include/linux/iio/buffer.h

   1 /* The industrial I/O core - generic buffer interfaces.
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #ifndef _IIO_BUFFER_GENERIC_H_
  11 #define _IIO_BUFFER_GENERIC_H_
  12 #include <linux/sysfs.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/kref.h>
  15
  16 #ifdef CONFIG_IIO_BUFFER
  17
  18 struct iio_buffer;
  19
  20 /**
  21  * struct iio_buffer_access_funcs - access functions for buffers.
  22  * @store_to:           actually store stuff to the buffer
  23  * @read_first_n:       try to get a specified number of bytes (must exist)
  24  * @data_available:     indicates how much data is available for reading from
  25  *                      the buffer.
  26  * @request_update:     if a parameter change has been marked, update underlying
  27  *                      storage.
  28  * @set_bytes_per_datum:set number of bytes per datum
  29  * @set_length:         set number of datums in buffer
  30  * @release:            called when the last reference to the buffer is dropped,
  31  *                      should free all resources allocated by the buffer.
  32  * @modes:              Supported operating modes by this buffer type
  33  *
  34  * The purpose of this structure is to make the buffer element
  35  * modular as event for a given driver, different usecases may require
  36  * different buffer designs (space efficiency vs speed for example).
  37  *
  38  * It is worth noting that a given buffer implementation may only support a
  39  * small proportion of these functions.  The core code 'should' cope fine with
  40  * any of them not existing.
  41  **/
  42 struct iio_buffer_access_funcs {
  43         int (*store_to)(struct iio_buffer *buffer, const void *data);
  44         int (*read_first_n)(struct iio_buffer *buffer,
  45                             size_t n,
  46                             char __user *buf);
  47         size_t (*data_available)(struct iio_buffer *buffer);
  48
  49         int (*request_update)(struct iio_buffer *buffer);
  50
  51         int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
  52         int (*set_length)(struct iio_buffer *buffer, int length);
  53
  54         void (*release)(struct iio_buffer *buffer);
  55
  56         unsigned int modes;
  57 };
  58
  59 /**
  60  * struct iio_buffer - general buffer structure
  61  * @length:             [DEVICE] number of datums in buffer
  62  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  63  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  64  *                      control method is used
  65  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  66  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  67  * @access:             [DRIVER] buffer access functions associated with the
  68  *                      implementation.
  69  * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
  70  * @scan_el_group:      [DRIVER] attribute group for those attributes not
  71  *                      created from the iio_chan_info array.
  72  * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
  73  * @stufftoread:        [INTERN] flag to indicate new data.
  74  * @demux_list:         [INTERN] list of operations required to demux the scan.
  75  * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
  76  * @buffer_list:        [INTERN] entry in the devices list of current buffers.
  77  * @ref:                [INTERN] reference count of the buffer.
  78  * @watermark:          [INTERN] number of datums to wait for poll/read.
  79  */
  80 struct iio_buffer {
  81         int                                     length;
  82         int                                     bytes_per_datum;
  83         struct attribute_group                  *scan_el_attrs;
  84         long                                    *scan_mask;
  85         bool                                    scan_timestamp;
  86         const struct iio_buffer_access_funcs    *access;
  87         struct list_head                        scan_el_dev_attr_list;
  88         struct attribute_group                  buffer_group;
  89         struct attribute_group                  scan_el_group;
  90         wait_queue_head_t                       pollq;
  91         bool                                    stufftoread;
  92         const struct attribute                  **attrs;
  93         struct list_head                        demux_list;
  94         void                                    *demux_bounce;
  95         struct list_head                        buffer_list;
  96         struct kref                             ref;
  97         unsigned int                            watermark;
  98 };
  99
 100 /**
 101  * iio_update_buffers() - add or remove buffer from active list
 102  * @indio_dev:          device to add buffer to
 103  * @insert_buffer:      buffer to insert
 104  * @remove_buffer:      buffer_to_remove
 105  *
 106  * Note this will tear down the all buffering and build it up again
 107  */
 108 int iio_update_buffers(struct iio_dev *indio_dev,
 109                        struct iio_buffer *insert_buffer,
 110                        struct iio_buffer *remove_buffer);
 111
 112 /**
 113  * iio_buffer_init() - Initialize the buffer structure
 114  * @buffer:             buffer to be initialized
 115  **/
 116 void iio_buffer_init(struct iio_buffer *buffer);
 117
 118 int iio_scan_mask_query(struct iio_dev *indio_dev,
 119                         struct iio_buffer *buffer, int bit);
 120
 121 /**
 122  * iio_push_to_buffers() - push to a registered buffer.
 123  * @indio_dev:          iio_dev structure for device.
 124  * @data:               Full scan.
 125  */
 126 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
 127
 128 /*
 129  * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
 130  * @indio_dev:          iio_dev structure for device.
 131  * @data:               sample data
 132  * @timestamp:          timestamp for the sample data
 133  *
 134  * Pushes data to the IIO device's buffers. If timestamps are enabled for the
 135  * device the function will store the supplied timestamp as the last element in
 136  * the sample data buffer before pushing it to the device buffers. The sample
 137  * data buffer needs to be large enough to hold the additional timestamp
 138  * (usually the buffer should be indio->scan_bytes bytes large).
 139  *
 140  * Returns 0 on success, a negative error code otherwise.
 141  */
 142 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
 143         void *data, int64_t timestamp)
 144 {
 145         if (indio_dev->scan_timestamp) {
 146                 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
 147                 ((int64_t *)data)[ts_offset] = timestamp;
 148         }
 149
 150         return iio_push_to_buffers(indio_dev, data);
 151 }
 152
 153 int iio_update_demux(struct iio_dev *indio_dev);
 154
 155 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 156         const unsigned long *mask);
 157
 158 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
 159 void iio_buffer_put(struct iio_buffer *buffer);
 160
 161 /**
 162  * iio_device_attach_buffer - Attach a buffer to a IIO device
 163  * @indio_dev: The device the buffer should be attached to
 164  * @buffer: The buffer to attach to the device
 165  *
 166  * This function attaches a buffer to a IIO device. The buffer stays attached to
 167  * the device until the device is freed. The function should only be called at
 168  * most once per device.
 169  */
 170 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
 171         struct iio_buffer *buffer)
 172 {
 173         indio_dev->buffer = iio_buffer_get(buffer);
 174 }
 175
 176 #else /* CONFIG_IIO_BUFFER */
 177
 178 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
 179 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
 180
 181 #endif /* CONFIG_IIO_BUFFER */
 182
 183 #endif /* _IIO_BUFFER_GENERIC_H_ */