[PATCH v2 2/6] gpiolib: add support for pull up/down to lineevent_create

[Kent Gibson <warthog618@xxxxxxxxx>]

This patch adds support for pull up/down to lineevent_create.
Use cases include receiving asynchronous presses from a
push button without an external pull up/down.

Move all the flags sanitization before any memory allocation in
lineevent_create() in order to remove a couple unneeded gotos.
(from Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>)

Signed-off-by: Kent Gibson <warthog618@xxxxxxxxx>
---
 drivers/gpio/gpiolib.c | 60 +++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 24 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9d2a5e2f6e77..053847b6187f 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -905,6 +905,38 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
 		return -EFAULT;
 
+	offset = eventreq.lineoffset;
+	lflags = eventreq.handleflags;
+	eflags = eventreq.eventflags;
+
+	if (offset >= gdev->ngpio)
+		return -EINVAL;
+
+	/* Return an error if a unknown flag is set */
+	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
+	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
+		return -EINVAL;
+
+	/* This is just wrong: we don't look for events on output lines */
+	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
+	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
+	    (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;
+
+	/*
+	 * Do not allow both pull-up and pull-down flags to be set as they
+	 *  are contradictory.
+	 */
+	if ((lflags & GPIOHANDLE_REQUEST_PULL_UP) &&
+	    (lflags & GPIOHANDLE_REQUEST_PULL_DOWN))
+		return -EINVAL;
+
 	le = kzalloc(sizeof(*le), GFP_KERNEL);
 	if (!le)
 		return -ENOMEM;
@@ -922,30 +954,6 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 		}
 	}
 
-	offset = eventreq.lineoffset;
-	lflags = eventreq.handleflags;
-	eflags = eventreq.eventflags;
-
-	if (offset >= gdev->ngpio) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
-	/* Return an error if a unknown flag is set */
-	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
-	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
-	/* This is just wrong: we don't look for events on output lines */
-	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
-	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
-	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
 	desc = &gdev->descs[offset];
 	ret = gpiod_request(desc, le->label);
 	if (ret)
@@ -955,6 +963,10 @@ 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 & GPIOHANDLE_REQUEST_PULL_DOWN)
+		set_bit(FLAG_PULL_DOWN, &desc->flags);
+	if (lflags & GPIOHANDLE_REQUEST_PULL_UP)
+		set_bit(FLAG_PULL_UP, &desc->flags);
 
 	ret = gpiod_direction_input(desc);
 	if (ret)
-- 
2.23.0