An IIO device usually corresponds to a single hardware sensor and it
provides all the information needed by a driver handling a device.
Let’s first have a look at the functionality embedded in an IIO device
then we will show how a device driver makes use of an IIO device.
There are two ways for a user space application to interact with an IIO driver.
IIO device channels
struct iio_chan_spec - specification of a single channel
An IIO device channel is a representation of a data channel. An IIO device can
have one or multiple channels. For example:
- a thermometer sensor has one channel representing the temperature measurement.
- a light sensor with two channels indicating the measurements in the visible
and infrared spectrum.
- an accelerometer can have up to 3 channels representing acceleration on X, Y
and Z axes.
An IIO channel is described by the struct iio_chan_spec.
A thermometer driver for the temperature sensor in the example above would
have to describe its channel as follows:
static const struct iio_chan_spec temp_channel[] = {
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
},
};
Channel sysfs attributes exposed to userspace are specified in the form of
bitmasks. Depending on their shared info, attributes can be set in one of the
following masks:
- info_mask_separate, attributes will be specific to
this channel
- info_mask_shared_by_type, attributes are shared by all channels of the
same type
- info_mask_shared_by_dir, attributes are shared by all channels of the same
direction
- info_mask_shared_by_all, attributes are shared by all channels
When there are multiple data channels per channel type we have two ways to
distinguish between them:
- set .modified field of iio_chan_spec to 1. Modifiers are
specified using .channel2 field of the same iio_chan_spec
structure and are used to indicate a physically unique characteristic of the
channel such as its direction or spectral response. For example, a light
sensor can have two channels, one for infrared light and one for both
infrared and visible light.
- set .indexed field of iio_chan_spec to 1. In this case the
channel is simply another instance with an index specified by the .channel
field.
Here is how we can make use of the channel’s modifiers:
static const struct iio_chan_spec light_channels[] = {
{
.type = IIO_INTENSITY,
.modified = 1,
.channel2 = IIO_MOD_LIGHT_IR,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ),
},
{
.type = IIO_INTENSITY,
.modified = 1,
.channel2 = IIO_MOD_LIGHT_BOTH,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ),
},
{
.type = IIO_LIGHT,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
.info_mask_shared = BIT(IIO_CHAN_INFO_SAMP_FREQ),
},
}
This channel’s definition will generate two separate sysfs files for raw data
retrieval:
- /sys/bus/iio/iio:deviceX/in_intensity_ir_raw
- /sys/bus/iio/iio:deviceX/in_intensity_both_raw
one file for processed data:
- /sys/bus/iio/iio:deviceX/in_illuminance_input
and one shared sysfs file for sampling frequency:
- /sys/bus/iio/iio:deviceX/sampling_frequency.
Here is how we can make use of the channel’s indexing:
static const struct iio_chan_spec light_channels[] = {
{
.type = IIO_VOLTAGE,
.indexed = 1,
.channel = 0,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
},
{
.type = IIO_VOLTAGE,
.indexed = 1,
.channel = 1,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
},
}
This will generate two separate attributes files for raw data retrieval:
- /sys/bus/iio/devices/iio:deviceX/in_voltage0_raw, representing
voltage measurement for channel 0.
- /sys/bus/iio/devices/iio:deviceX/in_voltage1_raw, representing
voltage measurement for channel 1.
More details
-
struct iio_chan_spec_ext_info
Extended channel info attribute
Definition
struct iio_chan_spec_ext_info {
const char * name;
enum iio_shared_by shared;
ssize_t (* read) (struct iio_dev *, uintptr_t private,struct iio_chan_spec const *, char *buf);
ssize_t (* write) (struct iio_dev *, uintptr_t private,struct iio_chan_spec const *, const char *buf,size_t len);
uintptr_t private;
};
Members
- name
- Info attribute name
- shared
- Whether this attribute is shared between all channels.
- read
- Read callback for this info attribute, may be NULL.
- write
- Write callback for this info attribute, may be NULL.
- private
- Data private to the driver.
-
struct iio_enum
Enum channel info attribute
Definition
struct iio_enum {
const char *const * items;
unsigned int num_items;
int (* set) (struct iio_dev *, const struct iio_chan_spec *, unsigned int);
int (* get) (struct iio_dev *, const struct iio_chan_spec *);
};
Members
- items
- An array of strings.
- num_items
- Length of the item array.
- set
- Set callback function, may be NULL.
- get
- Get callback function, may be NULL.
Description
The iio_enum struct can be used to implement enum style channel attributes.
Enum style attributes are those which have a set of strings which map to
unsigned integer values. The IIO enum helper code takes care of mapping
between value and string as well as generating a “_available” file which
contains a list of all available items. The set callback will be called when
the attribute is updated. The last parameter is the index to the newly
activated item. The get callback will be used to query the currently active
item and is supposed to return the index for it.
-
IIO_ENUM(_name, _shared, _e)
Initialize enum extended channel attribute
Parameters
- _name
- Attribute name
- _shared
- Whether the attribute is shared between all channels
- _e
- Pointer to an iio_enum struct
Description
This should usually be used together with IIO_ENUM_AVAILABLE()
-
IIO_ENUM_AVAILABLE(_name, _e)
Initialize enum available extended channel attribute
Parameters
- _name
- Attribute name (“_available” will be appended to the name)
- _e
- Pointer to an iio_enum struct
Description
Creates a read only attribute which lists all the available enum items in a
space separated list. This should usually be used together with IIO_ENUM()
-
struct iio_mount_matrix
iio mounting matrix
Definition
struct iio_mount_matrix {
const char * rotation[9];
};
Members
- rotation[9]
- 3 dimensional space rotation matrix defining sensor alignment with
main hardware
-
IIO_MOUNT_MATRIX(_shared, _get)
Initialize mount matrix extended channel attribute
Parameters
- _shared
- Whether the attribute is shared between all channels
- _get
- Pointer to an iio_get_mount_matrix_t accessor
-
struct iio_event_spec
specification for a channel event
Definition
struct iio_event_spec {
enum iio_event_type type;
enum iio_event_direction dir;
unsigned long mask_separate;
unsigned long mask_shared_by_type;
unsigned long mask_shared_by_dir;
unsigned long mask_shared_by_all;
};
Members
- type
- Type of the event
- dir
- Direction of the event
- mask_separate
- Bit mask of enum iio_event_info values. Attributes
set in this mask will be registered per channel.
- mask_shared_by_type
- Bit mask of enum iio_event_info values. Attributes
set in this mask will be shared by channel type.
- mask_shared_by_dir
- Bit mask of enum iio_event_info values. Attributes
set in this mask will be shared by channel type and
direction.
- mask_shared_by_all
- Bit mask of enum iio_event_info values. Attributes
set in this mask will be shared by all channels.
-
struct iio_chan_spec
specification of a single channel
Definition
struct iio_chan_spec {
enum iio_chan_type type;
int channel;
int channel2;
unsigned long address;
int scan_index;
struct scan_type;
long info_mask_separate;
long info_mask_separate_available;
long info_mask_shared_by_type;
long info_mask_shared_by_type_available;
long info_mask_shared_by_dir;
long info_mask_shared_by_dir_available;
long info_mask_shared_by_all;
long info_mask_shared_by_all_available;
const struct iio_event_spec * event_spec;
unsigned int num_event_specs;
const struct iio_chan_spec_ext_info * ext_info;
const char * extend_name;
const char * datasheet_name;
unsigned modified:1;
unsigned indexed:1;
unsigned output:1;
unsigned differential:1;
};
Members
- type
- What type of measurement is the channel making.
- channel
- What number do we wish to assign the channel.
- channel2
- If there is a second number for a differential
channel then this is it. If modified is set then the
value here specifies the modifier.
- address
- Driver specific identifier.
- scan_index
- Monotonic index to give ordering in scans when read
from a buffer.
- scan_type
sign: ‘s’ or ‘u’ to specify signed or unsigned
realbits: Number of valid bits of data
storagebits: Realbits + padding
shift: Shift right by this before masking out
realbits.
- repeat: Number of times real/storage bits
- repeats. When the repeat element is
more than 1, then the type element in
sysfs will show a repeat value.
Otherwise, the number of repetitions is
omitted.
endianness: little or big endian
- info_mask_separate
- What information is to be exported that is specific to
this channel.
- info_mask_separate_available
- What availability information is to be
exported that is specific to this channel.
- info_mask_shared_by_type
- What information is to be exported that is shared
by all channels of the same type.
- info_mask_shared_by_type_available
- What availability information is to be
exported that is shared by all channels of the same
type.
- info_mask_shared_by_dir
- What information is to be exported that is shared
by all channels of the same direction.
- info_mask_shared_by_dir_available
- What availability information is to be
exported that is shared by all channels of the same
direction.
- info_mask_shared_by_all
- What information is to be exported that is shared
by all channels.
- info_mask_shared_by_all_available
- What availability information is to be
exported that is shared by all channels.
- event_spec
- Array of events which should be registered for this
channel.
- num_event_specs
- Size of the event_spec array.
- ext_info
- Array of extended info attributes for this channel.
The array is NULL terminated, the last element should
have its name field set to NULL.
- extend_name
- Allows labeling of channel attributes with an
informative name. Note this has no effect codes etc,
unlike modifiers.
- datasheet_name
- A name used in in-kernel mapping of channels. It should
correspond to the first name that the channel is referred
to by in the datasheet (e.g. IND), or the nearest
possible compound name (e.g. IND-INC).
- modified
- Does a modifier apply to this channel. What these are
depends on the channel type. Modifier is set in
channel2. Examples are IIO_MOD_X for axial sensors about
the ‘x’ axis.
- indexed
- Specify the channel has a numerical index. If not,
the channel index number will be suppressed for sysfs
attributes but not for event codes.
- output
- Channel is output.
- differential
- Channel is differential.
-
bool iio_channel_has_info(const struct iio_chan_spec * chan, enum iio_chan_info_enum type)
Checks whether a channel supports a info attribute
Parameters
- const struct iio_chan_spec * chan
- The channel to be queried
- enum iio_chan_info_enum type
- Type of the info attribute to be checked
Description
Returns true if the channels supports reporting values for the given info
attribute type, false otherwise.
-
bool iio_channel_has_available(const struct iio_chan_spec * chan, enum iio_chan_info_enum type)
Checks if a channel has an available attribute
Parameters
- const struct iio_chan_spec * chan
- The channel to be queried
- enum iio_chan_info_enum type
- Type of the available attribute to be checked
Description
Returns true if the channel supports reporting available values for the
given attribute type, false otherwise.
-
struct iio_info
constant information about device
Definition
struct iio_info {
struct module * driver_module;
const struct attribute_group * event_attrs;
const struct attribute_group * attrs;
int (* read_raw) (struct iio_dev *indio_dev,struct iio_chan_spec const *chan,int *val,int *val2,long mask);
int (* read_raw_multi) (struct iio_dev *indio_dev,struct iio_chan_spec const *chan,int max_len,int *vals,int *val_len,long mask);
int (* read_avail) (struct iio_dev *indio_dev,struct iio_chan_spec const *chan,const int **vals,int *type,int *length,long mask);
int (* write_raw) (struct iio_dev *indio_dev,struct iio_chan_spec const *chan,int val,int val2,long mask);
int (* write_raw_get_fmt) (struct iio_dev *indio_dev,struct iio_chan_spec const *chan,long mask);
int (* read_event_config) (struct iio_dev *indio_dev,const struct iio_chan_spec *chan,enum iio_event_type type,enum iio_event_direction dir);
int (* write_event_config) (struct iio_dev *indio_dev,const struct iio_chan_spec *chan,enum iio_event_type type,enum iio_event_direction dir,int state);
int (* read_event_value) (struct iio_dev *indio_dev,const struct iio_chan_spec *chan,enum iio_event_type type,enum iio_event_direction dir,enum iio_event_info info, int *val, int *val2);
int (* write_event_value) (struct iio_dev *indio_dev,const struct iio_chan_spec *chan,enum iio_event_type type,enum iio_event_direction dir,enum iio_event_info info, int val, int val2);
int (* validate_trigger) (struct iio_dev *indio_dev,struct iio_trigger *trig);
int (* update_scan_mode) (struct iio_dev *indio_dev,const unsigned long *scan_mask);
int (* debugfs_reg_access) (struct iio_dev *indio_dev,unsigned reg, unsigned writeval,unsigned *readval);
int (* of_xlate) (struct iio_dev *indio_dev,const struct of_phandle_args *iiospec);
int (* hwfifo_set_watermark) (struct iio_dev *indio_dev, unsigned val);
int (* hwfifo_flush_to_buffer) (struct iio_dev *indio_dev,unsigned count);
};
Members
- driver_module
- module structure used to ensure correct
ownership of chrdevs etc
- event_attrs
- event control attributes
- attrs
- general purpose device attributes
- read_raw
- function to request a value from the device.
mask specifies which value. Note 0 means a reading of
the channel in question. Return value will specify the
type of value returned by the device. val and val2 will
contain the elements making up the returned value.
- read_raw_multi
- function to return values from the device.
mask specifies which value. Note 0 means a reading of
the channel in question. Return value will specify the
type of value returned by the device. vals pointer
contain the elements making up the returned value.
max_len specifies maximum number of elements
vals pointer can contain. val_len is used to return
length of valid elements in vals.
- read_avail
- function to return the available values from the device.
mask specifies which value. Note 0 means the available
values for the channel in question. Return value
specifies if a IIO_AVAIL_LIST or a IIO_AVAIL_RANGE is
returned in vals. The type of the vals are returned in
type and the number of vals is returned in length. For
ranges, there are always three vals returned; min, step
and max. For lists, all possible values are enumerated.
- write_raw
- function to write a value to the device.
Parameters are the same as for read_raw.
- write_raw_get_fmt
- callback function to query the expected
format/precision. If not set by the driver, write_raw
returns IIO_VAL_INT_PLUS_MICRO.
- read_event_config
- find out if the event is enabled.
- write_event_config
- set if the event is enabled.
- read_event_value
- read a configuration value associated with the event.
- write_event_value
- write a configuration value for the event.
- validate_trigger
- function to validate the trigger when the
current trigger gets changed.
- update_scan_mode
- function to configure device and scan buffer when
channels have changed
- debugfs_reg_access
- function to read or write register value of device
- of_xlate
- function pointer to obtain channel specifier index.
When #iio-cells is greater than ‘0’, the driver could
provide a custom of_xlate function that reads the
args and returns the appropriate index in registered
IIO channels array.
- hwfifo_set_watermark
- function pointer to set the current hardware
fifo watermark level; see hwfifo_* entries in
Documentation/ABI/testing/sysfs-bus-iio for details on
how the hardware fifo operates
- hwfifo_flush_to_buffer
- function pointer to flush the samples stored
in the hardware fifo to the device buffer. The driver
should not flush more than count samples. The function
must return the number of samples flushed, 0 if no
samples were flushed or a negative integer if no samples
were flushed and there was an error.
-
struct iio_buffer_setup_ops
buffer setup related callbacks
Definition
struct iio_buffer_setup_ops {
int (* preenable) (struct iio_dev *);
int (* postenable) (struct iio_dev *);
int (* predisable) (struct iio_dev *);
int (* postdisable) (struct iio_dev *);
bool (* validate_scan_mask) (struct iio_dev *indio_dev,const unsigned long *scan_mask);
};
Members
- preenable
- [DRIVER] function to run prior to marking buffer enabled
- postenable
- [DRIVER] function to run after marking buffer enabled
- predisable
- [DRIVER] function to run prior to marking buffer
disabled
- postdisable
- [DRIVER] function to run after marking buffer disabled
- validate_scan_mask
- [DRIVER] function callback to check whether a given
scan mask is valid for the device.
-
struct iio_dev
industrial I/O device
Definition
struct iio_dev {
int id;
int modes;
int currentmode;
struct device dev;
struct iio_event_interface * event_interface;
struct iio_buffer * buffer;
struct list_head buffer_list;
int scan_bytes;
struct mutex mlock;
const unsigned long * available_scan_masks;
unsigned masklength;
const unsigned long * active_scan_mask;
bool scan_timestamp;
unsigned scan_index_timestamp;
struct iio_trigger * trig;
struct iio_poll_func * pollfunc;
struct iio_poll_func * pollfunc_event;
struct iio_chan_spec const * channels;
int num_channels;
struct list_head channel_attr_list;
struct attribute_group chan_attr_group;
const char * name;
const struct iio_info * info;
clockid_t clock_id;
struct mutex info_exist_lock;
const struct iio_buffer_setup_ops * setup_ops;
struct cdev chrdev;
#define IIO_MAX_GROUPS 6
const struct attribute_group * groups[IIO_MAX_GROUPS + 1];
int groupcounter;
unsigned long flags;
#if defined(CONFIG_DEBUG_FS)
struct dentry * debugfs_dentry;
unsigned cached_reg_addr;
#endif
};
Members
- id
- [INTERN] used to identify device internally
- modes
- [DRIVER] operating modes supported by device
- currentmode
- [DRIVER] current operating mode
- dev
- [DRIVER] device structure, should be assigned a parent
and owner
- event_interface
- [INTERN] event chrdevs associated with interrupt lines
- buffer
- [DRIVER] any buffer present
- buffer_list
- [INTERN] list of all buffers currently attached
- scan_bytes
- [INTERN] num bytes captured to be fed to buffer demux
- mlock
- [DRIVER] lock used to prevent simultaneous device state
changes
- available_scan_masks
- [DRIVER] optional array of allowed bitmasks
- masklength
- [INTERN] the length of the mask established from
channels
- active_scan_mask
- [INTERN] union of all scan masks requested by buffers
- scan_timestamp
- [INTERN] set if any buffers have requested timestamp
- scan_index_timestamp
- [INTERN] cache of the index to the timestamp
- trig
- [INTERN] current device trigger (buffer modes)
trig_readonly [INTERN] mark the current trigger immutable
- pollfunc
- [DRIVER] function run on trigger being received
- pollfunc_event
- [DRIVER] function run on events trigger being received
- channels
- [DRIVER] channel specification structure table
- num_channels
- [DRIVER] number of channels specified in channels.
- channel_attr_list
- [INTERN] keep track of automatically created channel
attributes
- chan_attr_group
- [INTERN] group for all attrs in base directory
- name
- [DRIVER] name of the device.
- info
- [DRIVER] callbacks and constant info from driver
- clock_id
- [INTERN] timestamping clock posix identifier
- info_exist_lock
- [INTERN] lock to prevent use during removal
- setup_ops
- [DRIVER] callbacks to call before and after buffer
enable/disable
- chrdev
- [INTERN] associated character device
- groups[IIO_MAX_GROUPS + 1]
- [INTERN] attribute groups
- groupcounter
- [INTERN] index of next attribute group
- flags
- [INTERN] file ops related flags including busy flag.
- debugfs_dentry
- [INTERN] device specific debugfs dentry.
- cached_reg_addr
- [INTERN] cached register address for debugfs reads.
-
void iio_device_put(struct iio_dev * indio_dev)
reference counted deallocation of struct device
Parameters
- struct iio_dev * indio_dev
- IIO device structure containing the device
-
clockid_t iio_device_get_clock(const struct iio_dev * indio_dev)
Retrieve current timestamping clock for the device
Parameters
- const struct iio_dev * indio_dev
- IIO device structure containing the device
-
struct iio_dev * dev_to_iio_dev(struct device * dev)
Get IIO device struct from a device struct
Parameters
- struct device * dev
- The device embedded in the IIO device
Note
The device must be a IIO device, otherwise the result is undefined.
-
struct iio_dev * iio_device_get(struct iio_dev * indio_dev)
increment reference count for the device
Parameters
- struct iio_dev * indio_dev
- IIO device structure
Return
The passed IIO device
-
void iio_device_set_drvdata(struct iio_dev * indio_dev, void * data)
Set device driver data
Parameters
- struct iio_dev * indio_dev
- IIO device structure
- void * data
- Driver specific data
Description
Allows to attach an arbitrary pointer to an IIO device, which can later be
retrieved by iio_device_get_drvdata().
-
void * iio_device_get_drvdata(struct iio_dev * indio_dev)
Get device driver data
Parameters
- struct iio_dev * indio_dev
- IIO device structure
Description
Returns the data previously set with iio_device_set_drvdata()
-
bool iio_buffer_enabled(struct iio_dev * indio_dev)
helper function to test if the buffer is enabled
Parameters
- struct iio_dev * indio_dev
- IIO device structure for device
-
struct dentry * iio_get_debugfs_dentry(struct iio_dev * indio_dev)
helper function to get the debugfs_dentry
Parameters
- struct iio_dev * indio_dev
- IIO device structure for device
-
IIO_DEGREE_TO_RAD(deg)
Convert degree to rad
Parameters
- deg
- A value in degree
Description
Returns the given value converted from degree to rad
-
IIO_RAD_TO_DEGREE(rad)
Convert rad to degree
Parameters
- rad
- A value in rad
Description
Returns the given value converted from rad to degree
-
IIO_G_TO_M_S_2(g)
Convert g to meter / second**2
Parameters
- g
- A value in g
Description
Returns the given value converted from g to meter / second**2
-
IIO_M_S_2_TO_G(ms2)
Convert meter / second**2 to g
Parameters
- ms2
- A value in meter / second**2
Description
Returns the given value converted from meter / second**2 to g
-
s64 iio_get_time_ns(const struct iio_dev * indio_dev)
utility function to get a time stamp for events etc
Parameters
- const struct iio_dev * indio_dev
- device
-
unsigned int iio_get_time_res(const struct iio_dev * indio_dev)
utility function to get time stamp clock resolution in nano seconds.
Parameters
- const struct iio_dev * indio_dev
- device
-
int of_iio_read_mount_matrix(const struct device * dev, const char * propname, struct iio_mount_matrix * matrix)
retrieve iio device mounting matrix from device-tree “mount-matrix” property
Parameters
- const struct device * dev
- device the mounting matrix property is assigned to
- const char * propname
- device specific mounting matrix property name
- struct iio_mount_matrix * matrix
- where to store retrieved matrix
Description
If device is assigned no mounting matrix property, a default 3x3 identity
matrix will be filled in.
Return
0 if success, or a negative error code on failure.
-
ssize_t iio_format_value(char * buf, unsigned int type, int size, int * vals)
Formats a IIO value into its string representation
Parameters
- char * buf
- The buffer to which the formatted value gets written
which is assumed to be big enough (i.e. PAGE_SIZE).
- unsigned int type
- One of the IIO_VAL_... constants. This decides how the val
and val2 parameters are formatted.
- int size
- Number of IIO value entries contained in vals
- int * vals
- Pointer to the values, exact meaning depends on the
type parameter.
Return
- 0 by default, a negative number on failure or the
- total number of characters written for a type that belongs
to the IIO_VAL_... constant.
-
int iio_str_to_fixpoint(const char * str, int fract_mult, int * integer, int * fract)
Parse a fixed-point number from a string
Parameters
- const char * str
- The string to parse
- int fract_mult
- Multiplier for the first decimal place, should be a power of 10
- int * integer
- The integer part of the number
- int * fract
- The fractional part of the number
Description
Returns 0 on success, or a negative error code if the string could not be
parsed.
-
struct iio_dev * iio_device_alloc(int sizeof_priv)
allocate an iio_dev from a driver
Parameters
- int sizeof_priv
- Space to allocate for private structure.
-
void iio_device_free(struct iio_dev * dev)
free an iio_dev from a driver
Parameters
- struct iio_dev * dev
- the iio_dev associated with the device
-
struct iio_dev * devm_iio_device_alloc(struct device * dev, int sizeof_priv)
Resource-managed iio_device_alloc()
Parameters
- struct device * dev
- Device to allocate iio_dev for
- int sizeof_priv
- Space to allocate for private structure.
Description
Managed iio_device_alloc. iio_dev allocated with this function is
automatically freed on driver detach.
If an iio_dev allocated with this function needs to be freed separately,
devm_iio_device_free() must be used.
Return
Pointer to allocated iio_dev on success, NULL on failure.
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void devm_iio_device_free(struct device * dev, struct iio_dev * iio_dev)
Resource-managed iio_device_free()
Parameters
- struct device * dev
- Device this iio_dev belongs to
- struct iio_dev * iio_dev
- the iio_dev associated with the device
Description
Free iio_dev allocated with devm_iio_device_alloc().
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int iio_device_register(struct iio_dev * indio_dev)
register a device with the IIO subsystem
Parameters
- struct iio_dev * indio_dev
- Device structure filled by the device driver
-
void iio_device_unregister(struct iio_dev * indio_dev)
unregister a device from the IIO subsystem
Parameters
- struct iio_dev * indio_dev
- Device structure representing the device.
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int devm_iio_device_register(struct device * dev, struct iio_dev * indio_dev)
Resource-managed iio_device_register()
Parameters
- struct device * dev
- Device to allocate iio_dev for
- struct iio_dev * indio_dev
- Device structure filled by the device driver
Description
Managed iio_device_register. The IIO device registered with this
function is automatically unregistered on driver detach. This function
calls iio_device_register() internally. Refer to that function for more
information.
If an iio_dev registered with this function needs to be unregistered
separately, devm_iio_device_unregister() must be used.
Return
0 on success, negative error number on failure.
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void devm_iio_device_unregister(struct device * dev, struct iio_dev * indio_dev)
Resource-managed iio_device_unregister()
Parameters
- struct device * dev
- Device this iio_dev belongs to
- struct iio_dev * indio_dev
- the iio_dev associated with the device
Description
Unregister iio_dev registered with devm_iio_device_register().
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int iio_device_claim_direct_mode(struct iio_dev * indio_dev)
Keep device in direct mode
Parameters
- struct iio_dev * indio_dev
- the iio_dev associated with the device
Description
If the device is in direct mode it is guaranteed to stay
that way until iio_device_release_direct_mode() is called.
Use with iio_device_release_direct_mode()
Return
0 on success, -EBUSY on failure
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void iio_device_release_direct_mode(struct iio_dev * indio_dev)
releases claim on direct mode
Parameters
- struct iio_dev * indio_dev
- the iio_dev associated with the device
Description
Release the claim. Device is no longer guaranteed to stay
in direct mode.
Use with iio_device_claim_direct_mode()