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kernel/include/linux/counter.h
William Breathitt Gray 0040a390d2 counter: Introduce the Generic Counter interface 
This patch introduces the Generic Counter interface for supporting
counter devices.

In the context of the Generic Counter interface, a counter is defined as
a device that reports one or more "counts" based on the state changes of
one or more "signals" as evaluated by a defined "count function."

Driver callbacks should be provided to communicate with the device: to
read and write various Signals and Counts, and to set and get the
"action mode" and "count function" for various Synapses and Counts
respectively.

To support a counter device, a driver must first allocate the available
Counter Signals via counter_signal structures. These Signals should
be stored as an array and set to the signals array member of an
allocated counter_device structure before the Counter is registered to
the system.

Counter Counts may be allocated via counter_count structures, and
respective Counter Signal associations (Synapses) made via
counter_synapse structures. Associated counter_synapse structures are
stored as an array and set to the the synapses array member of the
respective counter_count structure. These counter_count structures are
set to the counts array member of an allocated counter_device structure
before the Counter is registered to the system.

A counter device is registered to the system by passing the respective
initialized counter_device structure to the counter_register function;
similarly, the counter_unregister function unregisters the respective
Counter. The devm_counter_register and devm_counter_unregister functions
serve as device memory-managed versions of the counter_register and
counter_unregister functions respectively.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-25 21:33:37 +02:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Counter interface
* Copyright (C) 2018 William Breathitt Gray
*/
#ifndef _COUNTER_H_
#define _COUNTER_H_
#include <linux/counter_enum.h>
#include <linux/device.h>
#include <linux/types.h>
enum counter_count_direction {
COUNTER_COUNT_DIRECTION_FORWARD = 0,
COUNTER_COUNT_DIRECTION_BACKWARD
};
extern const char *const counter_count_direction_str[2];
enum counter_count_mode {
COUNTER_COUNT_MODE_NORMAL = 0,
COUNTER_COUNT_MODE_RANGE_LIMIT,
COUNTER_COUNT_MODE_NON_RECYCLE,
COUNTER_COUNT_MODE_MODULO_N
};
extern const char *const counter_count_mode_str[4];
struct counter_device;
struct counter_signal;
/**
* struct counter_signal_ext - Counter Signal extensions
* @name: attribute name
* @read: read callback for this attribute; may be NULL
* @write: write callback for this attribute; may be NULL
* @priv: data private to the driver
*/
struct counter_signal_ext {
const char *name;
ssize_t (*read)(struct counter_device *counter,
struct counter_signal *signal, void *priv, char *buf);
ssize_t (*write)(struct counter_device *counter,
struct counter_signal *signal, void *priv,
const char *buf, size_t len);
void *priv;
};
/**
* struct counter_signal - Counter Signal node
* @id: unique ID used to identify signal
* @name: device-specific Signal name; ideally, this should match the name
* as it appears in the datasheet documentation
* @ext: optional array of Counter Signal extensions
* @num_ext: number of Counter Signal extensions specified in @ext
* @priv: optional private data supplied by driver
*/
struct counter_signal {
int id;
const char *name;
const struct counter_signal_ext *ext;
size_t num_ext;
void *priv;
};
/**
* struct counter_signal_enum_ext - Signal enum extension attribute
* @items: Array of strings
* @num_items: Number of items specified in @items
* @set: Set callback function; may be NULL
* @get: Get callback function; may be NULL
*
* The counter_signal_enum_ext structure can be used to implement enum style
* Signal extension attributes. Enum style attributes are those which have a set
* of strings that map to unsigned integer values. The Generic Counter Signal
* enum extension 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 get callback is used to query the currently active item; the index
* of the item within the respective items array is returned via the 'item'
* parameter. The set callback is called when the attribute is updated; the
* 'item' parameter contains the index of the newly activated item within the
* respective items array.
*/
struct counter_signal_enum_ext {
const char * const *items;
size_t num_items;
int (*get)(struct counter_device *counter,
struct counter_signal *signal, size_t *item);
int (*set)(struct counter_device *counter,
struct counter_signal *signal, size_t item);
};
/**
* COUNTER_SIGNAL_ENUM() - Initialize Signal enum extension
* @_name: Attribute name
* @_e: Pointer to a counter_signal_enum_ext structure
*
* This should usually be used together with COUNTER_SIGNAL_ENUM_AVAILABLE()
*/
#define COUNTER_SIGNAL_ENUM(_name, _e) \
{ \
.name = (_name), \
.read = counter_signal_enum_read, \
.write = counter_signal_enum_write, \
.priv = (_e) \
}
/**
* COUNTER_SIGNAL_ENUM_AVAILABLE() - Initialize Signal enum available extension
* @_name: Attribute name ("_available" will be appended to the name)
* @_e: Pointer to a counter_signal_enum_ext structure
*
* Creates a read only attribute that lists all the available enum items in a
* newline separated list. This should usually be used together with
* COUNTER_SIGNAL_ENUM()
*/
#define COUNTER_SIGNAL_ENUM_AVAILABLE(_name, _e) \
{ \
.name = (_name "_available"), \
.read = counter_signal_enum_available_read, \
.priv = (_e) \
}
enum counter_synapse_action {
COUNTER_SYNAPSE_ACTION_NONE = 0,
COUNTER_SYNAPSE_ACTION_RISING_EDGE,
COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
COUNTER_SYNAPSE_ACTION_BOTH_EDGES
};
/**
* struct counter_synapse - Counter Synapse node
* @action: index of current action mode
* @actions_list: array of available action modes
* @num_actions: number of action modes specified in @actions_list
* @signal: pointer to associated signal
*/
struct counter_synapse {
size_t action;
const enum counter_synapse_action *actions_list;
size_t num_actions;
struct counter_signal *signal;
};
struct counter_count;
/**
* struct counter_count_ext - Counter Count extension
* @name: attribute name
* @read: read callback for this attribute; may be NULL
* @write: write callback for this attribute; may be NULL
* @priv: data private to the driver
*/
struct counter_count_ext {
const char *name;
ssize_t (*read)(struct counter_device *counter,
struct counter_count *count, void *priv, char *buf);
ssize_t (*write)(struct counter_device *counter,
struct counter_count *count, void *priv,
const char *buf, size_t len);
void *priv;
};
enum counter_count_function {
COUNTER_COUNT_FUNCTION_INCREASE = 0,
COUNTER_COUNT_FUNCTION_DECREASE,
COUNTER_COUNT_FUNCTION_PULSE_DIRECTION,
COUNTER_COUNT_FUNCTION_QUADRATURE_X1_A,
COUNTER_COUNT_FUNCTION_QUADRATURE_X1_B,
COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B,
COUNTER_COUNT_FUNCTION_QUADRATURE_X4
};
/**
* struct counter_count - Counter Count node
* @id: unique ID used to identify Count
* @name: device-specific Count name; ideally, this should match
* the name as it appears in the datasheet documentation
* @function: index of current function mode
* @functions_list: array available function modes
* @num_functions: number of function modes specified in @functions_list
* @synapses: array of synapses for initialization
* @num_synapses: number of synapses specified in @synapses
* @ext: optional array of Counter Count extensions
* @num_ext: number of Counter Count extensions specified in @ext
* @priv: optional private data supplied by driver
*/
struct counter_count {
int id;
const char *name;
size_t function;
const enum counter_count_function *functions_list;
size_t num_functions;
struct counter_synapse *synapses;
size_t num_synapses;
const struct counter_count_ext *ext;
size_t num_ext;
void *priv;
};
/**
* struct counter_count_enum_ext - Count enum extension attribute
* @items: Array of strings
* @num_items: Number of items specified in @items
* @set: Set callback function; may be NULL
* @get: Get callback function; may be NULL
*
* The counter_count_enum_ext structure can be used to implement enum style
* Count extension attributes. Enum style attributes are those which have a set
* of strings that map to unsigned integer values. The Generic Counter Count
* enum extension 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 get callback is used to query the currently active item; the index
* of the item within the respective items array is returned via the 'item'
* parameter. The set callback is called when the attribute is updated; the
* 'item' parameter contains the index of the newly activated item within the
* respective items array.
*/
struct counter_count_enum_ext {
const char * const *items;
size_t num_items;
int (*get)(struct counter_device *counter, struct counter_count *count,
size_t *item);
int (*set)(struct counter_device *counter, struct counter_count *count,
size_t item);
};
/**
* COUNTER_COUNT_ENUM() - Initialize Count enum extension
* @_name: Attribute name
* @_e: Pointer to a counter_count_enum_ext structure
*
* This should usually be used together with COUNTER_COUNT_ENUM_AVAILABLE()
*/
#define COUNTER_COUNT_ENUM(_name, _e) \
{ \
.name = (_name), \
.read = counter_count_enum_read, \
.write = counter_count_enum_write, \
.priv = (_e) \
}
/**
* COUNTER_COUNT_ENUM_AVAILABLE() - Initialize Count enum available extension
* @_name: Attribute name ("_available" will be appended to the name)
* @_e: Pointer to a counter_count_enum_ext structure
*
* Creates a read only attribute that lists all the available enum items in a
* newline separated list. This should usually be used together with
* COUNTER_COUNT_ENUM()
*/
#define COUNTER_COUNT_ENUM_AVAILABLE(_name, _e) \
{ \
.name = (_name "_available"), \
.read = counter_count_enum_available_read, \
.priv = (_e) \
}
/**
* struct counter_device_attr_group - internal container for attribute group
* @attr_group: Counter sysfs attributes group
* @attr_list: list to keep track of created Counter sysfs attributes
* @num_attr: number of Counter sysfs attributes
*/
struct counter_device_attr_group {
struct attribute_group attr_group;
struct list_head attr_list;
size_t num_attr;
};
/**
* struct counter_device_state - internal state container for a Counter device
* @id: unique ID used to identify the Counter
* @dev: internal device structure
* @groups_list: attribute groups list (for Signals, Counts, and ext)
* @num_groups: number of attribute groups containers
* @groups: Counter sysfs attribute groups (to populate @dev.groups)
*/
struct counter_device_state {
int id;
struct device dev;
struct counter_device_attr_group *groups_list;
size_t num_groups;
const struct attribute_group **groups;
};
/**
* struct counter_signal_read_value - Opaque Signal read value
* @buf: string representation of Signal read value
* @len: length of string in @buf
*/
struct counter_signal_read_value {
char *buf;
size_t len;
};
/**
* struct counter_count_read_value - Opaque Count read value
* @buf: string representation of Count read value
* @len: length of string in @buf
*/
struct counter_count_read_value {
char *buf;
size_t len;
};
/**
* struct counter_count_write_value - Opaque Count write value
* @buf: string representation of Count write value
*/
struct counter_count_write_value {
const char *buf;
};
/**
* struct counter_ops - Callbacks from driver
* @signal_read: optional read callback for Signal attribute. The read
* value of the respective Signal should be passed back via
* the val parameter. val points to an opaque type which
* should be set only by calling the
* counter_signal_read_value_set function from within the
* signal_read callback.
* @count_read: optional read callback for Count attribute. The read
* value of the respective Count should be passed back via
* the val parameter. val points to an opaque type which
* should be set only by calling the
* counter_count_read_value_set function from within the
* count_read callback.
* @count_write: optional write callback for Count attribute. The write
* value for the respective Count is passed in via the val
* parameter. val points to an opaque type which should be
* accessed only by calling the
* counter_count_write_value_get function.
* @function_get: function to get the current count function mode. Returns
* 0 on success and negative error code on error. The index
* of the respective Count's returned function mode should
* be passed back via the function parameter.
* @function_set: function to set the count function mode. function is the
* index of the requested function mode from the respective
* Count's functions_list array.
* @action_get: function to get the current action mode. Returns 0 on
* success and negative error code on error. The index of
* the respective Signal's returned action mode should be
* passed back via the action parameter.
* @action_set: function to set the action mode. action is the index of
* the requested action mode from the respective Synapse's
* actions_list array.
*/
struct counter_ops {
int (*signal_read)(struct counter_device *counter,
struct counter_signal *signal,
struct counter_signal_read_value *val);
int (*count_read)(struct counter_device *counter,
struct counter_count *count,
struct counter_count_read_value *val);
int (*count_write)(struct counter_device *counter,
struct counter_count *count,
struct counter_count_write_value *val);
int (*function_get)(struct counter_device *counter,
struct counter_count *count, size_t *function);
int (*function_set)(struct counter_device *counter,
struct counter_count *count, size_t function);
int (*action_get)(struct counter_device *counter,
struct counter_count *count,
struct counter_synapse *synapse, size_t *action);
int (*action_set)(struct counter_device *counter,
struct counter_count *count,
struct counter_synapse *synapse, size_t action);
};
/**
* struct counter_device_ext - Counter device extension
* @name: attribute name
* @read: read callback for this attribute; may be NULL
* @write: write callback for this attribute; may be NULL
* @priv: data private to the driver
*/
struct counter_device_ext {
const char *name;
ssize_t (*read)(struct counter_device *counter, void *priv, char *buf);
ssize_t (*write)(struct counter_device *counter, void *priv,
const char *buf, size_t len);
void *priv;
};
/**
* struct counter_device_enum_ext - Counter enum extension attribute
* @items: Array of strings
* @num_items: Number of items specified in @items
* @set: Set callback function; may be NULL
* @get: Get callback function; may be NULL
*
* The counter_device_enum_ext structure can be used to implement enum style
* Counter extension attributes. Enum style attributes are those which have a
* set of strings that map to unsigned integer values. The Generic Counter enum
* extension 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 get callback is used to query the currently active item; the index
* of the item within the respective items array is returned via the 'item'
* parameter. The set callback is called when the attribute is updated; the
* 'item' parameter contains the index of the newly activated item within the
* respective items array.
*/
struct counter_device_enum_ext {
const char * const *items;
size_t num_items;
int (*get)(struct counter_device *counter, size_t *item);
int (*set)(struct counter_device *counter, size_t item);
};
/**
* COUNTER_DEVICE_ENUM() - Initialize Counter enum extension
* @_name: Attribute name
* @_e: Pointer to a counter_device_enum_ext structure
*
* This should usually be used together with COUNTER_DEVICE_ENUM_AVAILABLE()
*/
#define COUNTER_DEVICE_ENUM(_name, _e) \
{ \
.name = (_name), \
.read = counter_device_enum_read, \
.write = counter_device_enum_write, \
.priv = (_e) \
}
/**
* COUNTER_DEVICE_ENUM_AVAILABLE() - Initialize Counter enum available extension
* @_name: Attribute name ("_available" will be appended to the name)
* @_e: Pointer to a counter_device_enum_ext structure
*
* Creates a read only attribute that lists all the available enum items in a
* newline separated list. This should usually be used together with
* COUNTER_DEVICE_ENUM()
*/
#define COUNTER_DEVICE_ENUM_AVAILABLE(_name, _e) \
{ \
.name = (_name "_available"), \
.read = counter_device_enum_available_read, \
.priv = (_e) \
}
/**
* struct counter_device - Counter data structure
* @name: name of the device as it appears in the datasheet
* @parent: optional parent device providing the counters
* @device_state: internal device state container
* @ops: callbacks from driver
* @signals: array of Signals
* @num_signals: number of Signals specified in @signals
* @counts: array of Counts
* @num_counts: number of Counts specified in @counts
* @ext: optional array of Counter device extensions
* @num_ext: number of Counter device extensions specified in @ext
* @priv: optional private data supplied by driver
*/
struct counter_device {
const char *name;
struct device *parent;
struct counter_device_state *device_state;
const struct counter_ops *ops;
struct counter_signal *signals;
size_t num_signals;
struct counter_count *counts;
size_t num_counts;
const struct counter_device_ext *ext;
size_t num_ext;
void *priv;
};
enum counter_signal_level {
COUNTER_SIGNAL_LEVEL_LOW = 0,
COUNTER_SIGNAL_LEVEL_HIGH
};
enum counter_signal_value_type {
COUNTER_SIGNAL_LEVEL = 0
};
enum counter_count_value_type {
COUNTER_COUNT_POSITION = 0,
};
void counter_signal_read_value_set(struct counter_signal_read_value *const val,
const enum counter_signal_value_type type,
void *const data);
void counter_count_read_value_set(struct counter_count_read_value *const val,
const enum counter_count_value_type type,
void *const data);
int counter_count_write_value_get(void *const data,
const enum counter_count_value_type type,
const struct counter_count_write_value *const val);
int counter_register(struct counter_device *const counter);
void counter_unregister(struct counter_device *const counter);
int devm_counter_register(struct device *dev,
struct counter_device *const counter);
void devm_counter_unregister(struct device *dev,
struct counter_device *const counter);
#endif /* _COUNTER_H_ */
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