[PATCH v5] iio: Add OF support

Guenter Roeck
2013-02-07T17:09:00Z

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