Re: [PATCH v3 5/7] iio: Support triggered events

[Vladimir Barinov <vladimir.barinov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>]

Hi Jonathan,

Thank you for review.
Find some comments below.

Regards,
Vladimir

On 16.08.2015 12:20, Jonathan Cameron wrote:
> On 29/07/15 13:57, Vladimir Barinov wrote:
>> Support triggered events.
>>
>> This is useful for chips that don't have their own interrupt sources.
>> It allows to use generic/standalone iio triggers for those drivers.
> As we have concluded this is a good thing to have, I've take a closer
> look at it.
>
> I think we need to slightly separate the buffer and event uses of
> triggers as it's entirely plausible both might be enabled at the same
> time.  Don't think this should be hard however.
>
> I can concieve of weird restrictions from certain hardware (particularly
> where hardware buffers are concerned) in which events are not monitored
> when we are reading through the buffer but we can tackle that when we
> actually need to.
>
> Anyhow, few bits inline.  Thanks for your persistence with this!
>
> Jonathan
>
>> Signed-off-by: Vladimir Barinov <vladimir.barinov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>
>> ---
>> Changes in version 2:
>> - initially added
>> Changes in version 3:
>> - fixed grammar in patch description
>> - changed license header to match "GNU Public License v2 or later"
>>
>>   drivers/iio/Kconfig                        |  6 +++
>>   drivers/iio/Makefile                       |  1 +
>>   drivers/iio/industrialio-core.c            |  4 +-
>>   drivers/iio/industrialio-trigger.c         | 12 +++++-
>>   drivers/iio/industrialio-triggered-event.c | 68 ++++++++++++++++++++++++++++++
>>   include/linux/iio/iio.h                    |  1 +
>>   include/linux/iio/triggered_event.h        | 11 +++++
>>   7 files changed, 99 insertions(+), 4 deletions(-)
>>   create mode 100644 drivers/iio/industrialio-triggered-event.c
>>   create mode 100644 include/linux/iio/triggered_event.h
>>
>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>> index 4011eff..8fcc92f 100644
>> --- a/drivers/iio/Kconfig
>> +++ b/drivers/iio/Kconfig
>> @@ -58,6 +58,12 @@ config IIO_CONSUMERS_PER_TRIGGER
>>   	This value controls the maximum number of consumers that a
>>   	given trigger may handle. Default is 2.
>>   
>> +config IIO_TRIGGERED_EVENT
>> +	tristate
>> +	select IIO_TRIGGER
>> +	help
>> +	  Provides helper functions for setting up triggered events.
>> +
>>   source "drivers/iio/accel/Kconfig"
>>   source "drivers/iio/adc/Kconfig"
>>   source "drivers/iio/amplifiers/Kconfig"
>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>> index 698afc2..40dc13e 100644
>> --- a/drivers/iio/Makefile
>> +++ b/drivers/iio/Makefile
>> @@ -9,6 +9,7 @@ industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o
>>   industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o
>>   
>>   obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o
>> +obj-$(CONFIG_IIO_TRIGGERED_EVENT) += industrialio-triggered-event.o
>>   obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
>>   
>>   obj-y += accel/
>> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
>> index 3524b0d..54d71ea 100644
>> --- a/drivers/iio/industrialio-core.c
>> +++ b/drivers/iio/industrialio-core.c
>> @@ -948,7 +948,7 @@ static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
>>   static void iio_dev_release(struct device *device)
>>   {
>>   	struct iio_dev *indio_dev = dev_to_iio_dev(device);
>> -	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
>> +	if (indio_dev->modes & (INDIO_BUFFER_TRIGGERED | INDIO_EVENT_TRIGGERED))
>>   		iio_device_unregister_trigger_consumer(indio_dev);
>>   	iio_device_unregister_eventset(indio_dev);
>>   	iio_device_unregister_sysfs(indio_dev);
>> @@ -1218,7 +1218,7 @@ int iio_device_register(struct iio_dev *indio_dev)
>>   			"Failed to register event set\n");
>>   		goto error_free_sysfs;
>>   	}
>> -	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
>> +	if (indio_dev->modes & (INDIO_BUFFER_TRIGGERED | INDIO_EVENT_TRIGGERED))
>>   		iio_device_register_trigger_consumer(indio_dev);
>>   
>>   	if ((indio_dev->modes & INDIO_ALL_BUFFER_MODES) &&
>> diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
>> index d31098e..72b63e7 100644
>> --- a/drivers/iio/industrialio-trigger.c
>> +++ b/drivers/iio/industrialio-trigger.c
>> @@ -345,10 +345,18 @@ static ssize_t iio_trigger_write_current(struct device *dev,
>>   
>>   	indio_dev->trig = trig;
>>   
>> -	if (oldtrig)
>> +	if (oldtrig) {
>> +		if (indio_dev->currentmode == INDIO_EVENT_TRIGGERED)
>> +			iio_trigger_detach_poll_func(oldtrig,
>> +						     indio_dev->pollfunc);
>>   		iio_trigger_put(oldtrig);
>> -	if (indio_dev->trig)
>> +	}
>> +	if (indio_dev->trig) {
>>   		iio_trigger_get(indio_dev->trig);
>> +		if (indio_dev->currentmode == INDIO_EVENT_TRIGGERED)
>> +			iio_trigger_attach_poll_func(indio_dev->trig,
>> +						     indio_dev->pollfunc);
>> +	}
>>   
>>   	return len;
>>   }
>> diff --git a/drivers/iio/industrialio-triggered-event.c b/drivers/iio/industrialio-triggered-event.c
>> new file mode 100644
>> index 0000000..1e5ad33
>> --- /dev/null
>> +++ b/drivers/iio/industrialio-triggered-event.c
>> @@ -0,0 +1,68 @@
>> + /*
>> + * Copyright (C) 2015 Cogent Embedded, Inc.
>> + *
>> + * This program is free software; you can redistribute  it and/or modify it
>> + * under  the terms of  the GNU General  Public License as published by the
>> + * Free Software Foundation;  either version 2 of the  License, or (at your
>> + * option) any later version.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/export.h>
>> +#include <linux/module.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/triggered_event.h>
>> +#include <linux/iio/trigger_consumer.h>
>> +
>> +/**
>> + * iio_triggered_event_setup() - Setup pollfunc for triggered event
>> + * @indio_dev:		IIO device structure
>> + * @pollfunc_bh:	Function which will be used as pollfunc bottom half
>> + * @pollfunc_th:	Function which will be used as pollfunc top half
>> + *
>> + * This function combines some common tasks which will normally be performed
>> + * when setting up a triggered event. It will allocate the pollfunc and
>> + * set mode to use it for triggered event.
>> + *
>> + * Before calling this function the indio_dev structure should already be
>> + * completely initialized, but not yet registered. In practice this means that
>> + * this function should be called right before iio_device_register().
>> + *
>> + * To free the resources allocated by this function call
>> + * iio_triggered_event_cleanup().
>> + */
>> +int iio_triggered_event_setup(struct iio_dev *indio_dev,
>> +	irqreturn_t (*pollfunc_bh)(int irq, void *p),
>> +	irqreturn_t (*pollfunc_th)(int irq, void *p))
>> +{
>> +	indio_dev->pollfunc = iio_alloc_pollfunc(pollfunc_bh,
>> +						 pollfunc_th,
>> +						 IRQF_ONESHOT,
>> +						 indio_dev,
>> +						 "%s_consumer%d",
>> +						 indio_dev->name,
>> +						 indio_dev->id);
>> +	if (indio_dev->pollfunc == NULL)
>> +		return -ENOMEM;
>> +
>> +	/* Flag that pollfunc is used for triggered event */
>> +	indio_dev->modes |= INDIO_EVENT_TRIGGERED;
>> +	indio_dev->currentmode = INDIO_EVENT_TRIGGERED;
> Can conceive of a corner case here.  What if both buffer
> and event are being triggered?  No real problem with
> running them off the same trigger, but right now enabling
> one will take out the other.
To avoid conflict it should be separate pollfunc
(indio_dev->pollfunc_event = ...) since we do runtime pollfunc
attach/detach for both buffer and event interfaces.

>
> Might also want to not enable triggered event mode
> until we enable some events?
I think it will need to change most drivers that use event interface since
events are enabled inside them via write_event_config() callback or
events may have already been enabled during driver probe.

>
> Perhaps we need separate indio_dev->event_mode and
event_modes ?
This probably not necessary since iio stack checks for flags set in
indio_dev->modes value.
> indio_dev->current_event_mode fields to make the two
> configurable independently?
I think it works, but with separate indio_dev->pollfunc_event.

Should it be inidio_dev->current_event_mode or 
inidio_dev->currentmode_event for
consistency?

I will verify your idea with using one trigger for both event and buffer 
interface on hi8435 driver
by adding buffer interface that I will try internally (will not send).

>
> I get the feeling this particular feature is going to evolve
> somewhat as we get a feel for how it is being used.
>
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(iio_triggered_event_setup);
>> +
>> +/**
>> + * iio_triggered_event_cleanup() - Free resources allocated by iio_triggered_event_setup()
>> + * @indio_dev: IIO device structure
>> + */
>> +void iio_triggered_event_cleanup(struct iio_dev *indio_dev)
>> +{
>> +	iio_dealloc_pollfunc(indio_dev->pollfunc);
>> +}
>> +EXPORT_SYMBOL(iio_triggered_event_cleanup);
>> +
>> +MODULE_AUTHOR("Vladimir Barinov");
>> +MODULE_DESCRIPTION("IIO helper functions for setting up triggered events");
>> +MODULE_LICENSE("GPL");
>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>> index f791482..b691ee0 100644
>> --- a/include/linux/iio/iio.h
>> +++ b/include/linux/iio/iio.h
>> @@ -294,6 +294,7 @@ static inline s64 iio_get_time_ns(void)
>>   #define INDIO_BUFFER_TRIGGERED		0x02
>>   #define INDIO_BUFFER_SOFTWARE		0x04
>>   #define INDIO_BUFFER_HARDWARE		0x08
>> +#define INDIO_EVENT_TRIGGERED		0x10
>>   
>>   #define INDIO_ALL_BUFFER_MODES					\
>>   	(INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE | INDIO_BUFFER_SOFTWARE)
>> diff --git a/include/linux/iio/triggered_event.h b/include/linux/iio/triggered_event.h
>> new file mode 100644
>> index 0000000..e9894e9
>> --- /dev/null
>> +++ b/include/linux/iio/triggered_event.h
>> @@ -0,0 +1,11 @@
>> +#ifndef _LINUX_IIO_TRIGGERED_EVENT_H_
>> +#define _LINUX_IIO_TRIGGERED_EVENT_H_
>> +
>> +#include <linux/interrupt.h>
>> +
>> +int iio_triggered_event_setup(struct iio_dev *indio_dev,
>> +	irqreturn_t (*pollfunc_bh)(int irq, void *p),
>> +	irqreturn_t (*pollfunc_th)(int irq, void *p));
> We renamed the parameters of the equivalent buffer function recently
> to avoid some confusion.  Could you follow that for this one as well.
Ok

>
>> +void iio_triggered_event_cleanup(struct iio_dev *indio_dev);
>> +
>> +#endif
>>