Re: [PATCH v3 3/6] iio: Add support for indicating fixed watermarks

[Jonathan Cameron <jic23@kernel.org>]

On 13/10/15 17:10, Lars-Peter Clausen wrote:
> For buffers which have a fixed wake-up watermark the watermark attribute
> should be read-only. Add a new FIXED_WATERMARK flag to the
> struct iio_buffer_access_funcs, which can be set by a buffer
> implementation.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Applied.
> ---
>  drivers/iio/industrialio-buffer.c | 5 +++++
>  include/linux/iio/buffer.h        | 8 ++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index 5f2c8c8..98a6447 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -998,6 +998,8 @@ static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
>  		   iio_buffer_show_enable, iio_buffer_store_enable);
>  static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
>  		   iio_buffer_show_watermark, iio_buffer_store_watermark);
> +static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
> +	S_IRUGO, iio_buffer_show_watermark, NULL);
>  
>  static struct attribute *iio_buffer_attrs[] = {
>  	&dev_attr_length.attr,
> @@ -1040,6 +1042,9 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
>  	if (!buffer->access->set_length)
>  		attr[0] = &dev_attr_length_ro.attr;
>  
> +	if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
> +		attr[2] = &dev_attr_watermark_ro.attr;
> +
>  	if (buffer->attrs)
>  		memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
>  		       sizeof(struct attribute *) * attrcount);
> diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h
> index 1600c55..4d99a53 100644
> --- a/include/linux/iio/buffer.h
> +++ b/include/linux/iio/buffer.h
> @@ -18,6 +18,12 @@
>  struct iio_buffer;
>  
>  /**
> + * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
> + *   configured. It has a fixed value which will be buffer specific.
> + */
> +#define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
> +
> +/**
>   * struct iio_buffer_access_funcs - access functions for buffers.
>   * @store_to:		actually store stuff to the buffer
>   * @read_first_n:	try to get a specified number of bytes (must exist)
> @@ -30,6 +36,7 @@ struct iio_buffer;
>   * @release:		called when the last reference to the buffer is dropped,
>   *			should free all resources allocated by the buffer.
>   * @modes:		Supported operating modes by this buffer type
> + * @flags:		A bitmask combination of INDIO_BUFFER_FLAG_*
>   *
>   * The purpose of this structure is to make the buffer element
>   * modular as event for a given driver, different usecases may require
> @@ -54,6 +61,7 @@ struct iio_buffer_access_funcs {
>  	void (*release)(struct iio_buffer *buffer);
>  
>  	unsigned int modes;
> +	unsigned int flags;
>  };
>  
>  /**
>