[PATCH v2 09/16] cxl: Add support for FWCTL get driver information callback

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

Add definition for fwctl_ops->info() to return driver information. The
function will return a data structure with a reserved u32. This is setup
for future usages.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Set command_info to reserved. (Dan)
---
 drivers/cxl/fwctl.c      | 18 ++++++++++++++++--
 include/cxl/mailbox.h    |  1 +
 include/uapi/fwctl/cxl.h | 19 +++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 include/uapi/fwctl/cxl.h

diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
index d8fd68ac8982..b7984c98645c 100644
--- a/drivers/cxl/fwctl.c
+++ b/drivers/cxl/fwctl.c
@@ -6,6 +6,8 @@
 #include "cxlmem.h"
 #include "features.h"
 
+#define to_cxl_features_state(fwctl) container_of(fwctl, struct cxl_features_state, fwctl)
+
 static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
 {
 	return 0;
@@ -17,8 +19,20 @@ 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);
+	struct fwctl_device *fwctl = uctx->fwctl;
+	struct cxl_features_state *cxlfs = to_cxl_features_state(fwctl);
+	struct fwctl_info_cxl *info;
+
+	if (!cxlfs->num_user_features)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	*length = sizeof(*info);
+
+	return info;
 }
 
 static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h
index 99d3bbe1ba2a..bbbbff3af61f 100644
--- a/include/cxl/mailbox.h
+++ b/include/cxl/mailbox.h
@@ -4,6 +4,7 @@
 #define __CXL_MBOX_H__
 #include <linux/rcuwait.h>
 #include <cxl/features.h>
+#include <uapi/fwctl/cxl.h>
 #include <uapi/linux/cxl_mem.h>
 
 /**
diff --git a/include/uapi/fwctl/cxl.h b/include/uapi/fwctl/cxl.h
new file mode 100644
index 000000000000..4e766ffb1388
--- /dev/null
+++ b/include/uapi/fwctl/cxl.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2024, Intel Corporation
+ *
+ * These are definitions for the mailbox command interface of CXL subsystem.
+ */
+#ifndef _UAPI_FWCTL_CXL_H_
+#define _UAPI_FWCTL_CXL_H_
+
+#include <linux/types.h>
+
+/**
+ * struct fwctl_info_cxl - ioctl(FWCTL_INFO) out_device_data
+ * @reserved: Place older for future usages
+ */
+struct fwctl_info_cxl {
+	__u32 reserved;
+};
+#endif
-- 
2.48.1