[PATCH 3/5] gpiolib: pull requires explicit input mode

[Kent Gibson <warthog618@gmail.com>]

This patch prevents pull up/down flags being applied to as-is line
requests, which should be left as-is, and for output mode for which
setting pulls is not currently supported.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/gpiolib.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 0912a00b2960..a634c340920b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -559,6 +559,12 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	     (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
 		return -EINVAL;
 
+	/* PULL_UP and PULL_DOWN flags only make sense for input mode. */
+	if (!(lflags & GPIOHANDLE_REQUEST_INPUT) &&
+	    ((lflags & GPIOHANDLE_REQUEST_PULL_UP) ||
+	     (lflags & GPIOHANDLE_REQUEST_PULL_DOWN)))
+		return -EINVAL;
+
 	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
 	if (!lh)
 		return -ENOMEM;
-- 
2.23.0