Re: [PATCH v2] Staging: iio: Move evgen interrupt generation to irq_work

[Daniel Baluta]

On Sat, Sep 12, 2015 at 12:14 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 11/09/15 14:59, Cristina Opriceana wrote:
>> Enhance interrupt generation in the dummy driver and expand its usage
>> by introducing the irq_work infrastructure to trigger an interrupt.
>>
>> This way, the irq_work_queue() wrapper permits calling both of the top
>> half and threaded part from a hard irq context, unlike handle_nested_irq(),
>> which only calls the threaded part.
>>
>> As an outcome, the driver succeeds in simulating real hardware
>> interrupts, while keeping the normal interrupt flow.
>>
>> Signed-off-by: Cristina Opriceana <cristina.opriceana@xxxxxxxxx>

Acked-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>

>
> Looks good to me.  Will let this sit on the list for a little while
> though to give others plenty of time to comment.
>
> Thanks for doing this, ended up simpler than I thought it would
> be which is always nice ;)

Indeed!

Jonathan, let us now if there are any other things to be done
in order to move this out of staging.

Cristina also worked on removing the hard coded number of device instances
and replaced it by adding support to configfs, but we'll have to wait a little
bit more for that until I get some time to finally finish the configfs patches.

Daniel.

>
> Jonathan
>> ---
>>  Changes since v1:
>>   - keep irq_chip and the normal interrupt flow
>>   - run top half and threaded part from hardirq context
>>   - add demo function that registers current timestamp and uses it in the
>>   threaded interrupt handler
>>
>>  drivers/staging/iio/iio_dummy_evgen.c         | 26 +++++++++++++++++++++++++-
>>  drivers/staging/iio/iio_simple_dummy.h        |  1 +
>>  drivers/staging/iio/iio_simple_dummy_events.c | 19 ++++++++++++++-----
>>  3 files changed, 40 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/staging/iio/iio_dummy_evgen.c b/drivers/staging/iio/iio_dummy_evgen.c
>> index 6d38854..2bb4350 100644
>> --- a/drivers/staging/iio/iio_dummy_evgen.c
>> +++ b/drivers/staging/iio/iio_dummy_evgen.c
>> @@ -24,9 +24,21 @@
>>  #include "iio_dummy_evgen.h"
>>  #include <linux/iio/iio.h>
>>  #include <linux/iio/sysfs.h>
>> +#include <linux/irq_work.h>
>>
>>  /* Fiddly bit of faking and irq without hardware */
>>  #define IIO_EVENTGEN_NO 10
>> +
>> +/**
>> + * struct iio_dummy_handle_irq - helper struct to simulate interrupt generation
>> + * @work: irq_work used to run handlers from hardirq context
>> + * @irq: fake irq line number to trigger an interrupt
>> + */
>> +struct iio_dummy_handle_irq {
>> +     struct irq_work work;
>> +     int irq;
>> +};
>> +
>>  /**
>>   * struct iio_dummy_evgen - evgen state
>>   * @chip: irq chip we are faking
>> @@ -35,6 +47,7 @@
>>   * @inuse: mask of which irqs are connected
>>   * @regs: irq regs we are faking
>>   * @lock: protect the evgen state
>> + * @handler: helper for a 'hardware-like' interrupt simulation
>>   */
>>  struct iio_dummy_eventgen {
>>       struct irq_chip chip;
>> @@ -43,6 +56,7 @@ struct iio_dummy_eventgen {
>>       bool inuse[IIO_EVENTGEN_NO];
>>       struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
>>       struct mutex lock;
>> +     struct iio_dummy_handle_irq handler;
>>  };
>>
>>  /* We can only ever have one instance of this 'device' */
>> @@ -67,6 +81,14 @@ static void iio_dummy_event_irqunmask(struct irq_data *d)
>>       evgen->enabled[d->irq - evgen->base] = true;
>>  }
>>
>> +void iio_dummy_work_handler(struct irq_work *work)
>> +{
>> +     struct iio_dummy_handle_irq *irq_handler;
>> +
>> +     irq_handler = container_of(work, struct iio_dummy_handle_irq, work);
>> +     handle_simple_irq(irq_handler->irq, irq_to_desc(irq_handler->irq));
>> +}
>> +
>>  static int iio_dummy_evgen_create(void)
>>  {
>>       int ret, i;
>> @@ -91,6 +113,7 @@ static int iio_dummy_evgen_create(void)
>>                                 IRQ_NOREQUEST | IRQ_NOAUTOEN,
>>                                 IRQ_NOPROBE);
>>       }
>> +     init_irq_work(&iio_evgen->handler.work, iio_dummy_work_handler);
>>       mutex_init(&iio_evgen->lock);
>>       return 0;
>>  }
>> @@ -169,8 +192,9 @@ static ssize_t iio_evgen_poke(struct device *dev,
>>       iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
>>       iio_evgen->regs[this_attr->address].reg_data = event;
>>
>> +     iio_evgen->handler.irq = iio_evgen->base + this_attr->address;
>>       if (iio_evgen->enabled[this_attr->address])
>> -             handle_nested_irq(iio_evgen->base + this_attr->address);
>> +             irq_work_queue(&iio_evgen->handler.work);
>>
>>       return len;
>>  }
>> diff --git a/drivers/staging/iio/iio_simple_dummy.h b/drivers/staging/iio/iio_simple_dummy.h
>> index 8d00224..5c2f4d0 100644
>> --- a/drivers/staging/iio/iio_simple_dummy.h
>> +++ b/drivers/staging/iio/iio_simple_dummy.h
>> @@ -46,6 +46,7 @@ struct iio_dummy_state {
>>       int event_irq;
>>       int event_val;
>>       bool event_en;
>> +     s64 event_timestamp;
>>  #endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
>>  };
>>
>> diff --git a/drivers/staging/iio/iio_simple_dummy_events.c b/drivers/staging/iio/iio_simple_dummy_events.c
>> index 73108ba..bfbf1c5 100644
>> --- a/drivers/staging/iio/iio_simple_dummy_events.c
>> +++ b/drivers/staging/iio/iio_simple_dummy_events.c
>> @@ -153,6 +153,15 @@ int iio_simple_dummy_write_event_value(struct iio_dev *indio_dev,
>>       return 0;
>>  }
>>
>> +static irqreturn_t iio_simple_dummy_get_timestamp(int irq, void *private)
>> +{
>> +     struct iio_dev *indio_dev = private;
>> +     struct iio_dummy_state *st = iio_priv(indio_dev);
>> +
>> +     st->event_timestamp = iio_get_time_ns();
>> +     return IRQ_HANDLED;
>> +}
>> +
>>  /**
>>   * iio_simple_dummy_event_handler() - identify and pass on event
>>   * @irq: irq of event line
>> @@ -177,7 +186,7 @@ static irqreturn_t iio_simple_dummy_event_handler(int irq, void *private)
>>                              IIO_EVENT_CODE(IIO_VOLTAGE, 0, 0,
>>                                             IIO_EV_DIR_RISING,
>>                                             IIO_EV_TYPE_THRESH, 0, 0, 0),
>> -                            iio_get_time_ns());
>> +                            st->event_timestamp);
>>               break;
>>       case 1:
>>               if (st->activity_running > st->event_val)
>> @@ -187,7 +196,7 @@ static irqreturn_t iio_simple_dummy_event_handler(int irq, void *private)
>>                                                     IIO_EV_DIR_RISING,
>>                                                     IIO_EV_TYPE_THRESH,
>>                                                     0, 0, 0),
>> -                                    iio_get_time_ns());
>> +                                    st->event_timestamp);
>>               break;
>>       case 2:
>>               if (st->activity_walking < st->event_val)
>> @@ -197,14 +206,14 @@ static irqreturn_t iio_simple_dummy_event_handler(int irq, void *private)
>>                                                     IIO_EV_DIR_FALLING,
>>                                                     IIO_EV_TYPE_THRESH,
>>                                                     0, 0, 0),
>> -                                    iio_get_time_ns());
>> +                                    st->event_timestamp);
>>               break;
>>       case 3:
>>               iio_push_event(indio_dev,
>>                              IIO_EVENT_CODE(IIO_STEPS, 0, IIO_NO_MOD,
>>                                             IIO_EV_DIR_NONE,
>>                                             IIO_EV_TYPE_CHANGE, 0, 0, 0),
>> -                            iio_get_time_ns());
>> +                            st->event_timestamp);
>>               break;
>>       default:
>>               break;
>> @@ -238,7 +247,7 @@ int iio_simple_dummy_events_register(struct iio_dev *indio_dev)
>>       st->regs = iio_dummy_evgen_get_regs(st->event_irq);
>>
>>       ret = request_threaded_irq(st->event_irq,
>> -                                NULL,
>> +                                &iio_simple_dummy_get_timestamp,
>>                                  &iio_simple_dummy_event_handler,
>>                                  IRQF_ONESHOT,
>>                                  "iio_simple_event",
>>
>
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