Re: [PATCH v5] iio: Add OF support

Guenter Roeck
2013-02-20T18:11:19Z

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 ?

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);
> >
>
>