[PATCH v8 1/9] cxl: Add FWCTL support to CXL

[Dave Jiang <dave.jiang@intel.com>]

Add fwctl support code to allow sending of CXL feature commands from
userspace through as ioctls via FWCTL. Provide initial setup bits. The
CXL PCI probe function will call devm_cxl_setup_fwctl() after the
cxl_memdev has been enumerated in order to setup FWCTL char device under
the cxl_memdev like the existing memdev char device for issuing CXL raw
mailbox commands from userspace via ioctls.

Link: https://patch.msgid.link/r/20250220194438.2281088-8-dave.jiang@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/cxl/Kconfig          |  1 +
 drivers/cxl/core/features.c  | 74 ++++++++++++++++++++++++++++++++++++
 drivers/cxl/pci.c            |  4 ++
 include/cxl/features.h       | 10 +++++
 include/uapi/fwctl/fwctl.h   |  1 +
 tools/testing/cxl/test/mem.c |  4 ++
 6 files changed, 94 insertions(+)

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index ad2e796e4ac6..2b6e662c89bf 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -105,6 +105,7 @@ config CXL_MEM
 config CXL_FEATURES
 	bool "CXL: Features"
 	depends on CXL_PCI
+	select FWCTL
 	help
 	  Enable support for CXL Features. A CXL device that includes a mailbox
 	  supports commands that allows listing, getting, and setting of
diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index 048ba4fc3538..846de3294a5e 100644
--- a/drivers/cxl/core/features.c
+++ b/drivers/cxl/core/features.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+#include <linux/fwctl.h>
 #include <linux/device.h>
 #include <cxl/mailbox.h>
 #include <cxl/features.h>
@@ -331,3 +332,76 @@ int cxl_set_feature(struct cxl_mailbox *cxl_mbox,
 		}
 	} while (true);
 }
+
+/* FWCTL support */
+
+static inline struct cxl_memdev *fwctl_to_memdev(struct fwctl_device *fwctl_dev)
+{
+	return to_cxl_memdev(fwctl_dev->dev.parent);
+}
+
+static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
+{
+	return 0;
+}
+
+static void cxlctl_close_uctx(struct fwctl_uctx *uctx)
+{
+}
+
+static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
+			   void *in, size_t in_len, size_t *out_len)
+{
+	/* Place holder */
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static const struct fwctl_ops cxlctl_ops = {
+	.device_type = FWCTL_DEVICE_TYPE_CXL,
+	.uctx_size = sizeof(struct fwctl_uctx),
+	.open_uctx = cxlctl_open_uctx,
+	.close_uctx = cxlctl_close_uctx,
+	.fw_rpc = cxlctl_fw_rpc,
+};
+
+DEFINE_FREE(free_fwctl_dev, struct fwctl_device *, if (_T) fwctl_put(_T))
+
+static void free_memdev_fwctl(void *_fwctl_dev)
+{
+	struct fwctl_device *fwctl_dev = _fwctl_dev;
+
+	fwctl_unregister(fwctl_dev);
+	fwctl_put(fwctl_dev);
+}
+
+int devm_cxl_setup_fwctl(struct cxl_memdev *cxlmd)
+{
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_features_state *cxlfs;
+	int rc;
+
+	cxlfs = to_cxlfs(cxlds);
+	if (!cxlfs)
+		return -ENODEV;
+
+	/* No need to setup FWCTL if there are no user allowed features found */
+	if (!cxlfs->entries->num_user_features)
+		return -ENODEV;
+
+	struct fwctl_device *fwctl_dev __free(free_fwctl_dev) =
+		_fwctl_alloc_device(&cxlmd->dev, &cxlctl_ops, sizeof(*fwctl_dev));
+	if (!fwctl_dev)
+		return -ENOMEM;
+
+	rc = fwctl_register(fwctl_dev);
+	if (rc)
+		return rc;
+
+	cxlfs->fwctl_dev = fwctl_dev;
+
+	return devm_add_action_or_reset(&cxlmd->dev, free_memdev_fwctl,
+					no_free_ptr(fwctl_dev));
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_fwctl, "CXL");
+
+MODULE_IMPORT_NS("FWCTL");
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 3e666ec51580..993fa60fe453 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -1013,6 +1013,10 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		return rc;
 
+	rc = devm_cxl_setup_fwctl(cxlmd);
+	if (rc)
+		dev_dbg(&pdev->dev, "No CXL FWCTL setup\n");
+
 	pmu_count = cxl_count_regblock(pdev, CXL_REGLOC_RBI_PMU);
 	if (pmu_count < 0)
 		return pmu_count;
diff --git a/include/cxl/features.h b/include/cxl/features.h
index d2cde46b0fec..fce3c2dbde5a 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -4,6 +4,7 @@
 #define __CXL_FEATURES_H__
 
 #include <linux/uuid.h>
+#include <linux/fwctl.h>
 
 /* Feature UUIDs used by the kernel */
 #define CXL_FEAT_PATROL_SCRUB_UUID						\
@@ -162,6 +163,7 @@ enum cxl_set_feat_flag_data_transfer {
  * @entries: CXl feature entry context
  *	@num_features: total Features supported by the device
  *	@ent: Flex array of Feature detail entries from the device
+ * @fwctl_dev: Firmware Control device
  */
 struct cxl_features_state {
 	struct cxl_dev_state *cxlds;
@@ -170,12 +172,15 @@ struct cxl_features_state {
 		int num_user_features;
 		struct cxl_feat_entry ent[] __counted_by(num_features);
 	} *entries;
+	struct fwctl_device *fwctl_dev;
 };
 
 struct cxl_mailbox;
+struct cxl_memdev;
 #ifdef CONFIG_CXL_FEATURES
 inline struct cxl_features_state *to_cxlfs(struct cxl_dev_state *cxlds);
 int devm_cxl_setup_features(struct cxl_dev_state *cxlds);
+int devm_cxl_setup_fwctl(struct cxl_memdev *cxlmd);
 #else
 static inline struct cxl_features_state *to_cxlfs(struct cxl_dev_state *cxlds)
 {
@@ -186,6 +191,11 @@ static inline int devm_cxl_setup_features(struct cxl_dev_state *cxlds)
 {
 	return -EOPNOTSUPP;
 }
+
+static inline int devm_cxl_setup_fwctl(struct cxl_memdev *cxlmd)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #endif
diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h
index 584a5ea8ecee..c2d5abc5a726 100644
--- a/include/uapi/fwctl/fwctl.h
+++ b/include/uapi/fwctl/fwctl.h
@@ -43,6 +43,7 @@ enum {
 enum fwctl_device_type {
 	FWCTL_DEVICE_TYPE_ERROR = 0,
 	FWCTL_DEVICE_TYPE_MLX5 = 1,
+	FWCTL_DEVICE_TYPE_CXL = 2,
 };
 
 /**
diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 4809a90ff9b6..848db399102c 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -1646,6 +1646,10 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
+	rc = devm_cxl_setup_fwctl(cxlmd);
+	if (rc)
+		dev_dbg(dev, "No CXL FWCTL setup\n");
+
 	cxl_mem_get_event_records(mds, CXLDEV_EVENT_STATUS_ALL);
 
 	return 0;
-- 
2.48.1