1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Copyright(c) 2022 Intel Corporation. All rights reserved. */ 3 #include <linux/debugfs.h> 4 #include <linux/device.h> 5 #include <linux/module.h> 6 #include <linux/pci.h> 7 8 #include "cxlmem.h" 9 #include "cxlpci.h" 10 11 /** 12 * DOC: cxl mem 13 * 14 * CXL memory endpoint devices and switches are CXL capable devices that are 15 * participating in CXL.mem protocol. Their functionality builds on top of the 16 * CXL.io protocol that allows enumerating and configuring components via 17 * standard PCI mechanisms. 18 * 19 * The cxl_mem driver owns kicking off the enumeration of this CXL.mem 20 * capability. With the detection of a CXL capable endpoint, the driver will 21 * walk up to find the platform specific port it is connected to, and determine 22 * if there are intervening switches in the path. If there are switches, a 23 * secondary action is to enumerate those (implemented in cxl_core). Finally the 24 * cxl_mem driver adds the device it is bound to as a CXL endpoint-port for use 25 * in higher level operations. 26 */ 27 28 static void enable_suspend(void *data) 29 { 30 cxl_mem_active_dec(); 31 } 32 33 static void remove_debugfs(void *dentry) 34 { 35 debugfs_remove_recursive(dentry); 36 } 37 38 static int cxl_mem_dpa_show(struct seq_file *file, void *data) 39 { 40 struct device *dev = file->private; 41 struct cxl_memdev *cxlmd = to_cxl_memdev(dev); 42 43 cxl_dpa_debug(file, cxlmd->cxlds); 44 45 return 0; 46 } 47 48 static int cxl_mem_probe(struct device *dev) 49 { 50 struct cxl_memdev *cxlmd = to_cxl_memdev(dev); 51 struct cxl_port *parent_port; 52 struct cxl_dport *dport; 53 struct dentry *dentry; 54 int rc; 55 56 /* 57 * Someone is trying to reattach this device after it lost its port 58 * connection (an endpoint port previously registered by this memdev was 59 * disabled). This racy check is ok because if the port is still gone, 60 * no harm done, and if the port hierarchy comes back it will re-trigger 61 * this probe. Port rescan and memdev detach work share the same 62 * single-threaded workqueue. 63 */ 64 if (work_pending(&cxlmd->detach_work)) 65 return -EBUSY; 66 67 dentry = cxl_debugfs_create_dir(dev_name(dev)); 68 debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show); 69 rc = devm_add_action_or_reset(dev, remove_debugfs, dentry); 70 if (rc) 71 return rc; 72 73 rc = devm_cxl_enumerate_ports(cxlmd); 74 if (rc) 75 return rc; 76 77 parent_port = cxl_mem_find_port(cxlmd, &dport); 78 if (!parent_port) { 79 dev_err(dev, "CXL port topology not found\n"); 80 return -ENXIO; 81 } 82 83 device_lock(&parent_port->dev); 84 if (!parent_port->dev.driver) { 85 dev_err(dev, "CXL port topology %s not enabled\n", 86 dev_name(&parent_port->dev)); 87 rc = -ENXIO; 88 goto unlock; 89 } 90 91 rc = devm_cxl_add_endpoint(cxlmd, dport); 92 unlock: 93 device_unlock(&parent_port->dev); 94 put_device(&parent_port->dev); 95 if (rc) 96 return rc; 97 98 /* 99 * The kernel may be operating out of CXL memory on this device, 100 * there is no spec defined way to determine whether this device 101 * preserves contents over suspend, and there is no simple way 102 * to arrange for the suspend image to avoid CXL memory which 103 * would setup a circular dependency between PCI resume and save 104 * state restoration. 105 * 106 * TODO: support suspend when all the regions this device is 107 * hosting are locked and covered by the system address map, 108 * i.e. platform firmware owns restoring the HDM configuration 109 * that it locked. 110 */ 111 cxl_mem_active_inc(); 112 return devm_add_action_or_reset(dev, enable_suspend, NULL); 113 } 114 115 static struct cxl_driver cxl_mem_driver = { 116 .name = "cxl_mem", 117 .probe = cxl_mem_probe, 118 .id = CXL_DEVICE_MEMORY_EXPANDER, 119 }; 120 121 module_cxl_driver(cxl_mem_driver); 122 123 MODULE_LICENSE("GPL v2"); 124 MODULE_IMPORT_NS(CXL); 125 MODULE_ALIAS_CXL(CXL_DEVICE_MEMORY_EXPANDER); 126 /* 127 * create_endpoint() wants to validate port driver attach immediately after 128 * endpoint registration. 129 */ 130 MODULE_SOFTDEP("pre: cxl_port"); 131