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    SubjectRe: [PATCH] iio: inkern: Add of_xlate function to struct iio_dev
    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 <iivanov@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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