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@xxxxxxxxxx> 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; > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html