From: Grégor Boirie <gregor.boirie@xxxxxxxxxx>
Add a sysfs file entry for each interrupt trigger instance allowing
userspace to :
* poll for interrupt events ;
* retrieve number of interrupts that occurred since trigger was
* initialized
Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
---
.../ABI/testing/sysfs-bus-iio-trig-interrupt | 22 ++++++
drivers/iio/trigger/iio-trig-interrupt.c | 88 ++++++++++++++++------
2 files changed, 88 insertions(+), 22 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-trig-interrupt
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-trig-interrupt b/Documentation/ABI/testing/sysfs-bus-iio-trig-interrupt
new file mode 100644
index 0000000..cb246d2
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-trig-interrupt
@@ -0,0 +1,22 @@
+What: /sys/bus/iio/devices/triggerX/name
+KernelVersion: 3.11
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ The name attribute holds a description string for the current
+ trigger. In order to associate the trigger with an IIO device
+ one should write this name string to
+ /sys/bus/iio/devices/iio:deviceY/trigger/current_trigger.
+
+What: /sys/bus/iio/devices/triggerX/count
+KernelVersion: 4.5
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ The count attribute is a unsigned int counter holding the number
+ of times the attached interrupt occurred since trigger was
+ initialized.
+ You can poll(2) on that file and poll(2) will return whenever
+ the interrupt was triggered. If you use poll(2), set the events
+ POLLPRI and POLLERR. If you use select(2), set the file
+ descriptor in exceptfds. After poll(2) returns, either lseek(2)
+ to the beginning of the sysfs file and read the new value or
+ close the file and re-open it to read the value.
diff --git a/drivers/iio/trigger/iio-trig-interrupt.c b/drivers/iio/trigger/iio-trig-interrupt.c
index 3c4e18f..1bf3986 100644
--- a/drivers/iio/trigger/iio-trig-interrupt.c
+++ b/drivers/iio/trigger/iio-trig-interrupt.c
@@ -17,14 +17,53 @@
#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>
-
struct iio_interrupt_trigger_info {
+ struct kernfs_node *poll;
+ atomic_t count;
unsigned int irq;
};
+/*
+ * If interested by counter value, userspace should read often enough since
+ * counter may wrap. Userspace will miss interrupt events when counter wraps
+ * twice or more between 2 consecutive reads.
+ */
+ssize_t iio_interrupt_trigger_show_count(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_trigger *trig = to_iio_trigger(dev);
+ struct iio_interrupt_trigger_info *info = iio_trigger_get_drvdata(trig);
+ unsigned int count = atomic_read(&info->count);
+
+ return snprintf(buf, PAGE_SIZE, "%u\n", count);
+}
+
+static DEVICE_ATTR(count, S_IRUGO, iio_interrupt_trigger_show_count, NULL);
+
+static struct attribute *iio_interrupt_trigger_attrs[] = {
+ &dev_attr_count.attr,
+ NULL,
+};
+
+static const struct attribute_group iio_interrupt_trigger_attr_group = {
+ .attrs = iio_interrupt_trigger_attrs,
+};
+
+static const struct attribute_group *iio_interrupt_trigger_attr_groups[] = {
+ &iio_interrupt_trigger_attr_group,
+ NULL
+};
+
static irqreturn_t iio_interrupt_trigger_poll(int irq, void *private)
{
- iio_trigger_poll(private);
+ struct iio_trigger *trig = private;
+ struct iio_interrupt_trigger_info *info = iio_trigger_get_drvdata(trig);
+
+ atomic_inc(&info->count);
+ sysfs_notify_dirent(info->poll);
+ iio_trigger_poll(trig);
+
return IRQ_HANDLED;
}
@@ -36,17 +75,12 @@ static int iio_interrupt_trigger_probe(struct platform_device *pdev)
{
struct iio_interrupt_trigger_info *trig_info;
struct iio_trigger *trig;
- unsigned long irqflags;
struct resource *irq_res;
int irq, ret = 0;
irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-
- if (irq_res == NULL)
+ if (!irq_res)
return -ENODEV;
-
- irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
-
irq = irq_res->start;
trig = iio_trigger_alloc("irqtrig%d", irq);
@@ -60,27 +94,36 @@ static int iio_interrupt_trigger_probe(struct platform_device *pdev)
ret = -ENOMEM;
goto error_put_trigger;
}
- iio_trigger_set_drvdata(trig, trig_info);
+
+ atomic_set(&trig_info->count, 0);
trig_info->irq = irq;
+ iio_trigger_set_drvdata(trig, trig_info);
trig->ops = &iio_interrupt_trigger_ops;
- ret = request_irq(irq, iio_interrupt_trigger_poll,
- irqflags, trig->name, trig);
- if (ret) {
- dev_err(&pdev->dev,
- "request IRQ-%d failed", irq);
+ trig->dev.groups = iio_interrupt_trigger_attr_groups;
+ ret = iio_trigger_register(trig);
+ if (ret)
goto error_free_trig_info;
+
+ /* Create a sysfs entry which the userspace may poll for irq events. */
+ trig_info->poll = sysfs_get_dirent(trig->dev.kobj.sd, "count");
+ if (!trig_info->poll) {
+ ret = -ENOENT;
+ goto error_unregister_trig;
}
- ret = iio_trigger_register(trig);
- if (ret)
- goto error_release_irq;
- platform_set_drvdata(pdev, trig);
+ ret = request_irq(irq, iio_interrupt_trigger_poll,
+ (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED,
+ trig->name, trig);
+ if (!ret) {
+ platform_set_drvdata(pdev, trig);
+ return 0;
+ }
- return 0;
+ sysfs_put(trig_info->poll);
/* First clean up the partly allocated trigger */
-error_release_irq:
- free_irq(irq, trig);
+error_unregister_trig:
+ iio_trigger_unregister(trig);
error_free_trig_info:
kfree(trig_info);
error_put_trigger:
@@ -96,8 +139,9 @@ static int iio_interrupt_trigger_remove(struct platform_device *pdev)
trig = platform_get_drvdata(pdev);
trig_info = iio_trigger_get_drvdata(trig);
- iio_trigger_unregister(trig);
free_irq(trig_info->irq, trig);
+ sysfs_put(trig_info->poll);
+ iio_trigger_unregister(trig);
kfree(trig_info);
iio_trigger_put(trig);
--
2.1.4
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