i2c: at91: fix crash when using 'i2c probe'
When issuing 'i2c probe', the driver was crashing, because at probe
there is a request with zero length buffer to write to i2c bus.
The xfer_msg function assumes the buffer is always there, and never
checks for the buffer length.
=> i2c dev 0
Setting bus to 0
=> i2c probe
Valid chip addresses:
data abort
pc : [<7ffa97dc>] lr : [<7ffa96f8>]
reloc pc : [<66f277dc>] lr : [<66f276f8>]
sp : 7fb7c110 ip : 7ff87a28 fp : 7ff99938
r10: 00000002 r9 : 7fb7dec0 r8 : 00000000
r7 : e181c600 r6 : 7fb88c20 r5 : 00000000 r4 : 7fb7c128
r3 : 00000000 r2 : 00000001 r1 : 00000000 r0 : 00000009
Flags: nZCv IRQs off FIQs off Mode SVC_32
Code: eb0092f4 e1a00005 e8bd81f0 e594300c (e5d33000)
Resetting CPU ...
Fixes: 8800e0fa20 ("i2c: atmel: add i2c driver")
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/drivers/i2c/at91_i2c.c b/drivers/i2c/at91_i2c.c
index aca8de9..6b4c0e4 100644
--- a/drivers/i2c/at91_i2c.c
+++ b/drivers/i2c/at91_i2c.c
@@ -51,6 +51,10 @@
u32 i;
int ret = 0;
+ /* if there is no message to send/receive, just exit quietly */
+ if (msg->len == 0)
+ return ret;
+
readl(®->sr);
if (is_read) {
writel(TWI_CR_START, ®->cr);