = _port;

	device_lock_assert(port_to_host(port));
	port->dead = true;
	device_unregister(&port->dev);
}

static void cxl_unlink_uport(void *_port)
{
	struct cxl_port *port = _port;

	sysfs_remove_link(&port->dev.kobj, "uport");
}

static int devm_cxl_link_uport(struct device *host, struct cxl_port *port)
{
	int rc;

	rc = sysfs_create_link(&port->dev.kobj, &port->uport_dev->kobj,
			       "uport");
	if (rc)
		return rc;
	return devm_add_action_or_reset(host, cxl_unlink_uport, port);
}

static void cxl_unlink_parent_dport(void *_port)
{
	struct cxl_port *port = _port;

	sysfs_remove_link(&port->dev.kobj, "parent_dport");
}

static int devm_cxl_link_parent_dport(struct device *host,
				      struct cxl_port *port,
				      struct cxl_dport *parent_dport)
{
	int rc;

	if (!parent_dport)
		return 0;

	rc = sysfs_create_link(&port->dev.kobj, &parent_dport->dport_dev->kobj,
			       "parent_dport");
	if (rc)
		return rc;
	return devm_add_action_or_reset(host, cxl_unlink_parent_dport, port);
}

static struct lock_class_key cxl_port_key;

static struct cxl_port *cxl_port_alloc(struct device *uport_dev,
				       struct cxl_dport *parent_dport)
{
	struct cxl_root *cxl_root __free(kfree) = NULL;
	struct cxl_port *port, *_port __free(kfree) = NULL;
	struct device *dev;
	int rc;

	/* No parent_dport, root cxl_port */
	if (!parent_dport) {
		cxl_root = kzalloc_obj(*cxl_root);
		if (!cxl_root)
			return ERR_PTR(-ENOMEM);
	} else {
		_port = kzalloc_obj(*port);
		if (!_port)
			return ERR_PTR(-ENOMEM);
	}

	rc = ida_alloc(&cxl_port_ida, GFP_KERNEL);
	if (rc < 0)
		return ERR_PTR(rc);

	if (cxl_root)
		port = &no_free_ptr(cxl_root)->port;
	else
		port = no_free_ptr(_port);

	port->id = rc;
	port->uport_dev = uport_dev;

	/*
	 * The top-level cxl_port "cxl_root" does not have a cxl_port as
	 * its parent and it does not have any corresponding component
	 * registers as its decode is described by a fixed platform
	 * description.
	 */
	dev = &port->dev;
	if (parent_dport) {
		struct cxl_port *parent_port = parent_dport->port;
		struct cxl_port *iter;

		dev->parent = &parent_port->dev;
		get_device(dev->parent);
		port->depth = parent_port->depth + 1;
		port->parent_dport = parent_dport;

		/*
		 * walk to the host bridge, or the first ancestor that knows
		 * the host bridge
		 */
		iter = port;
		while (!iter->host_bridge &&
		       !is_cxl_root(to_cxl_port(iter->dev.parent)))
			iter = to_cxl_port(iter->dev.parent);
		if (iter->host_bridge)
			port->host_bridge = iter->host_bridge;
		else if (parent_dport->rch)
			port->host_bridge = parent_dport->dport_dev;
		else
			port->host_bridge = iter->uport_dev;
		dev_dbg(uport_dev, "host-bridge: %s\n",
			dev_name(port->host_bridge));
	} else
		dev->parent = uport_dev;

	ida_init(&port->decoder_ida);
	port->hdm_end = -1;
	port->commit_end = -1;
	xa_init(&port->dports);
	xa_init(&port->endpoints);
	xa_init(&port->regions);
	port->component_reg_phys = CXL_RESOURCE_NONE;

	device_initialize(dev);
	lockdep_set_class_and_subclass(&dev->mutex, &cxl_port_key, port->depth);
	device_set_pm_not_required(dev);
	dev->bus = &cxl_bus_type;
	dev->type = &cxl_port_type;

	return port;
}

static int cxl_setup_comp_regs(struct device *host, struct cxl_register_map *map,
			       resource_size_t component_reg_phys)
{
	*map = (struct cxl_register_map) {
		.host = host,
		.reg_type = CXL_REGLOC_RBI_EMPTY,
		.resource = component_reg_phys,
	};

	if (component_reg_phys == CXL_RESOURCE_NONE)
		return 0;

	map->reg_type = CXL_REGLOC_RBI_COMPONENT;
	map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;

	return cxl_setup_regs(map);
}

int cxl_port_setup_regs(struct cxl_port *port,
			resource_size_t component_reg_phys)
{
	if (dev_is_platform(port->uport_dev))
		return 0;
	return cxl_setup_comp_regs(&port->dev, &port->reg_map,
				   component_reg_phys);
}
EXPORT_SYMBOL_NS_GPL(cxl_port_setup_regs, "CXL");

static int cxl_dport_setup_regs(struct device *host, struct cxl_dport *dport,
				resource_size_t component_reg_phys)
{
	int rc;

	if (dev_is_platform(dport->dport_dev))
		return 0;

	/*
	 * use @dport->dport_dev for the context for error messages during
	 * register probing, and fixup @host after the fact, since @host may be
	 * NULL.
	 */
	rc = cxl_setup_comp_regs(dport->dport_dev, &dport->reg_map,
				 component_reg_phys);
	dport->reg_map.host = host;
	return rc;
}

DEFINE_SHOW_ATTRIBUTE(einj_cxl_available_error_type);

static int cxl_einj_inject(void *data, u64 type)
{
	struct cxl_dport *dport = data;

	if (dport->rch)
		return einj_cxl_inject_rch_error(dport->rcrb.base, type);

	return einj_cxl_inject_error(to_pci_dev(dport->dport_dev), type);
}
DEFINE_DEBUGFS_ATTRIBUTE(cxl_einj_inject_fops, NULL, cxl_einj_inject,
			 "0x%llx\n");

static void cxl_debugfs_create_dport_dir(struct cxl_dport *dport)
{
	struct cxl_port *parent = parent_port_of(dport->port);
	struct dentry *dir;

	if (!einj_cxl_is_initialized())
		return;

	/*
	 * Protocol error injection is only available for CXL 2.0+ root ports
	 * and CXL 1.1 downstream ports
	 */
	if (!dport->rch &&
	    !(dev_is_pci(dport->dport_dev) && parent && is_cxl_root(parent)))
		return;

	dir = cxl_debugfs_create_dir(dev_name(dport->dport_dev));

	debugfs_create_file("einj_inject", 0200, dir, dport,
			    &cxl_einj_inject_fops);
}

static int cxl_port_add(struct cxl_port *port,
			resource_size_t component_reg_phys,
			struct cxl_dport *parent_dport)
{
	struct device *dev __free(put_device) = &port->dev;
	int rc;

	if (is_cxl_memdev(port->uport_dev)) {
		struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
		struct cxl_dev_state *cxlds = cxlmd->cxlds;

		rc = dev_set_name(dev, "endpoint%d", port->id);
		if (rc)
			return rc;

		/*
		 * The endpoint driver already enumerated the component and RAS
		 * registers. Reuse that enumeration while prepping them to be
		 * mapped by the cxl_port driver.
		 */
		port->reg_map = cxlds->reg_map;
		port->reg_map.host = &port->dev;
		cxlmd->endpoint = port;
	} else if (parent_dport) {
		rc = dev_set_name(dev, "port%d", port->id);
		if (rc)
			return rc;

		port->component_reg_phys = component_reg_phys;
	} else {
		rc = dev_set_name(dev, "root%d", port->id);
		if (rc)
			return rc;
	}

	rc = device_add(dev);
	if (rc)
		return rc;

	/* Inhibit the cleanup function invoked */
	dev = NULL;
	return 0;
}

static struct cxl_port *__devm_cxl_add_port(struct device *host,
					    struct device *uport_dev,
					    resource_size_t component_reg_phys,
					    struct cxl_dport *parent_dport)
{
	struct cxl_port *port;
	int rc;

	port = cxl_port_alloc(uport_dev, parent_dport);
	if (IS_ERR(port))
		return port;

	rc = cxl_port_add(port, component_reg_phys, parent_dport);
	if (rc)
		return ERR_PTR(rc);

	rc = devm_add_action_or_reset(host, unregister_port, port);
	if (rc)
		return ERR_PTR(rc);

	rc = devm_cxl_link_uport(host, port);
	if (rc)
		return ERR_PTR(rc);

	rc = devm_cxl_link_parent_dport(host, port, parent_dport);
	if (rc)
		return ERR_PTR(rc);

	if (parent_dport && dev_is_pci(uport_dev))
		port->pci_latency = cxl_pci_get_latency(to_pci_dev(uport_dev));

	return port;
}

/**
 * devm_cxl_add_port - register a cxl_port in CXL memory decode hierarchy
 * @host: host device for devm operations
 * @uport_dev: "physical" device implementing this upstream port
 * @component_reg_phys: (optional) for configurable cxl_port instances
 * @parent_dport: next hop up in the CXL memory decode hierarchy
 */
struct cxl_port *devm_cxl_add_port(struct device *host,
				   struct device *uport_dev,
				   resource_size_t component_reg_phys,
				   struct cxl_dport *parent_dport)
{
	struct cxl_port *port, *parent_port;

	port = __devm_cxl_add_port(host, uport_dev, component_reg_phys,
				   parent_dport);

	parent_port = parent_dport ? parent_dport->port : NULL;
	if (IS_ERR(port)) {
		dev_dbg(uport_dev, "Failed to add%s%s%s: %ld\n",
			parent_port ? " port to " : "",
			parent_port ? dev_name(&parent_port->dev) : "",
			parent_port ? "" : " root port",
			PTR_ERR(port));
	} else {
		dev_dbg(uport_dev, "%s added%s%s%s\n",
			dev_name(&port->dev),
			parent_port ? " to " : "",
			parent_port ? dev_name(&parent_port->dev) : "",
			parent_port ? "" : " (root port)");
	}

	return port;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_port, "CXL");

struct cxl_root *devm_cxl_add_root(struct device *host)
{
	struct cxl_port *port;

	port = devm_cxl_add_port(host, host, CXL_RESOURCE_NONE, NULL);
	if (IS_ERR(port))
		return ERR_CAST(port);

	return to_cxl_root(port);
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_root, "CXL");

struct pci_bus *cxl_port_to_pci_bus(struct cxl_port *port)
{
	/* There is no pci_bus associated with a CXL platform-root port */
	if (is_cxl_root(port))
		return NULL;

	if (dev_is_pci(port->uport_dev)) {
		struct pci_dev *pdev = to_pci_dev(port->uport_dev);

		return pdev->subordinate;
	}

	return xa_load(&cxl_root_buses, (unsigned long)port->uport_dev);
}
EXPORT_SYMBOL_NS_GPL(cxl_port_to_pci_bus, "CXL");

static void unregister_pci_bus(void *uport_dev)
{
	xa_erase(&cxl_root_buses, (unsigned long)uport_dev);
}

int devm_cxl_register_pci_bus(struct device *host, struct device *uport_dev,
			      struct pci_bus *bus)
{
	int rc;

	if (dev_is_pci(uport_dev))
		return -EINVAL;

	rc = xa_insert(&cxl_root_buses, (unsigned long)uport_dev, bus,
		       GFP_KERNEL);
	if (rc)
		return rc;
	return devm_add_action_or_reset(host, unregister_pci_bus, uport_dev);
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_register_pci_bus, "CXL");

static bool dev_is_cxl_root_child(struct device *dev)
{
	struct cxl_port *port, *parent;

	if (!is_cxl_port(dev))
		return false;

	port = to_cxl_port(dev);
	if (is_cxl_root(port))
		return false;

	parent = to_cxl_port(port->dev.parent);
	if (is_cxl_root(parent))
		return true;

	return false;
}

struct cxl_root *find_cxl_root(struct cxl_port *port)
{
	struct cxl_port *iter = port;

	while (iter && !is_cxl_root(iter))
		iter = to_cxl_port(iter->dev.parent);

	if (!iter)
		return NULL;
	get_device(&iter->dev);
	return to_cxl_root(iter);
}
EXPORT_SYMBOL_NS_GPL(find_cxl_root, "CXL");

static struct cxl_dport *find_dport(struct cxl_port *port, int id)
{
	struct cxl_dport *dport;
	unsigned long index;

	device_lock_assert(&port->dev);
	xa_for_each(&port->dports, index, dport)
		if (dport->port_id == id)
			return dport;
	return NULL;
}

static int add_dport(struct cxl_port *port, struct cxl_dport *dport)
{
	struct cxl_dport *dup;
	int rc;

	device_lock_assert(&port->dev);
	dup = find_dport(port, dport->port_id);
	if (dup) {
		dev_err(&port->dev,
			"unable to add dport%d-%s non-unique port id (%s)\n",
			dport->port_id, dev_name(dport->dport_dev),
			dev_name(dup->dport_dev));
		return -EBUSY;
	}

	/* Arrange for dport_dev to be valid through remove_dport() */
	struct device *dev __free(put_device) = get_device(dport->dport_dev);

	rc = xa_insert(&port->dports, (unsigned long)dport->dport_dev, dport,
		       GFP_KERNEL);
	if (rc)
		return rc;

	retain_and_null_ptr(dev);
	port->nr_dports++;
	return 0;
}

/*
 * Since root-level CXL dports cannot be enumerated by PCI they are not
 * enumerated by the common port driver that acquires the port lock over
 * dport add/remove. Instead, root dports are manually added by a
 * platform driver and cond_cxl_root_lock() is used to take the missing
 * port lock in that case.
 */
static void cond_cxl_root_lock(struct cxl_port *port)
{
	if (is_cxl_root(port))
		device_lock(&port->dev);
}

static void cond_cxl_root_unlock(struct cxl_port *port)
{
	if (is_cxl_root(port))
		device_unlock(&port->dev);
}

static void cxl_dport_remove(void *data)
{
	struct cxl_dport *dport = data;
	struct cxl_port *port = dport->port;

	port->nr_dports--;
	xa_erase(&port->dports, (unsigned long) dport->dport_dev);
	put_device(dport->dport_dev);
}

static void cxl_dport_unlink(void *data)
{
	struct cxl_dport *dport = data;
	struct cxl_port *port = dport->port;
	char link_name[CXL_TARGET_STRLEN];

	sprintf(link_name, "dport%d", dport->port_id);
	sysfs_remove_link(&port->dev.kobj, link_name);
}

static void free_dport(void *dport)
{
	kfree(dport);
}

/*
 * Upon return either a group is established with one action (free_dport()), or
 * no group established and @dport is freed.
 */
static void *cxl_dport_open_dr_group_or_free(struct cxl_dport *dport)
{
	int rc;
	struct device *host = dport_to_host(dport);
	void *group = devres_open_group(host, dport, GFP_KERNEL);

	if (!group) {
		kfree(dport);
		return NULL;
	}

	rc = devm_add_action_or_reset(host, free_dport, dport);
	if (rc) {
		devres_release_group(host, group);
		return NULL;
	}

	return group;
}

static void cxl_dport_close_dr_group(struct cxl_dport *dport, void *group)
{
	devres_close_group(dport_to_host(dport), group);
}

static void del_dport(struct cxl_dport *dport)
{
	devres_release_group(dport_to_host(dport), dport);
}

/* The dport group id is the dport */
DEFINE_FREE(cxl_dport_release_dr_group, void *, if (_T) del_dport(_T))

static struct cxl_dport *
__devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
		     int port_id, resource_size_t component_reg_phys,
		     resource_size_t rcrb)
{
	char link_name[CXL_TARGET_STRLEN];
	struct cxl_dport *dport;
	struct device *host;
	int rc;

	if (is_cxl_root(port))
		host = port->uport_dev;
	else
		host = &port->dev;

	if (!host->driver) {
		dev_WARN_ONCE(&port->dev, 1, "dport:%s bad devm context\n",
			      dev_name(dport_dev));
		return ERR_PTR(-ENXIO);
	}

	if (snprintf(link_name, CXL_TARGET_STRLEN, "dport%d", port_id) >=
	    CXL_TARGET_STRLEN)
		return ERR_PTR(-EINVAL);

	dport = kzalloc_obj(*dport);
	if (!dport)
		return ERR_PTR(-ENOMEM);

	/* Just enough init to manage the devres group */
	dport->dport_dev = dport_dev;
	dport->port_id = port_id;
	dport->port = port;

	void *dport_dr_group __free(cxl_dport_release_dr_group) =
		cxl_dport_open_dr_group_or_free(dport);
	if (!dport_dr_group)
		return ERR_PTR(-ENOMEM);

	if (rcrb == CXL_RESOURCE_NONE) {
		rc = cxl_dport_setup_regs(&port->dev, dport,
					  component_reg_phys);
		if (rc)
			return ERR_PTR(rc);
	} else {
		dport->rcrb.base = rcrb;
		component_reg_phys = __rcrb_to_component(dport_dev, &dport->rcrb,
							 CXL_RCRB_DOWNSTREAM);
		if (component_reg_phys == CXL_RESOURCE_NONE) {
			dev_warn(dport_dev, "Invalid Component Registers in RCRB");
			return ERR_PTR(-ENXIO);
		}

		/*
		 * RCH @dport is not ready to map until associated with its
		 * memdev
		 */
		rc = cxl_dport_setup_regs(NULL, dport, component_reg_phys);
		if (rc)
			return ERR_PTR(rc);

		dport->rch = true;
	}

	if (component_reg_phys != CXL_RESOURCE_NONE)
		dev_dbg(dport_dev, "Component Registers found for dport: %pa\n",
			&component_reg_phys);

	cond_cxl_root_lock(port);
	rc = add_dport(port, dport);
	cond_cxl_root_unlock(port);
	if (rc)
		return ERR_PTR(rc);

	rc = devm_add_action_or_reset(host, cxl_dport_remove, dport);
	if (rc)
		return ERR_PTR(rc);

	rc = sysfs_create_link(&port->dev.kobj, &dport_dev->kobj, link_name);
	if (rc)
		return ERR_PTR(rc);

	rc = devm_add_action_or_reset(host, cxl_dport_unlink, dport);
	if (rc)
		return ERR_PTR(rc);

	if (dev_is_pci(dport_dev))
		dport->link_latency = cxl_pci_get_latency(to_pci_dev(dport_dev));

	cxl_debugfs_create_dport_dir(dport);

	if (!dport->rch)
		devm_cxl_dport_ras_setup(dport);

	/* keep the group, and mark the end of devm actions */
	cxl_dport_close_dr_group(dport, no_free_ptr(dport_dr_group));

	return dport;
}

/**
 * devm_cxl_add_dport - append VH downstream port data to a cxl_port
 * @port: the cxl_port that references this dport
 * @dport_dev: firmware or PCI device representing the dport
 * @port_id: identifier for this dport in a decoder's target list
 * @component_reg_phys: optional location of CXL component registers
 *
 * Note that dports are appended to the devm release action's of the
 * either the port's host (for root ports), or the port itself (for
 * switch ports)
 */
struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,
				     struct device *dport_dev, int port_id,
				     resource_size_t component_reg_phys)
{
	struct cxl_dport *dport;

	dport = __devm_cxl_add_dport(port, dport_dev, port_id,
				     component_reg_phys, CXL_RESOURCE_NONE);
	if (IS_ERR(dport)) {
		dev_dbg(dport_dev, "failed to add dport to %s: %ld\n",
			dev_name(&port->dev), PTR_ERR(dport));
	} else {
		dev_dbg(dport_dev, "dport added to %s\n",
			dev_name(&port->dev));
	}

	return dport;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_dport, "CXL");

/**
 * devm_cxl_add_rch_dport - append RCH downstream port data to a cxl_port
 * @port: the cxl_port that references this dport
 * @dport_dev: firmware or PCI device representing the dport
 * @port_id: identifier for this dport in a decoder's target list
 * @rcrb: mandatory location of a Root Complex Register Block
 *
 * See CXL 3.0 9.11.8 CXL Devices Attached to an RCH
 */
struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
					 struct device *dport_dev, int port_id,
					 resource_size_t rcrb)
{
	struct cxl_dport *dport;

	if (rcrb == CXL_RESOURCE_NONE) {
		dev_dbg(&port->dev, "failed to add RCH dport, missing RCRB\n");
		return ERR_PTR(-EINVAL);
	}

	dport = __devm_cxl_add_dport(port, dport_dev, port_id,
				     CXL_RESOURCE_NONE, rcrb);
	if (IS_ERR(dport)) {
		dev_dbg(dport_dev, "failed to add RCH dport to %s: %ld\n",
			dev_name(&port->dev), PTR_ERR(dport));
	} else {
		dev_dbg(dport_dev, "RCH dport added to %s\n",
			dev_name(&port->dev));
	}

	return dport;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_rch_dport, "CXL");

static int add_ep(struct cxl_ep *new)
{
	struct cxl_port *port = new->dport->port;

	guard(device)(&port->dev);
	if (port->dead)
		return -ENXIO;

	return xa_insert(&port->endpoints, (unsigned long)new->ep,
			 new, GFP_KERNEL);
}

/**
 * cxl_add_ep - register an endpoint's interest in a port
 * @dport: the dport that routes to @ep_dev
 * @ep_dev: device representing the endpoint
 *
 * Intermediate CXL ports are scanned based on the arrival of endpoints.
 * When those endpoints depart the port can be destroyed once all
 * endpoints that care about that port have been removed.
 */
static int cxl_add_ep(struct cxl_dport *dport, struct device *ep_dev)
{
	struct cxl_ep *ep;
	int rc;

	ep = kzalloc_obj(*ep);
	if (!ep)
		return -ENOMEM;

	ep->ep = get_device(ep_dev);
	ep->dport = dport;

	rc = add_ep(ep);
	if (rc)
		cxl_ep_release(ep);
	return rc;
}

struct cxl_find_port_ctx {
	const struct device *dport_dev;
	const struct cxl_port *parent_port;
	struct cxl_dport **dport;
};

static int match_port_by_dport(struct device *dev, const void *data)
{
	const struct cxl_find_port_ctx *ctx = data;
	struct cxl_dport *dport;
	struct cxl_port *port;

	if (!is_cxl_port(dev))
		return 0;
	if (ctx->parent_port && dev->parent != &ctx->parent_port->dev)
		return 0;

	port = to_cxl_port(dev);
	dport = cxl_find_dport_by_dev(port, ctx->dport_dev);
	if (ctx->dport)
		*ctx->dport = dport;
	return dport != NULL;
}

static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
{
	struct device *dev;

	if (!ctx->dport_dev)
		return NULL;

	dev = bus_find_device(&cxl_bus_type, NULL, ctx, match_port_by_dport);
	if (dev)
		return to_cxl_port(dev);
	return NULL;
}

static struct cxl_port *find_cxl_port(struct device *dport_dev,
				      struct cxl_dport **dport)
{
	struct cxl_find_port_ctx ctx = {
		.dport_dev = dport_dev,
		.dport = dport,
	};
	struct cxl_port *port;

	port = __find_cxl_port(&ctx);
	return port;
}

/*
 * All users of grandparent() are using it to walk PCIe-like switch port
 * hierarchy. A PCIe switch is comprised of a bridge device representing the
 * upstream switch port and N bridges representing downstream switch ports. When
 * bridges stack the grand-parent of a downstream switch port is another
 * downstream switch port in the immediate ancestor switch.
 */
static struct device *grandparent(struct device *dev)
{
	if (dev && dev->parent)
		return dev->parent->parent;
	return NULL;
}

static void delete_endpoint(void *data)
{
	struct cxl_memdev *cxlmd = data;
	struct cxl_port *endpoint = cxlmd->endpoint;
	struct device *host = port_to_host(endpoint);

	scoped_guard(device, host) {
		if (host->driver && !endpoint->dead) {
			devm_release_action(host, cxl_unlink_parent_dport, endpoint);
			devm_release_action(host, cxl_unlink_uport, endpoint);
			devm_release_action(host, unregister_port, endpoint);
		}
		cxlmd->endpoint = NULL;
	}
	put_device(&endpoint->dev);
	put_device(host);
}

int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint)
{
	struct device *host = port_to_host(endpoint);
	struct device *dev = &cxlmd->dev;

	get_device(host);
	get_device(&endpoint->dev);
	cxlmd->depth = endpoint->depth;
	return devm_add_action_or_reset(dev, delete_endpoint, cxlmd);
}
EXPORT_SYMBOL_NS_GPL(cxl_endpoint_autoremove, "CXL");

/*
 * The natural end of life of a non-root 'cxl_port' is when its parent port goes
 * through a ->remove() event ("top-down" unregistration). The unnatural trigger
 * for a port to be unregistered is when all memdevs beneath that port have gone
 * through ->remove(). This "bottom-up" removal selectively removes individual
 * child ports manually. This depends on devm_cxl_add_port() to not change is
 * devm action registration order, and for dports to have already been
 * destroyed by del_dports().
 */
static void delete_switch_port(struct cxl_port *port)
{
	devm_release_action(port->dev.parent, cxl_unlink_parent_dport, port);
	devm_release_action(port->dev.parent, cxl_unlink_uport, port);
	devm_release_action(port->dev.parent, unregister_port, port);
}

static void del_dports(struct cxl_port *port)
{
	struct cxl_dport *dport;
	unsigned long index;

	device_lock_assert(&port->dev);

	xa_for_each(&port->dports, index, dport)
		del_dport(dport);
}

struct detach_ctx {
	struct cxl_memdev *cxlmd;
	int depth;
};

static int port_has_memdev(struct device *dev, const void *data)
{
	const struct detach_ctx *ctx = data;
	struct cxl_port *port;

	if (!is_cxl_port(dev))
		return 0;

	port = to_cxl_port(dev);
	if (port->depth != ctx->depth)
		return 0;

	return !!cxl_ep_load(port, ctx->cxlmd);
}

static void cxl_detach_ep(void *data)
{
	struct cxl_memdev *cxlmd = data;

	for (int i = cxlmd->depth - 1; i >= 1; i--) {
		struct cxl_port *port, *parent_port;
		struct detach_ctx ctx = {
			.cxlmd = cxlmd,
			.depth = i,
		};
		struct cxl_ep *ep;
		bool died = false;

		struct device *dev __free(put_device) =
			bus_find_device(&cxl_bus_type, NULL, &ctx, port_has_memdev);
		if (!dev)
			continue;
		port = to_cxl_port(dev);

		parent_port = to_cxl_port(port->dev.parent);
		device_lock(&parent_port->dev);
		device_lock(&port->dev);
		ep = cxl_ep_load(port, cxlmd);
		dev_dbg(&cxlmd->dev, "disconnect %s from %s\n",
			ep ? dev_name(ep->ep) : "", dev_name(&port->dev));
		cxl_ep_remove(port, ep);
		if (ep && !port->dead && xa_empty(&port->endpoints) &&
		    !is_cxl_root(parent_port) && parent_port->dev.driver) {
			/*
			 * This was the last ep attached to a dynamically
			 * enumerated port. Block new cxl_add_ep() and garbage
			 * collect the port.
			 */
			died = true;
			port->dead = true;
			del_dports(port);
		}
		device_unlock(&port->dev);

		if (died) {
			dev_dbg(&cxlmd->dev, "delete %s\n",
				dev_name(&port->dev));
			delete_switch_port(port);
		}
		device_unlock(&parent_port->dev);
	}
}

static resource_size_t find_component_registers(struct device *dev)
{
	struct cxl_register_map map;
	struct pci_dev *pdev;

	/*
	 * Theoretically, CXL component registers can be hosted on a
	 * non-PCI device, in practice, only cxl_test hits this case.
	 */
	if (!dev_is_pci(dev))
		return CXL_RESOURCE_NONE;

	pdev = to_pci_dev(dev);

	cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
	return map.resource;
}

static int match_port_by_uport(struct device *dev, const void *data)
{
	const struct device *uport_dev = data;
	struct cxl_port *port;

	if (!is_cxl_port(dev))
		return 0;

	port = to_cxl_port(dev);
	/* Endpoint ports are hosted by memdevs */
	if (is_cxl_memdev(port->uport_dev))
		return uport_dev == port->uport_dev->parent;
	return uport_dev == port->uport_dev;
}

/**
 * find_cxl_port_by_uport - Find a CXL port device companion
 * @uport_dev: Device that acts as a switch or endpoint in the CXL hierarchy
 *
 * In the case of endpoint ports recall that port->uport_dev points to a 'struct
 * cxl_memdev' device. So, the @uport_dev argument is the parent device of the
 * 'struct cxl_memdev' in that case.
 *
 * Function takes a device reference on the port device. Caller should do a
 * put_device() when done.
 */
static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
{
	struct device *dev;

	dev = bus_find_device(&cxl_bus_type, NULL, uport_dev, match_port_by_uport);
	if (dev)
		return to_cxl_port(dev);
	return NULL;
}

static int update_decoder_targets(struct device *dev, void *data)
{
	struct cxl_dport *dport = data;
	struct cxl_switch_decoder *cxlsd;
	struct cxl_decoder *cxld;
	int i;

	if (!is_switch_decoder(dev))
		return 0;

	cxlsd = to_cxl_switch_decoder(dev);
	cxld = &cxlsd->cxld;
	guard(rwsem_write)(&cxl_rwsem.region);

	for (i = 0; i < cxld->interleave_ways; i++) {
		if (cxld->target_map[i] == dport->port_id) {
			cxlsd->target[i] = dport;
			dev_dbg(dev, "dport%d found in target list, index %d\n",
				dport->port_id, i);
			return 0;
		}
	}

	return 0;
}

void cxl_port_update_decoder_targets(struct cxl_port *port,
				     struct cxl_dport *dport)
{
	device_for_each_child(&port->dev, dport, update_decoder_targets);
}
EXPORT_SYMBOL_NS_GPL(cxl_port_update_decoder_targets, "CXL");

static bool dport_exists(struct cxl_port *port, struct device *dport_dev)
{
	struct cxl_dport *dport = cxl_find_dport_by_dev(port, dport_dev);

	if (dport) {
		dev_dbg(&port->dev, "dport%d:%s already exists\n",
			dport->port_id, dev_name(dport_dev));
		return true;
	}

	return false;
}

static struct cxl_dport *probe_dport(struct cxl_port *port,
				     struct device *dport_dev)
{
	struct cxl_driver *drv;

	device_lock_assert(&port->dev);
	if (!port->dev.driver)
		return ERR_PTR(-ENXIO);

	if (dport_exists(port, dport_dev))
		return ERR_PTR(-EBUSY);

	drv = container_of(port->dev.driver, struct cxl_driver, drv);
	if (!drv->add_dport)
		return ERR_PTR(-ENXIO);

	/* see cxl_port_add_dport() */
	return drv->add_dport(port, dport_dev);
}

static struct cxl_dport *devm_cxl_create_port(struct device *ep_dev,
					      struct cxl_port *parent_port,
					      struct cxl_dport *parent_dport,
					      struct device *uport_dev,
					      struct device *dport_dev)
{
	resource_size_t component_reg_phys;

	device_lock_assert(&parent_port->dev);
	if (!parent_port->dev.driver) {
		dev_warn(ep_dev,
			 "port %s:%s:%s disabled, failed to enumerate CXL.mem\n",
			 dev_name(&parent_port->dev), dev_name(uport_dev),
			 dev_name(dport_dev));
	}

	struct cxl_port *port __free(put_cxl_port) =
		find_cxl_port_by_uport(uport_dev);
	if (!port) {
		component_reg_phys = find_component_registers(uport_dev);
		port = devm_cxl_add_port(&parent_port->dev, uport_dev,
					 component_reg_phys, parent_dport);
		if (IS_ERR(port))
			return ERR_CAST(port);

		/*
		 * retry to make sure a port is found. a port device
		 * reference is taken.
		 */
		port = find_cxl_port_by_uport(uport_dev);
		if (!port)
			return ERR_PTR(-ENODEV);

		dev_dbg(ep_dev, "created port %s:%s\n",
			dev_name(&port->dev), dev_name(port->uport_dev));
	} else {
		/*
		 * Port was created before right before this function is
		 * called. Signal the caller to deal with it.
		 */
		return ERR_PTR(-EAGAIN);
	}

	guard(device)(&port->dev);
	return probe_dport(port, dport_dev);
}

static int add_port_attach_ep(struct cxl_memdev *cxlmd,
			      struct device *uport_dev,
			      struct device *dport_dev)
{
	struct device *dparent = grandparent(dport_dev);
	struct cxl_dport *dport, *parent_dport;
	int rc;

	if (is_cxl_host_bridge(dparent)) {
		/*
		 * The iteration reached the topology root without finding the
		 * CXL-root 'cxl_port' on a previous iteration, fail for now to
		 * be re-probed after platform driver attaches.
		 */
		dev_dbg(&cxlmd->dev, "%s is a root dport\n",
			dev_name(dport_dev));
		return -ENXIO;
	}

	struct cxl_port *parent_port __free(put_cxl_port) =
		find_cxl_port_by_uport(dparent->parent);
	if (!parent_port) {
		/* iterate to create this parent_port */
		return -EAGAIN;
	}

	scoped_guard(device, &parent_port->dev) {
		parent_dport = cxl_find_dport_by_dev(parent_port, dparent);
		if (!parent_dport) {
			parent_dport = probe_dport(parent_port, dparent);
			if (IS_ERR(parent_dport))
				return PTR_ERR(parent_dport);
		}

		dport = devm_cxl_create_port(&cxlmd->dev, parent_port,
					     parent_dport, uport_dev,
					     dport_dev);
		if (IS_ERR(dport)) {
			/* Port already exists, restart iteration */
			if (PTR_ERR(dport) == -EAGAIN)
				return 0;
			return PTR_ERR(dport);
		}
	}

	rc = cxl_add_ep(dport, &cxlmd->dev);
	if (rc == -EBUSY) {
		/*
		 * "can't" happen, but this error code means
		 * something to the caller, so translate it.
		 */
		rc = -ENXIO;
	}

	return rc;
}

static struct cxl_dport *find_or_add_dport(struct cxl_port *port,
					   struct device *dport_dev)
{
	struct cxl_dport *dport;

	/*
	 * The port is already visible in CXL hierarchy, but it may still
	 * be in the process of binding to the CXL port driver at this point.
	 *
	 * port creation and driver binding are protected by the port's host
	 * lock, so acquire the host lock here to ensure the port has completed
	 * driver binding before proceeding with dport addition.
	 */
	guard(device)(port_to_host(port));
	guard(device)(&port->dev);
	dport = cxl_find_dport_by_dev(port, dport_dev);
	if (!dport) {
		dport = probe_dport(port, dport_dev);
		if (IS_ERR(dport))
			return dport;

		/* New dport added, restart iteration */
		return ERR_PTR(-EAGAIN);
	}

	return dport;
}

int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
{
	struct device *dev = &cxlmd->dev;
	struct device *iter;
	int rc;

	/*
	 * Skip intermediate port enumeration in the RCH case, there
	 * are no ports in between a host bridge and an endpoint.
	 */
	if (cxlmd->cxlds->rcd)
		return 0;

	rc = devm_add_action_or_reset(&cxlmd->dev, cxl_detach_ep, cxlmd);
	if (rc)
		return rc;

	/*
	 * Scan for and add all cxl_ports in this device's ancestry.
	 * Repeat until no more ports are added. Abort if a port add
	 * attempt fails.
	 */
retry:
	for (iter = dev; iter; iter = grandparent(iter)) {
		struct device *dport_dev = grandparent(iter);
		struct device *uport_dev;
		struct cxl_dport *dport;

		if (is_cxl_host_bridge(dport_dev))
			return 0;

		uport_dev = dport_dev->parent;
		if (!uport_dev) {
			dev_warn(dev, "at %s no parent for dport: %s\n",
				 dev_name(iter), dev_name(dport_dev));
			return -ENXIO;
		}

		dev_dbg(dev, "scan: iter: %s dport_dev: %s parent: %s\n",
			dev_name(iter), dev_name(dport_dev),
			dev_name(uport_dev));
		struct cxl_port *port __free(put_cxl_port) =
			find_cxl_port_by_uport(uport_dev);
		if (port) {
			dev_dbg(&cxlmd->dev,
				"found already registered port %s:%s\n",
				dev_name(&port->dev),
				dev_name(port->uport_dev));

			/*
			 * RP port enumerated by cxl_acpi without dport will
			 * have the dport added here.
			 */
			dport = find_or_add_dport(port, dport_dev);
			if (IS_ERR(dport)) {
				if (PTR_ERR(dport) == -EAGAIN)
					goto retry;
				return PTR_ERR(dport);
			}

			rc = cxl_add_ep(dport, &cxlmd->dev);

			/*
			 * If the endpoint already exists in the port's list,
			 * that's ok, it was added on a previous pass.
			 * Otherwise, retry in add_port_attach_ep() after taking
			 * the parent_port lock as the current port may be being
			 * reaped.
			 */
			if (rc && rc != -EBUSY)
				return rc;

			cxl_gpf_port_setup(dport);

			/* Any more ports to add between this one and the root? */
			if (!dev_is_cxl_root_child(&port->dev))
				continue;

			return 0;
		}

		rc = add_port_attach_ep(cxlmd, uport_dev, dport_dev);
		/* port missing, try to add parent */
		if (rc == -EAGAIN)
			continue;
		/* failed to add ep or port */
		if (rc)
			return rc;
		/* port added, new descendants possible, start over */
		goto retry;
	}

	return 0;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_ports, "CXL");

struct cxl_port *cxl_pci_find_port(struct pci_dev *pdev,
				   struct cxl_dport **dport)
{
	return find_cxl_port(pdev->dev.parent, dport);
}
EXPORT_SYMBOL_NS_GPL(cxl_pci_find_port, "CXL");

struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
				   struct cxl_dport **dport)
{
	return find_cxl_port(grandparent(&cxlmd->dev), dport);
}
EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, "CXL");

static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
				    struct cxl_port *port)
{
	struct cxl_decoder *cxld = &cxlsd->cxld;
	int i;

	device_lock_assert(&port->dev);

	if (xa_empty(&port->dports))
		return 0;

	guard(rwsem_write)(&cxl_rwsem.region);
	for (i = 0; i < cxlsd->cxld.interleave_ways; i++) {
		struct cxl_dport *dport = find_dport(port, cxld->target_map[i]);

		if (!dport) {
			/* dport may be activated later */
			continue;
		}
		cxlsd->target[i] = dport;
	}

	return 0;
}

static struct lock_class_key cxl_decoder_key;

/**
 * cxl_decoder_init - Common decoder setup / initialization
 * @port: owning port of this decoder
 * @cxld: common decoder properties to initialize
 *
 * A port may contain one or more decoders. Each of those decoders
 * enable some address space for CXL.mem utilization. A decoder is
 * expected to be configured by the caller before registering via
 * cxl_decoder_add()
 */
static int cxl_decoder_init(struct cxl_port *port, struct cxl_decoder *cxld)
{
	struct device *dev;
	int rc;

	rc = ida_alloc(&port->decoder_ida, GFP_KERNEL);
	if (rc < 0)
		return rc;

	/* need parent to stick around to release the id */
	get_device(&port->dev);
	cxld->id = rc;

	dev = &cxld->dev;
	device_initialize(dev);
	lockdep_set_class(&dev->mutex, &cxl_decoder_key);
	device_set_pm_not_required(dev);
	dev->parent = &port->dev;
	dev->bus = &cxl_bus_type;

	/* Pre initialize an "empty" decoder */
	cxld->interleave_ways = 1;
	cxld->interleave_granularity = PAGE_SIZE;
	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
	cxld->hpa_range = (struct range) {
		.start = 0,
		.end = -1,
	};

	return 0;
}

static int cxl_switch_decoder_init(struct cxl_port *port,
				   struct cxl_switch_decoder *cxlsd,
				   int nr_targets)
{
	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
		return -EINVAL;

	cxlsd->nr_targets = nr_targets;
	return cxl_decoder_init(port, &cxlsd->cxld);
}

/**
 * cxl_root_decoder_alloc - Allocate a root level decoder
 * @port: owning CXL root of this decoder
 * @nr_targets: static number of downstream targets
 *
 * Return: A new cxl decoder to be registered by cxl_decoder_add(). A
 * 'CXL root' decoder is one that decodes from a top-level / static platform
 * firmware description of CXL resources into a CXL standard decode
 * topology.
 */
struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
						unsigned int nr_targets)
{
	struct cxl_root_decoder *cxlrd;
	struct cxl_switch_decoder *cxlsd;
	struct cxl_decoder *cxld;
	int rc;

	if (!is_cxl_root(port))
		return ERR_PTR(-EINVAL);

	cxlrd = kzalloc_flex(*cxlrd, cxlsd.target, nr_targets);
	if (!cxlrd)
		return ERR_PTR(-ENOMEM);

	cxlsd = &cxlrd->cxlsd;
	rc = cxl_switch_decoder_init(port, cxlsd, nr_targets);
	if (rc) {
		kfree(cxlrd);
		return ERR_PTR(rc);
	}

	mutex_init(&cxlrd->range_lock);

	cxld = &cxlsd->cxld;
	cxld->dev.type = &cxl_decoder_root_type;
	/*
	 * cxl_root_decoder_release() special cases negative ids to
	 * detect memregion_alloc() failures.
	 */
	atomic_set(&cxlrd->region_id, -1);
	rc = memregion_alloc(GFP_KERNEL);
	if (rc < 0) {
		put_device(&cxld->dev);
		return ERR_PTR(rc);
	}

	atomic_set(&cxlrd->region_id, rc);
	cxlrd->qos_class = CXL_QOS_CLASS_INVALID;
	return cxlrd;
}
EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, "CXL");

/**
 * cxl_switch_decoder_alloc - Allocate a switch level decoder
 * @port: owning CXL switch port of this decoder
 * @nr_targets: max number of dynamically addressable downstream targets
 *
 * Return: A new cxl decoder to be registered by cxl_decoder_add(). A
 * 'switch' decoder is any decoder that can be enumerated by PCIe
 * topology and the HDM Decoder Capability. This includes the decoders
 * that sit between Switch Upstream Ports / Switch Downstream Ports and
 * Host Bridges / Root Ports.
 */
struct cxl_switch_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
						    unsigned int nr_targets)
{
	struct cxl_switch_decoder *cxlsd;
	struct cxl_decoder *cxld;
	int rc;

	if (is_cxl_root(port) || is_cxl_endpoint(port))
		return ERR_PTR(-EINVAL);

	cxlsd = kzalloc_flex(*cxlsd, target, nr_targets);
	if (!cxlsd)
		return ERR_PTR(-ENOMEM);

	rc = cxl_switch_decoder_init(port, cxlsd, nr_targets);
	if (rc) {
		kfree(cxlsd);
		return ERR_PTR(rc);
	}

	cxld = &cxlsd->cxld;
	cxld->dev.type = &cxl_decoder_switch_type;
	return cxlsd;
}
EXPORT_SYMBOL_NS_GPL(cxl_switch_decoder_alloc, "CXL");

/**
 * cxl_endpoint_decoder_alloc - Allocate an endpoint decoder
 * @port: owning port of this decoder
 *
 * Return: A new cxl decoder to be registered by cxl_decoder_add()
 */
struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port)
{
	struct cxl_endpoint_decoder *cxled;
	struct cxl_decoder *cxld;
	int rc;

	if (!is_cxl_endpoint(port))
		return ERR_PTR(-EINVAL);

	cxled = kzalloc_obj(*cxled);
	if (!cxled)
		return ERR_PTR(-ENOMEM);

	cxled->pos = -1;
	cxled->part = -1;
	cxld = &cxled->cxld;
	rc = cxl_decoder_init(port, cxld);
	if (rc)	 {
		kfree(cxled);
		return ERR_PTR(rc);
	}

	cxld->dev.type = &cxl_decoder_endpoint_type;
	return cxled;
}
EXPORT_SYMBOL_NS_GPL(cxl_endpoint_decoder_alloc, "CXL");

/**
 * cxl_decoder_add_locked - Add a decoder with targets
 * @cxld: The cxl decoder allocated by cxl_<type>_decoder_alloc()
 *
 * Certain types of decoders may not have any targets. The main example of this
 * is an endpoint device. A more awkward example is a hostbridge whose root
 * ports get hot added (technically possible, though unlikely).
 *
 * This is the locked variant of cxl_decoder_add().
 *
 * Context: Process context. Expects the device lock of the port that owns the
 *	    @cxld to be held.
 *
 * Return: Negative error code if the decoder wasn't properly configured; else
 *	   returns 0.
 */
int cxl_decoder_add_locked(struct cxl_decoder *cxld)
{
	struct cxl_port *port;
	struct device *dev;
	int rc;

	if (WARN_ON_ONCE(!cxld))
		return -EINVAL;

	if (WARN_ON_ONCE(IS_ERR(cxld)))
		return PTR_ERR(cxld);

	if (cxld->interleave_ways < 1)
		return -EINVAL;

	dev = &cxld->dev;

	port = to_cxl_port(cxld->dev.parent);
	if (!is_endpoint_decoder(dev)) {
		struct cxl_switch_decoder *cxlsd = to_cxl_switch_decoder(dev);

		rc = decoder_populate_targets(cxlsd, port);
		if (rc && (cxld->flags & CXL_DECODER_F_ENABLE)) {
			dev_err(&port->dev,
				"Failed to populate active decoder targets\n");
			return rc;
		}
	}

	rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
	if (rc)
		return rc;

	return device_add(dev);
}
EXPORT_SYMBOL_NS_GPL(cxl_decoder_add_locked, "CXL");

/**
 * cxl_decoder_add - Add a decoder with targets
 * @cxld: The cxl decoder allocated by cxl_<type>_decoder_alloc()
 *
 * This is the unlocked variant of cxl_decoder_add_locked().
 * See cxl_decoder_add_locked().
 *
 * Context: Process context. Takes and releases the device lock of the port that
 *	    owns the @cxld.
 */
int cxl_decoder_add(struct cxl_decoder *cxld)
{
	struct cxl_port *port;

	if (WARN_ON_ONCE(!cxld))
		return -EINVAL;

	if (WARN_ON_ONCE(IS_ERR(cxld)))
		return PTR_ERR(cxld);

	port = to_cxl_port(cxld->dev.parent);

	guard(device)(&port->dev);
	return cxl_decoder_add_locked(cxld);
}
EXPORT_SYMBOL_NS_GPL(cxl_decoder_add, "CXL");

static void cxld_unregister(void *dev)
{
	if (is_endpoint_decoder(dev))
		cxl_decoder_detach(NULL, to_cxl_endpoint_decoder(dev), -1,
				   DETACH_INVALIDATE);

	device_unregister(dev);
}

int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld)
{
	return devm_add_action_or_reset(host, cxld_unregister, &cxld->dev);
}
EXPORT_SYMBOL_NS_GPL(cxl_decoder_autoremove, "CXL");

/**
 * __cxl_driver_register - register a driver for the cxl bus
 * @cxl_drv: cxl driver structure to attach
 * @owner: owning module/driver
 * @modname: KBUILD_MODNAME for parent driver
 */
int __cxl_driver_register(struct cxl_driver *cxl_drv, struct module *owner,
			  const char *modname)
{
	if (!cxl_drv->probe) {
		pr_debug("%s ->probe() must be specified\n", modname);
		return -EINVAL;
	}

	if (!cxl_drv->name) {
		pr_debug("%s ->name must be specified\n", modname);
		return -EINVAL;
	}

	if (!cxl_drv->id) {
		pr_debug("%s ->id must be specified\n", modname);
		return -EINVAL;
	}

	cxl_drv->drv.bus = &cxl_bus_type;
	cxl_drv->drv.owner = owner;
	cxl_drv->drv.mod_name = modname;
	cxl_drv->drv.name = cxl_drv->name;

	return driver_register(&cxl_drv->drv);
}
EXPORT_SYMBOL_NS_GPL(__cxl_driver_register, "CXL");

void cxl_driver_unregister(struct cxl_driver *cxl_drv)
{
	driver_unregister(&cxl_drv->drv);
}
EXPORT_SYMBOL_NS_GPL(cxl_driver_unregister, "CXL");

static int cxl_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
{
	return add_uevent_var(env, "MODALIAS=" CXL_MODALIAS_FMT,
			      cxl_device_id(dev));
}

static int cxl_bus_match(struct device *dev, const struct device_driver *drv)
{
	return cxl_device_id(dev) == to_cxl_drv(drv)->id;
}

static int cxl_bus_probe(struct device *dev)
{
	int rc;

	rc = to_cxl_drv(dev->driver)->probe(dev);
	dev_dbg(dev, "probe: %d\n", rc);
	return rc;
}

static void cxl_bus_remove(struct device *dev)
{
	struct cxl_driver *cxl_drv = to_cxl_drv(dev->driver);

	if (cxl_drv->remove)
		cxl_drv->remove(dev);
}

static struct workqueue_struct *cxl_bus_wq;

static int cxl_rescan_attach(struct device *dev, void *data)
{
	int rc = device_attach(dev);

	dev_vdbg(dev, "rescan: %s\n", rc ? "attach" : "detached");

	return 0;
}

static void cxl_bus_rescan_queue(struct work_struct *w)
{
	bus_for_each_dev(&cxl_bus_type, NULL, NULL, cxl_rescan_attach);
}

void cxl_bus_rescan(void)
{
	static DECLARE_WORK(rescan_work, cxl_bus_rescan_queue);

	queue_work(cxl_bus_wq, &rescan_work);
}
EXPORT_SYMBOL_NS_GPL(cxl_bus_rescan, "CXL");

void cxl_bus_drain(void)
{
	drain_workqueue(cxl_bus_wq);
}
EXPORT_SYMBOL_NS_GPL(cxl_bus_drain, "CXL");

bool schedule_cxl_memdev_detach(struct cxl_memdev *cxlmd)
{
	return queue_work(cxl_bus_wq, &cxlmd->detach_work);
}
EXPORT_SYMBOL_NS_GPL(schedule_cxl_memdev_detach, "CXL");

static void add_latency(struct access_coordinate *c, long latency)
{
	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++) {
		c[i].write_latency += latency;
		c[i].read_latency += latency;
	}
}

static bool coordinates_valid(struct access_coordinate *c)
{
	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++) {
		if (c[i].read_bandwidth && c[i].write_bandwidth &&
		    c[i].read_latency && c[i].write_latency)
			continue;
		return false;
	}

	return true;
}

static void set_min_bandwidth(struct access_coordinate *c, unsigned int bw)
{
	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++) {
		c[i].write_bandwidth = min(c[i].write_bandwidth, bw);
		c[i].read_bandwidth = min(c[i].read_bandwidth, bw);
	}
}

static void set_access_coordinates(struct access_coordinate *out,
				   struct access_coordinate *in)
{
	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++)
		out[i] = in[i];
}

static bool parent_port_is_cxl_root(struct cxl_port *port)
{
	return is_cxl_root(to_cxl_port(port->dev.parent));
}

/**
 * cxl_endpoint_get_perf_coordinates - Retrieve performance numbers stored in dports
 *				   of CXL path
 * @port: endpoint cxl_port
 * @coord: output performance data
 *
 * Return: errno on failure, 0 on success.
 */
int cxl_endpoint_get_perf_coordinates(struct cxl_port *port,
				      struct access_coordinate *coord)
{
	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
	struct access_coordinate c[] = {
		{
			.read_bandwidth = UINT_MAX,
			.write_bandwidth = UINT_MAX,
		},
		{
			.read_bandwidth = UINT_MAX,
			.write_bandwidth = UINT_MAX,
		},
	};
	struct cxl_port *iter = port;
	struct cxl_dport *dport;
	struct pci_dev *pdev;
	struct device *dev;
	unsigned int bw;
	bool is_cxl_root;

	if (!is_cxl_endpoint(port))
		return -EINVAL;

	/*
	 * Skip calculation for RCD. Expectation is HMAT already covers RCD case
	 * since RCH does not support hotplug.
	 */
	if (cxlmd->cxlds->rcd)
		return 0;

	/*
	 * Exit the loop when the parent port of the current iter port is cxl
	 * root. The iterative loop starts at the endpoint and gathers the
	 * latency of the CXL link from the current device/port to the connected
	 * downstream port each iteration.
	 */
	do {
		dport = iter->parent_dport;
		iter = to_cxl_port(iter->dev.parent);
		is_cxl_root = parent_port_is_cxl_root(iter);

		/*
		 * There's no valid access_coordinate for a root port since RPs do not
		 * have CDAT and therefore needs to be skipped.
		 */
		if (!is_cxl_root) {
			if (!coordinates_valid(dport->coord))
				return -EINVAL;
			cxl_coordinates_combine(c, c, dport->coord);
		}
		add_latency(c, dport->link_latency);
	} while (!is_cxl_root);

	dport = iter->parent_dport;
	/* Retrieve HB coords */
	if (!coordinates_valid(dport->coord))
		return -EINVAL;
	cxl_coordinates_combine(c, c, dport->coord);

	dev = port->uport_dev->parent;
	if (!dev_is_pci(dev))
		return -ENODEV;

	/* Get the calculated PCI paths bandwidth */
	pdev = to_pci_dev(dev);
	bw = pcie_bandwidth_available(pdev, NULL, NULL, NULL);
	if (bw == 0)
		return -ENXIO;
	bw /= BITS_PER_BYTE;

	set_min_bandwidth(c, bw);
	set_access_coordinates(coord, c);

	return 0;
}
EXPORT_SYMBOL_NS_GPL(cxl_endpoint_get_perf_coordinates, "CXL");

int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
					struct access_coordinate *c)
{
	struct cxl_dport *dport = port->parent_dport;

	/* Check this port is connected to a switch DSP and not an RP */
	if (parent_port_is_cxl_root(to_cxl_port(port->dev.parent)))
		return -ENODEV;

	if (!coordinates_valid(dport->coord))
		return -EINVAL;

	for (int i = 0; i < ACCESS_COORDINATE_MAX; i++) {
		c[i].read_bandwidth = dport->coord[i].read_bandwidth;
		c[i].write_bandwidth = dport->coord[i].write_bandwidth;
	}

	return 0;
}

/* for user tooling to ensure port disable work has completed */
static ssize_t flush_store(const struct bus_type *bus, const char *buf, size_t count)
{
	if (sysfs_streq(buf, "1")) {
		flush_workqueue(cxl_bus_wq);
		return count;
	}

	return -EINVAL;
}

static BUS_ATTR_WO(flush);

static struct attribute *cxl_bus_attributes[] = {
	&bus_attr_flush.attr,
	NULL,
};

static struct attribute_group cxl_bus_attribute_group = {
	.attrs = cxl_bus_attributes,
};

static const struct attribute_group *cxl_bus_attribute_groups[] = {
	&cxl_bus_attribute_group,
	NULL,
};

const struct bus_type cxl_bus_type = {
	.name = "cxl",
	.uevent = cxl_bus_uevent,
	.match = cxl_bus_match,
	.probe = cxl_bus_probe,
	.remove = cxl_bus_remove,
	.bus_groups = cxl_bus_attribute_groups,
};
EXPORT_SYMBOL_NS_GPL(cxl_bus_type, "CXL");

static struct dentry *cxl_debugfs;

struct dentry *cxl_debugfs_create_dir(const char *dir)
{
	return debugfs_create_dir(dir, cxl_debugfs);
}
EXPORT_SYMBOL_NS_GPL(cxl_debugfs_create_dir, "CXL");

static __init int cxl_core_init(void)
{
	int rc;

	cxl_debugfs = debugfs_create_dir("cxl", NULL);

	if (einj_cxl_is_initialized())
		debugfs_create_file("einj_types", 0400, cxl_debugfs, NULL,
				    &einj_cxl_available_error_type_fops);

	cxl_mbox_init();

	rc = cxl_memdev_init();
	if (rc)
		return rc;

	cxl_bus_wq = alloc_ordered_workqueue("cxl_port", 0);
	if (!cxl_bus_wq) {
		rc = -ENOMEM;
		goto err_wq;
	}

	rc = bus_register(&cxl_bus_type);
	if (rc)
		goto err_bus;

	rc = cxl_region_init();
	if (rc)
		goto err_region;

	rc = cxl_ras_init();
	if (rc)
		goto err_ras;

	return 0;

err_ras:
	cxl_region_exit();
err_region:
	bus_unregister(&cxl_bus_type);
err_bus:
	destroy_workqueue(cxl_bus_wq);
err_wq:
	cxl_memdev_exit();
	return rc;
}

static void cxl_core_exit(void)
{
	cxl_ras_exit();
	cxl_region_exit();
	bus_unregister(&cxl_bus_type);
	destroy_workqueue(cxl_bus_wq);
	cxl_memdev_exit();
	debugfs_remove_recursive(cxl_debugfs);
}

subsys_initcall(cxl_core_init);
module_exit(cxl_core_exit);
MODULE_DESCRIPTION("CXL: Core Compute Express Link support");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("CXL");