1 files changed, 140 insertions, 0 deletions
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
new file mode 100644
index 000000000000..8365839856dc
--- /dev/null
+++ b/drivers/cxl/pmem.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
+#include <linux/libnvdimm.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "cxl.h"
+
+/*
+ * Ordered workqueue for cxl nvdimm device arrival and departure
+ * to coordinate bus rescans when a bridge arrives and trigger remove
+ * operations when the bridge is removed.
+ */
+static struct workqueue_struct *cxl_pmem_wq;
+
+static int cxl_pmem_ctl(struct nvdimm_bus_descriptor *nd_desc,
+			struct nvdimm *nvdimm, unsigned int cmd, void *buf,
+			unsigned int buf_len, int *cmd_rc)
+{
+	return -ENOTTY;
+}
+
+static bool online_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb)
+{
+	if (cxl_nvb->nvdimm_bus)
+		return true;
+	cxl_nvb->nvdimm_bus =
+		nvdimm_bus_register(&cxl_nvb->dev, &cxl_nvb->nd_desc);
+	return cxl_nvb->nvdimm_bus != NULL;
+}
+
+static void offline_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb)
+{
+	if (!cxl_nvb->nvdimm_bus)
+		return;
+	nvdimm_bus_unregister(cxl_nvb->nvdimm_bus);
+	cxl_nvb->nvdimm_bus = NULL;
+}
+
+static void cxl_nvb_update_state(struct work_struct *work)
+{
+	struct cxl_nvdimm_bridge *cxl_nvb =
+		container_of(work, typeof(*cxl_nvb), state_work);
+	bool release = false;
+
+	device_lock(&cxl_nvb->dev);
+	switch (cxl_nvb->state) {
+	case CXL_NVB_ONLINE:
+		if (!online_nvdimm_bus(cxl_nvb)) {
+			dev_err(&cxl_nvb->dev,
+				"failed to establish nvdimm bus\n");
+			release = true;
+		}
+		break;
+	case CXL_NVB_OFFLINE:
+	case CXL_NVB_DEAD:
+		offline_nvdimm_bus(cxl_nvb);
+		break;
+	default:
+		break;
+	}
+	device_unlock(&cxl_nvb->dev);
+
+	if (release)
+		device_release_driver(&cxl_nvb->dev);
+
+	put_device(&cxl_nvb->dev);
+}
+
+static void cxl_nvdimm_bridge_remove(struct device *dev)
+{
+	struct cxl_nvdimm_bridge *cxl_nvb = to_cxl_nvdimm_bridge(dev);
+
+	if (cxl_nvb->state == CXL_NVB_ONLINE)
+		cxl_nvb->state = CXL_NVB_OFFLINE;
+	if (queue_work(cxl_pmem_wq, &cxl_nvb->state_work))
+		get_device(&cxl_nvb->dev);
+}
+
+static int cxl_nvdimm_bridge_probe(struct device *dev)
+{
+	struct cxl_nvdimm_bridge *cxl_nvb = to_cxl_nvdimm_bridge(dev);
+
+	if (cxl_nvb->state == CXL_NVB_DEAD)
+		return -ENXIO;
+
+	if (cxl_nvb->state == CXL_NVB_NEW) {
+		cxl_nvb->nd_desc = (struct nvdimm_bus_descriptor) {
+			.provider_name = "CXL",
+			.module = THIS_MODULE,
+			.ndctl = cxl_pmem_ctl,
+		};
+
+		INIT_WORK(&cxl_nvb->state_work, cxl_nvb_update_state);
+	}
+
+	cxl_nvb->state = CXL_NVB_ONLINE;
+	if (queue_work(cxl_pmem_wq, &cxl_nvb->state_work))
+		get_device(&cxl_nvb->dev);
+
+	return 0;
+}
+
+static struct cxl_driver cxl_nvdimm_bridge_driver = {
+	.name = "cxl_nvdimm_bridge",
+	.probe = cxl_nvdimm_bridge_probe,
+	.remove = cxl_nvdimm_bridge_remove,
+	.id = CXL_DEVICE_NVDIMM_BRIDGE,
+};
+
+static __init int cxl_pmem_init(void)
+{
+	int rc;
+
+	cxl_pmem_wq = alloc_ordered_workqueue("cxl_pmem", 0);
+	if (!cxl_pmem_wq)
+		return -ENXIO;
+
+	rc = cxl_driver_register(&cxl_nvdimm_bridge_driver);
+	if (rc)
+		goto err;
+
+	return 0;
+
+err:
+	destroy_workqueue(cxl_pmem_wq);
+	return rc;
+}
+
+static __exit void cxl_pmem_exit(void)
+{
+	cxl_driver_unregister(&cxl_nvdimm_bridge_driver);
+	destroy_workqueue(cxl_pmem_wq);
+}
+
+MODULE_LICENSE("GPL v2");
+module_init(cxl_pmem_init);
+module_exit(cxl_pmem_exit);
+MODULE_IMPORT_NS(CXL);
+MODULE_ALIAS_CXL(CXL_DEVICE_NVDIMM_BRIDGE);