Re: [PATCH 28/70] staging:iio: Add infrastructure for irq_chip based triggers

[Jonathan Cameron <jic23@cam.ac.uk>]

Change of plan here.

It's perfectly possible, (but somewhat under utilized) to call irq_alloc_descs
to give us a dynamically allocated range of irq's. It may be dependant on sparse irq
though so will need to look into that or provide alternative method such
as this one.
> fix to merge back for the incorrect multiple trigger handling
> 
> V2: Stop silly name duplication.
>     Move pool handling to industrialio-trigger as that is the only user.
>     Changed over to using irq_modify_status rather than the arm
>     specific set_irq_flags as per Thomas Gleixner's suggestion.
> 
> Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
> ---
>  drivers/staging/Makefile                      |    2 +-
>  drivers/staging/iio/Kconfig                   |   12 ++
>  drivers/staging/iio/Makefile                  |    2 +
>  drivers/staging/iio/iio-board-info.h          |   24 +++
>  drivers/staging/iio/iio-core.h                |   13 ++
>  drivers/staging/iio/industrialio-board-info.c |   25 +++
>  drivers/staging/iio/industrialio-trigger.c    |  200 +++++++++++++++++++++----
>  drivers/staging/iio/trigger.h                 |   57 +++++++-
>  8 files changed, 298 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
> index eb93012..0955c7c 100644
> --- a/drivers/staging/Makefile
> +++ b/drivers/staging/Makefile
> @@ -41,7 +41,7 @@ obj-$(CONFIG_VT6656)		+= vt6656/
>  obj-$(CONFIG_HYPERV)		+= hv/
>  obj-$(CONFIG_VME_BUS)		+= vme/
>  obj-$(CONFIG_DX_SEP)            += sep/
> -obj-$(CONFIG_IIO)		+= iio/
> +obj-y				+= iio/
>  obj-$(CONFIG_CS5535_GPIO)	+= cs5535_gpio/
>  obj-$(CONFIG_ZRAM)		+= zram/
>  obj-$(CONFIG_XVMALLOC)		+= zram/
> diff --git a/drivers/staging/iio/Kconfig b/drivers/staging/iio/Kconfig
> index 6775bf9..df9aa08 100644
> --- a/drivers/staging/iio/Kconfig
> +++ b/drivers/staging/iio/Kconfig
> @@ -12,6 +12,10 @@ menuconfig IIO
>  	  Documentation/industrialio for more information.
>  if IIO
>  
> +config IIO_BOARDINFO
> +       boolean
> +       default y
> +
>  config IIO_RING_BUFFER
>  	bool "Enable ring buffer support within IIO"
>  	help
> @@ -42,12 +46,20 @@ endif # IIO_RINGBUFFER
>  
>  config IIO_TRIGGER
>  	boolean "Enable triggered sampling support"
> +	depends on IIO_BOARDINFO
>  	help
>  	  Provides IIO core support for triggers.  Currently these
>  	  are used to initialize capture of samples to push into
>  	  ring buffers.  The triggers are effectively a 'capture
>  	  data now' interrupt.
>  
> +config IIO_CONSUMERS_PER_TRIGGER
> +       int "Maximum number of consumers per trigger"
> +       depends on IIO_TRIGGER
> +       default "2"
> +       help
> +	This value controls the maximum number of consumers that a
> +	given trigger may handle. Default is 2.
>  
>  source "drivers/staging/iio/accel/Kconfig"
>  source "drivers/staging/iio/adc/Kconfig"
> diff --git a/drivers/staging/iio/Makefile b/drivers/staging/iio/Makefile
> index bb5c95c..37b4d12 100644
> --- a/drivers/staging/iio/Makefile
> +++ b/drivers/staging/iio/Makefile
> @@ -2,6 +2,8 @@
>  # Makefile for the industrial I/O core.
>  #
>  
> +obj-$(CONFIG_IIO_BOARDINFO) += industrialio-board-info.o
> +
>  obj-$(CONFIG_IIO) += industrialio.o
>  industrialio-y := industrialio-core.o
>  industrialio-$(CONFIG_IIO_RING_BUFFER) += industrialio-ring.o
> diff --git a/drivers/staging/iio/iio-board-info.h b/drivers/staging/iio/iio-board-info.h
> new file mode 100644
> index 0000000..c608a4d
> --- /dev/null
> +++ b/drivers/staging/iio/iio-board-info.h
> @@ -0,0 +1,24 @@
> +/*
> + * Board information for IIO.
> + *
> + * Copyright (c) 2011 Jonathan Cameron <jic23@cam.ac.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifdef CONFIG_IIO_BOARDINFO
> +
> +/**
> + * iio_set_irq_pool() - provid iio with a pool of virtaul interrupts to use
> + * @start: start of the pool
> + * @num: number of interupts in the pool
> + **/
> +void iio_set_irq_pool(int start, int num);
> +
> +#else
> +
> +static inline void iio_set_irq_pool(int start, int num) {};
> +
> +#endif
> diff --git a/drivers/staging/iio/iio-core.h b/drivers/staging/iio/iio-core.h
> new file mode 100644
> index 0000000..2c4f433
> --- /dev/null
> +++ b/drivers/staging/iio/iio-core.h
> @@ -0,0 +1,13 @@
> +/*
> + * IIO core header. Should never be included by drivers.
> + *
> + * Copyright (c) 2011 Jonathan Cameron <jic23@cam.ac.uk>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#define IIO_MAX_POOL 128
> +extern int __iio_irqstart;
> +extern int __iio_irqnum;
> diff --git a/drivers/staging/iio/industrialio-board-info.c b/drivers/staging/iio/industrialio-board-info.c
> new file mode 100644
> index 0000000..28f9156
> --- /dev/null
> +++ b/drivers/staging/iio/industrialio-board-info.c
> @@ -0,0 +1,25 @@
> +/* IIO Board info
> + *
> + * Copyright (c) 2011 Jonathan Cameron
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include "iio-core.h"
> +
> +int __iio_irqstart;
> +EXPORT_SYMBOL(__iio_irqstart);
> +int __iio_irqnum;
> +EXPORT_SYMBOL(__iio_irqnum);
> +
> +void __init iio_set_irq_pool(int start, int num)
> +{
> +	__iio_irqstart = start;
> +	__iio_irqnum = num;
> +	if (num > IIO_MAX_POOL)
> +		__iio_irqnum = IIO_MAX_POOL;
> +}
> diff --git a/drivers/staging/iio/industrialio-trigger.c b/drivers/staging/iio/industrialio-trigger.c
> index 083847c..9ccc789 100644
> --- a/drivers/staging/iio/industrialio-trigger.c
> +++ b/drivers/staging/iio/industrialio-trigger.c
> @@ -19,6 +19,7 @@
>  #include "iio.h"
>  #include "trigger.h"
>  #include "trigger_consumer.h"
> +#include "iio-core.h"
>  
>  /* RFC - Question of approach
>   * Make the common case (single sensor single trigger)
> @@ -38,6 +39,31 @@ static DEFINE_SPINLOCK(iio_trigger_idr_lock);
>  static LIST_HEAD(iio_trigger_list);
>  static DEFINE_MUTEX(iio_trigger_list_lock);
>  
> +static DEFINE_MUTEX(iio_irq_pool_lock);
> +static unsigned long iio_irq_pool_mask[BITS_TO_LONGS(IIO_MAX_POOL)] = {};
> +
> +static int iio_irq_pool_get_range(int num)
> +{
> +	int ret;
> +
> +	mutex_lock(&iio_irq_pool_lock);
> +	ret = bitmap_find_free_region(iio_irq_pool_mask,
> +				      __iio_irqnum, ilog2(num));
> +	if (ret >= 0)
> +		ret += __iio_irqstart;
> +	mutex_unlock(&iio_irq_pool_lock);
> +
> +	return ret;
> +}
> +
> +static void iio_irq_pool_put_range(int start, int num)
> +{
> +	mutex_lock(&iio_irq_pool_lock);
> +	bitmap_release_region(iio_irq_pool_mask,
> +			      start - __iio_irqstart, ilog2(num));
> +	mutex_unlock(&iio_irq_pool_lock);
> +}
> +
>  /**
>   * iio_trigger_register_sysfs() - create a device for this trigger
>   * @trig_info:	the trigger
> @@ -163,6 +189,7 @@ static struct iio_trigger *iio_trigger_find_by_name(const char *name,
>  
>  void iio_trigger_poll(struct iio_trigger *trig, s64 time)
>  {
> +	int i;
>  	struct iio_poll_func *pf_cursor;
>  
>  	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
> @@ -178,6 +205,13 @@ void iio_trigger_poll(struct iio_trigger *trig, s64 time)
>  			trig->use_count++;
>  		}
>  	}
> +	if (!trig->use_count) {
> +		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++)
> +			if (trig->subirqs[i].enabled) {
> +				trig->use_count++;
> +				generic_handle_irq(trig->subirq_base + i);
> +			}
> +	}
>  }
>  EXPORT_SYMBOL(iio_trigger_poll);
>  
> @@ -219,16 +253,31 @@ int iio_trigger_attach_poll_func(struct iio_trigger *trig,
>  	int ret = 0;
>  	unsigned long flags;
>  
> -	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
> -	list_add_tail(&pf->list, &trig->pollfunc_list);
> -	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
> -
> -	if (trig->set_trigger_state)
> -		ret = trig->set_trigger_state(trig, true);
> -	if (ret) {
> -		printk(KERN_ERR "set trigger state failed\n");
> -		list_del(&pf->list);
> +	if (pf->thread) {
> +		bool notinuse
> +			= bitmap_empty(trig->pool,
> +				       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
> +
> +		pf->irq = iio_trigger_get_irq(trig);
> +		ret = request_threaded_irq(pf->irq, pf->h, pf->thread,
> +					   pf->type, pf->name,
> +					   pf);
> +		if (trig->set_trigger_state && notinuse) {
> +			ret = trig->set_trigger_state(trig, true);
> +	} else {
> +		spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
> +		list_add_tail(&pf->list, &trig->pollfunc_list);
> +		spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
> +
> +		if (trig->set_trigger_state)
> +			ret = trig->set_trigger_state(trig, true);
> +		}
> +		if (ret) {
> +			printk(KERN_ERR "set trigger state failed\n");
> +			list_del(&pf->list);
> +		}
>  	}
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL(iio_trigger_attach_poll_func);
> @@ -240,37 +289,63 @@ int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
>  	unsigned long flags;
>  	int ret = -EINVAL;
>  
> -	spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
> -	list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
> -		if (pf_cursor == pf) {
> -			ret = 0;
> -			break;
> -		}
> -	if (!ret) {
> -		if (list_is_singular(&trig->pollfunc_list)
> -		    && trig->set_trigger_state) {
> -			spin_unlock_irqrestore(&trig->pollfunc_list_lock,
> -					       flags);
> -			/* May sleep hence cannot hold the spin lock */
> +	if (pf->thread) {
> +		bool no_other_users
> +			= (bitmap_weight(trig->pool,
> +					 CONFIG_IIO_CONSUMERS_PER_TRIGGER)
> +			   == 1);
> +		if (trig->set_trigger_state && no_other_users) {
>  			ret = trig->set_trigger_state(trig, false);
>  			if (ret)
>  				goto error_ret;
> -			spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
> +		} else
> +			ret = 0;
> +		iio_trigger_put_irq(trig, pf->irq);
> +		free_irq(pf->irq, pf);
> +	} else {
> +		spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
> +		list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
> +			if (pf_cursor == pf) {
> +				ret = 0;
> +				break;
> +			}
> +		if (!ret) {
> +			if (list_is_singular(&trig->pollfunc_list)
> +			    && trig->set_trigger_state) {
> +				spin_unlock_irqrestore(&trig
> +						       ->pollfunc_list_lock,
> +						       flags);
> +				/* May sleep hence cannot hold the spin lock */
> +				ret = trig->set_trigger_state(trig, false);
> +				if (ret)
> +					goto error_ret;
> +				spin_lock_irqsave(&trig->pollfunc_list_lock,
> +						  flags);
> +			}
> +			/*
> +			 * Now we can delete safe in the knowledge that, if
> +			 * this is the last pollfunc then we have disabled
> +			 * the trigger anyway and so nothing should be able
> +			 * to call the pollfunc.
> +			 */
> +			list_del(&pf_cursor->list);
>  		}
> -		/*
> -		 * Now we can delete safe in the knowledge that, if this is
> -		 * the last pollfunc then we have disabled the trigger anyway
> -		 * and so nothing should be able to call the pollfunc.
> -		 */
> -		list_del(&pf_cursor->list);
> +		spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
>  	}
> -	spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
>  
>  error_ret:
>  	return ret;
>  }
>  EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
>  
> +irqreturn_t iio_pollfunc_store_time(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	pf->timestamp = iio_get_time_ns();
> +	return IRQ_WAKE_THREAD;
> +}
> +EXPORT_SYMBOL(iio_pollfunc_store_time);
> +
>  /**
>   * iio_trigger_read_currrent() - trigger consumer sysfs query which trigger
>   *
> @@ -337,6 +412,22 @@ static const struct attribute_group iio_trigger_consumer_attr_group = {
>  static void iio_trig_release(struct device *device)
>  {
>  	struct iio_trigger *trig = to_iio_trigger(device);
> +	int i;
> +
> +	if (trig->subirq_base) {
> +		for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
> +			irq_modify_status(trig->subirq_base + i,
> +					  IRQ_NOAUTOEN,
> +					  IRQ_NOREQUEST | IRQ_NOPROBE);
> +			irq_set_chip(trig->subirq_base + i,
> +				     NULL);
> +			irq_set_handler(trig->subirq_base + i,
> +					NULL);
> +		}
> +
> +		iio_irq_pool_put_range(trig->subirq_base,
> +				       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
> +	}
>  	kfree(trig);
>  	iio_put();
>  }
> @@ -345,11 +436,30 @@ static struct device_type iio_trig_type = {
>  	.release = iio_trig_release,
>  };
>  
> -struct iio_trigger *iio_allocate_trigger(void)
> +static void iio_trig_subirqmask(struct irq_data *d)
> +{
> +	struct irq_chip *chip = irq_data_get_irq_chip(d);
> +	struct iio_trigger *trig
> +		= container_of(chip,
> +			       struct iio_trigger, subirq_chip);
> +	trig->subirqs[d->irq - trig->subirq_base].enabled = false;
> +}
> +
> +static void iio_trig_subirqunmask(struct irq_data *d)
> +{
> +	struct irq_chip *chip = irq_data_get_irq_chip(d);
> +	struct iio_trigger *trig
> +		= container_of(chip,
> +			       struct iio_trigger, subirq_chip);
> +	trig->subirqs[d->irq - trig->subirq_base].enabled = true;
> +}
> +
> +struct iio_trigger *iio_allocate_trigger_named(const char *name)
>  {
>  	struct iio_trigger *trig;
>  	trig = kzalloc(sizeof *trig, GFP_KERNEL);
>  	if (trig) {
> +		int i;
>  		trig->dev.type = &iio_trig_type;
>  		trig->dev.bus = &iio_bus_type;
>  		device_initialize(&trig->dev);
> @@ -357,10 +467,40 @@ struct iio_trigger *iio_allocate_trigger(void)
>  		spin_lock_init(&trig->pollfunc_list_lock);
>  		INIT_LIST_HEAD(&trig->list);
>  		INIT_LIST_HEAD(&trig->pollfunc_list);
> +
> +		if (name) {
> +			mutex_init(&trig->pool_lock);
> +			trig->subirq_base
> +				= iio_irq_pool_get_range(
> +					CONFIG_IIO_CONSUMERS_PER_TRIGGER);
> +			if (trig->subirq_base < 0) {
> +				kfree(trig);
> +				return NULL;
> +			}
> +			trig->name = name;
> +			trig->subirq_chip.name = name;
> +			trig->subirq_chip.irq_mask = &iio_trig_subirqmask;
> +			trig->subirq_chip.irq_unmask = &iio_trig_subirqunmask;
> +			for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
> +				irq_set_chip(trig->subirq_base + i,
> +					     &trig->subirq_chip);
> +				irq_set_handler(trig->subirq_base + i,
> +						&handle_simple_irq);
> +				irq_modify_status(trig->subirq_base + i,
> +						  IRQ_NOREQUEST | IRQ_NOAUTOEN,
> +						  IRQ_NOPROBE);
> +			}
> +		}
>  		iio_get();
>  	}
>  	return trig;
>  }
> +EXPORT_SYMBOL(iio_allocate_trigger_named);
> +
> +struct iio_trigger *iio_allocate_trigger(void)
> +{
> +	return iio_allocate_trigger_named(NULL);
> +}
>  EXPORT_SYMBOL(iio_allocate_trigger);
>  
>  void iio_free_trigger(struct iio_trigger *trig)
> diff --git a/drivers/staging/iio/trigger.h b/drivers/staging/iio/trigger.h
> index c6ab32f..0c44c5e 100644
> --- a/drivers/staging/iio/trigger.h
> +++ b/drivers/staging/iio/trigger.h
> @@ -6,9 +6,15 @@
>   * under the terms of the GNU General Public License version 2 as published by
>   * the Free Software Foundation.
>   */
> +#include <linux/irq.h>
> +
>  #ifndef _IIO_TRIGGER_H_
>  #define _IIO_TRIGGER_H_
>  
> +struct iio_subirq {
> +	bool enabled;
> +};
> +
>  /**
>   * struct iio_trigger - industrial I/O trigger device
>   *
> @@ -43,6 +49,13 @@ struct iio_trigger {
>  
>  	int (*set_trigger_state)(struct iio_trigger *trig, bool state);
>  	int (*try_reenable)(struct iio_trigger *trig);
> +
> +	struct irq_chip			subirq_chip;
> +	int				subirq_base;
> +
> +	struct iio_subirq subirqs[CONFIG_IIO_CONSUMERS_PER_TRIGGER];
> +	unsigned long pool[BITS_TO_LONGS(CONFIG_IIO_CONSUMERS_PER_TRIGGER)];
> +	struct mutex			pool_lock;
>  };
>  
>  static inline struct iio_trigger *to_iio_trigger(struct device *d)
> @@ -114,6 +127,27 @@ int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
>  void iio_trigger_poll(struct iio_trigger *trig, s64 time);
>  void iio_trigger_notify_done(struct iio_trigger *trig);
>  
> +static inline int iio_trigger_get_irq(struct iio_trigger *trig)
> +{
> +	int ret;
> +	mutex_lock(&trig->pool_lock);
> +	ret = bitmap_find_free_region(trig->pool,
> +				      CONFIG_IIO_CONSUMERS_PER_TRIGGER,
> +				      ilog2(1));
> +	mutex_unlock(&trig->pool_lock);
> +	if (ret >= 0)
> +		ret += trig->subirq_base;
> +
> +	return ret;
> +};
> +
> +static inline void iio_trigger_put_irq(struct iio_trigger *trig, int irq)
> +{
> +	mutex_lock(&trig->pool_lock);
> +	clear_bit(irq - trig->subirq_base, trig->pool);
> +	mutex_unlock(&trig->pool_lock);
> +};
> +
>  /**
>   * struct iio_poll_func - poll function pair
>   *
> @@ -125,11 +159,14 @@ void iio_trigger_notify_done(struct iio_trigger *trig);
>   * @poll_func_main:		function in here is run after all immediates.
>   *				Reading from sensor etc typically involves
>   *				scheduling from here.
> - *
> - * The two stage approach used here is only important when multiple sensors are
> - * being triggered by a single trigger. This really comes into its own with
> - * simultaneous sampling devices where a simple latch command can be used to
> - * make the device store the values on all inputs.
> + * @h:				the function that is actually run on trigger
> + * @thread:			threaded interrupt part
> + * @type:			the type of interrupt (basically if oneshot)
> + * @irq:			the corresponding irq as allocated from the
> + *				trigger pool
> + * @timestamp:			some devices need a timestamp grabbed as soon
> + *				as possible after the trigger - hence handler
> + *				passes it via here.
>   **/
>  struct iio_poll_func {
>  	struct				list_head list;
> @@ -137,12 +174,20 @@ struct iio_poll_func {
>  	void (*poll_func_immediate)(struct iio_dev *indio_dev);
>  	void (*poll_func_main)(struct iio_dev *private_data, s64 time);
>  
> +	irqreturn_t (*h)(int irq, void *p);
> +	irqreturn_t (*thread)(int irq, void *p);
> +	int type;
> +	char *name;
> +	int irq;
> +	s64 timestamp;
>  };
>  
>  int iio_alloc_pollfunc(struct iio_dev *indio_dev,
>  		       void (*immediate)(struct iio_dev *indio_dev),
>  		       void (*main)(struct iio_dev *private_data, s64 time));
>  
> +irqreturn_t iio_pollfunc_store_time(int irq, void *p);
> +
>  /*
>   * Two functions for common case where all that happens is a pollfunc
>   * is attached and detached from a trigger
> @@ -151,7 +196,7 @@ int iio_triggered_ring_postenable(struct iio_dev *indio_dev);
>  int iio_triggered_ring_predisable(struct iio_dev *indio_dev);
>  
>  struct iio_trigger *iio_allocate_trigger(void);
> -
> +struct iio_trigger *iio_allocate_trigger_named(const char *name);
>  void iio_free_trigger(struct iio_trigger *trig);
>  
>  #endif /* _IIO_TRIGGER_H_ */