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 whether data for reading from the buffer is
  25  *                      available.
  26  * @request_update:     if a parameter change has been marked, update underlying
  27  *                      storage.
  28  * @get_bytes_per_datum:get current bytes per datum
  29  * @set_bytes_per_datum:set number of bytes per datum
  30  * @get_length:         get number of datums in buffer
  31  * @set_length:         set number of datums in buffer
  32  * @release:            called when the last reference to the buffer is dropped,
  33  *                      should free all resources allocated by the buffer.
  34  *
  35  * The purpose of this structure is to make the buffer element
  36  * modular as event for a given driver, different usecases may require
  37  * different buffer designs (space efficiency vs speed for example).
  38  *
  39  * It is worth noting that a given buffer implementation may only support a
  40  * small proportion of these functions.  The core code 'should' cope fine with
  41  * any of them not existing.
  42  **/
  43 struct iio_buffer_access_funcs {
  44         int (*store_to)(struct iio_buffer *buffer, const void *data);
  45         int (*read_first_n)(struct iio_buffer *buffer,
  46                             size_t n,
  47                             char __user *buf);
  48         bool (*data_available)(struct iio_buffer *buffer);
  49
  50         int (*request_update)(struct iio_buffer *buffer);
  51
  52         int (*get_bytes_per_datum)(struct iio_buffer *buffer);
  53         int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
  54         int (*get_length)(struct iio_buffer *buffer);
  55         int (*set_length)(struct iio_buffer *buffer, int length);
  56
  57         void (*release)(struct iio_buffer *buffer);
  58 };
  59
  60 /**
  61  * struct iio_buffer - general buffer structure
  62  * @length:             [DEVICE] number of datums in buffer
  63  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  64  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  65  *                      control method is used
  66  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  67  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  68  * @access:             [DRIVER] buffer access functions associated with the
  69  *                      implementation.
  70  * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
  71  * @scan_el_group:      [DRIVER] attribute group for those attributes not
  72  *                      created from the iio_chan_info array.
  73  * @pollq:              [INTERN] wait queue to allow for polling on the buffer.
  74  * @stufftoread:        [INTERN] flag to indicate new data.
  75  * @demux_list:         [INTERN] list of operations required to demux the scan.
  76  * @demux_bounce:       [INTERN] buffer for doing gather from incoming scan.
  77  * @buffer_list:        [INTERN] entry in the devices list of current buffers.
  78  * @ref:                [INTERN] reference count of the buffer.
  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                  scan_el_group;
  89         wait_queue_head_t                       pollq;
  90         bool                                    stufftoread;
  91         const struct attribute_group *attrs;
  92         struct list_head                        demux_list;
  93         void                                    *demux_bounce;
  94         struct list_head                        buffer_list;
  95         struct kref                             ref;
  96 };
  97
  98 /**
  99  * iio_update_buffers() - add or remove buffer from active list
 100  * @indio_dev:          device to add buffer to
 101  * @insert_buffer:      buffer to insert
 102  * @remove_buffer:      buffer_to_remove
 103  *
 104  * Note this will tear down the all buffering and build it up again
 105  */
 106 int iio_update_buffers(struct iio_dev *indio_dev,
 107                        struct iio_buffer *insert_buffer,
 108                        struct iio_buffer *remove_buffer);
 109
 110 /**
 111  * iio_buffer_init() - Initialize the buffer structure
 112  * @buffer:             buffer to be initialized
 113  **/
 114 void iio_buffer_init(struct iio_buffer *buffer);
 115
 116 int iio_scan_mask_query(struct iio_dev *indio_dev,
 117                         struct iio_buffer *buffer, int bit);
 118
 119 /**
 120  * iio_scan_mask_set() - set particular bit in the scan mask
 121  * @indio_dev           IIO device structure
 122  * @buffer:             the buffer whose scan mask we are interested in
 123  * @bit:                the bit to be set.
 124  **/
 125 int iio_scan_mask_set(struct iio_dev *indio_dev,
 126                       struct iio_buffer *buffer, int bit);
 127
 128 /**
 129  * iio_push_to_buffers() - push to a registered buffer.
 130  * @indio_dev:          iio_dev structure for device.
 131  * @data:               Full scan.
 132  */
 133 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
 134
 135 /*
 136  * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
 137  * @indio_dev:          iio_dev structure for device.
 138  * @data:               sample data
 139  * @timestamp:          timestamp for the sample data
 140  *
 141  * Pushes data to the IIO device's buffers. If timestamps are enabled for the
 142  * device the function will store the supplied timestamp as the last element in
 143  * the sample data buffer before pushing it to the device buffers. The sample
 144  * data buffer needs to be large enough to hold the additional timestamp
 145  * (usually the buffer should be indio->scan_bytes bytes large).
 146  *
 147  * Returns 0 on success, a negative error code otherwise.
 148  */
 149 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
 150         void *data, int64_t timestamp)
 151 {
 152         if (indio_dev->scan_timestamp) {
 153                 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
 154                 ((int64_t *)data)[ts_offset] = timestamp;
 155         }
 156
 157         return iio_push_to_buffers(indio_dev, data);
 158 }
 159
 160 int iio_update_demux(struct iio_dev *indio_dev);
 161
 162 /**
 163  * iio_buffer_register() - register the buffer with IIO core
 164  * @indio_dev:          device with the buffer to be registered
 165  * @channels:           the channel descriptions used to construct buffer
 166  * @num_channels:       the number of channels
 167  **/
 168 int iio_buffer_register(struct iio_dev *indio_dev,
 169                         const struct iio_chan_spec *channels,
 170                         int num_channels);
 171
 172 /**
 173  * iio_buffer_unregister() - unregister the buffer from IIO core
 174  * @indio_dev:          the device with the buffer to be unregistered
 175  **/
 176 void iio_buffer_unregister(struct iio_dev *indio_dev);
 177
 178 /**
 179  * iio_buffer_read_length() - attr func to get number of datums in the buffer
 180  **/
 181 ssize_t iio_buffer_read_length(struct device *dev,
 182                                struct device_attribute *attr,
 183                                char *buf);
 184 /**
 185  * iio_buffer_write_length() - attr func to set number of datums in the buffer
 186  **/
 187 ssize_t iio_buffer_write_length(struct device *dev,
 188                               struct device_attribute *attr,
 189                               const char *buf,
 190                               size_t len);
 191 /**
 192  * iio_buffer_store_enable() - attr to turn the buffer on
 193  **/
 194 ssize_t iio_buffer_store_enable(struct device *dev,
 195                                 struct device_attribute *attr,
 196                                 const char *buf,
 197                                 size_t len);
 198 /**
 199  * iio_buffer_show_enable() - attr to see if the buffer is on
 200  **/
 201 ssize_t iio_buffer_show_enable(struct device *dev,
 202                                struct device_attribute *attr,
 203                                char *buf);
 204 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,   \
 205                                            iio_buffer_read_length,      \
 206                                            iio_buffer_write_length)
 207
 208 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,   \
 209                                            iio_buffer_show_enable,      \
 210                                            iio_buffer_store_enable)
 211
 212 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 213         const unsigned long *mask);
 214
 215 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
 216 void iio_buffer_put(struct iio_buffer *buffer);
 217
 218 /**
 219  * iio_device_attach_buffer - Attach a buffer to a IIO device
 220  * @indio_dev: The device the buffer should be attached to
 221  * @buffer: The buffer to attach to the device
 222  *
 223  * This function attaches a buffer to a IIO device. The buffer stays attached to
 224  * the device until the device is freed. The function should only be called at
 225  * most once per device.
 226  */
 227 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
 228         struct iio_buffer *buffer)
 229 {
 230         indio_dev->buffer = iio_buffer_get(buffer);
 231 }
 232
 233 #else /* CONFIG_IIO_BUFFER */
 234
 235 static inline int iio_buffer_register(struct iio_dev *indio_dev,
 236                                            const struct iio_chan_spec *channels,
 237                                            int num_channels)
 238 {
 239         return 0;
 240 }
 241
 242 static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
 243 {}
 244
 245 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
 246 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
 247
 248 #endif /* CONFIG_IIO_BUFFER */
 249
 250 #endif /* _IIO_BUFFER_GENERIC_H_ */