Blackfin: outs[lwb]: make sure count is greater than 0

Some devices will use the outs* funcs with a length of zero, so make sure
we do not write any data in that case.

Reported-by: Gilbert Inho <gneny@edevice.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/arch/blackfin/lib/outs.S b/arch/blackfin/lib/outs.S
index 250f4d4b9436..06a5e674401f 100644
--- a/arch/blackfin/lib/outs.S
+++ b/arch/blackfin/lib/outs.S
@@ -13,6 +13,8 @@
 .align 2
 
 ENTRY(_outsl)
+        CC = R2 == 0;
+        IF CC JUMP 1f;
         P0 = R0;        /* P0 = port */
         P1 = R1;        /* P1 = address */
         P2 = R2;        /* P2 = count */
@@ -20,10 +22,12 @@ ENTRY(_outsl)
         LSETUP( .Llong_loop_s, .Llong_loop_e) LC0 = P2;
 .Llong_loop_s: R0 = [P1++];
 .Llong_loop_e: [P0] = R0;
-        RTS;
+1:      RTS;
 ENDPROC(_outsl)
 
 ENTRY(_outsw)
+        CC = R2 == 0;
+        IF CC JUMP 1f;
         P0 = R0;        /* P0 = port */
         P1 = R1;        /* P1 = address */
         P2 = R2;        /* P2 = count */
@@ -31,10 +35,12 @@ ENTRY(_outsw)
         LSETUP( .Lword_loop_s, .Lword_loop_e) LC0 = P2;
 .Lword_loop_s: R0 = W[P1++];
 .Lword_loop_e: W[P0] = R0;
-        RTS;
+1:      RTS;
 ENDPROC(_outsw)
 
 ENTRY(_outsb)
+        CC = R2 == 0;
+        IF CC JUMP 1f;
         P0 = R0;        /* P0 = port */
         P1 = R1;        /* P1 = address */
         P2 = R2;        /* P2 = count */
@@ -42,10 +48,12 @@ ENTRY(_outsb)
         LSETUP( .Lbyte_loop_s, .Lbyte_loop_e) LC0 = P2;
 .Lbyte_loop_s: R0 = B[P1++];
 .Lbyte_loop_e: B[P0] = R0;
-        RTS;
+1:      RTS;
 ENDPROC(_outsb)
 
 ENTRY(_outsw_8)
+        CC = R2 == 0;
+        IF CC JUMP 1f;
         P0 = R0;        /* P0 = port */
         P1 = R1;        /* P1 = address */
         P2 = R2;        /* P2 = count */
@@ -56,5 +64,5 @@ ENTRY(_outsw_8)
                 R0 = R0 << 8;
                 R0 = R0 + R1;
 .Lword8_loop_e: W[P0] = R0;
-        RTS;
+1:      RTS;
 ENDPROC(_outsw_8)