Date:	Wed, 20 Feb 2013 08:53:59 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Jonathan Cameron <jic23@...23.retrosnub.co.uk>
Cc:	linux-iio@...r.kernel.org, Jonathan Cameron <jic23@...nel.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 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.

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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