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() - escalate or add as appropriate
  29  * @ring_buf:           ring buffer that is the event source
  30  * @event_code:         event indentification code
  31  * @timestamp:          time of event
  32  *
  33  * Typical usecase is to escalate a 50% ring full to 75% full if noone has yet
  34  * read the first event. Clearly the 50% full is no longer of interest in
  35  * typical use case.
  36  **/
  37 int iio_push_or_escallate_ring_event(struct iio_ring_buffer *ring_buf,
  38                                      int event_code,
  39                                      s64 timestamp);
  40
  41 /**
  42  * struct iio_ring_access_funcs - access functions for ring buffers.
  43  * @mark_in_use:        reference counting, typically to prevent module removal
  44  * @unmark_in_use:      reduce reference count when no longer using ring buffer
  45  * @store_to:           actually store stuff to the ring buffer
  46  * @read_last:          get the last element stored
  47  * @rip_lots:           try to get a specified number of elements (must exist)
  48  * @mark_param_change:  notify ring that some relevant parameter has changed
  49  *                      Often this means the underlying storage may need to
  50  *                      change.
  51  * @request_update:     if a parameter change has been marked, update underlying
  52  *                      storage.
  53  * @get_bpd:            get current bytes per datum
  54  * @set_bpd:            set number of bytes per datum
  55  * @get_length:         get number of datums in ring
  56  * @set_length:         set number of datums in ring
  57  * @is_enabled:         query if ring is currently being used
  58  * @enable:             enable the ring
  59  *
  60  * The purpose of this structure is to make the ring buffer element
  61  * modular as event for a given driver, different usecases may require
  62  * different ring designs (space efficiency vs speed for example).
  63  *
  64  * It is worth noting that a given ring implementation may only support a small
  65  * proportion of these functions.  The core code 'should' cope fine with any of
  66  * them not existing.
  67  **/
  68 struct iio_ring_access_funcs {
  69         void (*mark_in_use)(struct iio_ring_buffer *ring);
  70         void (*unmark_in_use)(struct iio_ring_buffer *ring);
  71
  72         int (*store_to)(struct iio_ring_buffer *ring, u8 *data, s64 timestamp);
  73         int (*read_last)(struct iio_ring_buffer *ring, u8 *data);
  74         int (*rip_lots)(struct iio_ring_buffer *ring,
  75                         size_t count,
  76                         u8 **data,
  77                         int *dead_offset);
  78
  79         int (*mark_param_change)(struct iio_ring_buffer *ring);
  80         int (*request_update)(struct iio_ring_buffer *ring);
  81
  82         int (*get_bpd)(struct iio_ring_buffer *ring);
  83         int (*set_bpd)(struct iio_ring_buffer *ring, size_t bpd);
  84         int (*get_length)(struct iio_ring_buffer *ring);
  85         int (*set_length)(struct iio_ring_buffer *ring, int length);
  86
  87         int (*is_enabled)(struct iio_ring_buffer *ring);
  88         int (*enable)(struct iio_ring_buffer *ring);
  89 };
  90
  91 /**
  92  * struct iio_ring_buffer - general ring buffer structure
  93  * @dev:                ring buffer device struct
  94  * @access_dev:         system device struct for the chrdev
  95  * @indio_dev:          industrial I/O device structure
  96  * @owner:              module that owns the ring buffer (for ref counting)
  97  * @id:                 unique id number
  98  * @access_id:          device id number
  99  * @length:             [DEVICE] number of datums in ring
 100  * @bpd:                [DEVICE] size of individual datum including timestamp
 101  * @loopcount:          [INTERN] number of times the ring has looped
 102  * @access_handler:     [INTERN] chrdev access handling
 103  * @ev_int:             [INTERN] chrdev interface for the event chrdev
 104  * @shared_ev_pointer:  [INTERN] the shared event pointer to allow escalation of
 105  *                      events
 106  * @access:             [DRIVER] ring access functions associated with the
 107  *                      implementation.
 108  * @preenable:          [DRIVER] function to run prior to marking ring enabled
 109  * @postenable:         [DRIVER] function to run after marking ring enabled
 110  * @predisable:         [DRIVER] function to run prior to marking ring disabled
 111  * @postdisable:        [DRIVER] function to run after marking ring disabled
 112   **/
 113 struct iio_ring_buffer {
 114         struct device dev;
 115         struct device access_dev;
 116         struct iio_dev *indio_dev;
 117         struct module *owner;
 118         int                             id;
 119         int                             access_id;
 120         int                             length;
 121         int                             bpd;
 122         int                             loopcount;
 123         struct iio_handler              access_handler;
 124         struct iio_event_interface      ev_int;
 125         struct iio_shared_ev_pointer    shared_ev_pointer;
 126         struct iio_ring_access_funcs    access;
 127         int                             (*preenable)(struct iio_dev *);
 128         int                             (*postenable)(struct iio_dev *);
 129         int                             (*predisable)(struct iio_dev *);
 130         int                             (*postdisable)(struct iio_dev *);
 131
 132 };
 133 void iio_ring_buffer_init(struct iio_ring_buffer *ring,
 134                           struct iio_dev *dev_info);
 135
 136 /**
 137  * __iio_init_ring_buffer() - initialize common elements of ring buffers
 138  * @ring:               ring buffer that is the event source
 139  * @bytes_per_datum:    size of individual datum including timestamp
 140  * @length:             number of datums in ring
 141  **/
 142 static inline void __iio_init_ring_buffer(struct iio_ring_buffer *ring,
 143                                  int bytes_per_datum, int length)
 144 {
 145         ring->bpd = bytes_per_datum;
 146         ring->length = length;
 147         ring->loopcount = 0;
 148         ring->shared_ev_pointer.ev_p = 0;
 149         spin_lock_init(&ring->shared_ev_pointer.lock);
 150 }
 151
 152 /**
 153  * struct iio_scan_el - an individual element of a scan
 154  * @dev_attr:           control attribute (if directly controllable)
 155  * @number:             unique identifier of element (used for bit mask)
 156  * @bit_count:          number of bits in scan element
 157  * @label:              useful data for the scan el (often reg address)
 158  * @set_state:          for some devices datardy signals are generated
 159  *                      for any enabled lines.  This allows unwanted lines
 160  *                      to be disabled and hence not get in the way.
 161  **/
 162 struct iio_scan_el {
 163         struct device_attribute         dev_attr;
 164         unsigned int                    number;
 165         int                             bit_count;
 166         unsigned int                    label;
 167
 168         int (*set_state)(struct iio_scan_el *scanel,
 169                          struct iio_dev *dev_info,
 170                          bool state);
 171 };
 172
 173 #define to_iio_scan_el(_dev_attr)                               \
 174         container_of(_dev_attr, struct iio_scan_el, dev_attr);
 175
 176 /**
 177  * iio_scan_el_store() - sysfs scan element selection interface
 178  * @dev: the target device
 179  * @attr: the device attribute that is being processed
 180  * @buf: input from userspace
 181  * @len: length of input
 182  *
 183  * A generic function used to enable various scan elements.  In some
 184  * devices explicit read commands for each channel mean this is merely
 185  * a software switch.  In others this must actively disable the channel.
 186  * Complexities occur when this interacts with data ready type triggers
 187  * which may not reset unless every channel that is enabled is explicitly
 188  * read.
 189  **/
 190 ssize_t iio_scan_el_store(struct device *dev, struct device_attribute *attr,
 191                           const char *buf, size_t len);
 192 /**
 193  * iio_scal_el_show() - sysfs interface to query whether a scan element is
 194  *                      is enabled or not
 195  * @dev: the target device
 196  * @attr: the device attribute that is being processed
 197  * @buf: output buffer
 198  **/
 199 ssize_t iio_scan_el_show(struct device *dev, struct device_attribute *attr,
 200                          char *buf);
 201 /**
 202  * IIO_SCAN_EL - declare and initialize a scan element without control func
 203  * @_name:      identifying name. Resulting struct is iio_scan_el_##_name,
 204  *              sysfs element, scan_en_##_name.
 205  * @_number:    unique id number for the scan element.
 206  * @_bits:      number of bits in the scan element result (used in mixed bit
 207  *              length devices).
 208  * @_label:     indentification variable used by drivers.  Often a reg address.
 209  **/
 210 #define IIO_SCAN_EL(_name, _number, _bits, _label)                      \
 211         struct iio_scan_el iio_scan_el_##_name = {                      \
 212                 .dev_attr = __ATTR(scan_en_##_name,                     \
 213                                    S_IRUGO | S_IWUSR,                   \
 214                                    iio_scan_el_show,                    \
 215                                    iio_scan_el_store),                  \
 216                 .mask = (1 << _number),                                 \
 217                 .bit_count = _bits,                                     \
 218                 .label = _label,                                        \
 219         }
 220
 221 ssize_t iio_scan_el_ts_store(struct device *dev, struct device_attribute *attr,
 222                              const char *buf, size_t len);
 223
 224 ssize_t iio_scan_el_ts_show(struct device *dev, struct device_attribute *attr,
 225                             char *buf);
 226 /**
 227  * IIO_SCAN_EL_C - declare and initialize a scan element with a control func
 228  *
 229  * @_name:      identifying name. Resulting struct is iio_scan_el_##_name,
 230  *              sysfs element, scan_en_##_name.
 231  * @_number:    unique id number for the scan element.
 232  * @_bits:      number of bits in the scan element result (used in mixed bit
 233  *              length devices).
 234  * @_label:     indentification variable used by drivers.  Often a reg address.
 235  * @_controlfunc: function used to notify hardware of whether state changes
 236  **/
 237 #define IIO_SCAN_EL_C(_name, _number, _bits, _label, _controlfunc)      \
 238         struct iio_scan_el iio_scan_el_##_name = {                      \
 239                 .dev_attr = __ATTR(scan_en_##_name,                     \
 240                                    S_IRUGO | S_IWUSR,                   \
 241                                    iio_scan_el_show,                    \
 242                                    iio_scan_el_store),                  \
 243                 .number =  _number,                                     \
 244                 .bit_count = _bits,                                     \
 245                 .label = _label,                                        \
 246                 .set_state = _controlfunc,                              \
 247         }
 248 /**
 249  * IIO_SCAN_EL_TIMESTAMP - declare a special scan element for timestamps
 250  *
 251  * Odd one out. Handled slightly differently from other scan elements.
 252  **/
 253 #define IIO_SCAN_EL_TIMESTAMP                                   \
 254         struct iio_scan_el iio_scan_el_timestamp = {            \
 255                 .dev_attr = __ATTR(scan_en_timestamp,           \
 256                                    S_IRUGO | S_IWUSR,           \
 257                                    iio_scan_el_ts_show,         \
 258                                    iio_scan_el_ts_store),       \
 259         }
 260
 261 static inline void iio_put_ring_buffer(struct iio_ring_buffer *ring)
 262 {
 263         put_device(&ring->dev);
 264 };
 265
 266 #define to_iio_ring_buffer(d)                   \
 267         container_of(d, struct iio_ring_buffer, dev)
 268 #define access_dev_to_iio_ring_buffer(d)                        \
 269         container_of(d, struct iio_ring_buffer, access_dev)
 270 int iio_ring_buffer_register(struct iio_ring_buffer *ring);
 271 void iio_ring_buffer_unregister(struct iio_ring_buffer *ring);
 272
 273 ssize_t iio_read_ring_length(struct device *dev,
 274                              struct device_attribute *attr,
 275                              char *buf);
 276 ssize_t iio_write_ring_length(struct device *dev,
 277                               struct device_attribute *attr,
 278                               const char *buf,
 279                               size_t len);
 280 ssize_t iio_read_ring_bps(struct device *dev,
 281                           struct device_attribute *attr,
 282                           char *buf);
 283 ssize_t iio_store_ring_enable(struct device *dev,
 284                               struct device_attribute *attr,
 285                               const char *buf,
 286                               size_t len);
 287 ssize_t iio_show_ring_enable(struct device *dev,
 288                              struct device_attribute *attr,
 289                              char *buf);
 290 #define IIO_RING_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,     \
 291                                          iio_read_ring_length,          \
 292                                          iio_write_ring_length)
 293 #define IIO_RING_BPS_ATTR DEVICE_ATTR(bps, S_IRUGO | S_IWUSR,   \
 294                                       iio_read_ring_bps, NULL)
 295 #define IIO_RING_ENABLE_ATTR DEVICE_ATTR(ring_enable, S_IRUGO | S_IWUSR, \
 296                                          iio_show_ring_enable,          \
 297                                          iio_store_ring_enable)
 298
 299 #endif /* _IIO_RING_GENERIC_H_ */