[PATCH v4 2/2] iio: Add OF support
Jonathan Cameron
jic23 at kernel.org
Thu Feb 7 06:37:37 EST 2013
On 02/06/2013 06:29 PM, Guenter Roeck wrote:
> Provide bindings and parse OF data during initialization.
>
> Signed-off-by: Guenter Roeck <linux at roeck-us.net>
looks good to me. Couple of little queries inline.
> ---
> 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.
>
> drivers/iio/iio_core.h | 1 +
> drivers/iio/industrialio-core.c | 8 +-
> drivers/iio/inkern.c | 171 ++++++++++++++++++++
> 4 files changed, 268 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..2475c2e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt
> @@ -0,0 +1,90 @@
> +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 at 35 {
> + compatible = "maxim,max1139";
> + reg = <0x35>;
> + #io-channel-cells = <1>;
> + };
> +
> +Example for a configuration with trigger:
> +
> + adc at 35 {
> + compatible = "maxim,max1139";
> + reg = <0x35>;
> +
> + adc: iio-device {
> + #io-channel-cells = <1>;
> + };
> + trigger: iio-trigger {
> + #io-channel-cells = <1>;
Why would the trigger have channel-cells?
So far we don't have any device tree stuff for the triggers.
> + };
> + };
> +
> +==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 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";
This example still seems a little odd. Why give one where there are
more channels than names?
> + };
> 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;
> +
I guess that's sensible, though I'd be inclined to check it and throw a wobbly
if it isn't defined. That way we have one 'right' place to do it.
> /* 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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