On 02/10/14 13:32, Ivan T. Ivanov wrote:
> When #iio-cells is greater than '0', the driver could provide
> a custom of_xlate function that reads the *args* and returns
> the appropriate index in registered IIO channels array.
>
> Add simple translation function, suitable for the most 1:1
> mapped channels in IIO chips, and use it when driver did not
> provide custom implementation.
>
> Signed-off-by: Ivan T. Ivanov <iiva...@mm-sol.com>
Any more comments on this? Been sat a while and the discussions seems
to have died out.
As Ivan has pointed out, very similar approaches are used
elsewhere (gpio for example).
> ---
> drivers/iio/inkern.c | 32 +++++++++++++++++++++++++++-----
> include/linux/iio/iio.h | 8 ++++++++
> 2 files changed, 35 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index f084610..6c3e478 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -100,6 +100,28 @@ static int iio_dev_node_match(struct device *dev, void
> *data)
> return dev->of_node == data && dev->type == &iio_device_type;
> }
>
> +/**
> + * __of_iio_simple_xlate - translate iiospec to the IIO channel index
> + * @indio_dev: pointer to the iio_dev structure
> + * @iiospec: IIO specifier as found in the device tree
> + *
> + * This is simple translation function, suitable for the most 1:1 mapped
> + * channels in IIO chips. This function performs only one sanity check:
> + * whether IIO index is less than num_channels (that is specified in the
> + * iio_dev).
> + */
> +static int __of_iio_simple_xlate(struct iio_dev *indio_dev,
> + const struct of_phandle_args *iiospec)
> +{
> + if (!iiospec->args_count)
> + return 0;
> +
> + if (iiospec->args[0] >= indio_dev->num_channels)
> + return -EINVAL;
> +
> + return iiospec->args[0];
> +}
> +
> static int __of_iio_channel_get(struct iio_channel *channel,
> struct device_node *np, int index)
> {
> @@ -122,18 +144,18 @@ static int __of_iio_channel_get(struct iio_channel
> *channel,
>
> indio_dev = dev_to_iio_dev(idev);
> channel->indio_dev = indio_dev;
> - index = iiospec.args_count ? iiospec.args[0] : 0;
> - if (index >= indio_dev->num_channels) {
> - err = -EINVAL;
> + if (!indio_dev->of_xlate)
> + indio_dev->of_xlate = __of_iio_simple_xlate;
> + index = indio_dev->of_xlate(indio_dev, &iiospec);
> + if (index < 0)
> goto err_put;
> - }
> channel->channel = &indio_dev->channels[index];
>
> return 0;
>
> err_put:
> iio_device_put(indio_dev);
> - return err;
> + return index;
> }
>
> static struct iio_channel *of_iio_channel_get(struct device_node *np, int
> index)
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index 15dc6bc..d5bb219 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -13,6 +13,7 @@
> #include <linux/device.h>
> #include <linux/cdev.h>
> #include <linux/iio/types.h>
> +#include <linux/of.h>
> /* IIO TODO LIST */
> /*
> * Provide means of adjusting timer accuracy.
> @@ -413,6 +414,11 @@ struct iio_buffer_setup_ops {
> * @currentmode: [DRIVER] current operating mode
> * @dev: [DRIVER] device structure, should be assigned a parent
> * and owner
> + * @of_xlate: [DRIVER] function pointer to obtain channel
> specifier
> + * index. When #iio-cells is greater than '0', the driver
> + * could provide a custom of_xlate function that reads
> + * the *args* and returns the appropriate index in
> + * registered IIO channels array.
> * @event_interface: [INTERN] event chrdevs associated with interrupt lines
> * @buffer: [DRIVER] any buffer present
> * @buffer_list: [INTERN] list of all buffers currently attached
> @@ -451,6 +457,8 @@ struct iio_dev {
> int currentmode;
> struct device dev;
>
> + int (*of_xlate)(struct iio_dev *indio_dev,
> + const struct of_phandle_args *iiospec);
> struct iio_event_interface *event_interface;
>
> struct iio_buffer *buffer;
>
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