Date:	Wed, 20 Feb 2013 17:17:05 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>,
	Jonathan Cameron <jic23@...23.retrosnub.co.uk>
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



Guenter Roeck <linux@...ck-us.net> wrote:

>On Fri, Feb 08, 2013 at 08:30:48AM +0000, Jonathan Cameron wrote:
>> On 07/02/13 17:09, Guenter Roeck wrote:
>> >Provide bindings and parse OF data during initialization.
>> >
>> >Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>> Looks fine to me.  Will give it a few more days to see what others
>> have to say.
>> 
>Hi Jonathan,
>
>Any further feedback on this ? If there is anything else I need to do
>to get it accepted, please let me know.
Was kind of hoping for a few ack/ reviewed by comments! Missed current merge window so I will pick it up for start of next cycle and assume silence means everyone else is happy!
>
>Thanks,
>Guenter
>
>> Thanks Guenter
>> >---
>> >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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