// SPDX-License-Identifier: GPL-2.0-only
/*
* Framework to handle complex IIO aggregate devices.
*
* The typical architecture is to have one device as the frontend device which
* can be "linked" against one or multiple backend devices. All the IIO and
* userspace interface is expected to be registers/managed by the frontend
* device which will callback into the backends when needed (to get/set some
* configuration that it does not directly control).
*
* -------------------------------------------------------
* ------------------ | ------------ ------------ ------- FPGA|
* | ADC |------------------------| | ADC CORE |---------| DMA CORE |------| RAM | |
* | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend) |---------| |------| | |
* | |------------------------| ------------ ------------ ------- |
* ------------------ -------------------------------------------------------
*
* The framework interface is pretty simple:
* - Backends should register themselves with devm_iio_backend_register()
* - Frontend devices should get backends with devm_iio_backend_get()
*
* Also to note that the primary target for this framework are converters like
* ADC/DACs so iio_backend_ops will have some operations typical of converter
* devices. On top of that, this is "generic" for all IIO which means any kind
* of device can make use of the framework. That said, If the iio_backend_ops
* struct begins to grow out of control, we can always refactor things so that
* the industrialio-backend.c is only left with the really generic stuff. Then,
* we can build on top of it depending on the needs.
*
* Copyright (C) 2023-2024 Analog Devices Inc.
*/
#define dev_fmt(fmt) "iio-backend: " fmt
#include <linux/cleanup.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/stringify.h>
#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;
const char *name;
unsigned int cached_reg_addr;
/*
* This index is relative to the frontend. Meaning that for
* frontends with multiple backends, this will be the index of this
* backend. Used for the debugfs directory name.
*/
u8 idx;
};
/*
* Helper struct for requesting buffers. This ensures that we have all data
* that we need to free the buffer in a device managed action.
*/
struct iio_backend_buffer_pair {
struct iio_backend *back;
struct iio_buffer *buffer;
};
static LIST_HEAD(iio_back_list);
static DEFINE_MUTEX(iio_back_lock);
/*
* Helper macros to call backend ops. Makes sure the option is supported.
*/
#define iio_backend_check_op(back, op) ({ \
struct iio_backend *____back = back; \
int ____ret = 0; \
\
if (!____back->ops->op) \
____ret = -EOPNOTSUPP; \
\
____ret; \
})
#define iio_backend_op_call(back, op, args...) ({ \
struct iio_backend *__back = back; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (!__ret) \
__ret = __back->ops->op(__back, ##args); \
\
__ret; \
})
#define iio_backend_ptr_op_call(back, op, args...) ({ \
struct iio_backend *__back = back; \
void *ptr_err; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (__ret) \
ptr_err = ERR_PTR(__ret); \
else \
ptr_err = __back->ops->op(__back, ##args); \
\
ptr_err; \
})
#define iio_backend_void_op_call(back, op, args...) { \
struct iio_backend *__back = back; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (!__ret) \
__back->ops->op(__back, ##args); \
else \
dev_dbg(__back->dev, "Op(%s) not implemented\n",\
__stringify(op)); \
}
static ssize_t iio_backend_debugfs_read_reg(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
char read_buf[20];
unsigned int val;
int ret, len;
ret = iio_backend_op_call(back, debugfs_reg_access,
back->cached_reg_addr, 0, &val);
if (ret)
return ret;
len = scnprintf(read_buf, sizeof(read_buf), "0x%X\n", val);
return simple_read_from_buffer(userbuf, count, ppos, read_buf, len);
}
static ssize_t iio_backend_debugfs_write_reg(struct file *file,
const char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
unsigned int val;
char buf[80];
ssize_t rc;
int ret;
rc = simple_write_to_buffer(buf, sizeof(buf), ppos, userbuf, count);
if (rc < 0)
return rc;
ret = sscanf(buf, "%i %i", &back->cached_reg_addr, &val);
switch (ret) {
case 1:
return count;
case 2:
ret = iio_backend_op_call(back, debugfs_reg_access,
back->cached_reg_addr, val, NULL);
if (ret)
return ret;
return count;
default:
return -EINVAL;
}
}
static const struct file_operations iio_backend_debugfs_reg_fops = {
.open = simple_open,
.read = iio_backend_debugfs_read_reg,
.write = iio_backend_debugfs_write_reg,
};
static ssize_t iio_backend_debugfs_read_name(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
char name[128];
int len;
len = scnprintf(name, sizeof(name), "%s\n", back->name);
return simple_read_from_buffer(userbuf, count, ppos, name, len);
}
static const struct file_operations iio_backend_debugfs_name_fops = {
.open = simple_open,
.read = iio_backend_debugfs_read_name,
};
/**
* iio_backend_debugfs_add - Add debugfs interfaces for Backends
* @back: Backend device
* @indio_dev: IIO device
*/
void iio_backend_debugfs_add(struct iio_backend *back,
struct iio_dev *indio_dev)
{
struct dentry *d = iio_get_debugfs_dentry(indio_dev);
struct dentry *back_d;
char name[128];
if (!IS_ENABLED(CONFIG_DEBUG_FS) || !d)
return;
if (!back->ops->debugfs_reg_access && !back->name)
return;
snprintf(name, sizeof(name), "backend%d", back->idx);
back_d = debugfs_create_dir(name, d);
if (IS_ERR(back_d))
return;
if (back->ops->debugfs_reg_access)
debugfs_create_file("direct_reg_access", 0600, back_d, back,
&iio_backend_debugfs_reg_fops);
if (back->name)
debugfs_create_file("name", 0400, back_d, back,
&iio_backend_debugfs_name_fops);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_add, IIO_BACKEND);
/**
* iio_backend_debugfs_print_chan_status - Print channel status
* @back: Backend device
* @chan: Channel number
* @buf: Buffer where to print the status
* @len: Available space
*
* One usecase where this is useful is for testing test tones in a digital
* interface and "ask" the backend to dump more details on why a test tone might
* have errors.
*
* RETURNS:
* Number of copied bytes on success, negative error code on failure.
*/
ssize_t iio_backend_debugfs_print_chan_status(struct iio_backend *back,
unsigned int chan, char *buf,
size_t len)
{
if (!IS_ENABLED(CONFIG_DEBUG_FS))
return -ENODEV;
return iio_backend_op_call(back, debugfs_print_chan_status, chan, buf,
len);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_print_chan_status, IIO_BACKEND);
/**
* iio_backend_chan_enable - Enable a backend channel
* @back: Backend device
* @chan: Channel number
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan)
{
return iio_backend_op_call(back, chan_enable, chan);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_enable, IIO_BACKEND);
/**
* iio_backend_chan_disable - Disable a backend channel
* @back: Backend device
* @chan: Channel number
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan)
{
return iio_backend_op_call(back, chan_disable, chan);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_disable, IIO_BACKEND);
static void __iio_backend_disable(void *back)
{
iio_backend_void_op_call(back, disable);
}
/**
* iio_backend_disable - Backend disable
* @back: Backend device
*/
void iio_backend_disable(struct iio_backend *back)
{
__iio_backend_disable(back);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_disable, IIO_BACKEND);
/**
* iio_backend_enable - Backend enable
* @back: Backend device
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_enable(struct iio_backend *back)
{
return iio_backend_op_call(back, enable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_enable, IIO_BACKEND);
/**
* devm_iio_backend_enable - Device managed backend enable
* @dev: Consumer device for the backend
* @back: Backend device
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_enable(struct device *dev, struct iio_backend *back)
{
int ret;
ret = iio_backend_enable(back);
if (ret)
return ret;
return devm_add_action_or_reset(dev, __iio_backend_disable, back);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_enable, IIO_BACKEND);
/**
* iio_backend_data_format_set - Configure the channel data format
* @back: Backend device
* @chan: Channel number
* @data: Data format
*
* Properly configure a channel with respect to the expected data format. A
* @struct iio_backend_data_fmt must be passed with the settings.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
const struct iio_backend_data_fmt *data)
{
if (!data || data->type >= IIO_BACKEND_DATA_TYPE_MAX)
return -EINVAL;
return iio_backend_op_call(back, data_format_set, chan, data);
}
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);
/**
* iio_backend_test_pattern_set - Configure a test pattern
* @back: Backend device
* @chan: Channel number
* @pattern: Test pattern
*
* Configure a test pattern on the backend. This is typically used for
* calibrating the timings on the data digital interface.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_test_pattern_set(struct iio_backend *back,
unsigned int chan,
enum iio_backend_test_pattern pattern)
{
if (pattern >= IIO_BACKEND_TEST_PATTERN_MAX)
return -EINVAL;
return iio_backend_op_call(back, test_pattern_set, chan, pattern);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_test_pattern_set, IIO_BACKEND);
/**
* iio_backend_chan_status - Get the channel status
* @back: Backend device
* @chan: Channel number
* @error: Error indication
*
* Get the current state of the backend channel. Typically used to check if
* there were any errors sending/receiving data.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_status(struct iio_backend *back, unsigned int chan,
bool *error)
{
return iio_backend_op_call(back, chan_status, chan, error);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_status, IIO_BACKEND);
/**
* iio_backend_iodelay_set - Set digital I/O delay
* @back: Backend device
* @lane: Lane number
* @taps: Number of taps
*
* Controls delays on sending/receiving data. One usecase for this is to
* calibrate the data digital interface so we get the best results when
* transferring data. Note that @taps has no unit since the actual delay per tap
* is very backend specific. Hence, frontend devices typically should go through
* an array of @taps (the size of that array should typically match the size of
* calibration points on the frontend device) and call this API.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_iodelay_set(struct iio_backend *back, unsigned int lane,
unsigned int taps)
{
return iio_backend_op_call(back, iodelay_set, lane, taps);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_iodelay_set, IIO_BACKEND);
/**
* iio_backend_data_sample_trigger - Control when to sample data
* @back: Backend device
* @trigger: Data trigger
*
* Mostly useful for input backends. Configures the backend for when to sample
* data (eg: rising vs falling edge).
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_sample_trigger(struct iio_backend *back,
enum iio_backend_sample_trigger trigger)
{
if (trigger >= IIO_BACKEND_SAMPLE_TRIGGER_MAX)
return -EINVAL;
return iio_backend_op_call(back, data_sample_trigger, trigger);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_sample_trigger, IIO_BACKEND);
static void iio_backend_free_buffer(void *arg)
{
struct iio_backend_buffer_pair *pair = arg;
iio_backend_void_op_call(pair->back, free_buffer, pair->buffer);
}
/**
* devm_iio_backend_request_buffer - Device managed buffer request
* @dev: Consumer device for the backend
* @back: Backend device
* @indio_dev: IIO device
*
* Request an IIO buffer from the backend. The type of the buffer (typically
* INDIO_BUFFER_HARDWARE) is up to the backend to decide. This is because,
* normally, the backend dictates what kind of buffering we can get.
*
* The backend .free_buffer() hooks is automatically called on @dev detach.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_request_buffer(struct device *dev,
struct iio_backend *back,
struct iio_dev *indio_dev)
{
struct iio_backend_buffer_pair *pair;
struct iio_buffer *buffer;
pair = devm_kzalloc(dev, sizeof(*pair), GFP_KERNEL);
if (!pair)
return -ENOMEM;
buffer = iio_backend_ptr_op_call(back, request_buffer, indio_dev);
if (IS_ERR(buffer))
return PTR_ERR(buffer);
/* weak reference should be all what we need */
pair->back = back;
pair->buffer = buffer;
return devm_add_action_or_reset(dev, iio_backend_free_buffer, pair);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND);
/**
* iio_backend_read_raw - Read a channel attribute from a backend device.
* @back: Backend device
* @chan: IIO channel reference
* @val: First returned value
* @val2: Second returned value
* @mask: Specify the attribute to return
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_read_raw(struct iio_backend *back,
struct iio_chan_spec const *chan, int *val, int *val2,
long mask)
{
return iio_backend_op_call(back, read_raw, chan, val, val2, mask);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_read_raw, 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
* @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_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;
module_put(back->owner);
}
static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back)
{
struct device_link *link;
int ret;
/*
* Make sure the provider cannot be unloaded before the consumer module.
* Note that device_links would still guarantee that nothing is
* accessible (and breaks) but this makes it explicit that the consumer
* module must be also unloaded.
*/
if (!try_module_get(back->owner))
return dev_err_probe(dev, -ENODEV,
"Cannot get module reference\n");
ret = devm_add_action_or_reset(dev, iio_backend_release, back);
if (ret)
return ret;
link = device_link_add(dev, back->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
if (!link)
return dev_err_probe(dev, -EINVAL,
"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;
}
static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, const char *name,
struct fwnode_handle *fwnode)
{
struct fwnode_handle *fwnode_back;
struct iio_backend *back;
unsigned int index;
int ret;
if (name) {
ret = device_property_match_string(dev, "io-backend-names",
name);
if (ret < 0)
return ERR_PTR(ret);
index = ret;
} else {
index = 0;
}
fwnode_back = fwnode_find_reference(fwnode, "io-backends", index);
if (IS_ERR(fwnode))
return dev_err_cast_probe(dev, fwnode,
"Cannot get Firmware reference\n");
guard(mutex)(&iio_back_lock);
list_for_each_entry(back, &iio_back_list, entry) {
if (!device_match_fwnode(back->dev, fwnode_back))
continue;
fwnode_handle_put(fwnode_back);
ret = __devm_iio_backend_get(dev, back);
if (ret)
return ERR_PTR(ret);
if (name)
back->idx = index;
return back;
}
fwnode_handle_put(fwnode_back);
return ERR_PTR(-EPROBE_DEFER);
}
/**
* devm_iio_backend_get - Device managed backend device get
* @dev: Consumer device for the backend
* @name: Backend name
*
* Get's the backend associated with @dev.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
{
return __devm_iio_backend_fwnode_get(dev, name, dev_fwnode(dev));
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get, IIO_BACKEND);
/**
* devm_iio_backend_fwnode_get - Device managed backend firmware node get
* @dev: Consumer device for the backend
* @name: Backend name
* @fwnode: Firmware node of the backend consumer
*
* Get's the backend associated with a firmware node.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *devm_iio_backend_fwnode_get(struct device *dev,
const char *name,
struct fwnode_handle *fwnode)
{
return __devm_iio_backend_fwnode_get(dev, name, fwnode);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_fwnode_get, IIO_BACKEND);
/**
* __devm_iio_backend_get_from_fwnode_lookup - Device managed fwnode backend device get
* @dev: Consumer device for the backend
* @fwnode: Firmware node of the backend device
*
* Search the backend list for a device matching @fwnode.
* This API should not be used and it's only present for preventing the first
* user of this framework to break it's DT ABI.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *
__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
struct fwnode_handle *fwnode)
{
struct iio_backend *back;
int ret;
guard(mutex)(&iio_back_lock);
list_for_each_entry(back, &iio_back_list, entry) {
if (!device_match_fwnode(back->dev, fwnode))
continue;
ret = __devm_iio_backend_get(dev, back);
if (ret)
return ERR_PTR(ret);
return back;
}
return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup, IIO_BACKEND);
/**
* iio_backend_get_priv - Get driver private data
* @back: Backend device
*/
void *iio_backend_get_priv(const struct iio_backend *back)
{
return back->priv;
}
EXPORT_SYMBOL_NS_GPL(iio_backend_get_priv, IIO_BACKEND);
static void iio_backend_unregister(void *arg)
{
struct iio_backend *back = arg;
guard(mutex)(&iio_back_lock);
list_del(&back->entry);
}
/**
* devm_iio_backend_register - Device managed backend device register
* @dev: Backend device being registered
* @info: Backend info
* @priv: Device private data
*
* @info is mandatory. Not providing it results in -EINVAL.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_register(struct device *dev,
const struct iio_backend_info *info, void *priv)
{
struct iio_backend *back;
if (!info || !info->ops)
return dev_err_probe(dev, -EINVAL, "No backend ops given\n");
/*
* Through device_links, we guarantee that a frontend device cannot be
* bound/exist if the backend driver is not around. Hence, we can bind
* the backend object lifetime with the device being passed since
* removing it will tear the frontend/consumer down.
*/
back = devm_kzalloc(dev, sizeof(*back), GFP_KERNEL);
if (!back)
return -ENOMEM;
back->ops = info->ops;
back->name = info->name;
back->owner = dev->driver->owner;
back->dev = dev;
back->priv = priv;
scoped_guard(mutex, &iio_back_lock)
list_add(&back->entry, &iio_back_list);
return devm_add_action_or_reset(dev, iio_backend_unregister, back);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_register, IIO_BACKEND);
MODULE_AUTHOR("Nuno Sa <[email protected]>");
MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices");
MODULE_LICENSE("GPL");
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