Commit 87800c43 authored by Nuno Sa's avatar Nuno Sa Committed by Jonathan Cameron
Browse files

iio: backend: add new functionality 



This adds the needed backend ops for supporting a backend inerfacing
with an high speed dac. The new ops are:

* data_source_set();
* set_sampling_freq();
* extend_chan_spec();
* ext_info_set();
* ext_info_get().

Also to note the new helpers that are meant to be used by the backends
when extending an IIO channel (adding extended info):

* iio_backend_ext_info_set();
* iio_backend_ext_info_get().

Signed-off-by: default avatarNuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240419-iio-backend-axi-dac-v4-8-5ca45b4de294@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent a33486d3

drivers/iio/industrialio-backend.c

+179 −0
Original line number Diff line number Diff line
@@ -43,10 +43,12 @@ 
#include <linux/types.h>



#include <linux/iio/backend.h>

#include <linux/iio/iio.h>



struct iio_backend {

	struct list_head entry;

	const struct iio_backend_ops *ops;

	struct device *frontend_dev;

	struct device *dev;

	struct module *owner;

	void *priv;
@@ -186,6 +188,44 @@ int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan, 
}

EXPORT_SYMBOL_NS_GPL(iio_backend_data_format_set, IIO_BACKEND);



/**

 * iio_backend_data_source_set - Select data source

 * @back:	Backend device

 * @chan:	Channel number

 * @data:	Data source

 *

 * A given backend may have different sources to stream/sync data. This allows

 * to choose that source.

 *

 * RETURNS:

 * 0 on success, negative error number on failure.

 */

int iio_backend_data_source_set(struct iio_backend *back, unsigned int chan,

				enum iio_backend_data_source data)

{

	if (data >= IIO_BACKEND_DATA_SOURCE_MAX)

		return -EINVAL;



	return iio_backend_op_call(back, data_source_set, chan, data);

}

EXPORT_SYMBOL_NS_GPL(iio_backend_data_source_set, IIO_BACKEND);



/**

 * iio_backend_set_sampling_freq - Set channel sampling rate

 * @back:		Backend device

 * @chan:		Channel number

 * @sample_rate_hz:	Sample rate

 *

 * RETURNS:

 * 0 on success, negative error number on failure.

 */

int iio_backend_set_sampling_freq(struct iio_backend *back, unsigned int chan,

				  u64 sample_rate_hz)

{

	return iio_backend_op_call(back, set_sample_rate, chan, sample_rate_hz);

}

EXPORT_SYMBOL_NS_GPL(iio_backend_set_sampling_freq, IIO_BACKEND);



static void iio_backend_free_buffer(void *arg)

{

	struct iio_backend_buffer_pair *pair = arg;
@@ -231,6 +271,143 @@ int devm_iio_backend_request_buffer(struct device *dev, 
}

EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND);



static struct iio_backend *iio_backend_from_indio_dev_parent(const struct device *dev)

{

	struct iio_backend *back = ERR_PTR(-ENODEV), *iter;



	/*

	 * We deliberately go through all backends even after finding a match.

	 * The reason is that we want to catch frontend devices which have more

	 * than one backend in which case returning the first we find is bogus.

	 * For those cases, frontends need to explicitly define

	 * get_iio_backend() in struct iio_info.

	 */

	guard(mutex)(&iio_back_lock);

	list_for_each_entry(iter, &iio_back_list, entry) {

		if (dev == iter->frontend_dev) {

			if (!IS_ERR(back)) {

				dev_warn(dev,

					 "Multiple backends! get_iio_backend() needs to be implemented");

				return ERR_PTR(-ENODEV);

			}



			back = iter;

		}

	}



	return back;

}



/**

 * iio_backend_ext_info_get - IIO ext_info read callback

 * @indio_dev:	IIO device

 * @private:	Data private to the driver

 * @chan:	IIO channel

 * @buf:	Buffer where to place the attribute data

 *

 * This helper is intended to be used by backends that extend an IIO channel

 * (through iio_backend_extend_chan_spec()) with extended info. In that case,

 * backends are not supposed to give their own callbacks (as they would not have

 * a way to get the backend from indio_dev). This is the getter.

 *

 * RETURNS:

 * Number of bytes written to buf, negative error number on failure.

 */

ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,

				 const struct iio_chan_spec *chan, char *buf)

{

	struct iio_backend *back;



	/*

	 * The below should work for the majority of the cases. It will not work

	 * when one frontend has multiple backends in which case we'll need a

	 * new callback in struct iio_info so we can directly request the proper

	 * backend from the frontend. Anyways, let's only introduce new options

	 * when really needed...

	 */

	back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);

	if (IS_ERR(back))

		return PTR_ERR(back);



	return iio_backend_op_call(back, ext_info_get, private, chan, buf);

}

EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_get, IIO_BACKEND);



/**

 * iio_backend_ext_info_set - IIO ext_info write callback

 * @indio_dev:	IIO device

 * @private:	Data private to the driver

 * @chan:	IIO channel

 * @buf:	Buffer holding the sysfs attribute

 * @len:	Buffer length

 *

 * This helper is intended to be used by backends that extend an IIO channel

 * (trough iio_backend_extend_chan_spec()) with extended info. In that case,

 * backends are not supposed to give their own callbacks (as they would not have

 * a way to get the backend from indio_dev). This is the setter.

 *

 * RETURNS:

 * Buffer length on success, negative error number on failure.

 */

ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,

				 const struct iio_chan_spec *chan,

				 const char *buf, size_t len)

{

	struct iio_backend *back;



	back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);

	if (IS_ERR(back))

		return PTR_ERR(back);



	return iio_backend_op_call(back, ext_info_set, private, chan, buf, len);

}

EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_set, IIO_BACKEND);



/**

 * iio_backend_extend_chan_spec - Extend an IIO channel

 * @indio_dev:	IIO device

 * @back:	Backend device

 * @chan:	IIO channel

 *

 * Some backends may have their own functionalities and hence capable of

 * extending a frontend's channel.

 *

 * RETURNS:

 * 0 on success, negative error number on failure.

 */

int iio_backend_extend_chan_spec(struct iio_dev *indio_dev,

				 struct iio_backend *back,

				 struct iio_chan_spec *chan)

{

	const struct iio_chan_spec_ext_info *frontend_ext_info = chan->ext_info;

	const struct iio_chan_spec_ext_info *back_ext_info;

	int ret;



	ret = iio_backend_op_call(back, extend_chan_spec, chan);

	if (ret)

		return ret;

	/*

	 * Let's keep things simple for now. Don't allow to overwrite the

	 * frontend's extended info. If ever needed, we can support appending

	 * it.

	 */

	if (frontend_ext_info && chan->ext_info != frontend_ext_info)

		return -EOPNOTSUPP;

	if (!chan->ext_info)

		return 0;



	/* Don't allow backends to get creative and force their own handlers */

	for (back_ext_info = chan->ext_info; back_ext_info->name; back_ext_info++) {

		if (back_ext_info->read != iio_backend_ext_info_get)

			return -EINVAL;

		if (back_ext_info->write != iio_backend_ext_info_set)

			return -EINVAL;

	}



	return 0;

}

EXPORT_SYMBOL_NS_GPL(iio_backend_extend_chan_spec, IIO_BACKEND);



static void iio_backend_release(void *arg)

{

	struct iio_backend *back = arg;
@@ -263,6 +440,8 @@ static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back) 
				     "Could not link to supplier(%s)\n",

				     dev_name(back->dev));



	back->frontend_dev = dev;



	dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev));



	return 0;

include/linux/iio/backend.h

+49 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 


#include <linux/types.h>



struct iio_chan_spec;

struct fwnode_handle;

struct iio_backend;

struct device;
@@ -15,6 +16,26 @@ enum iio_backend_data_type { 
	IIO_BACKEND_DATA_TYPE_MAX

};



enum iio_backend_data_source {

	IIO_BACKEND_INTERNAL_CONTINUOS_WAVE,

	IIO_BACKEND_EXTERNAL,

	IIO_BACKEND_DATA_SOURCE_MAX

};



/**

 * IIO_BACKEND_EX_INFO - Helper for an IIO extended channel attribute

 * @_name:	Attribute name

 * @_shared:	Whether the attribute is shared between all channels

 * @_what:	Data private to the driver

 */

#define IIO_BACKEND_EX_INFO(_name, _shared, _what) {	\

	.name = (_name),				\

	.shared = (_shared),				\

	.read =  iio_backend_ext_info_get,		\

	.write = iio_backend_ext_info_set,		\

	.private = (_what),				\

}



/**

 * struct iio_backend_data_fmt - Backend data format

 * @type:		Data type.
@@ -35,8 +56,13 @@ struct iio_backend_data_fmt { 
 * @chan_enable:	Enable one channel.

 * @chan_disable:	Disable one channel.

 * @data_format_set:	Configure the data format for a specific channel.

 * @data_source_set:	Configure the data source for a specific channel.

 * @set_sample_rate:	Configure the sampling rate for a specific channel.

 * @request_buffer:	Request an IIO buffer.

 * @free_buffer:	Free an IIO buffer.

 * @extend_chan_spec:	Extend an IIO channel.

 * @ext_info_set:	Extended info setter.

 * @ext_info_get:	Extended info getter.

 **/

struct iio_backend_ops {

	int (*enable)(struct iio_backend *back);
@@ -45,10 +71,21 @@ struct iio_backend_ops { 
	int (*chan_disable)(struct iio_backend *back, unsigned int chan);

	int (*data_format_set)(struct iio_backend *back, unsigned int chan,

			       const struct iio_backend_data_fmt *data);

	int (*data_source_set)(struct iio_backend *back, unsigned int chan,

			       enum iio_backend_data_source data);

	int (*set_sample_rate)(struct iio_backend *back, unsigned int chan,

			       u64 sample_rate_hz);

	struct iio_buffer *(*request_buffer)(struct iio_backend *back,

					     struct iio_dev *indio_dev);

	void (*free_buffer)(struct iio_backend *back,

			    struct iio_buffer *buffer);

	int (*extend_chan_spec)(struct iio_backend *back,

				struct iio_chan_spec *chan);

	int (*ext_info_set)(struct iio_backend *back, uintptr_t private,

			    const struct iio_chan_spec *chan,

			    const char *buf, size_t len);

	int (*ext_info_get)(struct iio_backend *back, uintptr_t private,

			    const struct iio_chan_spec *chan, char *buf);

};



int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan);
@@ -56,10 +93,22 @@ int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan); 
int devm_iio_backend_enable(struct device *dev, struct iio_backend *back);

int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,

				const struct iio_backend_data_fmt *data);

int iio_backend_data_source_set(struct iio_backend *back, unsigned int chan,

				enum iio_backend_data_source data);

int iio_backend_set_sampling_freq(struct iio_backend *back, unsigned int chan,

				  u64 sample_rate_hz);

int devm_iio_backend_request_buffer(struct device *dev,

				    struct iio_backend *back,

				    struct iio_dev *indio_dev);

ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,

				 const struct iio_chan_spec *chan,

				 const char *buf, size_t len);

ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,

				 const struct iio_chan_spec *chan, char *buf);



int iio_backend_extend_chan_spec(struct iio_dev *indio_dev,

				 struct iio_backend *back,

				 struct iio_chan_spec *chan);

void *iio_backend_get_priv(const struct iio_backend *conv);

struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name);

struct iio_backend *