[RFC 10/11] iio: Add OF support
Jonathan Cameron
jic23 at kernel.org
Sat Feb 2 21:29:02 EST 2013
On 01/31/2013 09:43 PM, Guenter Roeck wrote:
> Provide bindings, new API access functions, and parse OF data
> during initialization.
>
Firstly thanks for working on this Guenter, it's been a big hole
for a while largely because non of our largest developers were
actually using development platforms with device tree support.
Given my knowledge of device tree is based on the odd article
and looking at similar sets of bindings this morning, my comments
are likely to be somewhat superficial and uninformed ;)
Mostly on this one I'll take a back seat and let those who
know this stuff better come to a consensus.
Jonathan
> Signed-off-by: Guenter Roeck <linux at roeck-us.net>
> ---
> .../devicetree/bindings/iio/iio-bindings.txt | 97 ++++++++
> drivers/iio/inkern.c | 241 ++++++++++++++++----
> include/linux/iio/consumer.h | 8 +
> 3 files changed, 299 insertions(+), 47 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..0f51c95
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt
> @@ -0,0 +1,97 @@
> +This binding is a work-in-progress, and are based on clock bindings and
> +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 more 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 clock 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.
> +
> +Optional properties:
> +io-channel-output-names:
> + Recommended to be a list of strings of IIO output signal
> + names indexed by the first cell in the IIO specifier.
> + However, the meaning of io-channel-output-names is domain
> + specific to the IIO provider, and is only provided to
> + encourage using the same meaning for the majority of IIO
> + providers. This format may not work for IIO providers
> + using a complex IIO specifier format. In those cases it
> + is recommended to omit this property and create a binding
> + specific names property.
> +
> + IIO consumer nodes must never directly reference
> + the provider's io-channel-output-names property.
> +
> +For example:
> +
> + adc: adc at 35 {
> + compatible = "maxim,max1139";
> + reg = <0x35>;
> + #io-channel-cells = <1>;
> + io-channel-output-names = "adc1", "adc2";
> + };
> +
> +- this node defines a device with two named IIO outputs, the first named
> + "adc1" and the second named "adc2". Consumer nodes always reference
> + IIO channels by index. The names should reflect the IIO output signal
> + names for the device.
> +
> +==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 #clock-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 at 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>, <&adc 10>, <&adc 11>;
> + io-channel-names = "vcc", "vdd", "vref", "1.2V";
Having different numbers of channels and channel names seems
unusual... Deliberate or you got bored making up channel names?
Why use indexed values for <&adc 0> etc rather than the output
channel names on adc? For the iio_map stuff we initialy used
indexes but got a lot of responses that it was a silly idea and
naming was much more consistent and easy to follow.
Is there a fundamental reason for it here?
(note I don't mind either way as this seems more compact and cleaner
in some ways)
> + };
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index c42aba6..af80a18 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"
> @@ -26,13 +27,55 @@ struct iio_map_internal {
> static LIST_HEAD(iio_map_list);
> static DEFINE_MUTEX(iio_map_list_lock);
>
> +static struct iio_map *iio_map_of_init(struct iio_dev *idev)
> +{
> + struct device_node *np = idev->dev.of_node;
> + struct iio_map *maps;
> + u32 cells, channels = 1;
> + int names, i, ret;
> +
> + ret = of_property_read_u32(np, "#io-channel-cells", &cells);
> + if (ret < 0 || cells > 1)
> + return ERR_PTR(-EINVAL);
> +
> + names = of_property_count_strings(np, "io-channel-output-names");
> + if (names < 0)
> + names = 0;
> +
> + if (channels < names)
> + channels = names;
> +
> + maps = devm_kzalloc(&idev->dev, sizeof(*maps) * (channels + 1),
> + GFP_KERNEL);
> + if (maps == NULL)
> + return ERR_PTR(-ENOMEM);
> +
> + for (i = 0; i < channels; i++) {
> + if (i < names) {
> + ret = of_property_read_string_index(np,
> + "io-channel-output-names", i,
> + &maps[i].consumer_channel);
> + if (ret < 0)
> + return ERR_PTR(ret);
> + }
> + /* Use dummy for consumer device names */
> + maps[i].consumer_dev_name = "of";
> + }
> + return maps;
> +}
> +
> int iio_map_array_register(struct iio_dev *indio_dev, struct iio_map *maps)
> {
> int i = 0, ret = 0;
> struct iio_map_internal *mapi;
>
> - if (maps == NULL)
> - return 0;
> + if (maps == NULL) {
> + maps = iio_map_of_init(indio_dev);
> + if (IS_ERR(maps))
> + return PTR_ERR(maps);
> + if (maps == NULL)
> + return 0;
> + }
>
> mutex_lock(&iio_map_list_lock);
> while (maps[i].consumer_dev_name != NULL) {
> @@ -92,30 +135,14 @@ static const struct iio_chan_spec
> return chan;
> }
>
> -
> -struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
> +struct iio_channel *iio_channel_get_common(struct iio_map_internal *c,
> + int index)
> {
> - struct iio_map_internal *c_i = NULL, *c = NULL;
> struct iio_channel *channel;
> int err;
>
> - if (name == NULL && channel_name == NULL)
> - return ERR_PTR(-ENODEV);
> -
> - /* first find matching entry the channel map */
> - mutex_lock(&iio_map_list_lock);
> - list_for_each_entry(c_i, &iio_map_list, l) {
> - if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
> - (channel_name &&
> - strcmp(channel_name, c_i->map->consumer_channel) != 0))
> - continue;
> - c = c_i;
> - iio_device_get(c->indio_dev);
> - break;
> - }
> - mutex_unlock(&iio_map_list_lock);
> if (c == NULL)
> - return ERR_PTR(-ENODEV);
> + return ERR_PTR(-EPROBE_DEFER);
>
> channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> if (channel == NULL) {
> @@ -125,7 +152,13 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
>
> channel->indio_dev = c->indio_dev;
>
> - if (c->map->adc_channel_label) {
> + if (index >= 0) {
> + if (index >= c->indio_dev->num_channels) {
> + err = -EINVAL;
> + goto error_no_chan;
> + }
> + channel->channel = &c->indio_dev->channels[index];
> + } else if (c->map->adc_channel_label) {
> channel->channel =
> iio_chan_spec_from_name(channel->indio_dev,
> c->map->adc_channel_label);
> @@ -144,6 +177,60 @@ error_no_mem:
> iio_device_put(c->indio_dev);
> return ERR_PTR(err);
> }
> +
> +struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
> +{
> + struct iio_map_internal *c_i, *c = NULL;
> + int err, map_index;
> + struct of_phandle_args iiospec;
> +
> + if (index < 0)
> + return ERR_PTR(-EINVAL);
> +
> + err = of_parse_phandle_with_args(np, "io-channels",
> + "#io-channel-cells",
> + index, &iiospec);
> + if (err)
> + return ERR_PTR(err);
> +
> + map_index = iiospec.args_count ? iiospec.args[0] : 0;
> +
> + mutex_lock(&iio_map_list_lock);
> + list_for_each_entry(c_i, &iio_map_list, l) {
> + if (iiospec.np == c_i->indio_dev->dev.of_node) {
> + c = c_i;
> + iio_device_get(c->indio_dev);
> + break;
> + }
> + }
> + of_node_put(iiospec.np);
> + mutex_unlock(&iio_map_list_lock);
> + return iio_channel_get_common(c, index);
> +}
> +EXPORT_SYMBOL_GPL(of_iio_channel_get);
> +
> +struct iio_channel *iio_channel_get(const char *name,
> + const char *channel_name)
> +{
> + struct iio_map_internal *c_i = NULL, *c = NULL;
> +
> + if (name == NULL && channel_name == NULL)
> + return ERR_PTR(-ENODEV);
> +
> + /* first find matching entry the channel map */
> + mutex_lock(&iio_map_list_lock);
> + list_for_each_entry(c_i, &iio_map_list, l) {
> + if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
> + (channel_name && strcmp(channel_name,
> + c_i->map->consumer_channel) != 0))
> + continue;
> + c = c_i;
> + iio_device_get(c->indio_dev);
> + break;
> + }
> + mutex_unlock(&iio_map_list_lock);
> + return iio_channel_get_common(c, -1);
> +}
> EXPORT_SYMBOL_GPL(iio_channel_get);
>
> void iio_channel_release(struct iio_channel *channel)
> @@ -159,24 +246,43 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
> struct iio_channel *chans;
> struct iio_map_internal *c = NULL;
> int nummaps = 0;
> - int mapind = 0;
> + int mapind;
> int i, ret;
>
> if (dev == NULL)
> return ERR_PTR(-EINVAL);
> +
> name = dev_name(dev);
>
> mutex_lock(&iio_map_list_lock);
> /* first count the matching maps */
> - list_for_each_entry(c, &iio_map_list, l)
> - if (name && strcmp(name, c->map->consumer_dev_name) != 0)
> - continue;
> - else
> - nummaps++;
> -
> - if (nummaps == 0) {
> - ret = -ENODEV;
> - goto error_ret;
> + if (dev->of_node) {
> + nummaps = 0;
> + do {
> + int ret;
> +
> + 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) {
> + ret = -ENODEV;
> + goto error_ret;
> + }
> + } else {
> + list_for_each_entry(c, &iio_map_list, l)
> + if (strcmp(name, c->map->consumer_dev_name) != 0)
> + continue;
> + else
> + nummaps++;
> + if (nummaps == 0) {
> + ret = -EPROBE_DEFER;
> + goto error_ret;
> + }
> }
>
> /* NULL terminated array to save passing size */
> @@ -187,24 +293,65 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
> }
>
> /* for each map fill in the chans element */
> - list_for_each_entry(c, &iio_map_list, l) {
> - if (name && strcmp(name, c->map->consumer_dev_name) != 0)
> - continue;
> - chans[mapind].indio_dev = c->indio_dev;
> - chans[mapind].data = c->map->consumer_data;
> - chans[mapind].channel =
> - iio_chan_spec_from_name(chans[mapind].indio_dev,
> + if (dev->of_node) {
> + /*
> + * Device-tree based mapping, search for OF matches.
> + */
> + for (mapind = 0; mapind < nummaps; mapind++) {
> + int channel;
> + struct of_phandle_args iiospec;
> +
> + ret = of_parse_phandle_with_args(dev->of_node,
> + "io-channels",
> + "#io-channel-cells",
> + mapind, &iiospec);
> + if (ret)
> + goto error_free_chans;
> + channel = iiospec.args_count ? iiospec.args[0] : 0;
> + ret = -EPROBE_DEFER;
> + list_for_each_entry(c, &iio_map_list, l) {
> + if (iiospec.np == c->indio_dev->dev.of_node) {
> + ret = 0;
> + break;
> + }
> + }
> + if (ret)
> + goto error_free_chans;
> + if (channel >= c->indio_dev->num_channels) {
> + ret = -EINVAL;
> + goto error_free_chans;
> + }
> + chans[mapind].indio_dev = c->indio_dev;
> + chans[mapind].data = c->map->consumer_data;
> + chans[mapind].channel =
> + &c->indio_dev->channels[channel];
> + iio_device_get(c->indio_dev);
> + }
> + } else {
> + /*
> + * Platform data based mapping, search for consumer
> + * device name.
> + */
> + mapind = 0;
> + list_for_each_entry(c, &iio_map_list, l) {
> + if (strcmp(name, c->map->consumer_dev_name) != 0)
> + continue;
> + chans[mapind].indio_dev = c->indio_dev;
> + chans[mapind].data = c->map->consumer_data;
> + chans[mapind].channel =
> + iio_chan_spec_from_name(c->indio_dev,
> c->map->adc_channel_label);
> - if (chans[mapind].channel == NULL) {
> - ret = -EINVAL;
> + if (chans[mapind].channel == NULL) {
> + ret = -EINVAL;
> + goto error_free_chans;
> + }
> + iio_device_get(c->indio_dev);
> + mapind++;
> + }
> + if (mapind < nummaps) {
> + ret = -EPROBE_DEFER;
> goto error_free_chans;
> }
> - iio_device_get(chans[mapind].indio_dev);
> - mapind++;
> - }
> - if (mapind == 0) {
> - ret = -ENODEV;
> - goto error_free_chans;
> }
> mutex_unlock(&iio_map_list_lock);
>
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index 6c44167..a347c15 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -41,6 +41,14 @@ struct iio_channel *iio_channel_get(const char *name,
> const char *consumer_channel);
>
> /**
> + * of_iio_channel_get() - get description of all that is needed to access
> + * channel from OF node pointer.
> + * @np: Consumer's OF node pointer.
> + * @index: Index pointing to the io-channels entry in np.
> + */
> +struct iio_channel *of_iio_channel_get(struct device_node *np, int index);
> +
> +/**
> * iio_channel_release() - release channels obtained via iio_channel_get
> * @chan: The channel to be released.
> */
>
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