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: Nuno Sa <nuno.sa@xxxxxxxxxx>
---
drivers/iio/industrialio-backend.c | 179 +++++++++++++++++++++++++++++++++++++
include/linux/iio/backend.h | 49 ++++++++++
2 files changed, 228 insertions(+)
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 2fea2bbbe47f..ac554798897f 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -29,6 +29,7 @@
*
* Copyright (C) 2023-2024 Analog Devices Inc.
*/
+#include "asm-generic/errno-base.h"
#define dev_fmt(fmt) "iio-backend: " fmt
#include <linux/cleanup.h>
@@ -43,10 +44,12 @@
#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 +189,44 @@ 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 +272,142 @@ 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;
+
+ if (indio_dev->info->get_iio_backend)
+ back = indio_dev->info->get_iio_backend(indio_dev, chan);
+ else
+ 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;
+
+ if (indio_dev->info->get_iio_backend)
+ back = indio_dev->info->get_iio_backend(indio_dev, chan);
+ else
+ 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;
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index a6d79381866e..9d144631134d 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -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 *
--
2.44.0
