i2c-bfin-twi: handle faulty slave devices better
Faulty slave devices might drive SDA low after a transfer finishes. So,
when this scenario is detected, have the master generate up to 9 extra
clocks until the SDA is properly released.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
index fb26e5c..1ee9d5a 100644
--- a/drivers/i2c/busses/i2c-bfin-twi.c
+++ b/drivers/i2c/busses/i2c-bfin-twi.c
@@ -20,6 +20,7 @@
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
+#include <linux/delay.h>
#include <asm/blackfin.h>
#include <asm/portmux.h>
@@ -159,6 +160,27 @@
if (mast_stat & BUFWRERR)
dev_dbg(&iface->adap.dev, "Buffer Write Error\n");
+ /* Faulty slave devices, may drive SDA low after a transfer
+ * finishes. To release the bus this code generates up to 9
+ * extra clocks until SDA is released.
+ */
+
+ if (read_MASTER_STAT(iface) & SDASEN) {
+ int cnt = 9;
+ do {
+ write_MASTER_CTL(iface, SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ udelay(6);
+ } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--);
+
+ write_MASTER_CTL(iface, SDAOVR | SCLOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, SDAOVR);
+ udelay(6);
+ write_MASTER_CTL(iface, 0);
+ }
+
/* If it is a quick transfer, only address without data,
* not an err, return 1.
*/