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  * @buffer_list:        [INTERN] entry in the devices list of current buffers.
  70  */
  71 struct iio_buffer {
  72         int                                     length;
  73         int                                     bytes_per_datum;
  74         struct attribute_group                  *scan_el_attrs;
  75         long                                    *scan_mask;
  76         bool                                    scan_timestamp;
  77         const struct iio_buffer_access_funcs    *access;
  78         struct list_head                        scan_el_dev_attr_list;
  79         struct attribute_group                  scan_el_group;
  80         wait_queue_head_t                       pollq;
  81         bool                                    stufftoread;
  82         const struct attribute_group *attrs;
  83         struct list_head                        demux_list;
  84         unsigned char                           *demux_bounce;
  85         struct list_head                        buffer_list;
  86 };
  87
  88 /**
  89  * iio_update_buffers() - add or remove buffer from active list
  90  * @indio_dev:          device to add buffer to
  91  * @insert_buffer:      buffer to insert
  92  * @remove_buffer:      buffer_to_remove
  93  *
  94  * Note this will tear down the all buffering and build it up again
  95  */
  96 int iio_update_buffers(struct iio_dev *indio_dev,
  97                        struct iio_buffer *insert_buffer,
  98                        struct iio_buffer *remove_buffer);
  99
 100 /**
 101  * iio_buffer_init() - Initialize the buffer structure
 102  * @buffer:             buffer to be initialized
 103  **/
 104 void iio_buffer_init(struct iio_buffer *buffer);
 105
 106 int iio_scan_mask_query(struct iio_dev *indio_dev,
 107                         struct iio_buffer *buffer, int bit);
 108
 109 /**
 110  * iio_scan_mask_set() - set particular bit in the scan mask
 111  * @indio_dev           IIO device structure
 112  * @buffer:             the buffer whose scan mask we are interested in
 113  * @bit:                the bit to be set.
 114  **/
 115 int iio_scan_mask_set(struct iio_dev *indio_dev,
 116                       struct iio_buffer *buffer, int bit);
 117
 118 /**
 119  * iio_push_to_buffers() - push to a registered buffer.
 120  * @indio_dev:          iio_dev structure for device.
 121  * @data:               Full scan.
 122  */
 123 int iio_push_to_buffers(struct iio_dev *indio_dev, unsigned char *data);
 124
 125 int iio_update_demux(struct iio_dev *indio_dev);
 126
 127 /**
 128  * iio_buffer_register() - register the buffer with IIO core
 129  * @indio_dev:          device with the buffer to be registered
 130  * @channels:           the channel descriptions used to construct buffer
 131  * @num_channels:       the number of channels
 132  **/
 133 int iio_buffer_register(struct iio_dev *indio_dev,
 134                         const struct iio_chan_spec *channels,
 135                         int num_channels);
 136
 137 /**
 138  * iio_buffer_unregister() - unregister the buffer from IIO core
 139  * @indio_dev:          the device with the buffer to be unregistered
 140  **/
 141 void iio_buffer_unregister(struct iio_dev *indio_dev);
 142
 143 /**
 144  * iio_buffer_read_length() - attr func to get number of datums in the buffer
 145  **/
 146 ssize_t iio_buffer_read_length(struct device *dev,
 147                                struct device_attribute *attr,
 148                                char *buf);
 149 /**
 150  * iio_buffer_write_length() - attr func to set number of datums in the buffer
 151  **/
 152 ssize_t iio_buffer_write_length(struct device *dev,
 153                               struct device_attribute *attr,
 154                               const char *buf,
 155                               size_t len);
 156 /**
 157  * iio_buffer_store_enable() - attr to turn the buffer on
 158  **/
 159 ssize_t iio_buffer_store_enable(struct device *dev,
 160                                 struct device_attribute *attr,
 161                                 const char *buf,
 162                                 size_t len);
 163 /**
 164  * iio_buffer_show_enable() - attr to see if the buffer is on
 165  **/
 166 ssize_t iio_buffer_show_enable(struct device *dev,
 167                                struct device_attribute *attr,
 168                                char *buf);
 169 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,   \
 170                                            iio_buffer_read_length,      \
 171                                            iio_buffer_write_length)
 172
 173 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,   \
 174                                            iio_buffer_show_enable,      \
 175                                            iio_buffer_store_enable)
 176
 177 int iio_sw_buffer_preenable(struct iio_dev *indio_dev);
 178
 179 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 180         const unsigned long *mask);
 181
 182 #else /* CONFIG_IIO_BUFFER */
 183
 184 static inline int iio_buffer_register(struct iio_dev *indio_dev,
 185                                            const struct iio_chan_spec *channels,
 186                                            int num_channels)
 187 {
 188         return 0;
 189 }
 190
 191 static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
 192 {}
 193
 194 #endif /* CONFIG_IIO_BUFFER */
 195
 196 #endif /* _IIO_BUFFER_GENERIC_H_ */