/* The industrial I/O core - generic ring buffer interfaces.
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#ifndef _IIO_RING_GENERIC_H_
#define _IIO_RING_GENERIC_H_
#include "iio.h"

struct iio_handler;
struct iio_ring_buffer;
struct iio_dev;

/**
 * iio_push_ring_event() - ring buffer specific push to event chrdev
 * @ring_buf:           ring buffer that is the event source
 * @event_code:         event indentification code
 * @timestamp:          time of event
 **/
int iio_push_ring_event(struct iio_ring_buffer *ring_buf,
                        int event_code,
                        s64 timestamp);
/**
 * iio_push_or_escallate_ring_event() - escallate or add as appropriate
 *
 * Typical usecase is to escallate a 50% ring full to 75% full if noone has yet
 * read the first event. Clearly the 50% full is no longer of interest in
 * typical use case.
 **/
int iio_push_or_escallate_ring_event(struct iio_ring_buffer *ring_buf,
                                     int event_code,
                                     s64 timestamp);

/**
 * struct iio_ring_access_funcs - access functions for ring buffers.
 * @create:             perform allocation
 * @init:               get ring buffer ready for use
 * @_exit:              reverse steps in init
 * @_free:              deallocate ring buffer
 * @mark_in_use:        reference counting, typically to prevent module removal
 * @unmark_in_use:      reduce reference count when no longer using ring buffer
 * @store_to:           actually store stuff to the ring buffer
 * @read_last:          get the last element stored
 * @rip_lots:           try to get a specified number of elements (must exist)
 * @mark_param_change:  notify ring that some relevant parameter has changed
 *                      Often this means the underlying storage may need to
 *                      change.
 * @request_update:     if a parameter change has been marked, update underlying
 *                      storage.
 * @get_bpd:            get current bytes per datum
 * @set_bpd:            set number of bytes per datum
 * @get_length:         get number of datums in ring
 * @set_length:         set number of datums in ring
 * @is_enabled:         query if ring is currently being used
 * @enable:             enable the ring
 *
 * The purpose of this structure is to make the ring buffer element
 * modular as event for a given driver, different usecases may require
 * different ring designs (space efficiency vs speed for example.
 *
 * It is worth noting that a given ring implementation may only support a small
 * proportion of these functions.  The core code 'should' cope fine with any of
 * them not existing.
 **/
struct iio_ring_access_funcs {
        void (*mark_in_use)(struct iio_ring_buffer *ring);
        void (*unmark_in_use)(struct iio_ring_buffer *ring);

        int (*store_to)(struct iio_ring_buffer *ring, u8 *data, s64 timestamp);
        int (*read_last)(struct iio_ring_buffer *ring, u8 *data);
        int (*rip_lots)(struct iio_ring_buffer *ring,
                        size_t count,
                        u8 **data,
                        int *dead_offset);

        int (*mark_param_change)(struct iio_ring_buffer *ring);
        int (*request_update)(struct iio_ring_buffer *ring);

        int (*get_bpd)(struct iio_ring_buffer *ring);
        int (*set_bpd)(struct iio_ring_buffer *ring, size_t bpd);
        int (*get_length)(struct iio_ring_buffer *ring);
        int (*set_length)(struct iio_ring_buffer *ring, int length);

        int (*is_enabled)(struct iio_ring_buffer *ring);
        int (*enable)(struct iio_ring_buffer *ring);
};

/**
 * struct iio_ring_buffer - general ring buffer structure
 * @length:             [DEVICE]number of datums in ring
 * @bpd:                [DEVICE]size of individual datum including timestamp
 * @loopcount:          [INTERN]number of times the ring has looped
 * @access_minor_name:  [INTERN]store of name of the access chrdev minor number
 *                      sysfs attribute
 * @access_handler:     [INTERN]chrdev access handling
 * @event_minor_name:   [INTERN]store of name of the event chrdev minor number
 *                      sysfs attribute
 * @ev_int:             [INTERN]chrdev interface for the event chrdev
 * @shared_ev_pointer:  [INTERN]the shared event pointer to allow escalation of
 *                      events
 * @ring_access:        [DRIVER]ring access functions associated with the
 *                      implementation.
 * @ring_prenable:      [DRIVER] function to run prior to marking ring enabled
 * @ring_postenable:    [DRIVER] function to run after marking ring enabled
 * @ring_predisable:    [DRIVER] function to run prior to marking ring disabled
 * @ring_postdisable:   [DRIVER] function to run after marking ring disabled
  **/
struct iio_ring_buffer {
        struct device dev;
        struct device access_dev;
        struct iio_dev *indio_dev;
        struct module *owner;
        int                             id;
        int                             access_id;
        int                             length;
        int                             bpd;
        int                             loopcount;
        struct iio_handler              access_handler;
        struct iio_event_interface      ev_int;
        struct iio_shared_ev_pointer    shared_ev_pointer;
        struct iio_ring_access_funcs    access;
        int                             (*preenable)(struct iio_dev *);
        int                             (*postenable)(struct iio_dev *);
        int                             (*predisable)(struct iio_dev *);
        int                             (*postdisable)(struct iio_dev *);

};
void iio_ring_buffer_init(struct iio_ring_buffer *ring,
                          struct iio_dev *dev_info);

/**
 * __iio_init_ring_buffer() - initialize common elements of ring buffers.
 **/
static inline void __iio_init_ring_buffer(struct iio_ring_buffer *ring,
                                 int bytes_per_datum, int length)
{
        ring->bpd = bytes_per_datum;
        ring->length = length;
        ring->loopcount = 0;
        ring->shared_ev_pointer.ev_p = 0;
        ring->shared_ev_pointer.lock =
                __SPIN_LOCK_UNLOCKED(ring->shared_ev_pointer->loc);
}

/**
 * struct iio_scan_el - an individual element of a scan
 * @dev_attr:           control attribute (if directly controllable)
 * @number:             unique identifier of element (used for bit mask)
 * @bit_count:          number of bits in scan element
 * @label:              useful data for the scan el (often reg address)
 * @set_state:          for some devices datardy signals are generated
 *                      for any enabled lines.  This allows unwanted lines
 *                      to be disabled and hence not get in the way.
 **/
struct iio_scan_el {
        struct device_attribute         dev_attr;
        unsigned int                    number;
        int                             bit_count;
        unsigned int                    label;

        int (*set_state)(struct iio_scan_el *scanel,
                         struct iio_dev *dev_info,
                         bool state);
};

#define to_iio_scan_el(_dev_attr)                               \
        container_of(_dev_attr, struct iio_scan_el, dev_attr);

/**
 * iio_scan_el_store() - sysfs scan element selection interface.
 *
 * A generic function used to enable various scan elements.  In some
 * devices explicit read commands for each channel mean this is merely
 * a software switch.  In others this must actively disable the channel.
 * Complexities occur when this interacts with data ready type triggers
 * which may not reset unless every channel that is enabled is explicitly
 * read.
 **/
ssize_t iio_scan_el_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t len);
/**
 * iio_scal_el_show() - sysfs interface to query whether a scan element is
 *                      is enabled or not.
 **/
ssize_t iio_scan_el_show(struct device *dev, struct device_attribute *attr,
                         char *buf);
/**
 * IIO_SCAN_EL: - declare and initialize a scan element without control func
 * @_name:      identifying name. Resulting struct is iio_scan_el_##_name,
 *              sysfs element, scan_en_##_name.
 * @_number:    unique id number for the scan element.
 * @_bits:      number of bits in the scan element result (used in mixed bit
 *              length devices).
 * @_label:     indentification variable used by drivers.  Often a reg address.
 **/
#define IIO_SCAN_EL(_name, _number, _bits, _label)                      \
        struct iio_scan_el iio_scan_el_##_name = {                      \
                .dev_attr = __ATTR(scan_en_##_name,                     \
                                   S_IRUGO | S_IWUSR,                   \
                                   iio_scan_el_show,                    \
                                   iio_scan_el_store),                  \
                .mask = (1 << _number),                                 \
                .bit_count = _bits,                                     \
                .label = _label,                                        \
        }

ssize_t iio_scan_el_ts_store(struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t len);

ssize_t iio_scan_el_ts_show(struct device *dev, struct device_attribute *attr,
                            char *buf);
/**
 * IIO_SCAN_EL_C: - declare and initialize a scan element with a control func
 *
 * @_controlfunc: function used to notify hardware of whether state changes
 **/
#define IIO_SCAN_EL_C(_name, _number, _bits, _label, _controlfunc)      \
        struct iio_scan_el iio_scan_el_##_name = {                      \
                .dev_attr = __ATTR(scan_en_##_name,                     \
                                   S_IRUGO | S_IWUSR,                   \
                                   iio_scan_el_show,                    \
                                   iio_scan_el_store),                  \
                .number =  _number,                                     \
                .bit_count = _bits,                                     \
                .label = _label,                                        \
                .set_state = _controlfunc,                              \
        }
/**
 * IIO_SCAN_EL_TIMESTAMP: - declare a special scan element for timestamps
 *
 * Odd one out. Handled slightly differently from other scan elements.
 **/
#define IIO_SCAN_EL_TIMESTAMP                                   \
        struct iio_scan_el iio_scan_el_timestamp = {            \
                .dev_attr = __ATTR(scan_en_timestamp,           \
                                   S_IRUGO | S_IWUSR,           \
                                   iio_scan_el_ts_show,         \
                                   iio_scan_el_ts_store),       \
        }

static inline void iio_put_ring_buffer(struct iio_ring_buffer *ring)
{
        put_device(&ring->dev);
};

#define to_iio_ring_buffer(d)                   \
        container_of(d, struct iio_ring_buffer, dev)
#define access_dev_to_iio_ring_buffer(d)                        \
        container_of(d, struct iio_ring_buffer, access_dev)
int iio_ring_buffer_register(struct iio_ring_buffer *ring);
void iio_ring_buffer_unregister(struct iio_ring_buffer *ring);

ssize_t iio_read_ring_length(struct device *dev,
                             struct device_attribute *attr,
                             char *buf);
ssize_t iio_write_ring_length(struct device *dev,
                              struct device_attribute *attr,
                              const char *buf,
                              size_t len);
ssize_t iio_read_ring_bps(struct device *dev,
                          struct device_attribute *attr,
                          char *buf);
ssize_t iio_store_ring_enable(struct device *dev,
                              struct device_attribute *attr,
                              const char *buf,
                              size_t len);
ssize_t iio_show_ring_enable(struct device *dev,
                             struct device_attribute *attr,
                             char *buf);
#define IIO_RING_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,     \
                                         iio_read_ring_length,          \
                                         iio_write_ring_length)
#define IIO_RING_BPS_ATTR DEVICE_ATTR(bps, S_IRUGO | S_IWUSR,   \
                                      iio_read_ring_bps, NULL)
#define IIO_RING_ENABLE_ATTR DEVICE_ATTR(ring_enable, S_IRUGO | S_IWUSR, \
                                         iio_show_ring_enable,          \
                                         iio_store_ring_enable)

#endif /* _IIO_RING_GENERIC_H_ */