[PATCH v4 07/15] 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 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.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/features.c  | 74 ++++++++++++++++++++++++++++++++++++
 drivers/cxl/pci.c            |  4 ++
 include/cxl/features.h       | 14 +++++++
 include/uapi/fwctl/fwctl.h   |  1 +
 tools/testing/cxl/test/mem.c |  4 ++
 5 files changed, 97 insertions(+)

diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index 82f21f64452a..81e8ff66c12e 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>
@@ -167,6 +168,13 @@ static void free_cxlfs(void *_cxlfs)
 
 	cxlds->cxlfs = NULL;
 	kvfree(cxlfs->entries);
+
+	if (cxlfs->cxl_fwctl) {
+		struct cxl_fwctl *fwctl = cxlfs->cxl_fwctl;
+
+		fwctl_unregister(&fwctl->fwctl_dev);
+		fwctl_put(&fwctl->fwctl_dev);
+	}
 	kfree(cxlfs);
 }
 
@@ -334,3 +342,69 @@ int cxl_set_feature(struct cxl_mailbox *cxl_mbox,
 	} while (true);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_set_feature, "CXL");
+
+static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
+{
+	return 0;
+}
+
+static void cxlctl_close_uctx(struct fwctl_uctx *uctx)
+{
+}
+
+static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
+{
+	/* Place holder */
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+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,
+	.info = cxlctl_info,
+	.fw_rpc = cxlctl_fw_rpc,
+};
+
+DEFINE_FREE(free_fwctl, struct cxl_fwctl *, if (_T) fwctl_put(&_T->fwctl_dev))
+
+int 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 cxl_fwctl *fwctl __free(free_fwctl) =
+		fwctl_alloc_device(&cxlmd->dev, &cxlctl_ops,
+				   struct cxl_fwctl, fwctl_dev);
+	if (!fwctl)
+		return -ENOMEM;
+
+	fwctl->cxlmd = cxlmd;
+	rc = fwctl_register(&fwctl->fwctl_dev);
+	if (rc)
+		return rc;
+
+	cxlfs->cxl_fwctl = no_free_ptr(fwctl);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_setup_fwctl, "CXL");
+
+MODULE_IMPORT_NS("FWCTL");
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 3e666ec51580..b093cb16de3e 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 = 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 1ab97e676c03..d0c94756e452 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						\
@@ -158,6 +159,9 @@ 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: CXL Firmware Control context
+ *	@fwctl_dev: Firmware Control device
+ *	@cxlfs: Pointer to CXL Features state
  */
 struct cxl_features_state {
 	struct cxl_dev_state *cxlds;
@@ -166,12 +170,17 @@ struct cxl_features_state {
 		int num_user_features;
 		struct cxl_feat_entry ent[] __counted_by(num_features);
 	} *entries;
+	struct cxl_fwctl {
+		struct fwctl_device fwctl_dev;
+		struct cxl_memdev *cxlmd;
+	} *cxl_fwctl;
 };
 
 struct cxl_mailbox;
 #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 cxl_setup_fwctl(struct cxl_memdev *cxlmd);
 size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 		       enum cxl_get_feat_selection selection,
 		       void *feat_out, size_t feat_out_size, u16 offset,
@@ -190,6 +199,11 @@ static inline int devm_cxl_setup_features(struct cxl_dev_state *cxlds)
 	return -EOPNOTSUPP;
 }
 
+static inline int cxl_setup_fwctl(struct cxl_memdev *cxlmd)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox,
 				     const uuid_t *feat_uuid,
 				     enum cxl_get_feat_selection selection,
diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h
index 518f054f02d2..f57f6d86b12f 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,
 	FWCTL_DEVICE_TYPE_BNXT = 3,
 };
 
diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 4809a90ff9b6..53ae16282541 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 = 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