Message-ID: <51322F93.7050803@kernel.org>
Date:	Sat, 02 Mar 2013 16:57:55 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	linux-iio@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	Naveen Krishna Chatradhi <ch.naveen@...sung.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Doug Anderson <dianders@...omium.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Anton Vorontsov <cbou@...l.ru>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v5] iio: Add OF support

On 02/07/2013 05:09 PM, Guenter Roeck wrote:
> Provide bindings and parse OF data during initialization.
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Applied to the togreg branch of iio.git with a small edit wrt
to removing the WIP line in the binding documenation.

I thought about putting something about subject to extension
but decided that was obviously the case so just removed the statement
and editting the next bit to make that work without it.

Thanks for your work on this Guenter.  Looks very good to me and
is clearly useful to have.

Will be in the togreg branch of
git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
shortly.
(I'll send a pull request to Greg in a week or so depending on
what else comes along, at that point it will be in the staging-next
tree and show up in Linux next.)

Jonathan
> ---
> v5:
> - Updated examples in bindings.
> v4:
> - Fixed wrong parameter to dummy of_iio_channel_get_by_name if CONFIG_OF is
>   undefined, and wrong return value.
> - Initialize indio_dev->of_node in iio_device_register if the calling driver
>   neglected to do it.
> v3:
> - Cleaned up documentation (formatting, left-over clock references)
> - Updated bindings description to permit sub-devices
> - When searching for iio devices, use the pointer to the iio device type instead
>   of strcmp. Rename iio_dev_type to iio_device_type (to match other device
>   types) and make it global for that purpose. Check the OF node first, then the
>   device type, as the node is less likely to match.
> - Move the common code in of_iio_channel_get and of_iio_channel_get_all to
>   __of_iio_channel_get.
> - Return NULL from of_iio_channel_get_by_name if nothing is found, or
>   an error if there is a problem with consistency or if the provider device is
>   not yet available.
> - In iio_channel_get, return if of_iio_channel_get_by_name() returns a channel
>   or an error, and continue otherwise.
> v2:
> - Rebased to iio/togreg
> - Documentation update per feedback
> - Dropped io-channel-output-names from the bindings document. The property is
>   not used in the code, and it is not entirely clear what it would be used for.
>   If there is a need for it, we can add it back in later on.
> - Don't export OF specific API calls
> - For OF support, no longer depend on iio_map
> - Add #ifdef CONFIG_OF where appropriate, and ensure that the code still builds
>   if it is not selected.
> - Change iio_channel_get to take device pointer as argument instead of device
>   name. Retain old API as of_iio_channel_get_sys.
> - iio_channel_get now works for both OF and non-OF configurations
> - Use regulator to get vref for max1363 driver.
> 
>  .../devicetree/bindings/iio/iio-bindings.txt       |   97 +++++++++++
>  drivers/iio/iio_core.h                             |    1 +
>  drivers/iio/industrialio-core.c                    |    8 +-
>  drivers/iio/inkern.c                               |  171 ++++++++++++++++++++
>  4 files changed, 275 insertions(+), 2 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..1182845
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt
> @@ -0,0 +1,97 @@
> +This binding is a work-in-progress. It is derived from clock bindings,
> +and based on 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 or 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 IIO 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.
> +
> +Example for a simple configuration with no trigger:
> +
> +	adc: voltage-sensor@35 {
> +		compatible = "maxim,max1139";
> +		reg = <0x35>;
> +		#io-channel-cells = <1>;
> +	};
> +
> +Example for a configuration with trigger:
> +
> +	adc@35 {
> +		compatible = "some-vendor,some-adc";
> +		reg = <0x35>;
> +
> +		adc1: iio-device@0 {
> +			#io-channel-cells = <1>;
> +			/* other properties */
> +		};
> +		adc2: iio-device@1 {
> +			#io-channel-cells = <1>;
> +			/* other properties */
> +		};
> +	};
> +
> +==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 #io-channel-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>;
> +	};
> +
> +	some_consumer {
> +		compatible = "some-consumer";
> +		io-channels = <&adc 10>, <&adc 11>;
> +		io-channel-names = "adc1", "adc2";
> +	};
> diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
> index f652e6a..05c1b74 100644
> --- a/drivers/iio/iio_core.h
> +++ b/drivers/iio/iio_core.h
> @@ -18,6 +18,7 @@
>  struct iio_chan_spec;
>  struct iio_dev;
>  
> +extern struct device_type iio_device_type;
>  
>  int __iio_add_chan_devattr(const char *postfix,
>  			   struct iio_chan_spec const *chan,
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 8848f16..6d8b027 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -847,7 +847,7 @@ static void iio_dev_release(struct device *device)
>  	kfree(indio_dev);
>  }
>  
> -static struct device_type iio_dev_type = {
> +struct device_type iio_device_type = {
>  	.name = "iio_device",
>  	.release = iio_dev_release,
>  };
> @@ -869,7 +869,7 @@ struct iio_dev *iio_device_alloc(int sizeof_priv)
>  
>  	if (dev) {
>  		dev->dev.groups = dev->groups;
> -		dev->dev.type = &iio_dev_type;
> +		dev->dev.type = &iio_device_type;
>  		dev->dev.bus = &iio_bus_type;
>  		device_initialize(&dev->dev);
>  		dev_set_drvdata(&dev->dev, (void *)dev);
> @@ -960,6 +960,10 @@ int iio_device_register(struct iio_dev *indio_dev)
>  {
>  	int ret;
>  
> +	/* If the calling driver did not initialize of_node, do it here */
> +	if (!indio_dev->dev.of_node && indio_dev->dev.parent)
> +		indio_dev->dev.of_node = indio_dev->dev.parent->of_node;
> +
>  	/* configure elements for the chrdev */
>  	indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
>  
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index b289915..795d100 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"
> @@ -92,6 +93,164 @@ static const struct iio_chan_spec
>  	return chan;
>  }
>  
> +#ifdef CONFIG_OF
> +
> +static int iio_dev_node_match(struct device *dev, void *data)
> +{
> +	return dev->of_node == data && dev->type == &iio_device_type;
> +}
> +
> +static int __of_iio_channel_get(struct iio_channel *channel,
> +				struct device_node *np, int index)
> +{
> +	struct device *idev;
> +	struct iio_dev *indio_dev;
> +	int err;
> +	struct of_phandle_args iiospec;
> +
> +	err = of_parse_phandle_with_args(np, "io-channels",
> +					 "#io-channel-cells",
> +					 index, &iiospec);
> +	if (err)
> +		return err;
> +
> +	idev = bus_find_device(&iio_bus_type, NULL, iiospec.np,
> +			       iio_dev_node_match);
> +	of_node_put(iiospec.np);
> +	if (idev == NULL)
> +		return -EPROBE_DEFER;
> +
> +	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) {
> +		return -EINVAL;
> +		goto err_put;
> +	}
> +	channel->channel = &indio_dev->channels[index];
> +
> +	return 0;
> +
> +err_put:
> +	iio_device_put(indio_dev);
> +	return err;
> +}
> +
> +static struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
> +{
> +	struct iio_channel *channel;
> +	int err;
> +
> +	if (index < 0)
> +		return ERR_PTR(-EINVAL);
> +
> +	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> +	if (channel == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	err = __of_iio_channel_get(channel, np, index);
> +	if (err)
> +		goto err_free_channel;
> +
> +	return channel;
> +
> +err_free_channel:
> +	kfree(channel);
> +	return ERR_PTR(err);
> +}
> +
> +static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
> +						      const char *name)
> +{
> +	struct iio_channel *chan = NULL;
> +
> +	/* Walk up the tree of devices looking for a matching iio channel */
> +	while (np) {
> +		int index = 0;
> +
> +		/*
> +		 * For named iio channels, first look up the name in the
> +		 * "io-channel-names" property.  If it cannot be found, the
> +		 * index will be an error code, and of_iio_channel_get()
> +		 * will fail.
> +		 */
> +		if (name)
> +			index = of_property_match_string(np, "io-channel-names",
> +							 name);
> +		chan = of_iio_channel_get(np, index);
> +		if (!IS_ERR(chan))
> +			break;
> +		else if (name && index >= 0) {
> +			pr_err("ERROR: could not get IIO channel %s:%s(%i)\n",
> +				np->full_name, name ? name : "", index);
> +			return chan;
> +		}
> +
> +		/*
> +		 * No matching IIO channel found on this node.
> +		 * If the parent node has a "io-channel-ranges" property,
> +		 * then we can try one of its channels.
> +		 */
> +		np = np->parent;
> +		if (np && !of_get_property(np, "io-channel-ranges", NULL))
> +			break;
> +	}
> +	return chan;
> +}
> +
> +static struct iio_channel *of_iio_channel_get_all(struct device *dev)
> +{
> +	struct iio_channel *chans;
> +	int i, mapind, nummaps = 0;
> +	int ret;
> +
> +	do {
> +		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)	/* no error, return NULL to search map table */
> +		return NULL;
> +
> +	/* NULL terminated array to save passing size */
> +	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
> +	if (chans == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Search for OF matches */
> +	for (mapind = 0; mapind < nummaps; mapind++) {
> +		ret = __of_iio_channel_get(&chans[mapind], dev->of_node,
> +					   mapind);
> +		if (ret)
> +			goto error_free_chans;
> +	}
> +	return chans;
> +
> +error_free_chans:
> +	for (i = 0; i < mapind; i++)
> +		iio_device_put(chans[i].indio_dev);
> +	kfree(chans);
> +	return ERR_PTR(ret);
> +}
> +
> +#else /* CONFIG_OF */
> +
> +static inline struct iio_channel *
> +of_iio_channel_get_by_name(struct device_node *np, const char *name)
> +{
> +	return NULL;
> +}
> +
> +static inline struct iio_channel *of_iio_channel_get_all(struct device *dev)
> +{
> +	return NULL;
> +}
> +
> +#endif /* CONFIG_OF */
>  
>  static struct iio_channel *iio_channel_get_sys(const char *name,
>  					       const char *channel_name)
> @@ -150,7 +309,14 @@ struct iio_channel *iio_channel_get(struct device *dev,
>  				    const char *channel_name)
>  {
>  	const char *name = dev ? dev_name(dev) : NULL;
> +	struct iio_channel *channel;
>  
> +	if (dev) {
> +		channel = of_iio_channel_get_by_name(dev->of_node,
> +						     channel_name);
> +		if (channel != NULL)
> +			return channel;
> +	}
>  	return iio_channel_get_sys(name, channel_name);
>  }
>  EXPORT_SYMBOL_GPL(iio_channel_get);
> @@ -173,6 +339,11 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
>  
>  	if (dev == NULL)
>  		return ERR_PTR(-EINVAL);
> +
> +	chans = of_iio_channel_get_all(dev);
> +	if (chans)
> +		return chans;
> +
>  	name = dev_name(dev);
>  
>  	mutex_lock(&iio_map_list_lock);
> 
--
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