Re: [RFC] gpio: expose pull-up/pull-down line flags to userspace

[Drew Fustini <drew@xxxxxxxx>]

set pull-up/down flags in lineevent_create and add sanity checks

Check the pull-up/down flags in lineevent_create() and set the
corresponding bits.

Add sanity checks to make pull-up and pull-down flags mutually
exclusive and only valid when the line is an input.

Signed-off-by: Drew Fustini <drew@xxxxxxxx>
---
 drivers/gpio/gpiolib.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 646ae4cffe26..babc26267561 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -554,6 +554,20 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	     (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
 		return -EINVAL;
 
+	/*
+	 * Do not allow PULL_UP & PULL_DOWN flags to be set as they are
+	 * contradictory.
+	 */
+	if ((lflags & GPIOHANDLE_REQUEST_PULL_UP) &&
+	    (lflags & GPIOHANDLE_REQUEST_PULL_DOWN))
+		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;
@@ -941,6 +955,24 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 		goto out_free_label;
 	}
 
+	/*
+	 * Do not allow PULL_UP & PULL_DOWN flags to be set as they are
+	 * contradictory.
+	 */
+	if ((lflags & GPIOHANDLE_REQUEST_PULL_UP) &&
+	    (lflags & GPIOHANDLE_REQUEST_PULL_DOWN)) {
+		ret = -EINVAL;
+		goto out_free_label;
+	}
+
+	/* 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))) {
+		ret = -EINVAL;
+		goto out_free_label;
+	}
+
 	desc = &gdev->descs[offset];
 	ret = gpiod_request(desc, le->label);
 	if (ret)
@@ -950,6 +982,10 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 
 	if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW)
 		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+	if (lflags & GPIO_PULL_UP)
+		set_bit(FLAG_PULL_UP, &desc->flags);
+	else if (lflags & GPIO_PULL_DOWN)
+		set_bit(FLAG_PULL_DOWN, &desc->flags);
 
 	ret = gpiod_direction_input(desc);
 	if (ret)
-- 
2.20.1