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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/pci.h>
#include "cxlmem.h"
#include "cxlpci.h"
/**
* DOC: cxl mem
*
* CXL memory endpoint devices and switches are CXL capable devices that are
* participating in CXL.mem protocol. Their functionality builds on top of the
* CXL.io protocol that allows enumerating and configuring components via
* standard PCI mechanisms.
*
* The cxl_mem driver owns kicking off the enumeration of this CXL.mem
* capability. With the detection of a CXL capable endpoint, the driver will
* walk up to find the platform specific port it is connected to, and determine
* if there are intervening switches in the path. If there are switches, a
* secondary action is to enumerate those (implemented in cxl_core). Finally the
* cxl_mem driver adds the device it is bound to as a CXL endpoint-port for use
* in higher level operations.
*/
static int create_endpoint(struct cxl_memdev *cxlmd,
struct cxl_port *parent_port)
{
struct cxl_dev_state *cxlds = cxlmd->cxlds;
struct cxl_port *endpoint;
endpoint = devm_cxl_add_port(&parent_port->dev, &cxlmd->dev,
cxlds->component_reg_phys, parent_port);
if (IS_ERR(endpoint))
return PTR_ERR(endpoint);
dev_dbg(&cxlmd->dev, "add: %s\n", dev_name(&endpoint->dev));
if (!endpoint->dev.driver) {
dev_err(&cxlmd->dev, "%s failed probe\n",
dev_name(&endpoint->dev));
return -ENXIO;
}
return cxl_endpoint_autoremove(cxlmd, endpoint);
}
static void enable_suspend(void *data)
{
cxl_mem_active_dec();
}
static int cxl_mem_probe(struct device *dev)
{
struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
struct cxl_port *parent_port;
int rc;
/*
* Someone is trying to reattach this device after it lost its port
* connection (an endpoint port previously registered by this memdev was
* disabled). This racy check is ok because if the port is still gone,
* no harm done, and if the port hierarchy comes back it will re-trigger
* this probe. Port rescan and memdev detach work share the same
* single-threaded workqueue.
*/
if (work_pending(&cxlmd->detach_work))
return -EBUSY;
rc = devm_cxl_enumerate_ports(cxlmd);
if (rc)
return rc;
parent_port = cxl_mem_find_port(cxlmd);
if (!parent_port) {
dev_err(dev, "CXL port topology not found\n");
return -ENXIO;
}
device_lock(&parent_port->dev);
if (!parent_port->dev.driver) {
dev_err(dev, "CXL port topology %s not enabled\n",
dev_name(&parent_port->dev));
rc = -ENXIO;
goto unlock;
}
rc = create_endpoint(cxlmd, parent_port);
unlock:
device_unlock(&parent_port->dev);
put_device(&parent_port->dev);
if (rc)
return rc;
/*
* The kernel may be operating out of CXL memory on this device,
* there is no spec defined way to determine whether this device
* preserves contents over suspend, and there is no simple way
* to arrange for the suspend image to avoid CXL memory which
* would setup a circular dependency between PCI resume and save
* state restoration.
*
* TODO: support suspend when all the regions this device is
* hosting are locked and covered by the system address map,
* i.e. platform firmware owns restoring the HDM configuration
* that it locked.
*/
cxl_mem_active_inc();
return devm_add_action_or_reset(dev, enable_suspend, NULL);
}
static struct cxl_driver cxl_mem_driver = {
.name = "cxl_mem",
.probe = cxl_mem_probe,
.id = CXL_DEVICE_MEMORY_EXPANDER,
};
module_cxl_driver(cxl_mem_driver);
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(CXL);
MODULE_ALIAS_CXL(CXL_DEVICE_MEMORY_EXPANDER);
/*
* create_endpoint() wants to validate port driver attach immediately after
* endpoint registration.
*/
MODULE_SOFTDEP("pre: cxl_port");
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