[PATCH 13/31] swim: Check for CRC errors

[Finn Thain <fthain@linux-m68k.org>]

After reading either the sector header or sector data, examine that flag
in the handshake register which holds the result of the CRC calculation.
CRC validation has to take place with the last byte still in the FIFO.
This flag can't be checked by the caller because by then all bytes will
have been retrieved from the FIFO. Return an error code when appropriate.

Fixes: 8852ecd97488 ("m68k: mac - Add SWIM floppy support")
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
---
 drivers/block/swim_asm.S | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/block/swim_asm.S b/drivers/block/swim_asm.S
index 31fc63b074dc..f40e19e48021 100644
--- a/drivers/block/swim_asm.S
+++ b/drivers/block/swim_asm.S
@@ -42,6 +42,8 @@
 	.equ	max_retry, 40
 	.equ	sector_size, 512
 
+	.equ	.Lhr_crc_error,		0x02
+
 	.global swim_read_sector_header
 swim_read_sector_header:
 	link	%a6, #0
@@ -128,12 +130,15 @@ crc0:	tstb	%a2@
 
 	moveq	#max_retry, %d2
 
-crc1:	tstb	%a2@
+crc1:	moveb	%a2@, %d5
 	dbmi	%d2, crc1
 	bpl	signal_nonyb
 
 	moveb	%a3@, %a4@(o_crc1)
 
+	andb	#.Lhr_crc_error, %d5
+	bne	signal_nonyb
+
 	tstb	%a3@(read_error - read_mark)
 
 	moveq	#0, %d0
@@ -212,17 +217,20 @@ data_crc0:
 	dbmi	%d2, data_crc0
 	bpl	data_exit
 
-	moveb	%a3@, %d5
+	moveb	%a3@, %d2
 
 	moveq	#max_retry, %d2
 
 data_crc1:
 
-	tstb	%a2@
+	moveb	%a2@, %d5
 	dbmi	%d2, data_crc1
 	bpl	data_exit
 
-	moveb	%a3@, %d5
+	moveb	%a3@, %d2
+
+	andb	#.Lhr_crc_error, %d5
+	bne	data_exit
 
 	tstb	%a3@(read_error - read_mark)
 
-- 
2.52.0