[PATCH 4.15 058/128] gpiolib: dont allow OPEN_DRAIN & OPEN_SOURCE flags simultaneously

Greg Kroah-Hartman
2018-03-16T15:23:19Z

From: Bartosz Golaszewski <brgl@bgdev.pl>

[ Upstream commit 588fc3bceaf81bbd62e18af6f7bd475e01c2b7e8 ]

Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
the hardware actually supports enabling both at the same time the
electrical result would be disastrous.

Suggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpio/gpiolib.c | 9 +++++++++
1 file changed, 9 insertions(+)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -460,6 +460,15 @@ static int linehandle_create(struct gpio
if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
return -EINVAL;

+ /*
+ * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
+ * the hardware actually supports enabling both at the same time the
+ * electrical result would be disastrous.
+ */
+ if ((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) &&
+ (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
+ return -EINVAL;
+
/* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */
if (!(lflags & GPIOHANDLE_REQUEST_OUTPUT) &&
((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||