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    Subject[PATCH v5] iio: Add OF support
    Date
    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].
    +
    +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);
    --
    1.7.9.7


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