[PATCH v6 0/7] gpio: mockup: improve the user-space testing interface

[PATCH v6 0/7] gpio: mockup: improve the user-space testing interface

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Marc,

as discussed. This is hopefully the last version. The irq_set_type()
callback now only accepts edge triggers.

v1 -> v2:
- instead of providing the irq_sim_get_type() helper, move the irq type
  logic into the simulator and provide a helper that allows users to specify
  the type of the fired interrupt

v2 -> v3:
- switch back to having irq_sim_type() and put the line state logic into the
  GPIO testing module

v3 -> v4:
- drop irq_sim_get_type() and use a notifier chain instead so that any change
  in type configuration can be pushed out to interested users
- change the locking mechanism in gpio-mockup to a spinlock as we can't take
  a mutex when a hardirq-safe spinlock in irq_desc is being held when the
  irq_set_type() callback is called
- refuse to set any other type than falling or rising edge in irq_set_config

v4 -> v5:
- drop the notifier, use irqd_set_trigger_type() instead

v5 -> v6:
- same as v5, but we're now validating the trigger type and only allow
  edge triggers

Bartosz Golaszewski (7):
  irq/irq_sim: add irq_set_type() callback
  gpio: mockup: add locking
  gpio: mockup: implement get_multiple()
  gpio: mockup: don't create the debugfs link named after the label
  gpio: mockup: change the type of 'offset' to unsigned int
  gpio: mockup: change the signature of unlocked get/set helpers
  gpio: mockup: rework debugfs interface

 drivers/gpio/gpio-mockup.c | 189 +++++++++++++++++++++++++++++++------
 kernel/irq/irq_sim.c       |  12 +++
 2 files changed, 174 insertions(+), 27 deletions(-)

-- 
2.20.1

[PATCH v6 1/7] irq/irq_sim: add irq_set_type() callback

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Implement the irq_set_type() callback and call irqd_set_trigger_type()
internally so that users interested in the configured trigger type can
later retrieve it using irqd_get_trigger_type(). We only support edge
trigger types.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 kernel/irq/irq_sim.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 98a20e1594ce..b992f88c5613 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -25,10 +25,22 @@ static void irq_sim_irqunmask(struct irq_data *data)
 	irq_ctx->enabled = true;
 }
 
+static int irq_sim_set_type(struct irq_data *data, unsigned int type)
+{
+	/* We only support rising and falling edge trigger types. */
+	if (type & ~IRQ_TYPE_EDGE_BOTH)
+		return -EINVAL;
+
+	irqd_set_trigger_type(data, type);
+
+	return 0;
+}
+
 static struct irq_chip irq_sim_irqchip = {
 	.name		= "irq_sim",
 	.irq_mask	= irq_sim_irqmask,
 	.irq_unmask	= irq_sim_irqunmask,
+	.irq_set_type	= irq_sim_set_type,
 };
 
 static void irq_sim_handle_irq(struct irq_work *work)
-- 
2.20.1

Re: [PATCH v6 1/7] irq/irq_sim: add irq_set_type() callback

[Marc Zyngier]

On Tue, 19 Feb 2019 17:06:44 +0100
Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Implement the irq_set_type() callback and call irqd_set_trigger_type()
> internally so that users interested in the configured trigger type can
> later retrieve it using irqd_get_trigger_type(). We only support edge
> trigger types.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  kernel/irq/irq_sim.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> index 98a20e1594ce..b992f88c5613 100644
> --- a/kernel/irq/irq_sim.c
> +++ b/kernel/irq/irq_sim.c
> @@ -25,10 +25,22 @@ static void irq_sim_irqunmask(struct irq_data *data)
>  	irq_ctx->enabled = true;
>  }
>  
> +static int irq_sim_set_type(struct irq_data *data, unsigned int type)
> +{
> +	/* We only support rising and falling edge trigger types. */
> +	if (type & ~IRQ_TYPE_EDGE_BOTH)
> +		return -EINVAL;
> +
> +	irqd_set_trigger_type(data, type);
> +
> +	return 0;
> +}
> +
>  static struct irq_chip irq_sim_irqchip = {
>  	.name		= "irq_sim",
>  	.irq_mask	= irq_sim_irqmask,
>  	.irq_unmask	= irq_sim_irqunmask,
> +	.irq_set_type	= irq_sim_set_type,
>  };
>  
>  static void irq_sim_handle_irq(struct irq_work *work)

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v6 1/7] irq/irq_sim: add irq_set_type() callback

[Bartosz Golaszewski]

wt., 19 lut 2019 o 17:14 Marc Zyngier <marc.zyngier@arm.com> napisał(a):
>
> On Tue, 19 Feb 2019 17:06:44 +0100
> Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> >
> > Implement the irq_set_type() callback and call irqd_set_trigger_type()
> > internally so that users interested in the configured trigger type can
> > later retrieve it using irqd_get_trigger_type(). We only support edge
> > trigger types.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > ---
> >  kernel/irq/irq_sim.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> > index 98a20e1594ce..b992f88c5613 100644
> > --- a/kernel/irq/irq_sim.c
> > +++ b/kernel/irq/irq_sim.c
> > @@ -25,10 +25,22 @@ static void irq_sim_irqunmask(struct irq_data *data)
> >       irq_ctx->enabled = true;
> >  }
> >
> > +static int irq_sim_set_type(struct irq_data *data, unsigned int type)
> > +{
> > +     /* We only support rising and falling edge trigger types. */
> > +     if (type & ~IRQ_TYPE_EDGE_BOTH)
> > +             return -EINVAL;
> > +
> > +     irqd_set_trigger_type(data, type);
> > +
> > +     return 0;
> > +}
> > +
> >  static struct irq_chip irq_sim_irqchip = {
> >       .name           = "irq_sim",
> >       .irq_mask       = irq_sim_irqmask,
> >       .irq_unmask     = irq_sim_irqunmask,
> > +     .irq_set_type   = irq_sim_set_type,
> >  };
> >
> >  static void irq_sim_handle_irq(struct irq_work *work)
>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
>

Thanks you! If you don't mind, I'll send this together with other
patches directly to Linus Walleij.

Bartosz

[PATCH v6 2/7] gpio: mockup: add locking

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

While no user reported any race condition problems with gpio-mockup,
let's be on the safe side and use a mutex when performing any changes
on the dummy chip structures.

Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 50 ++++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 6a50f9f59c90..b4c1de6acf74 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -54,6 +54,7 @@ struct gpio_mockup_chip {
 	struct gpio_mockup_line_status *lines;
 	struct irq_sim irqsim;
 	struct dentry *dbg_dir;
+	struct mutex lock;
 };
 
 struct gpio_mockup_dbgfs_private {
@@ -82,29 +83,53 @@ static int gpio_mockup_range_ngpio(unsigned int index)
 	return gpio_mockup_ranges[index * 2 + 1];
 }
 
-static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
+static int __gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
 	return chip->lines[offset].value;
 }
 
-static void gpio_mockup_set(struct gpio_chip *gc,
-			    unsigned int offset, int value)
+static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+	int val;
+
+	mutex_lock(&chip->lock);
+	val = __gpio_mockup_get(gc, offset);
+	mutex_unlock(&chip->lock);
+
+	return val;
+}
+
+static void __gpio_mockup_set(struct gpio_chip *gc,
+			      unsigned int offset, int value)
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
 	chip->lines[offset].value = !!value;
 }
 
+static void gpio_mockup_set(struct gpio_chip *gc,
+			   unsigned int offset, int value)
+{
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__gpio_mockup_set(gc, offset, value);
+	mutex_unlock(&chip->lock);
+}
+
 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 				     unsigned long *mask, unsigned long *bits)
 {
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 	unsigned int bit;
 
+	mutex_lock(&chip->lock);
 	for_each_set_bit(bit, mask, gc->ngpio)
-		gpio_mockup_set(gc, bit, test_bit(bit, bits));
-
+		__gpio_mockup_set(gc, bit, test_bit(bit, bits));
+	mutex_unlock(&chip->lock);
 }
 
 static int gpio_mockup_dirout(struct gpio_chip *gc,
@@ -112,8 +137,10 @@ static int gpio_mockup_dirout(struct gpio_chip *gc,
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
-	gpio_mockup_set(gc, offset, value);
+	mutex_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
+	__gpio_mockup_set(gc, offset, value);
+	mutex_unlock(&chip->lock);
 
 	return 0;
 }
@@ -122,7 +149,9 @@ static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
+	mutex_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
+	mutex_unlock(&chip->lock);
 
 	return 0;
 }
@@ -130,8 +159,13 @@ static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+	int direction;
 
-	return !chip->lines[offset].dir;
+	mutex_lock(&chip->lock);
+	direction = !chip->lines[offset].dir;
+	mutex_unlock(&chip->lock);
+
+	return direction;
 }
 
 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
@@ -283,6 +317,8 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 			return -ENOMEM;
 	}
 
+	mutex_init(&chip->lock);
+
 	gc = &chip->gc;
 	gc->base = base;
 	gc->ngpio = ngpio;
-- 
2.20.1

[PATCH v6 3/7] gpio: mockup: implement get_multiple()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

We already support set_multiple(). Implement get_multiple() as well.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index b4c1de6acf74..1c945c967f60 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -102,6 +102,22 @@ static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
 	return val;
 }
 
+static int gpio_mockup_get_multiple(struct gpio_chip *gc,
+				    unsigned long *mask, unsigned long *bits)
+{
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+	unsigned int bit, val;
+
+	mutex_lock(&chip->lock);
+	for_each_set_bit(bit, mask, gc->ngpio) {
+		val = __gpio_mockup_get(gc, bit);
+		__assign_bit(bit, bits, val);
+	}
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
 static void __gpio_mockup_set(struct gpio_chip *gc,
 			      unsigned int offset, int value)
 {
@@ -327,6 +343,7 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	gc->parent = dev;
 	gc->get = gpio_mockup_get;
 	gc->set = gpio_mockup_set;
+	gc->get_multiple = gpio_mockup_get_multiple;
 	gc->set_multiple = gpio_mockup_set_multiple;
 	gc->direction_output = gpio_mockup_dirout;
 	gc->direction_input = gpio_mockup_dirin;
-- 
2.20.1

[PATCH v6 4/7] gpio: mockup: don't create the debugfs link named after the label

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

User-space tests no longer use it and we're breaking the interface
anyway.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 1c945c967f60..0317917a3678 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -234,7 +234,7 @@ static void gpio_mockup_debugfs_setup(struct device *dev,
 				      struct gpio_mockup_chip *chip)
 {
 	struct gpio_mockup_dbgfs_private *priv;
-	struct dentry *evfile, *link;
+	struct dentry *evfile;
 	struct gpio_chip *gc;
 	const char *devname;
 	char *name;
@@ -247,10 +247,6 @@ static void gpio_mockup_debugfs_setup(struct device *dev,
 	if (IS_ERR_OR_NULL(chip->dbg_dir))
 		goto err;
 
-	link = debugfs_create_symlink(gc->label, gpio_mockup_dbg_dir, devname);
-	if (IS_ERR_OR_NULL(link))
-		goto err;
-
 	for (i = 0; i < gc->ngpio; i++) {
 		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 		if (!name)
-- 
2.20.1

[PATCH v6 5/7] gpio: mockup: change the type of 'offset' to unsigned int

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

This field can never be negative.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 0317917a3678..433adb3b4617 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -60,7 +60,7 @@ struct gpio_mockup_chip {
 struct gpio_mockup_dbgfs_private {
 	struct gpio_mockup_chip *chip;
 	struct gpio_desc *desc;
-	int offset;
+	unsigned int offset;
 };
 
 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
-- 
2.20.1

[PATCH v6 6/7] gpio: mockup: change the signature of unlocked get/set helpers

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

The unlocked variants only get called from places where we already have
the pointer to the underlying gpio_mockup_chip structure, so take it
as parameter instead of struct gpio_chip.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 433adb3b4617..c498b0fbbec8 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -83,10 +83,9 @@ static int gpio_mockup_range_ngpio(unsigned int index)
 	return gpio_mockup_ranges[index * 2 + 1];
 }
 
-static int __gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
+static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
+			     unsigned int offset)
 {
-	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
-
 	return chip->lines[offset].value;
 }
 
@@ -96,7 +95,7 @@ static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
 	int val;
 
 	mutex_lock(&chip->lock);
-	val = __gpio_mockup_get(gc, offset);
+	val = __gpio_mockup_get(chip, offset);
 	mutex_unlock(&chip->lock);
 
 	return val;
@@ -110,7 +109,7 @@ static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 
 	mutex_lock(&chip->lock);
 	for_each_set_bit(bit, mask, gc->ngpio) {
-		val = __gpio_mockup_get(gc, bit);
+		val = __gpio_mockup_get(chip, bit);
 		__assign_bit(bit, bits, val);
 	}
 	mutex_unlock(&chip->lock);
@@ -118,11 +117,9 @@ static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 	return 0;
 }
 
-static void __gpio_mockup_set(struct gpio_chip *gc,
+static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
 			      unsigned int offset, int value)
 {
-	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
-
 	chip->lines[offset].value = !!value;
 }
 
@@ -132,7 +129,7 @@ static void gpio_mockup_set(struct gpio_chip *gc,
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
 	mutex_lock(&chip->lock);
-	__gpio_mockup_set(gc, offset, value);
+	__gpio_mockup_set(chip, offset, value);
 	mutex_unlock(&chip->lock);
 }
 
@@ -144,7 +141,7 @@ static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 
 	mutex_lock(&chip->lock);
 	for_each_set_bit(bit, mask, gc->ngpio)
-		__gpio_mockup_set(gc, bit, test_bit(bit, bits));
+		__gpio_mockup_set(chip, bit, test_bit(bit, bits));
 	mutex_unlock(&chip->lock);
 }
 
@@ -155,7 +152,7 @@ static int gpio_mockup_dirout(struct gpio_chip *gc,
 
 	mutex_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
-	__gpio_mockup_set(gc, offset, value);
+	__gpio_mockup_set(chip, offset, value);
 	mutex_unlock(&chip->lock);
 
 	return 0;
-- 
2.20.1

[PATCH v6 7/7] gpio: mockup: rework debugfs interface

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Modify the way the debugfs interface works in gpio-mockup. Introduce
the concept of dummy pull config which will keep the mockup lines in
known state. The pull values can be modified by writing to the debugfs
files corresponding to lines. Lines in input mode always report the
current pull value, lines in output mode change the line value but
it will revert back to the one specified by current pull when released.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-mockup.c | 117 ++++++++++++++++++++++++++++++++-----
 1 file changed, 103 insertions(+), 14 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index c498b0fbbec8..154d959e8993 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -47,6 +47,7 @@ enum {
 struct gpio_mockup_line_status {
 	int dir;
 	int value;
+	int pull;
 };
 
 struct gpio_mockup_chip {
@@ -188,15 +189,56 @@ static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 	return irq_sim_irqnum(&chip->irqsim, offset);
 }
 
-static ssize_t gpio_mockup_event_write(struct file *file,
-				       const char __user *usr_buf,
-				       size_t size, loff_t *ppos)
+static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+
+	__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
+}
+
+static ssize_t gpio_mockup_debugfs_read(struct file *file,
+					char __user *usr_buf,
+					size_t size, loff_t *ppos)
 {
 	struct gpio_mockup_dbgfs_private *priv;
 	struct gpio_mockup_chip *chip;
 	struct seq_file *sfile;
+	struct gpio_chip *gc;
+	char buf[3];
+	int val, rv;
+
+	if (*ppos != 0)
+		return 0;
+
+	sfile = file->private_data;
+	priv = sfile->private;
+	chip = priv->chip;
+	gc = &chip->gc;
+
+	val = gpio_mockup_get(gc, priv->offset);
+	snprintf(buf, sizeof(buf), "%d\n", val);
+
+	rv = copy_to_user(usr_buf, buf, sizeof(buf));
+	if (rv)
+		return rv;
+
+	return sizeof(buf) - 1;
+}
+
+static ssize_t gpio_mockup_debugfs_write(struct file *file,
+					 const char __user *usr_buf,
+					 size_t size, loff_t *ppos)
+{
+	struct gpio_mockup_dbgfs_private *priv;
+	int rv, val, curr, irq, irq_type;
+	struct gpio_mockup_chip *chip;
+	struct seq_file *sfile;
 	struct gpio_desc *desc;
-	int rv, val;
+	struct gpio_chip *gc;
+	struct irq_sim *sim;
+
+	if (*ppos != 0)
+		return -EINVAL;
 
 	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 	if (rv)
@@ -206,24 +248,70 @@ static ssize_t gpio_mockup_event_write(struct file *file,
 
 	sfile = file->private_data;
 	priv = sfile->private;
-	desc = priv->desc;
 	chip = priv->chip;
+	gc = &chip->gc;
+	desc = &gc->gpiodev->descs[priv->offset];
+	sim = &chip->irqsim;
+
+	mutex_lock(&chip->lock);
+
+	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
+	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
+		curr = __gpio_mockup_get(chip, priv->offset);
+		if (curr == val)
+			goto out;
 
-	gpiod_set_value_cansleep(desc, val);
-	irq_sim_fire(&chip->irqsim, priv->offset);
+		irq = irq_sim_irqnum(sim, priv->offset);
+		irq_type = irq_get_trigger_type(irq);
+
+		if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
+		    (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
+			irq_sim_fire(sim, priv->offset);
+	}
+
+	/* Change the value unless we're actively driving the line. */
+	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+	    !test_bit(FLAG_IS_OUT, &desc->flags))
+		__gpio_mockup_set(chip, priv->offset, val);
+
+out:
+	chip->lines[priv->offset].pull = val;
+	mutex_unlock(&chip->lock);
 
 	return size;
 }
 
-static int gpio_mockup_event_open(struct inode *inode, struct file *file)
+static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, NULL, inode->i_private);
 }
 
-static const struct file_operations gpio_mockup_event_ops = {
+/*
+ * Each mockup chip is represented by a directory named after the chip's device
+ * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
+ * a file using the line's offset as the name under the chip's directory.
+ *
+ * Reading from the line's file yields the current *value*, writing to the
+ * line's file changes the current *pull*. Default pull for mockup lines is
+ * down.
+ *
+ * Examples:
+ * - when a line pulled down is requested in output mode and driven high, its
+ *   value will return to 0 once it's released
+ * - when the line is requested in output mode and driven high, writing 0 to
+ *   the corresponding debugfs file will change the pull to down but the
+ *   reported value will still be 1 until the line is released
+ * - line requested in input mode always reports the same value as its pull
+ *   configuration
+ * - when the line is requested in input mode and monitored for events, writing
+ *   the same value to the debugfs file will be a noop, while writing the
+ *   opposite value will generate a dummy interrupt with an appropriate edge
+ */
+static const struct file_operations gpio_mockup_debugfs_ops = {
 	.owner = THIS_MODULE,
-	.open = gpio_mockup_event_open,
-	.write = gpio_mockup_event_write,
+	.open = gpio_mockup_debugfs_open,
+	.read = gpio_mockup_debugfs_read,
+	.write = gpio_mockup_debugfs_write,
 	.llseek = no_llseek,
 };
 
@@ -258,7 +346,7 @@ static void gpio_mockup_debugfs_setup(struct device *dev,
 		priv->desc = &gc->gpiodev->descs[i];
 
 		evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
-					     &gpio_mockup_event_ops);
+					     &gpio_mockup_debugfs_ops);
 		if (IS_ERR_OR_NULL(evfile))
 			goto err;
 	}
@@ -266,7 +354,7 @@ static void gpio_mockup_debugfs_setup(struct device *dev,
 	return;
 
 err:
-	dev_err(dev, "error creating debugfs event files\n");
+	dev_err(dev, "error creating debugfs files\n");
 }
 
 static int gpio_mockup_name_lines(struct device *dev,
@@ -342,6 +430,7 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	gc->direction_input = gpio_mockup_dirin;
 	gc->get_direction = gpio_mockup_get_direction;
 	gc->to_irq = gpio_mockup_to_irq;
+	gc->free = gpio_mockup_free;
 
 	chip->lines = devm_kcalloc(dev, gc->ngpio,
 				   sizeof(*chip->lines), GFP_KERNEL);
@@ -415,7 +504,7 @@ static int __init gpio_mockup_init(void)
 			return -EINVAL;
 	}
 
-	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup-event", NULL);
+	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 	if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 		gpio_mockup_err("error creating debugfs directory\n");
 
-- 
2.20.1