Re: [PATCH v2 1/2] iio: Move scan mask management to the core

["Ardelean, Alexandru" <alexandru.Ardelean@analog.com>]

On Sun, 2020-05-03 at 13:51 +0100, Jonathan Cameron wrote:
> On Wed, 29 Apr 2020 18:17:39 +0300
> Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:
> 
> > From: Lars-Peter Clausen <lars@metafoo.de>
> > 
> > Let the core handle the buffer scan mask management including allocation
> > and channel selection. Having this handled in a central place rather than
> > open-coding it all over the place will make it easier to change the
> > implementation (if needed).
> > At the very least, this change abstracts scan-mask management away from
> > buffer implementations.
> > 
> > Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> 
> I'm not 100% happy with including the buffer_impl.h header in the inkern
> code, but I can't see a simple way around it.

I actually also tried to not do it [I suspect Lars may have tried as well].
But you end up either having to expose 'struct iio_channel' outside of
'inkern.c' or having to include 'iio/consumer.h' in industrialio-buffer.c

Since there will be a V3, I will probably try to look again at a potential
different solution. Maybe there is a better solution I haven't considered.

> 
> However, there are some missing statics in here and I'm feeling lazy
> so not going to fix them up for you.
> 

No problem from my side.
I'll fix them up.
I prefer it when people don't cleanup after me. Makes me feel less guilty.
Though I will admit, it's a double-edged feeling: I am greatful when someone
cleans up after me, but I also feel slightly guilty [about it].


> Thanks,
> 
> Jonathan
> 
> > ---
> > 
> > Changelog v1 -> v2:
> > - split away from initial series; the `buffer->channel_mask` attribute
> >   requires a bit more dicussion; or may even be dropped; just these 2
> >   patches helps with diff-ing 2 trees, as applying patches between my
> >   work tree & IIO has fewer conflicts
> > - return -EINVAL if masklength is 0 in iio_buffer_alloc_scanmask()
> > - convert 2nd parameter to `unsigned int masklength` in
> >   iio_buffer_alloc_scanmask()
> > 
> >  drivers/iio/buffer/industrialio-buffer-cb.c | 17 +++++-----
> >  drivers/iio/industrialio-buffer.c           | 36 +++++++++++++++------
> >  drivers/iio/inkern.c                        | 15 +++++++++
> >  include/linux/iio/consumer.h                | 10 ++++++
> >  4 files changed, 59 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/iio/buffer/industrialio-buffer-cb.c
> > b/drivers/iio/buffer/industrialio-buffer-cb.c
> > index 47c96f7f4976..dc5bb2ab533a 100644
> > --- a/drivers/iio/buffer/industrialio-buffer-cb.c
> > +++ b/drivers/iio/buffer/industrialio-buffer-cb.c
> > @@ -34,7 +34,7 @@ static void iio_buffer_cb_release(struct iio_buffer
> > *buffer)
> >  {
> >  	struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);
> >  
> > -	bitmap_free(cb_buff->buffer.scan_mask);
> > +	iio_buffer_free_scanmask(&cb_buff->buffer);
> >  	kfree(cb_buff);
> >  }
> >  
> > @@ -72,27 +72,26 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct
> > device *dev,
> >  	}
> >  
> >  	cb_buff->indio_dev = cb_buff->channels[0].indio_dev;
> > -	cb_buff->buffer.scan_mask = bitmap_zalloc(cb_buff->indio_dev-
> > >masklength,
> > -						  GFP_KERNEL);
> > -	if (cb_buff->buffer.scan_mask == NULL) {
> > -		ret = -ENOMEM;
> > +
> > +	ret = iio_buffer_alloc_scanmask(&cb_buff->buffer,
> > +					cb_buff->indio_dev->masklength);
> > +	if (ret)
> >  		goto error_release_channels;
> > -	}
> > +
> >  	chan = &cb_buff->channels[0];
> >  	while (chan->indio_dev) {
> >  		if (chan->indio_dev != cb_buff->indio_dev) {
> >  			ret = -EINVAL;
> >  			goto error_free_scan_mask;
> >  		}
> > -		set_bit(chan->channel->scan_index,
> > -			cb_buff->buffer.scan_mask);
> > +		iio_buffer_channel_enable(&cb_buff->buffer, chan);
> >  		chan++;
> >  	}
> >  
> >  	return cb_buff;
> >  
> >  error_free_scan_mask:
> > -	bitmap_free(cb_buff->buffer.scan_mask);
> > +	iio_buffer_free_scanmask(&cb_buff->buffer);
> >  error_release_channels:
> >  	iio_channel_release_all(cb_buff->channels);
> >  error_free_cb_buff:
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-
> > buffer.c
> > index eae39eaf49af..c6b63f4474ff 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -208,6 +208,26 @@ void iio_buffer_init(struct iio_buffer *buffer)
> >  }
> >  EXPORT_SYMBOL(iio_buffer_init);
> >  
> > +int iio_buffer_alloc_scanmask(struct iio_buffer *buffer,
> > +			      unsigned int masklength)
> > +{
> > +	if (!masklength)
> > +		return -EINVAL;
> > +
> > +	buffer->scan_mask = bitmap_zalloc(masklength, GFP_KERNEL);
> > +	if (buffer->scan_mask == NULL)
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_alloc_scanmask);
> > +
> > +void iio_buffer_free_scanmask(struct iio_buffer *buffer)
> > +{
> > +	bitmap_free(buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_free_scanmask);
> > +
> >  /**
> >   * iio_buffer_set_attrs - Set buffer specific attributes
> >   * @buffer: The buffer for which we are setting attributes
> > @@ -1306,14 +1326,10 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev
> > *indio_dev)
> >  				indio_dev->scan_index_timestamp =
> >  					channels[i].scan_index;
> >  		}
> > -		if (indio_dev->masklength && buffer->scan_mask == NULL) {
> > -			buffer->scan_mask = bitmap_zalloc(indio_dev->masklength,
> > -							  GFP_KERNEL);
> > -			if (buffer->scan_mask == NULL) {
> > -				ret = -ENOMEM;
> > -				goto error_cleanup_dynamic;
> > -			}
> > -		}
> > +
> > +		ret = iio_buffer_alloc_scanmask(buffer, indio_dev->masklength);
> > +		if (ret)
> > +			goto error_cleanup_dynamic;
> >  	}
> >  
> >  	buffer->scan_el_group.name = iio_scan_elements_group_name;
> > @@ -1334,7 +1350,7 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev
> > *indio_dev)
> >  	return 0;
> >  
> >  error_free_scan_mask:
> > -	bitmap_free(buffer->scan_mask);
> > +	iio_buffer_free_scanmask(buffer);
> >  error_cleanup_dynamic:
> >  	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> >  	kfree(buffer->buffer_group.attrs);
> > @@ -1349,7 +1365,7 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev
> > *indio_dev)
> >  	if (!buffer)
> >  		return;
> >  
> > -	bitmap_free(buffer->scan_mask);
> > +	iio_buffer_free_scanmask(buffer);
> >  	kfree(buffer->buffer_group.attrs);
> >  	kfree(buffer->scan_el_group.attrs);
> >  	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> > index ede99e0d5371..f35cb9985edc 100644
> > --- a/drivers/iio/inkern.c
> > +++ b/drivers/iio/inkern.c
> > @@ -11,6 +11,7 @@
> >  
> >  #include <linux/iio/iio.h>
> >  #include "iio_core.h"
> > +#include <linux/iio/buffer_impl.h>
> >  #include <linux/iio/machine.h>
> >  #include <linux/iio/driver.h>
> >  #include <linux/iio/consumer.h>
> > @@ -857,6 +858,20 @@ int iio_write_channel_raw(struct iio_channel *chan, int
> > val)
> >  }
> >  EXPORT_SYMBOL_GPL(iio_write_channel_raw);
> >  
> > +void iio_buffer_channel_enable(struct iio_buffer *buffer,
> > +			       const struct iio_channel *chan)
> > +{
> > +	set_bit(chan->channel->scan_index, buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_channel_enable);
> > +
> > +void iio_buffer_channel_disable(struct iio_buffer *buffer,
> > +				const struct iio_channel *chan)
> > +{
> > +	clear_bit(chan->channel->scan_index, buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_channel_disable);
> > +
> >  unsigned int iio_get_channel_ext_info_count(struct iio_channel *chan)
> >  {
> >  	const struct iio_chan_spec_ext_info *ext_info;
> > diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> > index c4118dcb8e05..9fcd320c2fb4 100644
> > --- a/include/linux/iio/consumer.h
> > +++ b/include/linux/iio/consumer.h
> > @@ -12,6 +12,7 @@
> >  
> >  struct iio_dev;
> >  struct iio_chan_spec;
> > +struct iio_buffer;
> >  struct device;
> >  
> >  /**
> > @@ -342,6 +343,15 @@ int iio_read_channel_scale(struct iio_channel *chan,
> > int *val,
> >  int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
> >  	int *processed, unsigned int scale);
> >  
> > +void iio_buffer_channel_enable(struct iio_buffer *buffer,
> > +			       const struct iio_channel *chan);
> > +void iio_buffer_channel_disable(struct iio_buffer *buffer,
> > +				const struct iio_channel *chan);
> > +
> > +int iio_buffer_alloc_scanmask(struct iio_buffer *buffer,
> > +			      unsigned int masklength);
> > +void iio_buffer_free_scanmask(struct iio_buffer *buffer);
> > +
> >  /**
> >   * iio_get_channel_ext_info_count() - get number of ext_info attributes
> >   *				      connected to the channel.