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  * @request_update:     if a parameter change has been marked, update underlying
  25  *                      storage.
  26  * @get_bytes_per_datum:get current bytes per datum
  27  * @set_bytes_per_datum:set number of bytes per datum
  28  * @get_length:         get number of datums in buffer
  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  *
  33  * The purpose of this structure is to make the buffer element
  34  * modular as event for a given driver, different usecases may require
  35  * different buffer designs (space efficiency vs speed for example).
  36  *
  37  * It is worth noting that a given buffer implementation may only support a
  38  * small proportion of these functions.  The core code 'should' cope fine with
  39  * any of them not existing.
  40  **/
  41 struct iio_buffer_access_funcs {
  42         int (*store_to)(struct iio_buffer *buffer, const void *data);
  43         int (*read_first_n)(struct iio_buffer *buffer,
  44                             size_t n,
  45                             char __user *buf);
  46
  47         int (*request_update)(struct iio_buffer *buffer);
  48
  49         int (*get_bytes_per_datum)(struct iio_buffer *buffer);
  50         int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
  51         int (*get_length)(struct iio_buffer *buffer);
  52         int (*set_length)(struct iio_buffer *buffer, int length);
  53
  54         void (*release)(struct iio_buffer *buffer);
  55 };
  56
  57 /**
  58  * struct iio_buffer - general buffer structure
  59  * @length:             [DEVICE] number of datums in buffer
  60  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  61  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  62  *                      control method is used
  63  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  64  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  65  * @access:             [DRIVER] buffer access functions associated with the
  66  *                      implementation.
  67  * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
  68  * @scan_el_group:      [DRIVER] attribute group for those attributes not
  69  *                      created from the iio_chan_info array.
  70  * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
  71  * @stufftoread:        [INTERN] flag to indicate new data.
  72  * @demux_list:         [INTERN] list of operations required to demux the scan.
  73  * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
  74  * @buffer_list:        [INTERN] entry in the devices list of current buffers.
  75  * @ref:                [INTERN] reference count of the buffer.
  76  */
  77 struct iio_buffer {
  78         int                                     length;
  79         int                                     bytes_per_datum;
  80         struct attribute_group                  *scan_el_attrs;
  81         long                                    *scan_mask;
  82         bool                                    scan_timestamp;
  83         const struct iio_buffer_access_funcs    *access;
  84         struct list_head                        scan_el_dev_attr_list;
  85         struct attribute_group                  scan_el_group;
  86         wait_queue_head_t                       pollq;
  87         bool                                    stufftoread;
  88         const struct attribute_group *attrs;
  89         struct list_head                        demux_list;
  90         void                                    *demux_bounce;
  91         struct list_head                        buffer_list;
  92         struct kref                             ref;
  93 };
  94
  95 /**
  96  * iio_update_buffers() - add or remove buffer from active list
  97  * @indio_dev:          device to add buffer to
  98  * @insert_buffer:      buffer to insert
  99  * @remove_buffer:      buffer_to_remove
 100  *
 101  * Note this will tear down the all buffering and build it up again
 102  */
 103 int iio_update_buffers(struct iio_dev *indio_dev,
 104                        struct iio_buffer *insert_buffer,
 105                        struct iio_buffer *remove_buffer);
 106
 107 /**
 108  * iio_buffer_init() - Initialize the buffer structure
 109  * @buffer:             buffer to be initialized
 110  **/
 111 void iio_buffer_init(struct iio_buffer *buffer);
 112
 113 int iio_scan_mask_query(struct iio_dev *indio_dev,
 114                         struct iio_buffer *buffer, int bit);
 115
 116 /**
 117  * iio_scan_mask_set() - set particular bit in the scan mask
 118  * @indio_dev           IIO device structure
 119  * @buffer:             the buffer whose scan mask we are interested in
 120  * @bit:                the bit to be set.
 121  **/
 122 int iio_scan_mask_set(struct iio_dev *indio_dev,
 123                       struct iio_buffer *buffer, int bit);
 124
 125 /**
 126  * iio_push_to_buffers() - push to a registered buffer.
 127  * @indio_dev:          iio_dev structure for device.
 128  * @data:               Full scan.
 129  */
 130 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
 131
 132 /*
 133  * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
 134  * @indio_dev:          iio_dev structure for device.
 135  * @data:               sample data
 136  * @timestamp:          timestamp for the sample data
 137  *
 138  * Pushes data to the IIO device's buffers. If timestamps are enabled for the
 139  * device the function will store the supplied timestamp as the last element in
 140  * the sample data buffer before pushing it to the device buffers. The sample
 141  * data buffer needs to be large enough to hold the additional timestamp
 142  * (usually the buffer should be indio->scan_bytes bytes large).
 143  *
 144  * Returns 0 on success, a negative error code otherwise.
 145  */
 146 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
 147         void *data, int64_t timestamp)
 148 {
 149         if (indio_dev->scan_timestamp) {
 150                 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
 151                 ((int64_t *)data)[ts_offset] = timestamp;
 152         }
 153
 154         return iio_push_to_buffers(indio_dev, data);
 155 }
 156
 157 int iio_update_demux(struct iio_dev *indio_dev);
 158
 159 /**
 160  * iio_buffer_register() - register the buffer with IIO core
 161  * @indio_dev:          device with the buffer to be registered
 162  * @channels:           the channel descriptions used to construct buffer
 163  * @num_channels:       the number of channels
 164  **/
 165 int iio_buffer_register(struct iio_dev *indio_dev,
 166                         const struct iio_chan_spec *channels,
 167                         int num_channels);
 168
 169 /**
 170  * iio_buffer_unregister() - unregister the buffer from IIO core
 171  * @indio_dev:          the device with the buffer to be unregistered
 172  **/
 173 void iio_buffer_unregister(struct iio_dev *indio_dev);
 174
 175 /**
 176  * iio_buffer_read_length() - attr func to get number of datums in the buffer
 177  **/
 178 ssize_t iio_buffer_read_length(struct device *dev,
 179                                struct device_attribute *attr,
 180                                char *buf);
 181 /**
 182  * iio_buffer_write_length() - attr func to set number of datums in the buffer
 183  **/
 184 ssize_t iio_buffer_write_length(struct device *dev,
 185                               struct device_attribute *attr,
 186                               const char *buf,
 187                               size_t len);
 188 /**
 189  * iio_buffer_store_enable() - attr to turn the buffer on
 190  **/
 191 ssize_t iio_buffer_store_enable(struct device *dev,
 192                                 struct device_attribute *attr,
 193                                 const char *buf,
 194                                 size_t len);
 195 /**
 196  * iio_buffer_show_enable() - attr to see if the buffer is on
 197  **/
 198 ssize_t iio_buffer_show_enable(struct device *dev,
 199                                struct device_attribute *attr,
 200                                char *buf);
 201 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,   \
 202                                            iio_buffer_read_length,      \
 203                                            iio_buffer_write_length)
 204
 205 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,   \
 206                                            iio_buffer_show_enable,      \
 207                                            iio_buffer_store_enable)
 208
 209 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 210         const unsigned long *mask);
 211
 212 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
 213 void iio_buffer_put(struct iio_buffer *buffer);
 214
 215 /**
 216  * iio_device_attach_buffer - Attach a buffer to a IIO device
 217  * @indio_dev: The device the buffer should be attached to
 218  * @buffer: The buffer to attach to the device
 219  *
 220  * This function attaches a buffer to a IIO device. The buffer stays attached to
 221  * the device until the device is freed. The function should only be called at
 222  * most once per device.
 223  */
 224 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
 225         struct iio_buffer *buffer)
 226 {
 227         indio_dev->buffer = iio_buffer_get(buffer);
 228 }
 229
 230 #else /* CONFIG_IIO_BUFFER */
 231
 232 static inline int iio_buffer_register(struct iio_dev *indio_dev,
 233                                            const struct iio_chan_spec *channels,
 234                                            int num_channels)
 235 {
 236         return 0;
 237 }
 238
 239 static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
 240 {}
 241
 242 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
 243 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
 244
 245 #endif /* CONFIG_IIO_BUFFER */
 246
 247 #endif /* _IIO_BUFFER_GENERIC_H_ */