/* The industrial I/O core - generic 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_BUFFER_GENERIC_H_
#define _IIO_BUFFER_GENERIC_H_
#include <linux/sysfs.h>
#include <linux/iio/iio.h>

#ifdef CONFIG_IIO_BUFFER

struct iio_buffer;

/**
 * struct iio_buffer_access_funcs - access functions for buffers.
 * @store_to:           actually store stuff to the buffer
 * @read_first_n:       try to get a specified number of bytes (must exist)
 * @request_update:     if a parameter change has been marked, update underlying
 *                      storage.
 * @get_bytes_per_datum:get current bytes per datum
 * @set_bytes_per_datum:set number of bytes per datum
 * @get_length:         get number of datums in buffer
 * @set_length:         set number of datums in buffer
 *
 * The purpose of this structure is to make the buffer element
 * modular as event for a given driver, different usecases may require
 * different buffer designs (space efficiency vs speed for example).
 *
 * It is worth noting that a given buffer implementation may only support a
 * small proportion of these functions.  The core code 'should' cope fine with
 * any of them not existing.
 **/
struct iio_buffer_access_funcs {
        int (*store_to)(struct iio_buffer *buffer, u8 *data);
        int (*read_first_n)(struct iio_buffer *buffer,
                            size_t n,
                            char __user *buf);

        int (*request_update)(struct iio_buffer *buffer);

        int (*get_bytes_per_datum)(struct iio_buffer *buffer);
        int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
        int (*get_length)(struct iio_buffer *buffer);
        int (*set_length)(struct iio_buffer *buffer, int length);
};

/**
 * struct iio_buffer - general buffer structure
 * @length:             [DEVICE] number of datums in buffer
 * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
 * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
 *                      control method is used
 * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
 * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
 * @access:             [DRIVER] buffer access functions associated with the
 *                      implementation.
 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
 * @scan_el_group:      [DRIVER] attribute group for those attributes not
 *                      created from the iio_chan_info array.
 * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
 * @stufftoread:        [INTERN] flag to indicate new data.
 * @demux_list:         [INTERN] list of operations required to demux the scan.
 * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
 * @buffer_list:        [INTERN] entry in the devices list of current buffers.
 */
struct iio_buffer {
        int                                     length;
        int                                     bytes_per_datum;
        struct attribute_group                  *scan_el_attrs;
        long                                    *scan_mask;
        bool                                    scan_timestamp;
        const struct iio_buffer_access_funcs    *access;
        struct list_head                        scan_el_dev_attr_list;
        struct attribute_group                  scan_el_group;
        wait_queue_head_t                       pollq;
        bool                                    stufftoread;
        const struct attribute_group *attrs;
        struct list_head                        demux_list;
        unsigned char                           *demux_bounce;
        struct list_head                        buffer_list;
};

/**
 * iio_update_buffers() - add or remove buffer from active list
 * @indio_dev:          device to add buffer to
 * @insert_buffer:      buffer to insert
 * @remove_buffer:      buffer_to_remove
 *
 * Note this will tear down the all buffering and build it up again
 */
int iio_update_buffers(struct iio_dev *indio_dev,
                       struct iio_buffer *insert_buffer,
                       struct iio_buffer *remove_buffer);

/**
 * iio_buffer_init() - Initialize the buffer structure
 * @buffer:             buffer to be initialized
 **/
void iio_buffer_init(struct iio_buffer *buffer);

int iio_scan_mask_query(struct iio_dev *indio_dev,
                        struct iio_buffer *buffer, int bit);

/**
 * iio_scan_mask_set() - set particular bit in the scan mask
 * @indio_dev           IIO device structure
 * @buffer:             the buffer whose scan mask we are interested in
 * @bit:                the bit to be set.
 **/
int iio_scan_mask_set(struct iio_dev *indio_dev,
                      struct iio_buffer *buffer, int bit);

/**
 * iio_push_to_buffers() - push to a registered buffer.
 * @indio_dev:          iio_dev structure for device.
 * @data:               Full scan.
 */
int iio_push_to_buffers(struct iio_dev *indio_dev, unsigned char *data);

int iio_update_demux(struct iio_dev *indio_dev);

/**
 * iio_buffer_register() - register the buffer with IIO core
 * @indio_dev:          device with the buffer to be registered
 * @channels:           the channel descriptions used to construct buffer
 * @num_channels:       the number of channels
 **/
int iio_buffer_register(struct iio_dev *indio_dev,
                        const struct iio_chan_spec *channels,
                        int num_channels);

/**
 * iio_buffer_unregister() - unregister the buffer from IIO core
 * @indio_dev:          the device with the buffer to be unregistered
 **/
void iio_buffer_unregister(struct iio_dev *indio_dev);

/**
 * iio_buffer_read_length() - attr func to get number of datums in the buffer
 **/
ssize_t iio_buffer_read_length(struct device *dev,
                               struct device_attribute *attr,
                               char *buf);
/**
 * iio_buffer_write_length() - attr func to set number of datums in the buffer
 **/
ssize_t iio_buffer_write_length(struct device *dev,
                              struct device_attribute *attr,
                              const char *buf,
                              size_t len);
/**
 * iio_buffer_store_enable() - attr to turn the buffer on
 **/
ssize_t iio_buffer_store_enable(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf,
                                size_t len);
/**
 * iio_buffer_show_enable() - attr to see if the buffer is on
 **/
ssize_t iio_buffer_show_enable(struct device *dev,
                               struct device_attribute *attr,
                               char *buf);
#define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,   \
                                           iio_buffer_read_length,      \
                                           iio_buffer_write_length)

#define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,   \
                                           iio_buffer_show_enable,      \
                                           iio_buffer_store_enable)

int iio_sw_buffer_preenable(struct iio_dev *indio_dev);

bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
        const unsigned long *mask);

#else /* CONFIG_IIO_BUFFER */

static inline int iio_buffer_register(struct iio_dev *indio_dev,
                                           const struct iio_chan_spec *channels,
                                           int num_channels)
{
        return 0;
}

static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
{}

#endif /* CONFIG_IIO_BUFFER */

#endif /* _IIO_BUFFER_GENERIC_H_ */