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From:   Orson Zhai <orsonzhai@gmail.com>
To:     Jonathan Corbet <corbet@lwn.net>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        Joe Perches <joe@perches.com>,
        Denis Efremov <efremov@linux.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Sourabh Jain <sourabhjain@linux.ibm.com>
Cc:     Orson Zhai <orson.zhai@unisoc.com>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Orson Zhai <orsonzhai@gmail.com>
Subject: [PATCH] include: sysfs: Add macro to assign show for RO attributes
Date:   Wed, 27 Jan 2021 12:19:22 +0800
Message-Id: <1611721162-29982-1-git-send-email-orsonzhai@gmail.com>
Precedence: bulk

In some circumstances, multiple __ATTR_RO attributes need to be assigned
with a single show function.

Add this macro to make life easier with simple code.

Signed-off-by: Orson Zhai <orsonzhai@gmail.com>
---
 Documentation/filesystems/sysfs.rst | 2 ++
 include/linux/sysfs.h               | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/Documentation/filesystems/sysfs.rst b/Documentation/filesystems/sysfs.rst
index 004d490..0e2274a 100644
--- a/Documentation/filesystems/sysfs.rst
+++ b/Documentation/filesystems/sysfs.rst
@@ -141,6 +141,8 @@ __ATTR_RO_MODE(name, mode):
 	         fore more restrictive RO access currently
                  only use case is the EFI System Resource Table
                  (see drivers/firmware/efi/esrt.c)
+__ATTR_RO_SHOW(name, show):
+		 assumes default mode 0444 with specified show.
 __ATTR_RW(name):
 	         assumes default name_show, name_store and setting
                  mode to 0644.
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 2caa34c..c851592 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -117,6 +117,11 @@ struct attribute_group {
 	.show	= _name##_show,						\
 }
 
+#define __ATTR_RO_SHOW(_name, _show) {					\
+	.attr	= { .name = __stringify(_name), .mode = 0444 },		\
+	.show	= _show,						\
+}
+
 #define __ATTR_RO_MODE(_name, _mode) {					\
 	.attr	= { .name = __stringify(_name),				\
 		    .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },		\
-- 
2.7.4