| // 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"); |