On 19/02/16 19:18, Gregor Boirie wrote:
> From: Grégor Boirie <gregor.boirie@xxxxxxxxxx>
>
Hi Gregor.
You certainly have some unusual requirements - or perhaps you are
simply the first person to show up with them here!
> Add a sysfs file entry for each interrupt trigger instance allowing
> userspace to :
> * poll for interrupt events ;
Why?
> * retrieve number of interrupts that occurred since trigger was
> * initialized
Again why?
This is interesting stuff, but I'd like to fully understand the question
of what you are doing with it before we go too far into the code.
>
> 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);
>
>
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