mlxsw: item: Add helpers for getting pointer into payload for char buffer item

Sometimes it is handy to get a pointer to a char buffer item and use it
direcly to write/read data. So add these helpers.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -225,6 +225,14 @@ static inline void __mlxsw_item_memcpy_to(char *buf, const char *src,
 	memcpy(&buf[offset], src, item->size.bytes);
 }
 
+static inline char *__mlxsw_item_data(char *buf, const struct mlxsw_item *item,
+				      unsigned short index)
+{
+	unsigned int offset = __mlxsw_item_offset(item, index, sizeof(char));
+
+	return &buf[offset];
+}
+
 static inline u16
 __mlxsw_item_bit_array_offset(const struct mlxsw_item *item,
 			      u16 index, u8 *shift)
@@ -468,6 +476,11 @@ 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 *								\
+mlxsw_##_type##_##_cname##_##_iname##_data(char *buf)				\
+{										\
+	return __mlxsw_item_data(buf, &__ITEM_NAME(_type, _cname, _iname), 0);	\
 }
 
 #define MLXSW_ITEM_BUF_INDEXED(_type, _cname, _iname, _offset, _sizebytes,	\
@@ -494,6 +507,12 @@ mlxsw_##_type##_##_cname##_##_iname##_memcpy_to(char *buf,			\
 {										\
 	__mlxsw_item_memcpy_to(buf, src,					\
 			       &__ITEM_NAME(_type, _cname, _iname), index);	\
+}										\
+static inline char *								\
+mlxsw_##_type##_##_cname##_##_iname##_data(char *buf, unsigned short index)	\
+{										\
+	return __mlxsw_item_data(buf,						\
+				 &__ITEM_NAME(_type, _cname, _iname), index);	\
 }
 
 #define MLXSW_ITEM_BIT_ARRAY(_type, _cname, _iname, _offset, _sizebytes,	\