Re: [RFC 10/11] iio: Add OF support

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Jan 31, 2013 at 11:20:54PM +0100, Peter Meerwald wrote:
> 
> > Provide bindings, new API access functions, and parse OF data
> > during initialization.
> 
> nitpicking below
> 
Hi Peter,

Still good feedback.

> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> > ---
> >  .../devicetree/bindings/iio/iio-bindings.txt       |   97 ++++++++
> >  drivers/iio/inkern.c                               |  241 ++++++++++++++++----
> >  include/linux/iio/consumer.h                       |    8 +
> >  3 files changed, 299 insertions(+), 47 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/iio/iio-bindings.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/iio-bindings.txt b/Documentation/devicetree/bindings/iio/iio-bindings.txt
> > new file mode 100644
> > index 0000000..0f51c95
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt
> > @@ -0,0 +1,97 @@
> > +This binding is a work-in-progress, and are based on clock bindings and
> 
> is based
> 
> At first I got confused how clock bindings relate to this.
> 
If you replace all mention of "IIO" with "clock", and "io-channel" with
"clocks", the text is almost the same as the text in
Documentation/devicetree/bindings/clock/clock-bindings.txt.
Not sure how to express that better. Please let me know if you have an idea.

Thanks,
Guenter

> > +suggestions from Lars-Peter Clausen [1].
> > +
> > +Sources of IIO channels can be represented by any node in the device
> > +tree.  Those nodes are designated as IIO providers.  IIO consumer
> > +nodes use a phandle and IIO specifier pair to connect IIO provider
> > +outputs to IIO inputs.  Similar to the gpio specifiers, an IIO
> > +specifier is an array of one more more cells identifying the IIO
> 
> of one or more cells?
> 
> > +output on a device.  The length of an IIO specifier is defined by the
> > +value of a #io-channel-cells property in the clock provider node.
> > +
> > +[1] http://marc.info/?l=linux-iio&m=135902119507483&w=2
> > +
> > +==IIO providers==
> > +
> > +Required properties:
> > +#io-channel-cells: Number of cells in an IIO specifier; Typically 0 for nodes
> > +		   with a single IIO output and 1 for nodes with multiple
> > +		   IIO outputs.
> > +
> > +Optional properties:
> > +io-channel-output-names:
> > +		    Recommended to be a list of strings of IIO output signal
> > +		    names indexed by the first cell in the IIO specifier.
> > +		    However, the meaning of io-channel-output-names is domain
> > +		    specific to the IIO provider, and is only provided to
> > +		    encourage using the same meaning for the majority of IIO
> > +		    providers.  This format may not work for IIO providers
> > +		    using a complex IIO specifier format.  In those cases it
> > +		    is recommended to omit this property and create a binding
> > +		    specific names property.
> > +
> > +		    IIO consumer nodes must never directly reference
> > +		    the provider's io-channel-output-names property.
> > +
> > +For example:
> > +
> > +    adc: adc@35 {
> > +	compatible = "maxim,max1139";
> > +	reg = <0x35>;
> > +        #io-channel-cells = <1>;
> > +        io-channel-output-names = "adc1", "adc2";
> > +    };
> > +
> > +- this node defines a device with two named IIO outputs, the first named
> > +  "adc1" and the second named "adc2".  Consumer nodes always reference
> > +  IIO channels by index. The names should reflect the IIO output signal
> > +  names for the device.
> 
> maybe start with: This node defines... as below?
> 
> > +
> > +==IIO consumers==
> > +
> > +Required properties:
> > +io-channels:	List of phandle and IIO specifier pairs, one pair
> > +		for each IIO input to the device.  Note: if the
> > +		IIO provider specifies '0' for #clock-cells, then
> > +		only the phandle portion of the pair will appear.
> > +
> > +Optional properties:
> > +io-channel-names:
> > +		List of IIO input name strings sorted in the same
> > +		order as the io-channels property.  Consumers drivers
> > +		will use io-channel-names to match IIO input names
> > +		with IIO specifiers.
> > +io-channel-ranges:
> > +		Empty property indicating that child nodes can inherit named
> > +		IIO channels from this node. Useful for bus nodes to provide
> > +		and IIO channel to their children.
> > +
> > +For example:
> > +
> > +    device {
> > +        io-channels = <&adc 1>, <&ref 0>;
> > +        io-channel-names = "vcc", "vdd";
> > +    };
> > +
> > +This represents a device with two IIO inputs, named "vcc" and "vdd".
> > +The vcc channel is connected to output 1 of the &adc device, and the
> > +vdd channel is connected to output 0 of the &ref device.
> > +
> > +==Example==
> > +
> > +	adc: max1139@35 {
> > +		compatible = "maxim,max1139";
> > +		reg = <0x35>;
> > +		#io-channel-cells = <1>;
> > +	};
> > +
> > +	...
> > +
> > +	iio_hwmon {
> > +		compatible = "iio-hwmon";
> > +		io-channels = <&adc 0>, <&adc 1>, <&adc 2>,
> > +			<&adc 3>, <&adc 4>, <&adc 5>,
> > +			<&adc 6>, <&adc 7>, <&adc 8>,
> > +			<&adc 9>, <&adc 10>, <&adc 11>;
> > +		io-channel-names = "vcc", "vdd", "vref", "1.2V";
> > +	};
> > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> > index c42aba6..af80a18 100644
> > --- a/drivers/iio/inkern.c
> > +++ b/drivers/iio/inkern.c
> > @@ -10,6 +10,7 @@
> >  #include <linux/export.h>
> >  #include <linux/slab.h>
> >  #include <linux/mutex.h>
> > +#include <linux/of.h>
> >  
> >  #include <linux/iio/iio.h>
> >  #include "iio_core.h"
> > @@ -26,13 +27,55 @@ struct iio_map_internal {
> >  static LIST_HEAD(iio_map_list);
> >  static DEFINE_MUTEX(iio_map_list_lock);
> >  
> > +static struct iio_map *iio_map_of_init(struct iio_dev *idev)
> > +{
> > +	struct device_node *np = idev->dev.of_node;
> > +	struct iio_map *maps;
> > +	u32 cells, channels = 1;
> > +	int names, i, ret;
> > +
> > +	ret = of_property_read_u32(np, "#io-channel-cells", &cells);
> > +	if (ret < 0 || cells > 1)
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	names = of_property_count_strings(np, "io-channel-output-names");
> > +	if (names < 0)
> > +		names = 0;
> > +
> > +	if (channels < names)
> > +		channels = names;
> > +
> > +	maps = devm_kzalloc(&idev->dev, sizeof(*maps) * (channels + 1),
> > +			    GFP_KERNEL);
> > +	if (maps == NULL)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	for (i = 0; i < channels; i++) {
> > +		if (i < names) {
> > +			ret = of_property_read_string_index(np,
> > +				    "io-channel-output-names", i,
> > +				    &maps[i].consumer_channel);
> > +			if (ret < 0)
> > +				return ERR_PTR(ret);
> > +		}
> > +		/* Use dummy for consumer device names */
> > +		maps[i].consumer_dev_name = "of";
> > +	}
> > +	return maps;
> > +}
> > +
> >  int iio_map_array_register(struct iio_dev *indio_dev, struct iio_map *maps)
> >  {
> >  	int i = 0, ret = 0;
> >  	struct iio_map_internal *mapi;
> >  
> > -	if (maps == NULL)
> > -		return 0;
> > +	if (maps == NULL) {
> > +		maps = iio_map_of_init(indio_dev);
> > +		if (IS_ERR(maps))
> > +			return PTR_ERR(maps);
> > +		if (maps == NULL)
> > +			return 0;
> > +	}
> >  
> >  	mutex_lock(&iio_map_list_lock);
> >  	while (maps[i].consumer_dev_name != NULL) {
> > @@ -92,30 +135,14 @@ static const struct iio_chan_spec
> >  	return chan;
> >  }
> >  
> > -
> > -struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
> > +struct iio_channel *iio_channel_get_common(struct iio_map_internal *c,
> > +					   int index)
> >  {
> > -	struct iio_map_internal *c_i = NULL, *c = NULL;
> >  	struct iio_channel *channel;
> >  	int err;
> >  
> > -	if (name == NULL && channel_name == NULL)
> > -		return ERR_PTR(-ENODEV);
> > -
> > -	/* first find matching entry the channel map */
> > -	mutex_lock(&iio_map_list_lock);
> > -	list_for_each_entry(c_i, &iio_map_list, l) {
> > -		if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
> > -		    (channel_name &&
> > -		     strcmp(channel_name, c_i->map->consumer_channel) != 0))
> > -			continue;
> > -		c = c_i;
> > -		iio_device_get(c->indio_dev);
> > -		break;
> > -	}
> > -	mutex_unlock(&iio_map_list_lock);
> >  	if (c == NULL)
> > -		return ERR_PTR(-ENODEV);
> > +		return ERR_PTR(-EPROBE_DEFER);
> >  
> >  	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> >  	if (channel == NULL) {
> > @@ -125,7 +152,13 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
> >  
> >  	channel->indio_dev = c->indio_dev;
> >  
> > -	if (c->map->adc_channel_label) {
> > +	if (index >= 0) {
> > +		if (index >= c->indio_dev->num_channels) {
> > +			err = -EINVAL;
> > +			goto error_no_chan;
> > +		}
> > +		channel->channel = &c->indio_dev->channels[index];
> > +	} else if (c->map->adc_channel_label) {
> >  		channel->channel =
> >  			iio_chan_spec_from_name(channel->indio_dev,
> >  						c->map->adc_channel_label);
> > @@ -144,6 +177,60 @@ error_no_mem:
> >  	iio_device_put(c->indio_dev);
> >  	return ERR_PTR(err);
> >  }
> > +
> > +struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
> > +{
> > +	struct iio_map_internal *c_i, *c = NULL;
> > +	int err, map_index;
> > +	struct of_phandle_args iiospec;
> > +
> > +	if (index < 0)
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	err = of_parse_phandle_with_args(np, "io-channels",
> > +					 "#io-channel-cells",
> > +					 index, &iiospec);
> > +	if (err)
> > +		return ERR_PTR(err);
> > +
> > +	map_index = iiospec.args_count ? iiospec.args[0] : 0;
> > +
> > +	mutex_lock(&iio_map_list_lock);
> > +	list_for_each_entry(c_i, &iio_map_list, l) {
> > +		if (iiospec.np == c_i->indio_dev->dev.of_node) {
> > +			c = c_i;
> > +			iio_device_get(c->indio_dev);
> > +			break;
> > +		}
> > +	}
> > +	of_node_put(iiospec.np);
> > +	mutex_unlock(&iio_map_list_lock);
> > +	return iio_channel_get_common(c, index);
> > +}
> > +EXPORT_SYMBOL_GPL(of_iio_channel_get);
> > +
> > +struct iio_channel *iio_channel_get(const char *name,
> > +				    const char *channel_name)
> > +{
> > +	struct iio_map_internal *c_i = NULL, *c = NULL;
> > +
> > +	if (name == NULL && channel_name == NULL)
> > +		return ERR_PTR(-ENODEV);
> > +
> > +	/* first find matching entry the channel map */
> 
> of the channel map?
> 
> > +	mutex_lock(&iio_map_list_lock);
> > +	list_for_each_entry(c_i, &iio_map_list, l) {
> > +		if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
> > +		    (channel_name && strcmp(channel_name,
> > +					    c_i->map->consumer_channel) != 0))
> > +			continue;
> > +		c = c_i;
> > +		iio_device_get(c->indio_dev);
> > +		break;
> > +	}
> > +	mutex_unlock(&iio_map_list_lock);
> > +	return iio_channel_get_common(c, -1);
> > +}
> >  EXPORT_SYMBOL_GPL(iio_channel_get);
> >  
> >  void iio_channel_release(struct iio_channel *channel)
> > @@ -159,24 +246,43 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
> >  	struct iio_channel *chans;
> >  	struct iio_map_internal *c = NULL;
> >  	int nummaps = 0;
> > -	int mapind = 0;
> > +	int mapind;
> >  	int i, ret;
> >  
> >  	if (dev == NULL)
> >  		return ERR_PTR(-EINVAL);
> > +
> >  	name = dev_name(dev);
> >  
> >  	mutex_lock(&iio_map_list_lock);
> >  	/* first count the matching maps */
> > -	list_for_each_entry(c, &iio_map_list, l)
> > -		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
> > -			continue;
> > -		else
> > -			nummaps++;
> > -
> > -	if (nummaps == 0) {
> > -		ret = -ENODEV;
> > -		goto error_ret;
> > +	if (dev->of_node) {
> > +		nummaps = 0;
> > +		do {
> > +			int ret;
> > +
> > +			ret = of_parse_phandle_with_args(dev->of_node,
> > +							 "io-channels",
> > +							 "#io-channel-cells",
> > +							 nummaps, NULL);
> > +			if (ret < 0)
> > +				break;
> > +		} while (++nummaps);
> > +
> > +		if (nummaps == 0) {
> > +			ret = -ENODEV;
> > +			goto error_ret;
> > +		}
> > +	} else {
> > +		list_for_each_entry(c, &iio_map_list, l)
> > +			if (strcmp(name, c->map->consumer_dev_name) != 0)
> > +				continue;
> > +			else
> > +				nummaps++;
> > +		if (nummaps == 0) {
> > +			ret = -EPROBE_DEFER;
> > +			goto error_ret;
> > +		}
> >  	}
> >  
> >  	/* NULL terminated array to save passing size */
> > @@ -187,24 +293,65 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
> >  	}
> >  
> >  	/* for each map fill in the chans element */
> > -	list_for_each_entry(c, &iio_map_list, l) {
> > -		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
> > -			continue;
> > -		chans[mapind].indio_dev = c->indio_dev;
> > -		chans[mapind].data = c->map->consumer_data;
> > -		chans[mapind].channel =
> > -			iio_chan_spec_from_name(chans[mapind].indio_dev,
> > +	if (dev->of_node) {
> > +		/*
> > +		 * Device-tree based mapping, search for OF matches.
> > +		 */
> > +		for (mapind = 0; mapind < nummaps; mapind++) {
> > +			int channel;
> > +			struct of_phandle_args iiospec;
> > +
> > +			ret = of_parse_phandle_with_args(dev->of_node,
> > +							 "io-channels",
> > +							 "#io-channel-cells",
> > +							 mapind, &iiospec);
> > +			if (ret)
> > +				goto error_free_chans;
> > +			channel = iiospec.args_count ? iiospec.args[0] : 0;
> > +			ret = -EPROBE_DEFER;
> > +			list_for_each_entry(c, &iio_map_list, l) {
> > +				if (iiospec.np == c->indio_dev->dev.of_node) {
> > +					ret = 0;
> > +					break;
> > +				}
> > +			}
> > +			if (ret)
> > +				goto error_free_chans;
> > +			if (channel >= c->indio_dev->num_channels) {
> > +				ret = -EINVAL;
> > +				goto error_free_chans;
> > +			}
> > +			chans[mapind].indio_dev = c->indio_dev;
> > +			chans[mapind].data = c->map->consumer_data;
> > +			chans[mapind].channel =
> > +			  &c->indio_dev->channels[channel];
> > +			iio_device_get(c->indio_dev);
> > +		}
> > +	} else {
> > +		/*
> > +		 * Platform data based mapping, search for consumer
> > +		 * device name.
> > +		 */
> > +		mapind = 0;
> > +		list_for_each_entry(c, &iio_map_list, l) {
> > +			if (strcmp(name, c->map->consumer_dev_name) != 0)
> > +				continue;
> > +			chans[mapind].indio_dev = c->indio_dev;
> > +			chans[mapind].data = c->map->consumer_data;
> > +			chans[mapind].channel =
> > +				iio_chan_spec_from_name(c->indio_dev,
> >  						c->map->adc_channel_label);
> > -		if (chans[mapind].channel == NULL) {
> > -			ret = -EINVAL;
> > +			if (chans[mapind].channel == NULL) {
> > +				ret = -EINVAL;
> > +				goto error_free_chans;
> > +			}
> > +			iio_device_get(c->indio_dev);
> > +			mapind++;
> > +		}
> > +		if (mapind < nummaps) {
> > +			ret = -EPROBE_DEFER;
> >  			goto error_free_chans;
> >  		}
> > -		iio_device_get(chans[mapind].indio_dev);
> > -		mapind++;
> > -	}
> > -	if (mapind == 0) {
> > -		ret = -ENODEV;
> > -		goto error_free_chans;
> >  	}
> >  	mutex_unlock(&iio_map_list_lock);
> >  
> > diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> > index 6c44167..a347c15 100644
> > --- a/include/linux/iio/consumer.h
> > +++ b/include/linux/iio/consumer.h
> > @@ -41,6 +41,14 @@ struct iio_channel *iio_channel_get(const char *name,
> >  				    const char *consumer_channel);
> >  
> >  /**
> > + * of_iio_channel_get() - get description of all that is needed to access
> > + *			channel from OF node pointer.
> > + * @np:			Consumer's OF node pointer.
> > + * @index:		Index pointing to the io-channels entry in np.
> > + */
> > +struct iio_channel *of_iio_channel_get(struct device_node *np, int index);
> > +
> > +/**
> >   * iio_channel_release() - release channels obtained via iio_channel_get
> >   * @chan:		The channel to be released.
> >   */
> > 
> 
> -- 
> 
> Peter Meerwald
> +43-664-2444418 (mobile)
>