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  * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
  22  *   configured. It has a fixed value which will be buffer specific.
  23  */
  24 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
  25
  26 /**
  27  * struct iio_buffer_access_funcs - access functions for buffers.
  28  * @store_to:           actually store stuff to the buffer
  29  * @read_first_n:       try to get a specified number of bytes (must exist)
  30  * @data_available:     indicates how much data is available for reading from
  31  *                      the buffer.
  32  * @request_update:     if a parameter change has been marked, update underlying
  33  *                      storage.
  34  * @set_bytes_per_datum:set number of bytes per datum
  35  * @set_length:         set number of datums in buffer
  36  * @enable:             called if the buffer is attached to a device and the
  37  *                      device starts sampling. Calls are balanced with
  38  *                      @disable.
  39  * @disable:            called if the buffer is attached to a device and the
  40  *                      device stops sampling. Calles are balanced with @enable.
  41  * @release:            called when the last reference to the buffer is dropped,
  42  *                      should free all resources allocated by the buffer.
  43  * @modes:              Supported operating modes by this buffer type
  44  * @flags:              A bitmask combination of INDIO_BUFFER_FLAG_*
  45  *
  46  * The purpose of this structure is to make the buffer element
  47  * modular as event for a given driver, different usecases may require
  48  * different buffer designs (space efficiency vs speed for example).
  49  *
  50  * It is worth noting that a given buffer implementation may only support a
  51  * small proportion of these functions.  The core code 'should' cope fine with
  52  * any of them not existing.
  53  **/
  54 struct iio_buffer_access_funcs {
  55         int (*store_to)(struct iio_buffer *buffer, const void *data);
  56         int (*read_first_n)(struct iio_buffer *buffer,
  57                             size_t n,
  58                             char __user *buf);
  59         size_t (*data_available)(struct iio_buffer *buffer);
  60
  61         int (*request_update)(struct iio_buffer *buffer);
  62
  63         int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
  64         int (*set_length)(struct iio_buffer *buffer, int length);
  65
  66         int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
  67         int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
  68
  69         void (*release)(struct iio_buffer *buffer);
  70
  71         unsigned int modes;
  72         unsigned int flags;
  73 };
  74
  75 /**
  76  * struct iio_buffer - general buffer structure
  77  * @length:             [DEVICE] number of datums in buffer
  78  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  79  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  80  *                      control method is used
  81  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  82  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  83  * @access:             [DRIVER] buffer access functions associated with the
  84  *                      implementation.
  85  * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
  86  * @scan_el_group:      [DRIVER] attribute group for those attributes not
  87  *                      created from the iio_chan_info array.
  88  * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
  89  * @stufftoread:        [INTERN] flag to indicate new data.
  90  * @demux_list:         [INTERN] list of operations required to demux the scan.
  91  * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
  92  * @buffer_list:        [INTERN] entry in the devices list of current buffers.
  93  * @ref:                [INTERN] reference count of the buffer.
  94  * @watermark:          [INTERN] number of datums to wait for poll/read.
  95  */
  96 struct iio_buffer {
  97         int                                     length;
  98         int                                     bytes_per_datum;
  99         struct attribute_group                  *scan_el_attrs;
 100         long                                    *scan_mask;
 101         bool                                    scan_timestamp;
 102         const struct iio_buffer_access_funcs    *access;
 103         struct list_head                        scan_el_dev_attr_list;
 104         struct attribute_group                  buffer_group;
 105         struct attribute_group                  scan_el_group;
 106         wait_queue_head_t                       pollq;
 107         bool                                    stufftoread;
 108         const struct attribute                  **attrs;
 109         struct list_head                        demux_list;
 110         void                                    *demux_bounce;
 111         struct list_head                        buffer_list;
 112         struct kref                             ref;
 113         unsigned int                            watermark;
 114 };
 115
 116 /**
 117  * iio_update_buffers() - add or remove buffer from active list
 118  * @indio_dev:          device to add buffer to
 119  * @insert_buffer:      buffer to insert
 120  * @remove_buffer:      buffer_to_remove
 121  *
 122  * Note this will tear down the all buffering and build it up again
 123  */
 124 int iio_update_buffers(struct iio_dev *indio_dev,
 125                        struct iio_buffer *insert_buffer,
 126                        struct iio_buffer *remove_buffer);
 127
 128 /**
 129  * iio_buffer_init() - Initialize the buffer structure
 130  * @buffer:             buffer to be initialized
 131  **/
 132 void iio_buffer_init(struct iio_buffer *buffer);
 133
 134 int iio_scan_mask_query(struct iio_dev *indio_dev,
 135                         struct iio_buffer *buffer, int bit);
 136
 137 /**
 138  * iio_push_to_buffers() - push to a registered buffer.
 139  * @indio_dev:          iio_dev structure for device.
 140  * @data:               Full scan.
 141  */
 142 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
 143
 144 /*
 145  * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
 146  * @indio_dev:          iio_dev structure for device.
 147  * @data:               sample data
 148  * @timestamp:          timestamp for the sample data
 149  *
 150  * Pushes data to the IIO device's buffers. If timestamps are enabled for the
 151  * device the function will store the supplied timestamp as the last element in
 152  * the sample data buffer before pushing it to the device buffers. The sample
 153  * data buffer needs to be large enough to hold the additional timestamp
 154  * (usually the buffer should be indio->scan_bytes bytes large).
 155  *
 156  * Returns 0 on success, a negative error code otherwise.
 157  */
 158 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
 159         void *data, int64_t timestamp)
 160 {
 161         if (indio_dev->scan_timestamp) {
 162                 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
 163                 ((int64_t *)data)[ts_offset] = timestamp;
 164         }
 165
 166         return iio_push_to_buffers(indio_dev, data);
 167 }
 168
 169 int iio_update_demux(struct iio_dev *indio_dev);
 170
 171 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 172         const unsigned long *mask);
 173
 174 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
 175 void iio_buffer_put(struct iio_buffer *buffer);
 176
 177 /**
 178  * iio_device_attach_buffer - Attach a buffer to a IIO device
 179  * @indio_dev: The device the buffer should be attached to
 180  * @buffer: The buffer to attach to the device
 181  *
 182  * This function attaches a buffer to a IIO device. The buffer stays attached to
 183  * the device until the device is freed. The function should only be called at
 184  * most once per device.
 185  */
 186 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
 187         struct iio_buffer *buffer)
 188 {
 189         indio_dev->buffer = iio_buffer_get(buffer);
 190 }
 191
 192 #else /* CONFIG_IIO_BUFFER */
 193
 194 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
 195 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
 196
 197 #endif /* CONFIG_IIO_BUFFER */
 198
 199 #endif /* _IIO_BUFFER_GENERIC_H_ */