mlxsw: item: Annotate item helpers with '__maybe_unused'

mlxsw is using helpers to get / set fields in messages exchanged with
the device. It is possible that some fields are only set or only get.
This causes LLVM to emit warnings such as the following when building
with W=1 [1]:

drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c:2022:1: warning: unused function 'mlxsw_afa_sampler_mirror_agent_get'

The fact that some fields are only set or only get is very much
intentional and not indicative of functions that need to be removed.

Therefore, annotate the item helpers with '__maybe_unused' to suppress
these warnings.

[1] https://lkml.org/lkml/2021/9/29/685

Cc: Nathan Chancellor <nathan@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20211008132315.90211-1-idosch@idosch.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlxsw/item.h

@@ -270,11 +270,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u8 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)	\
+static inline u8 __maybe_unused							\
+mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)			\
 {										\
 	return __mlxsw_item_get8(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }										\
-static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u8 val)\
+static inline void __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u8 val)			\
 {										\
 	__mlxsw_item_set8(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val);	\
 }
@@ -290,13 +292,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u8								\
+static inline u8 __maybe_unused							\
 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
 {										\
 	return __mlxsw_item_get8(buf, &__ITEM_NAME(_type, _cname, _iname),	\
 				 index);					\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index,	\
 					  u8 val)				\
 {										\
@@ -311,11 +313,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u16 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)	\
+static inline u16 __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)			\
 {										\
 	return __mlxsw_item_get16(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }										\
-static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 val)\
+static inline void __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 val)			\
 {										\
 	__mlxsw_item_set16(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val);	\
 }
@@ -331,13 +335,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u16								\
+static inline u16 __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
 {										\
 	return __mlxsw_item_get16(buf, &__ITEM_NAME(_type, _cname, _iname),	\
 				  index);					\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index,	\
 					  u16 val)				\
 {										\
@@ -352,11 +356,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u32 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)	\
+static inline u32 __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)			\
 {										\
 	return __mlxsw_item_get32(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }										\
-static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u32 val)\
+static inline void __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u32 val)			\
 {										\
 	__mlxsw_item_set32(buf, &__ITEM_NAME(_type, _cname, _iname), 0, val);	\
 }
@@ -372,13 +378,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u32								\
+static inline u32 __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
 {										\
 	return __mlxsw_item_get32(buf, &__ITEM_NAME(_type, _cname, _iname),	\
 				  index);					\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index,	\
 					  u32 val)				\
 {										\
@@ -393,11 +399,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u64 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)	\
+static inline u64 __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf)			\
 {										\
 	return __mlxsw_item_get64(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }										\
-static inline void mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u64 val)\
+static inline void __maybe_unused						\
+mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u64 val)			\
 {										\
 	__mlxsw_item_set64(buf, &__ITEM_NAME(_type, _cname, _iname), 0,	val);	\
 }
@@ -413,13 +421,13 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bits = _sizebits,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u64								\
+static inline u64 __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, unsigned short index)\
 {										\
 	return __mlxsw_item_get64(buf, &__ITEM_NAME(_type, _cname, _iname),	\
 				  index);					\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, unsigned short index,	\
 					  u64 val)				\
 {										\
@@ -433,19 +441,19 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bytes = _sizebytes,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf, char *dst)	\
 {										\
 	__mlxsw_item_memcpy_from(buf, dst,					\
 				 &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf, const char *src)	\
 {										\
 	__mlxsw_item_memcpy_to(buf, src,					\
 			       &__ITEM_NAME(_type, _cname, _iname), 0);		\
 }										\
-static inline char *								\
+static inline char * __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_data(char *buf)				\
 {										\
 	return __mlxsw_item_data(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
@@ -460,7 +468,7 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bytes = _sizebytes,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf,		\
 						  unsigned short index,		\
 						  char *dst)			\
@@ -468,7 +476,7 @@ mlxsw_##_type##_##_cname##_##_iname##_memcpy_from(const char *buf,		\
 	__mlxsw_item_memcpy_from(buf, dst,					\
 				 &__ITEM_NAME(_type, _cname, _iname), index);	\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf,			\
 						unsigned short index,		\
 						const char *src)		\
@@ -476,7 +484,7 @@ mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf,			\
 	__mlxsw_item_memcpy_to(buf, src,					\
 			       &__ITEM_NAME(_type, _cname, _iname), index);	\
 }										\
-static inline char *								\
+static inline char * __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_data(char *buf, unsigned short index)	\
 {										\
 	return __mlxsw_item_data(buf,						\
@@ -491,14 +499,14 @@ static struct mlxsw_item __ITEM_NAME(_type, _cname, _iname) = {			\
 	.size = {.bytes = _sizebytes,},						\
 	.name = #_type "_" #_cname "_" #_iname,					\
 };										\
-static inline u8								\
+static inline u8 __maybe_unused							\
 mlxsw_##_type##_##_cname##_##_iname##_get(const char *buf, u16 index)		\
 {										\
 	return __mlxsw_item_bit_array_get(buf,					\
 					  &__ITEM_NAME(_type, _cname, _iname),	\
 					  index);				\
 }										\
-static inline void								\
+static inline void __maybe_unused						\
 mlxsw_##_type##_##_cname##_##_iname##_set(char *buf, u16 index, u8 val)		\
 {										\
 	return __mlxsw_item_bit_array_set(buf,					\