[PATCH v4 0/7] gpio: mockup: improve the user-space testing interface

[PATCH v4 0/7] gpio: mockup: improve the user-space testing interface

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Hi Marc,

another try at the irq_sim stuff. This time I added a notifier chain to
irq_sim and made gpio-mockup register a notifier block. This way interested
users will get notified about a type config change.

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

Bartosz Golaszewski (7):
  irq/irq_sim: add a notifier chain
  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 | 215 ++++++++++++++++++++++++++++++++-----
 include/linux/irq_sim.h    |  22 +++-
 kernel/irq/irq_sim.c       |  40 +++++++
 3 files changed, 246 insertions(+), 31 deletions(-)

-- 
2.20.1

[PATCH v4 1/7] irq/irq_sim: add a notifier chain

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Provide a helper allowing users to register a notifier block with
a simulator. For now the only event we're notifying about is a change
in type configuration.

This is required by the gpio-mockup module which wants to track the
state of GPIO lines and simulate rising and falling edge interrupts.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 include/linux/irq_sim.h | 22 ++++++++++++++++++----
 kernel/irq/irq_sim.c    | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
index 4500d453a63e..e076693d0af7 100644
--- a/include/linux/irq_sim.h
+++ b/include/linux/irq_sim.h
@@ -8,12 +8,21 @@
 
 #include <linux/irq_work.h>
 #include <linux/device.h>
+#include <linux/notifier.h>
 
 /*
  * Provides a framework for allocating simulated interrupts which can be
  * requested like normal irqs and enqueued from process context.
  */
 
+#define IRQ_SIM_TYPE_CHANGED	1
+
+/* Passed to notifier callbacks when type changes. */
+struct irq_sim_irq_type {
+	unsigned int		offset;
+	unsigned int		type;
+};
+
 struct irq_sim_work_ctx {
 	struct irq_work		work;
 	unsigned long		*pending;
@@ -22,13 +31,16 @@ struct irq_sim_work_ctx {
 struct irq_sim_irq_ctx {
 	int			irqnum;
 	bool			enabled;
+	struct irq_sim		*parent;
+	struct irq_sim_irq_type	type;
 };
 
 struct irq_sim {
-	struct irq_sim_work_ctx	work_ctx;
-	int			irq_base;
-	unsigned int		irq_count;
-	struct irq_sim_irq_ctx	*irqs;
+	struct irq_sim_work_ctx		work_ctx;
+	int				irq_base;
+	unsigned int			irq_count;
+	struct irq_sim_irq_ctx		*irqs;
+	struct atomic_notifier_head	notifier;
 };
 
 int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
@@ -37,5 +49,7 @@ int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
 void irq_sim_fini(struct irq_sim *sim);
 void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
 int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
+int irq_sim_notifier_register(struct irq_sim *sim,
+			      struct notifier_block *nb);
 
 #endif /* _LINUX_IRQ_SIM_H */
diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 98a20e1594ce..a55641e78125 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -25,10 +25,34 @@ 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)
+{
+	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+	struct irq_sim *sim = irq_ctx->parent;
+	int rv;
+
+	/* Only support rising and falling edge types. */
+	if (type & ~IRQ_TYPE_EDGE_BOTH)
+		return -EINVAL;
+
+	irq_ctx->type.type = type;
+
+	rv = atomic_notifier_call_chain(&sim->notifier,
+					IRQ_SIM_TYPE_CHANGED,
+					&irq_ctx->type);
+	if (rv < 0) {
+		pr_err("%s: error calling the type notifier chain\n", __func__);
+		return rv;
+	}
+
+	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)
@@ -83,7 +107,9 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
 
 	for (i = 0; i < num_irqs; i++) {
 		sim->irqs[i].irqnum = sim->irq_base + i;
+		sim->irqs[i].parent = sim;
 		sim->irqs[i].enabled = false;
+		sim->irqs[i].type.offset = i;
 		irq_set_chip(sim->irq_base + i, &irq_sim_irqchip);
 		irq_set_chip_data(sim->irq_base + i, &sim->irqs[i]);
 		irq_set_handler(sim->irq_base + i, &handle_simple_irq);
@@ -91,6 +117,7 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
 				  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
 	}
 
+	ATOMIC_INIT_NOTIFIER_HEAD(&sim->notifier);
 	init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
 	sim->irq_count = num_irqs;
 
@@ -180,3 +207,16 @@ int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
 	return sim->irqs[offset].irqnum;
 }
 EXPORT_SYMBOL_GPL(irq_sim_irqnum);
+
+/**
+ * irq_sim_notifier_register - Subscribe for interrupt simulator events.
+ *
+ * @sim:       The interrupt simulator object.
+ * @nb:        Notifier block.
+ */
+int irq_sim_notifier_register(struct irq_sim *sim,
+			      struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&sim->notifier, nb);
+}
+EXPORT_SYMBOL_GPL(irq_sim_notifier_register);
-- 
2.20.1

[PATCH v4 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 spinlock when performing any
changes on the dummy chip structures. We're using a spinlock because
a subsequent patch will register an irq_sim notifier which holds
the irq_desc lock and if using a mutex we'd get the
"HARDIRQ-safe -> HARDIRQ-unsafe" lockdep error.

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..9697bf622284 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;
+	spinlock_t 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;
+
+	spin_lock(&chip->lock);
+	val = __gpio_mockup_get(gc, offset);
+	spin_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);
+
+	spin_lock(&chip->lock);
+	__gpio_mockup_set(gc, offset, value);
+	spin_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;
 
+	spin_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));
+	spin_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);
+	spin_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
+	__gpio_mockup_set(gc, offset, value);
+	spin_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);
 
+	spin_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
+	spin_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;
+	spin_lock(&chip->lock);
+	direction = !chip->lines[offset].dir;
+	spin_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;
 	}
 
+	spin_lock_init(&chip->lock);
+
 	gc = &chip->gc;
 	gc->base = base;
 	gc->ngpio = ngpio;
-- 
2.20.1

[PATCH v4 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 9697bf622284..6deed33dbbef 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;
+
+	spin_lock(&chip->lock);
+	for_each_set_bit(bit, mask, gc->ngpio) {
+		val = __gpio_mockup_get(gc, bit);
+		__assign_bit(bit, bits, val);
+	}
+	spin_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 v4 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 6deed33dbbef..9d279d641374 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 v4 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 9d279d641374..4e7688348c0e 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 v4 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 4e7688348c0e..f1807afd44ba 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;
 
 	spin_lock(&chip->lock);
-	val = __gpio_mockup_get(gc, offset);
+	val = __gpio_mockup_get(chip, offset);
 	spin_unlock(&chip->lock);
 
 	return val;
@@ -110,7 +109,7 @@ static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 
 	spin_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);
 	}
 	spin_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);
 
 	spin_lock(&chip->lock);
-	__gpio_mockup_set(gc, offset, value);
+	__gpio_mockup_set(chip, offset, value);
 	spin_unlock(&chip->lock);
 }
 
@@ -144,7 +141,7 @@ static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 
 	spin_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));
 	spin_unlock(&chip->lock);
 }
 
@@ -155,7 +152,7 @@ static int gpio_mockup_dirout(struct gpio_chip *gc,
 
 	spin_lock(&chip->lock);
 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
-	__gpio_mockup_set(gc, offset, value);
+	__gpio_mockup_set(chip, offset, value);
 	spin_unlock(&chip->lock);
 
 	return 0;
-- 
2.20.1

[PATCH v4 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 | 143 +++++++++++++++++++++++++++++++++----
 1 file changed, 129 insertions(+), 14 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index f1807afd44ba..f710df8ca737 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -47,6 +47,8 @@ enum {
 struct gpio_mockup_line_status {
 	int dir;
 	int value;
+	int pull;
+	int irq_type;
 };
 
 struct gpio_mockup_chip {
@@ -55,6 +57,7 @@ struct gpio_mockup_chip {
 	struct irq_sim irqsim;
 	struct dentry *dbg_dir;
 	spinlock_t lock;
+	struct notifier_block nb;
 };
 
 struct gpio_mockup_dbgfs_private {
@@ -73,6 +76,11 @@ module_param_named(gpio_mockup_named_lines,
 
 static struct dentry *gpio_mockup_dbg_dir;
 
+static struct gpio_mockup_chip *to_gpio_mockup_chip(struct notifier_block *nb)
+{
+	return container_of(nb, struct gpio_mockup_chip, nb);
+}
+
 static int gpio_mockup_range_base(unsigned int index)
 {
 	return gpio_mockup_ranges[index * 2];
@@ -188,15 +196,72 @@ 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 int gpio_mockup_irq_type_changed(struct notifier_block *nb,
+					unsigned long event, void *data)
+{
+	struct gpio_mockup_chip *chip = to_gpio_mockup_chip(nb);
+	struct irq_sim_irq_type *irq_type = data;
+
+	if (event != IRQ_SIM_TYPE_CHANGED)
+		return NOTIFY_DONE;
+
+	/* FIXME: add locking once we switch to spinlocks */
+	chip->lines[irq_type->offset].irq_type = irq_type->type;
+
+	return NOTIFY_OK;
+}
+
+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;
 	struct gpio_mockup_chip *chip;
 	struct seq_file *sfile;
 	struct gpio_desc *desc;
-	int rv, val;
+	unsigned int irq_type;
+	struct gpio_chip *gc;
+	struct irq_sim *sim;
+	int rv, val, curr;
+
+	if (*ppos != 0)
+		return -EINVAL;
 
 	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 	if (rv)
@@ -206,24 +271,68 @@ 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;
+
+	spin_lock(&chip->lock);
 
-	gpiod_set_value_cansleep(desc, val);
-	irq_sim_fire(&chip->irqsim, priv->offset);
+	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;
+
+		irq_type = chip->lines[priv->offset].irq_type;
+		if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
+		    (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
+			irq_sim_fire(&chip->irqsim, 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;
+	spin_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 +367,7 @@ 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 +375,7 @@ 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 +451,7 @@ 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);
@@ -358,6 +468,11 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	if (rv < 0)
 		return rv;
 
+	chip->nb.notifier_call = gpio_mockup_irq_type_changed;
+	rv = irq_sim_notifier_register(&chip->irqsim, &chip->nb);
+	if (rv)
+		return rv;
+
 	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 	if (rv)
 		return rv;
@@ -415,7 +530,7 @@ 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

Re: [PATCH v4 0/7] gpio: mockup: improve the user-space testing interface

[Bartosz Golaszewski]

czw., 14 lut 2019 o 14:42 Bartosz Golaszewski <brgl@bgdev.pl> napisał(a):
>
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Hi Marc,
>
> another try at the irq_sim stuff. This time I added a notifier chain to
> irq_sim and made gpio-mockup register a notifier block. This way interested
> users will get notified about a type config change.
>
> 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
>
> Bartosz Golaszewski (7):
>   irq/irq_sim: add a notifier chain
>   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 | 215 ++++++++++++++++++++++++++++++++-----
>  include/linux/irq_sim.h    |  22 +++-
>  kernel/irq/irq_sim.c       |  40 +++++++
>  3 files changed, 246 insertions(+), 31 deletions(-)
>
> --
> 2.20.1
>

Since this really is overkill, I sent v5 in which I simple store the
trigger type by calling irqd_set_trigger_type().

Superseded by v5.

Bartosz