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
  15 #ifdef CONFIG_IIO_BUFFER
  16
  17 struct iio_buffer;
  18
  19 /**
  20  * struct iio_buffer_access_funcs - access functions for buffers.
  21  * @store_to:           actually store stuff to the buffer
  22  * @read_first_n:       try to get a specified number of bytes (must exist)
  23  * @request_update:     if a parameter change has been marked, update underlying
  24  *                      storage.
  25  * @get_bytes_per_datum:get current bytes per datum
  26  * @set_bytes_per_datum:set number of bytes per datum
  27  * @get_length:         get number of datums in buffer
  28  * @set_length:         set number of datums in buffer
  29  *
  30  * The purpose of this structure is to make the buffer element
  31  * modular as event for a given driver, different usecases may require
  32  * different buffer designs (space efficiency vs speed for example).
  33  *
  34  * It is worth noting that a given buffer implementation may only support a
  35  * small proportion of these functions.  The core code 'should' cope fine with
  36  * any of them not existing.
  37  **/
  38 struct iio_buffer_access_funcs {
  39         int (*store_to)(struct iio_buffer *buffer, u8 *data);
  40         int (*read_first_n)(struct iio_buffer *buffer,
  41                             size_t n,
  42                             char __user *buf);
  43
  44         int (*request_update)(struct iio_buffer *buffer);
  45
  46         int (*get_bytes_per_datum)(struct iio_buffer *buffer);
  47         int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
  48         int (*get_length)(struct iio_buffer *buffer);
  49         int (*set_length)(struct iio_buffer *buffer, int length);
  50 };
  51
  52 /**
  53  * struct iio_buffer - general buffer structure
  54  * @length:             [DEVICE] number of datums in buffer
  55  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  56  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  57  *                      control method is used
  58  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  59  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  60  * @access:             [DRIVER] buffer access functions associated with the
  61  *                      implementation.
  62  * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
  63  * @scan_el_group:      [DRIVER] attribute group for those attributes not
  64  *                      created from the iio_chan_info array.
  65  * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
  66  * @stufftoread:        [INTERN] flag to indicate new data.
  67  * @demux_list:         [INTERN] list of operations required to demux the scan.
  68  * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
  69  **/
  70 struct iio_buffer {
  71         int                                     length;
  72         int                                     bytes_per_datum;
  73         struct attribute_group                  *scan_el_attrs;
  74         long                                    *scan_mask;
  75         bool                                    scan_timestamp;
  76         const struct iio_buffer_access_funcs    *access;
  77         struct list_head                        scan_el_dev_attr_list;
  78         struct attribute_group                  scan_el_group;
  79         wait_queue_head_t                       pollq;
  80         bool                                    stufftoread;
  81         const struct attribute_group *attrs;
  82         struct list_head                        demux_list;
  83         unsigned char                           *demux_bounce;
  84 };
  85
  86 /**
  87  * iio_buffer_init() - Initialize the buffer structure
  88  * @buffer:             buffer to be initialized
  89  **/
  90 void iio_buffer_init(struct iio_buffer *buffer);
  91
  92 /**
  93  * __iio_update_buffer() - update common elements of buffers
  94  * @buffer:             buffer that is the event source
  95  * @bytes_per_datum:    size of individual datum including timestamp
  96  * @length:             number of datums in buffer
  97  **/
  98 static inline void __iio_update_buffer(struct iio_buffer *buffer,
  99                                        int bytes_per_datum, int length)
 100 {
 101         buffer->bytes_per_datum = bytes_per_datum;
 102         buffer->length = length;
 103 }
 104
 105 int iio_scan_mask_query(struct iio_dev *indio_dev,
 106                         struct iio_buffer *buffer, int bit);
 107
 108 /**
 109  * iio_scan_mask_set() - set particular bit in the scan mask
 110  * @indio_dev           IIO device structure
 111  * @buffer:             the buffer whose scan mask we are interested in
 112  * @bit:                the bit to be set.
 113  **/
 114 int iio_scan_mask_set(struct iio_dev *indio_dev,
 115                       struct iio_buffer *buffer, int bit);
 116
 117 /**
 118  * iio_push_to_buffer() - push to a registered buffer.
 119  * @buffer:             IIO buffer structure for device
 120  * @data:               the data to push to the buffer
 121  */
 122 int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data);
 123
 124 int iio_update_demux(struct iio_dev *indio_dev);
 125
 126 /**
 127  * iio_buffer_register() - register the buffer with IIO core
 128  * @indio_dev:          device with the buffer to be registered
 129  * @channels:           the channel descriptions used to construct buffer
 130  * @num_channels:       the number of channels
 131  **/
 132 int iio_buffer_register(struct iio_dev *indio_dev,
 133                         const struct iio_chan_spec *channels,
 134                         int num_channels);
 135
 136 /**
 137  * iio_buffer_unregister() - unregister the buffer from IIO core
 138  * @indio_dev:          the device with the buffer to be unregistered
 139  **/
 140 void iio_buffer_unregister(struct iio_dev *indio_dev);
 141
 142 /**
 143  * iio_buffer_read_length() - attr func to get number of datums in the buffer
 144  **/
 145 ssize_t iio_buffer_read_length(struct device *dev,
 146                                struct device_attribute *attr,
 147                                char *buf);
 148 /**
 149  * iio_buffer_write_length() - attr func to set number of datums in the buffer
 150  **/
 151 ssize_t iio_buffer_write_length(struct device *dev,
 152                               struct device_attribute *attr,
 153                               const char *buf,
 154                               size_t len);
 155 /**
 156  * iio_buffer_store_enable() - attr to turn the buffer on
 157  **/
 158 ssize_t iio_buffer_store_enable(struct device *dev,
 159                                 struct device_attribute *attr,
 160                                 const char *buf,
 161                                 size_t len);
 162 /**
 163  * iio_buffer_show_enable() - attr to see if the buffer is on
 164  **/
 165 ssize_t iio_buffer_show_enable(struct device *dev,
 166                                struct device_attribute *attr,
 167                                char *buf);
 168 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,   \
 169                                            iio_buffer_read_length,      \
 170                                            iio_buffer_write_length)
 171
 172 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,   \
 173                                            iio_buffer_show_enable,      \
 174                                            iio_buffer_store_enable)
 175
 176 int iio_sw_buffer_preenable(struct iio_dev *indio_dev);
 177
 178 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 179         const unsigned long *mask);
 180
 181 #else /* CONFIG_IIO_BUFFER */
 182
 183 static inline int iio_buffer_register(struct iio_dev *indio_dev,
 184                                            struct iio_chan_spec *channels,
 185                                            int num_channels)
 186 {
 187         return 0;
 188 }
 189
 190 static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
 191 {}
 192
 193 #endif /* CONFIG_IIO_BUFFER */
 194
 195 #endif /* _IIO_BUFFER_GENERIC_H_ */