drivers/staging/iio/ring_generic.h

   1 /* The industrial I/O core - generic ring 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_RING_GENERIC_H_
  11 #define _IIO_RING_GENERIC_H_
  12 #include "iio.h"
  13
  14 struct iio_handler;
  15 struct iio_ring_buffer;
  16 struct iio_dev;
  17
  18 /**
  19  * iio_push_ring_event() - ring buffer specific push to event chrdev
  20  * @ring_buf:           ring buffer that is the event source
  21  * @event_code:         event indentification code
  22  * @timestamp:          time of event
  23  **/
  24 int iio_push_ring_event(struct iio_ring_buffer *ring_buf,
  25                         int event_code,
  26                         s64 timestamp);
  27 /**
  28  * iio_push_or_escallate_ring_event() - escallate or add as appropriate
  29  *
  30  * Typical usecase is to escallate a 50% ring full to 75% full if noone has yet
  31  * read the first event. Clearly the 50% full is no longer of interest in
  32  * typical use case.
  33  **/
  34 int iio_push_or_escallate_ring_event(struct iio_ring_buffer *ring_buf,
  35                                      int event_code,
  36                                      s64 timestamp);
  37
  38 /**
  39  * struct iio_ring_access_funcs - access functions for ring buffers.
  40  * @create:             perform allocation
  41  * @init:               get ring buffer ready for use
  42  * @_exit:              reverse steps in init
  43  * @_free:              deallocate ring buffer
  44  * @mark_in_use:        reference counting, typically to prevent module removal
  45  * @unmark_in_use:      reduce reference count when no longer using ring buffer
  46  * @store_to:           actually store stuff to the ring buffer
  47  * @read_last:          get the last element stored
  48  * @rip_lots:           try to get a specified number of elements (must exist)
  49  * @mark_param_change:  notify ring that some relevant parameter has changed
  50  *                      Often this means the underlying storage may need to
  51  *                      change.
  52  * @request_update:     if a parameter change has been marked, update underlying
  53  *                      storage.
  54  * @get_bpd:            get current bytes per datum
  55  * @set_bpd:            set number of bytes per datum
  56  * @get_length:         get number of datums in ring
  57  * @set_length:         set number of datums in ring
  58  * @is_enabled:         query if ring is currently being used
  59  * @enable:             enable the ring
  60  *
  61  * The purpose of this structure is to make the ring buffer element
  62  * modular as event for a given driver, different usecases may require
  63  * different ring designs (space efficiency vs speed for example.
  64  *
  65  * It is worth noting that a given ring implementation may only support a small
  66  * proportion of these functions.  The core code 'should' cope fine with any of
  67  * them not existing.
  68  **/
  69 struct iio_ring_access_funcs {
  70         void (*mark_in_use)(struct iio_ring_buffer *ring);
  71         void (*unmark_in_use)(struct iio_ring_buffer *ring);
  72
  73         int (*store_to)(struct iio_ring_buffer *ring, u8 *data, s64 timestamp);
  74         int (*read_last)(struct iio_ring_buffer *ring, u8 *data);
  75         int (*rip_lots)(struct iio_ring_buffer *ring,
  76                         size_t count,
  77                         u8 **data,
  78                         int *dead_offset);
  79
  80         int (*mark_param_change)(struct iio_ring_buffer *ring);
  81         int (*request_update)(struct iio_ring_buffer *ring);
  82
  83         int (*get_bpd)(struct iio_ring_buffer *ring);
  84         int (*set_bpd)(struct iio_ring_buffer *ring, size_t bpd);
  85         int (*get_length)(struct iio_ring_buffer *ring);
  86         int (*set_length)(struct iio_ring_buffer *ring, int length);
  87
  88         int (*is_enabled)(struct iio_ring_buffer *ring);
  89         int (*enable)(struct iio_ring_buffer *ring);
  90 };
  91
  92 /**
  93  * struct iio_ring_buffer - general ring buffer structure
  94  * @length:             [DEVICE]number of datums in ring
  95  * @bpd:                [DEVICE]size of individual datum including timestamp
  96  * @loopcount:          [INTERN]number of times the ring has looped
  97  * @access_minor_name:  [INTERN]store of name of the access chrdev minor number
  98  *                      sysfs attribute
  99  * @access_handler:     [INTERN]chrdev access handling
 100  * @event_minor_name:   [INTERN]store of name of the event chrdev minor number
 101  *                      sysfs attribute
 102  * @ev_int:             [INTERN]chrdev interface for the event chrdev
 103  * @shared_ev_pointer:  [INTERN]the shared event pointer to allow escalation of
 104  *                      events
 105  * @ring_access:        [DRIVER]ring access functions associated with the
 106  *                      implementation.
 107  * @ring_prenable:      [DRIVER] function to run prior to marking ring enabled
 108  * @ring_postenable:    [DRIVER] function to run after marking ring enabled
 109  * @ring_predisable:    [DRIVER] function to run prior to marking ring disabled
 110  * @ring_postdisable:   [DRIVER] function to run after marking ring disabled
 111   **/
 112 struct iio_ring_buffer {
 113         struct device dev;
 114         struct device access_dev;
 115         struct iio_dev *indio_dev;
 116         struct module *owner;
 117         int                             id;
 118         int                             access_id;
 119         int                             length;
 120         int                             bpd;
 121         int                             loopcount;
 122         struct iio_handler              access_handler;
 123         struct iio_event_interface      ev_int;
 124         struct iio_shared_ev_pointer    shared_ev_pointer;
 125         struct iio_ring_access_funcs    access;
 126         int                             (*preenable)(struct iio_dev *);
 127         int                             (*postenable)(struct iio_dev *);
 128         int                             (*predisable)(struct iio_dev *);
 129         int                             (*postdisable)(struct iio_dev *);
 130
 131 };
 132 void iio_ring_buffer_init(struct iio_ring_buffer *ring,
 133                           struct iio_dev *dev_info);
 134
 135 /**
 136  * __iio_init_ring_buffer() - initialize common elements of ring buffers.
 137  **/
 138 static inline void __iio_init_ring_buffer(struct iio_ring_buffer *ring,
 139                                  int bytes_per_datum, int length)
 140 {
 141         ring->bpd = bytes_per_datum;
 142         ring->length = length;
 143         ring->loopcount = 0;
 144         ring->shared_ev_pointer.ev_p = 0;
 145         ring->shared_ev_pointer.lock =
 146                 __SPIN_LOCK_UNLOCKED(ring->shared_ev_pointer->loc);
 147 }
 148
 149 /**
 150  * struct iio_scan_el - an individual element of a scan
 151  * @dev_attr:           control attribute (if directly controllable)
 152  * @number:             unique identifier of element (used for bit mask)
 153  * @bit_count:          number of bits in scan element
 154  * @label:              useful data for the scan el (often reg address)
 155  * @set_state:          for some devices datardy signals are generated
 156  *                      for any enabled lines.  This allows unwanted lines
 157  *                      to be disabled and hence not get in the way.
 158  **/
 159 struct iio_scan_el {
 160         struct device_attribute         dev_attr;
 161         unsigned int                    number;
 162         int                             bit_count;
 163         unsigned int                    label;
 164
 165         int (*set_state)(struct iio_scan_el *scanel,
 166                          struct iio_dev *dev_info,
 167                          bool state);
 168 };
 169
 170 #define to_iio_scan_el(_dev_attr)                               \
 171         container_of(_dev_attr, struct iio_scan_el, dev_attr);
 172
 173 /**
 174  * iio_scan_el_store() - sysfs scan element selection interface.
 175  *
 176  * A generic function used to enable various scan elements.  In some
 177  * devices explicit read commands for each channel mean this is merely
 178  * a software switch.  In others this must actively disable the channel.
 179  * Complexities occur when this interacts with data ready type triggers
 180  * which may not reset unless every channel that is enabled is explicitly
 181  * read.
 182  **/
 183 ssize_t iio_scan_el_store(struct device *dev, struct device_attribute *attr,
 184                           const char *buf, size_t len);
 185 /**
 186  * iio_scal_el_show() - sysfs interface to query whether a scan element is
 187  *                      is enabled or not.
 188  **/
 189 ssize_t iio_scan_el_show(struct device *dev, struct device_attribute *attr,
 190                          char *buf);
 191 /**
 192  * IIO_SCAN_EL: - declare and initialize a scan element without control func
 193  * @_name:      identifying name. Resulting struct is iio_scan_el_##_name,
 194  *              sysfs element, scan_en_##_name.
 195  * @_number:    unique id number for the scan element.
 196  * @_bits:      number of bits in the scan element result (used in mixed bit
 197  *              length devices).
 198  * @_label:     indentification variable used by drivers.  Often a reg address.
 199  **/
 200 #define IIO_SCAN_EL(_name, _number, _bits, _label)                      \
 201         struct iio_scan_el iio_scan_el_##_name = {                      \
 202                 .dev_attr = __ATTR(scan_en_##_name,                     \
 203                                    S_IRUGO | S_IWUSR,                   \
 204                                    iio_scan_el_show,                    \
 205                                    iio_scan_el_store),                  \
 206                 .mask = (1 << _number),                                 \
 207                 .bit_count = _bits,                                     \
 208                 .label = _label,                                        \
 209         }
 210
 211 ssize_t iio_scan_el_ts_store(struct device *dev, struct device_attribute *attr,
 212                              const char *buf, size_t len);
 213
 214 ssize_t iio_scan_el_ts_show(struct device *dev, struct device_attribute *attr,
 215                             char *buf);
 216 /**
 217  * IIO_SCAN_EL_C: - declare and initialize a scan element with a control func
 218  *
 219  * @_controlfunc: function used to notify hardware of whether state changes
 220  **/
 221 #define IIO_SCAN_EL_C(_name, _number, _bits, _label, _controlfunc)      \
 222         struct iio_scan_el iio_scan_el_##_name = {                      \
 223                 .dev_attr = __ATTR(scan_en_##_name,                     \
 224                                    S_IRUGO | S_IWUSR,                   \
 225                                    iio_scan_el_show,                    \
 226                                    iio_scan_el_store),                  \
 227                 .number =  _number,                                     \
 228                 .bit_count = _bits,                                     \
 229                 .label = _label,                                        \
 230                 .set_state = _controlfunc,                              \
 231         }
 232 /**
 233  * IIO_SCAN_EL_TIMESTAMP: - declare a special scan element for timestamps
 234  *
 235  * Odd one out. Handled slightly differently from other scan elements.
 236  **/
 237 #define IIO_SCAN_EL_TIMESTAMP                                   \
 238         struct iio_scan_el iio_scan_el_timestamp = {            \
 239                 .dev_attr = __ATTR(scan_en_timestamp,           \
 240                                    S_IRUGO | S_IWUSR,           \
 241                                    iio_scan_el_ts_show,         \
 242                                    iio_scan_el_ts_store),       \
 243         }
 244
 245 static inline void iio_put_ring_buffer(struct iio_ring_buffer *ring)
 246 {
 247         put_device(&ring->dev);
 248 };
 249
 250 #define to_iio_ring_buffer(d)                   \
 251         container_of(d, struct iio_ring_buffer, dev)
 252 #define access_dev_to_iio_ring_buffer(d)                        \
 253         container_of(d, struct iio_ring_buffer, access_dev)
 254 int iio_ring_buffer_register(struct iio_ring_buffer *ring);
 255 void iio_ring_buffer_unregister(struct iio_ring_buffer *ring);
 256
 257 ssize_t iio_read_ring_length(struct device *dev,
 258                              struct device_attribute *attr,
 259                              char *buf);
 260 ssize_t iio_write_ring_length(struct device *dev,
 261                               struct device_attribute *attr,
 262                               const char *buf,
 263                               size_t len);
 264 ssize_t iio_read_ring_bps(struct device *dev,
 265                           struct device_attribute *attr,
 266                           char *buf);
 267 ssize_t iio_store_ring_enable(struct device *dev,
 268                               struct device_attribute *attr,
 269                               const char *buf,
 270                               size_t len);
 271 ssize_t iio_show_ring_enable(struct device *dev,
 272                              struct device_attribute *attr,
 273                              char *buf);
 274 #define IIO_RING_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,     \
 275                                          iio_read_ring_length,          \
 276                                          iio_write_ring_length)
 277 #define IIO_RING_BPS_ATTR DEVICE_ATTR(bps, S_IRUGO | S_IWUSR,   \
 278                                       iio_read_ring_bps, NULL)
 279 #define IIO_RING_ENABLE_ATTR DEVICE_ATTR(ring_enable, S_IRUGO | S_IWUSR, \
 280                                          iio_show_ring_enable,          \
 281                                          iio_store_ring_enable)
 282
 283 #endif /* _IIO_RING_GENERIC_H_ */