Re: [PATCH v5 08/15] cxl: Add support for FWCTL get driver information callback

[Saeed Mahameed <saeed@kernel.org>]

On 11 Feb 11:28, Dave Jiang wrote:
>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>
>Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>Reviewed-by: Li Ming <ming.li@zohomail.com>
>Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>---
> drivers/cxl/core/features.c | 11 +++++++++--
> include/cxl/mailbox.h       |  1 +
> include/uapi/fwctl/cxl.h    | 19 +++++++++++++++++++
> 3 files changed, 29 insertions(+), 2 deletions(-)
> create mode 100644 include/uapi/fwctl/cxl.h
>
>diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
>index db48a8fbde81..923c054599ad 100644
>--- a/drivers/cxl/core/features.c
>+++ b/drivers/cxl/core/features.c
>@@ -354,8 +354,15 @@ 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_info_cxl *info;
>+
>+	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 c4e99e2e3a9d..60a26a0d8f1f 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..d21fd6b80c20
>--- /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: zero
>+ */
>+struct fwctl_info_cxl {
>+	__u32 reserved;
>+};

I would add some useful info such as: num_user_features, mbox->feature_cap,
etc ...

Maybe if the callback is not implemented by the fwctl driver, then fwctl
subsystem should make sure to return a default info struct or some zero
response buffer.

>+#endif
>-- 
>2.48.1
>
>