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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "cxlmem.h"
#include "cxlpci.h"
/**
* DOC: cxl port
*
* The port driver enumerates dport via PCI and scans for HDM
* (Host-managed-Device-Memory) decoder resources via the
* @component_reg_phys value passed in by the agent that registered the
* port. All descendant ports of a CXL root port (described by platform
* firmware) are managed in this drivers context. Each driver instance
* is responsible for tearing down the driver context of immediate
* descendant ports. The locking for this is validated by
* CONFIG_PROVE_CXL_LOCKING.
*
* The primary service this driver provides is presenting APIs to other
* drivers to utilize the decoders, and indicating to userspace (via bind
* status) the connectivity of the CXL.mem protocol throughout the
* PCIe topology.
*/
static void schedule_detach(void *cxlmd)
{
schedule_cxl_memdev_detach(cxlmd);
}
static int discover_region(struct device *dev, void *root)
{
struct cxl_endpoint_decoder *cxled;
int rc;
if (!is_endpoint_decoder(dev))
return 0;
cxled = to_cxl_endpoint_decoder(dev);
if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
return 0;
if (cxled->state != CXL_DECODER_STATE_AUTO)
return 0;
/*
* Region enumeration is opportunistic, if this add-event fails,
* continue to the next endpoint decoder.
*/
rc = cxl_add_to_region(root, cxled);
if (rc)
dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
return 0;
}
static int cxl_switch_port_probe(struct cxl_port *port)
{
struct cxl_hdm *cxlhdm;
int rc, nr_dports;
nr_dports = devm_cxl_port_enumerate_dports(port);
if (nr_dports < 0)
return nr_dports;
cxlhdm = devm_cxl_setup_hdm(port, NULL);
rc = devm_cxl_enable_hdm(port, cxlhdm);
if (rc)
return rc;
if (!IS_ERR(cxlhdm))
return devm_cxl_enumerate_decoders(cxlhdm, NULL);
if (PTR_ERR(cxlhdm) != -ENODEV) {
dev_err(&port->dev, "Failed to map HDM decoder capability\n");
return PTR_ERR(cxlhdm);
}
if (nr_dports == 1) {
dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
return devm_cxl_add_passthrough_decoder(port);
}
dev_err(&port->dev, "HDM decoder capability not found\n");
return -ENXIO;
}
static int cxl_endpoint_port_probe(struct cxl_port *port)
{
struct cxl_endpoint_dvsec_info info = { .port = port };
struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport);
struct cxl_dev_state *cxlds = cxlmd->cxlds;
struct cxl_hdm *cxlhdm;
struct cxl_port *root;
int rc;
rc = cxl_dvsec_rr_decode(cxlds->dev, cxlds->cxl_dvsec, &info);
if (rc < 0)
return rc;
cxlhdm = devm_cxl_setup_hdm(port, &info);
if (IS_ERR(cxlhdm))
return PTR_ERR(cxlhdm);
/* Cache the data early to ensure is_visible() works */
read_cdat_data(port);
get_device(&cxlmd->dev);
rc = devm_add_action_or_reset(&port->dev, schedule_detach, cxlmd);
if (rc)
return rc;
rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
if (rc)
return rc;
rc = devm_cxl_enumerate_decoders(cxlhdm, &info);
if (rc)
return rc;
/*
* This can't fail in practice as CXL root exit unregisters all
* descendant ports and that in turn synchronizes with cxl_port_probe()
*/
root = find_cxl_root(port);
/*
* Now that all endpoint decoders are successfully enumerated, try to
* assemble regions from committed decoders
*/
device_for_each_child(&port->dev, root, discover_region);
put_device(&root->dev);
return 0;
}
static int cxl_port_probe(struct device *dev)
{
struct cxl_port *port = to_cxl_port(dev);
if (is_cxl_endpoint(port))
return cxl_endpoint_port_probe(port);
return cxl_switch_port_probe(port);
}
static ssize_t CDAT_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t offset, size_t count)
{
struct device *dev = kobj_to_dev(kobj);
struct cxl_port *port = to_cxl_port(dev);
if (!port->cdat_available)
return -ENXIO;
if (!port->cdat.table)
return 0;
return memory_read_from_buffer(buf, count, &offset,
port->cdat.table,
port->cdat.length);
}
static BIN_ATTR_ADMIN_RO(CDAT, 0);
static umode_t cxl_port_bin_attr_is_visible(struct kobject *kobj,
struct bin_attribute *attr, int i)
{
struct device *dev = kobj_to_dev(kobj);
struct cxl_port *port = to_cxl_port(dev);
if ((attr == &bin_attr_CDAT) && port->cdat_available)
return attr->attr.mode;
return 0;
}
static struct bin_attribute *cxl_cdat_bin_attributes[] = {
&bin_attr_CDAT,
NULL,
};
static struct attribute_group cxl_cdat_attribute_group = {
.bin_attrs = cxl_cdat_bin_attributes,
.is_bin_visible = cxl_port_bin_attr_is_visible,
};
static const struct attribute_group *cxl_port_attribute_groups[] = {
&cxl_cdat_attribute_group,
NULL,
};
static struct cxl_driver cxl_port_driver = {
.name = "cxl_port",
.probe = cxl_port_probe,
.id = CXL_DEVICE_PORT,
.drv = {
.dev_groups = cxl_port_attribute_groups,
},
};
module_cxl_driver(cxl_port_driver);
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(CXL);
MODULE_ALIAS_CXL(CXL_DEVICE_PORT);
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