Re: [PATCH v5] iio: Add OF support

Jonathan Cameron
2013-02-20T18:51:19Z

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

>On Wed, Feb 20, 2013 at 11:38:22AM -0600, Rob Herring wrote:
>> On 02/07/2013 11:09 AM, Guenter Roeck wrote:
>> > Provide bindings and parse OF data during initialization.
>> >
>> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> > ---
>> > 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].
>>
>> Bindings are an ABI. It should not be a WIP. What part is a WIP?
>>
>The text is copied from clock bindings. I do not claim to be better
>than the clock subsystem is doing in respect to its bindings.
>
>I'll be more than happy to take this text out if it is a source of
>contention,
>even more so if that is what is holding up the patch. Jonathan ?
I don't really care about the wording though can see why Rob asked!
We will probably have other stuff to add anyway.

Jonathan
>
>Thanks,
>Guenter
>
>> Knowing nothing about IIO, the binding seems sane.
>>
>> Rob
>>
>> > +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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