1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
new file mode 100644
index 000000000000..49a4b1c47299
--- /dev/null
+++ b/drivers/cxl/mem.c
@@ -0,0 +1,228 @@
+// 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 wait_for_media(struct cxl_memdev *cxlmd)
+{
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_endpoint_dvsec_info *info = &cxlds->info;
+	int rc;
+
+	if (!info->mem_enabled)
+		return -EBUSY;
+
+	rc = cxlds->wait_media_ready(cxlds);
+	if (rc)
+		return rc;
+
+	/*
+	 * We know the device is active, and enabled, if any ranges are non-zero
+	 * we'll need to check later before adding the port since that owns the
+	 * HDM decoder registers.
+	 */
+	return 0;
+}
+
+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);
+}
+
+/**
+ * cxl_dvsec_decode_init() - Setup HDM decoding for the endpoint
+ * @cxlds: Device state
+ *
+ * Additionally, enables global HDM decoding. Warning: don't call this outside
+ * of probe. Once probe is complete, the port driver owns all access to the HDM
+ * decoder registers.
+ *
+ * Returns: false if DVSEC Ranges are being used instead of HDM
+ * decoders, or if it can not be determined if DVSEC Ranges are in use.
+ * Otherwise, returns true.
+ */
+__mock bool cxl_dvsec_decode_init(struct cxl_dev_state *cxlds)
+{
+	struct cxl_endpoint_dvsec_info *info = &cxlds->info;
+	struct cxl_register_map map;
+	struct cxl_component_reg_map *cmap = &map.component_map;
+	bool global_enable, do_hdm_init = false;
+	void __iomem *crb;
+	u32 global_ctrl;
+
+	/* map hdm decoder */
+	crb = ioremap(cxlds->component_reg_phys, CXL_COMPONENT_REG_BLOCK_SIZE);
+	if (!crb) {
+		dev_dbg(cxlds->dev, "Failed to map component registers\n");
+		return false;
+	}
+
+	cxl_probe_component_regs(cxlds->dev, crb, cmap);
+	if (!cmap->hdm_decoder.valid) {
+		dev_dbg(cxlds->dev, "Invalid HDM decoder registers\n");
+		goto out;
+	}
+
+	global_ctrl = readl(crb + cmap->hdm_decoder.offset +
+			    CXL_HDM_DECODER_CTRL_OFFSET);
+	global_enable = global_ctrl & CXL_HDM_DECODER_ENABLE;
+	if (!global_enable && info->ranges) {
+		dev_dbg(cxlds->dev,
+			"DVSEC ranges already programmed and HDM decoders not enabled.\n");
+		goto out;
+	}
+
+	do_hdm_init = true;
+
+	/*
+	 * Permanently (for this boot at least) opt the device into HDM
+	 * operation. Individual HDM decoders still need to be enabled after
+	 * this point.
+	 */
+	if (!global_enable) {
+		dev_dbg(cxlds->dev, "Enabling HDM decode\n");
+		writel(global_ctrl | CXL_HDM_DECODER_ENABLE,
+		       crb + cmap->hdm_decoder.offset +
+			       CXL_HDM_DECODER_CTRL_OFFSET);
+	}
+
+out:
+	iounmap(crb);
+	return do_hdm_init;
+}
+
+static int cxl_mem_probe(struct device *dev)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	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 = wait_for_media(cxlmd);
+	if (rc) {
+		dev_err(dev, "Media not active (%d)\n", rc);
+		return rc;
+	}
+
+	/*
+	 * If DVSEC ranges are being used instead of HDM decoder registers there
+	 * is no use in trying to manage those.
+	 */
+	if (!cxl_dvsec_decode_init(cxlds)) {
+		struct cxl_endpoint_dvsec_info *info = &cxlds->info;
+		int i;
+
+		/* */
+		for (i = 0; i < 2; i++) {
+			u64 base, size;
+
+			/*
+			 * Give a nice warning to the user that BIOS has really
+			 * botched things for them if it didn't place DVSEC
+			 * ranges in the memory map.
+			 */
+			base = info->dvsec_range[i].start;
+			size = range_len(&info->dvsec_range[i]);
+			if (size && !region_intersects(base, size,
+						       IORESOURCE_SYSTEM_RAM,
+						       IORES_DESC_NONE)) {
+				dev_err(dev,
+					"DVSEC range %#llx-%#llx must be reserved by BIOS, but isn't\n",
+					base, base + size - 1);
+			}
+		}
+		dev_err(dev,
+			"Active DVSEC range registers in use. Will not bind.\n");
+		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;
+	}
+
+	cxl_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 out;
+	}
+
+	rc = create_endpoint(cxlmd, parent_port);
+out:
+	cxl_device_unlock(&parent_port->dev);
+	put_device(&parent_port->dev);
+	return rc;
+}
+
+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");