Re: [RFC PATCH 08/14] iio: core: use new common ioctl() mechanism

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

On Sun, 2020-05-24 at 17:47 +0100, Jonathan Cameron wrote:
> [External]
> 
> On Fri, 8 May 2020 16:53:42 +0300
> Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:
> 
> > This change makes use of the new centralized ioctl() mechanism. The event
> > interface registers it's ioctl() handler to IIO device.
> > Both the buffer & event interface call 'iio_device_ioctl()', which should
> > take care of all of indio_dev's ioctl() calls.
> > 
> > Later, we may add per-buffer ioctl() calls, and since each buffer will get
> > it's own chardev, the buffer ioctl() handler will need a bit of tweaking
> > for the first/legacy buffer (i.e. indio_dev->buffer).
> 
> Do we have an ioctls that aren't safe if we just use them on 'any'
> buffer?  I don't think we do yet, though I guess we may have in the future.
> 

This was done in the idea that we may want to keep the /dev/iio:deviceX for
backwards compatibility.
But, it's undetermined yet how this will look.
I am currently working on more rework stuff [as you've seen].
I'd try to do some of the rework now, before adding more stuff [like
iio_dev_opaque].
To avoid adding this work, then having to rework it.

> 
> > Also, those per-buffer ioctl() calls will not be registered with this
> > mechanism.
> > 
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> > ---
> >  drivers/iio/iio_core.h            |  3 ---
> >  drivers/iio/industrialio-buffer.c |  2 +-
> >  drivers/iio/industrialio-event.c  | 14 ++++++++------
> >  3 files changed, 9 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
> > index 34c3e19229d8..f68de4af2738 100644
> > --- a/drivers/iio/iio_core.h
> > +++ b/drivers/iio/iio_core.h
> > @@ -54,9 +54,6 @@ ssize_t iio_format_value(char *buf, unsigned int type, int
> > size, int *vals);
> >  #ifdef CONFIG_IIO_BUFFER
> >  struct poll_table_struct;
> >  
> > -long iio_device_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
> > -			    unsigned int cmd, unsigned long arg);
> > -
> >  void iio_device_buffer_attach_chrdev(struct iio_dev *indio_dev);
> >  
> >  int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-
> > buffer.c
> > index 1400688f5e42..e7a847e7b103 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -1199,7 +1199,7 @@ static long iio_buffer_ioctl(struct file *filep,
> > unsigned int cmd,
> >  	if (!buffer || !buffer->access)
> >  		return -ENODEV;
> >  
> > -	return iio_device_event_ioctl(buffer->indio_dev, filep, cmd, arg);
> > +	return iio_device_ioctl(buffer->indio_dev, filep, cmd, arg);
> >  }
> >  
> >  static ssize_t iio_buffer_store_enable(struct device *dev,
> > diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-
> > event.c
> > index 0674b2117c98..1961c1d19370 100644
> > --- a/drivers/iio/industrialio-event.c
> > +++ b/drivers/iio/industrialio-event.c
> > @@ -32,6 +32,7 @@
> >   * @read_lock:		lock to protect kfifo read operations
> >   * @chrdev:		associated chardev for this event
> >   * @indio_dev:		IIO device to which this event interface belongs
> > to
> > + * @ioctl_handler:	handler for event ioctl() calls
> >   */
> >  struct iio_event_interface {
> >  	wait_queue_head_t	wait;
> > @@ -44,6 +45,7 @@ struct iio_event_interface {
> >  
> >  	struct cdev		chrdev;
> >  	struct iio_dev		*indio_dev;
> > +	struct iio_ioctl_handler	ioctl_handler;
> >  };
> >  
> >  bool iio_event_enabled(const struct iio_event_interface *ev_int)
> > @@ -261,15 +263,12 @@ static int iio_chrdev_release(struct inode *inode,
> > struct file *filp)
> >  	return 0;
> >  }
> >  
> > -long iio_device_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
> > +static long iio_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
> >  			    unsigned int cmd, unsigned long arg)
> >  {
> >  	int __user *ip = (int __user *)arg;
> >  	int fd;
> >  
> > -	if (!indio_dev->info)
> > -		return -ENODEV;
> > -
> >  	if (cmd == IIO_GET_EVENT_FD_IOCTL) {
> >  		fd = iio_event_getfd(indio_dev);
> >  		if (fd < 0)
> > @@ -278,7 +277,7 @@ long iio_device_event_ioctl(struct iio_dev *indio_dev,
> > struct file *filp,
> >  			return -EFAULT;
> >  		return 0;
> >  	}
> > -	return -EINVAL;
> > +	return IIO_IOCTL_UNHANDLED;
> >  }
> >  
> >  static long iio_event_ioctl_wrapper(struct file *filp, unsigned int cmd,
> > @@ -286,7 +285,7 @@ static long iio_event_ioctl_wrapper(struct file *filp,
> > unsigned int cmd,
> >  {
> >  	struct iio_event_interface *ev = filp->private_data;
> >  
> > -	return iio_device_event_ioctl(ev->indio_dev, filp, cmd, arg);
> > +	return iio_device_ioctl(ev->indio_dev, filp, cmd, arg);
> >  }
> >  
> >  static const struct file_operations iio_event_fileops = {
> > @@ -308,7 +307,10 @@ void iio_device_event_attach_chrdev(struct iio_dev
> > *indio_dev)
> >  	cdev_init(&ev->chrdev, &iio_event_fileops);
> >  
> >  	ev->indio_dev = indio_dev;
> > +	ev->ioctl_handler.ioctl = iio_event_ioctl;
> >  	indio_dev->chrdev = &ev->chrdev;
> > +
> > +	iio_device_ioctl_handler_register(indio_dev, &ev->ioctl_handler);
> >  }
> >  
> >  static const char * const iio_ev_type_text[] = {