asm-generic: introduce be48 unaligned accessors

The NVMe protocol extended the data integrity fields with unaligned
48-bit reference tags. Provide some helper accessors in
preparation for these.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220303201312.3255347-4-kbusch@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/asm-generic/unaligned.h

@@ -126,4 +126,30 @@ static inline void put_unaligned_le24(const u32 val, void *p)
 	__put_unaligned_le24(val, p);
 }
 
+static inline void __put_unaligned_be48(const u64 val, __u8 *p)
+{
+	*p++ = val >> 40;
+	*p++ = val >> 32;
+	*p++ = val >> 24;
+	*p++ = val >> 16;
+	*p++ = val >> 8;
+	*p++ = val;
+}
+
+static inline void put_unaligned_be48(const u64 val, void *p)
+{
+	__put_unaligned_be48(val, p);
+}
+
+static inline u64 __get_unaligned_be48(const u8 *p)
+{
+	return (u64)p[0] << 40 | (u64)p[1] << 32 | p[2] << 24 |
+		p[3] << 16 | p[4] << 8 | p[5];
+}
+
+static inline u64 get_unaligned_be48(const void *p)
+{
+	return __get_unaligned_be48(p);
+}
+
 #endif /* __ASM_GENERIC_UNALIGNED_H */