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Date:   Sun, 24 May 2020 17:47:38 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc:     <linux-iio@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <lars@metafoo.de>
Subject: Re: [RFC PATCH 08/14] iio: core: use new common ioctl() mechanism
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        <20200508135348.15229-9-alexandru.ardelean@analog.com>
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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.


> 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[] = {