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

[Lars-Peter Clausen <lars@metafoo.de>]

On 02/01/2013 03:33 PM, Guenter Roeck wrote:
> On Fri, Feb 01, 2013 at 12:58:02PM +0100, Lars-Peter Clausen wrote:
>> 013 10:43 PM, Guenter Roeck wrote:
>>> Provide bindings, new API access functions, and parse OF data
>>> during initialization.
>>>
>>
>> Hi Guenter,
>>
>> Thanks for taking care of this.
>>
>> I'd prefer to have only one iio_get_channel which handles both the dt and the
>> non-dt case. Otherwise we'll soon have constructs like
>>
>> if (dev->of_node)
>> 	chan = of_iio_get_channel(dev->of_node, 1);
>> else
>> 	chan = iio_get_channel(dev_name(dev), "vcc");
>>
>> appearing all over the place in drivers code. I'd keep the actual
>> implementation pretty close to what the clk framework does. E.g. take a look at
>> of_clk_get_by_name() and clk_get() in clkdev.c. And don't take a detour via the
>> iio_map lookup for the devicetree case, just loop over all IIO devices and
>> match by of_node. This should allow us to simplify the code quite a bit.
>>
> Yes, I just could not figure out how to loop over the list of iio devices. That
> is why I hijacked iio_map which does provide a list.
> 
> Any hints ?

Yes, use bus_find_device on iio_bus_type. A nice example how to use this to
lookup device by of node is of_find_i2c_device_by_node. For IIO you also need
to make sure that dev->type is iio_dev_type, since both devices and triggers
are registered on the same bus.

> 
> Thanks,
> Guenter
> 
>> - Lars
>>
>> On 01/31/2
>>
>>> 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
>>> +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
>>> +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.
>>> +
>>> +==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)
>>> +{
>>
>> To be honest I find this whole function a bit confusing. If we are using
>> devicetree, we shouldn't need to register iio_map. Maybe just skip over
>> io-channel-output-names for now, until we figure out if we really need this and
>> what for.
>>
>>> +	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 */
>>> +	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);
>>>  
>> [...]
>>
>>