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 <linux/sysfs.h>
  13 #include "iio.h"
  14 #include "chrdev.h"
  15
  16 #ifdef CONFIG_IIO_BUFFER
  17
  18 struct iio_ring_buffer;
  19
  20 /**
  21  * struct iio_ring_access_funcs - access functions for ring buffers.
  22  * @mark_in_use:        reference counting, typically to prevent module removal
  23  * @unmark_in_use:      reduce reference count when no longer using ring buffer
  24  * @store_to:           actually store stuff to the ring buffer
  25  * @read_last:          get the last element stored
  26  * @read_first_n:       try to get a specified number of elements (must exist)
  27  * @mark_param_change:  notify ring that some relevant parameter has changed
  28  *                      Often this means the underlying storage may need to
  29  *                      change.
  30  * @request_update:     if a parameter change has been marked, update underlying
  31  *                      storage.
  32  * @get_bytes_per_datum:get current bytes per datum
  33  * @set_bytes_per_datum:set number of bytes per datum
  34  * @get_length:         get number of datums in ring
  35  * @set_length:         set number of datums in ring
  36  * @is_enabled:         query if ring is currently being used
  37  * @enable:             enable the ring
  38  *
  39  * The purpose of this structure is to make the ring buffer element
  40  * modular as event for a given driver, different usecases may require
  41  * different ring designs (space efficiency vs speed for example).
  42  *
  43  * It is worth noting that a given ring implementation may only support a small
  44  * proportion of these functions.  The core code 'should' cope fine with any of
  45  * them not existing.
  46  **/
  47 struct iio_ring_access_funcs {
  48         void (*mark_in_use)(struct iio_ring_buffer *ring);
  49         void (*unmark_in_use)(struct iio_ring_buffer *ring);
  50
  51         int (*store_to)(struct iio_ring_buffer *ring, u8 *data, s64 timestamp);
  52         int (*read_last)(struct iio_ring_buffer *ring, u8 *data);
  53         int (*read_first_n)(struct iio_ring_buffer *ring,
  54                             size_t n,
  55                             char __user *buf);
  56
  57         int (*mark_param_change)(struct iio_ring_buffer *ring);
  58         int (*request_update)(struct iio_ring_buffer *ring);
  59
  60         int (*get_bytes_per_datum)(struct iio_ring_buffer *ring);
  61         int (*set_bytes_per_datum)(struct iio_ring_buffer *ring, size_t bpd);
  62         int (*get_length)(struct iio_ring_buffer *ring);
  63         int (*set_length)(struct iio_ring_buffer *ring, int length);
  64
  65         int (*is_enabled)(struct iio_ring_buffer *ring);
  66         int (*enable)(struct iio_ring_buffer *ring);
  67 };
  68
  69 /**
  70  * struct iio_ring_setup_ops - buffer setup related callbacks
  71  * @preenable:          [DRIVER] function to run prior to marking ring enabled
  72  * @postenable:         [DRIVER] function to run after marking ring enabled
  73  * @predisable:         [DRIVER] function to run prior to marking ring disabled
  74  * @postdisable:        [DRIVER] function to run after marking ring disabled
  75  */
  76 struct iio_ring_setup_ops {
  77         int                             (*preenable)(struct iio_dev *);
  78         int                             (*postenable)(struct iio_dev *);
  79         int                             (*predisable)(struct iio_dev *);
  80         int                             (*postdisable)(struct iio_dev *);
  81 };
  82
  83 /**
  84  * struct iio_ring_buffer - general ring buffer structure
  85  * @dev:                ring buffer device struct
  86  * @indio_dev:          industrial I/O device structure
  87  * @owner:              module that owns the ring buffer (for ref counting)
  88  * @length:             [DEVICE] number of datums in ring
  89  * @bytes_per_datum:    [DEVICE] size of individual datum including timestamp
  90  * @bpe:                [DEVICE] size of individual channel value
  91  * @scan_el_attrs:      [DRIVER] control of scan elements if that scan mode
  92  *                      control method is used
  93  * @scan_count: [INTERN] the number of elements in the current scan mode
  94  * @scan_mask:          [INTERN] bitmask used in masking scan mode elements
  95  * @scan_timestamp:     [INTERN] does the scan mode include a timestamp
  96  * @access:             [DRIVER] ring access functions associated with the
  97  *                      implementation.
  98  * @flags:              [INTERN] file ops related flags including busy flag.
  99  **/
 100 struct iio_ring_buffer {
 101         struct iio_dev                          *indio_dev;
 102         struct module                           *owner;
 103         int                                     length;
 104         int                                     bytes_per_datum;
 105         int                                     bpe;
 106         struct attribute_group                  *scan_el_attrs;
 107         int                                     scan_count;
 108         long                                    *scan_mask;
 109         bool                                    scan_timestamp;
 110         const struct iio_ring_access_funcs      *access;
 111         const struct iio_ring_setup_ops         *setup_ops;
 112         struct list_head                        scan_el_dev_attr_list;
 113         struct attribute_group                  scan_el_group;
 114         wait_queue_head_t                       pollq;
 115         bool                                    stufftoread;
 116         unsigned long                           flags;
 117         const struct attribute_group *attrs;
 118 };
 119
 120 /**
 121  * iio_ring_buffer_init() - Initialize the buffer structure
 122  * @ring: buffer to be initialized
 123  * @dev_info: the iio device the buffer is assocated with
 124  **/
 125 void iio_ring_buffer_init(struct iio_ring_buffer *ring,
 126                           struct iio_dev *dev_info);
 127
 128 void iio_ring_buffer_deinit(struct iio_ring_buffer *ring);
 129
 130 /**
 131  * __iio_update_ring_buffer() - update common elements of ring buffers
 132  * @ring:               ring buffer that is the event source
 133  * @bytes_per_datum:    size of individual datum including timestamp
 134  * @length:             number of datums in ring
 135  **/
 136 static inline void __iio_update_ring_buffer(struct iio_ring_buffer *ring,
 137                                             int bytes_per_datum, int length)
 138 {
 139         ring->bytes_per_datum = bytes_per_datum;
 140         ring->length = length;
 141 }
 142
 143 int iio_scan_mask_query(struct iio_ring_buffer *ring, int bit);
 144
 145 /**
 146  * iio_scan_mask_set() - set particular bit in the scan mask
 147  * @ring: the ring buffer whose scan mask we are interested in
 148  * @bit: the bit to be set.
 149  **/
 150 int iio_scan_mask_set(struct iio_ring_buffer *ring, int bit);
 151
 152 #define to_iio_ring_buffer(d)                           \
 153         container_of(d, struct iio_ring_buffer, dev)
 154
 155 /**
 156  * iio_ring_buffer_register() - register the buffer with IIO core
 157  * @indio_dev: device with the buffer to be registered
 158  **/
 159 int iio_ring_buffer_register(struct iio_dev *indio_dev,
 160                              const struct iio_chan_spec *channels,
 161                              int num_channels);
 162
 163 /**
 164  * iio_ring_buffer_unregister() - unregister the buffer from IIO core
 165  * @indio_dev: the device with the buffer to be unregistered
 166  **/
 167 void iio_ring_buffer_unregister(struct iio_dev *indio_dev);
 168
 169 /**
 170  * iio_read_ring_length() - attr func to get number of datums in the buffer
 171  **/
 172 ssize_t iio_read_ring_length(struct device *dev,
 173                              struct device_attribute *attr,
 174                              char *buf);
 175 /**
 176  * iio_write_ring_length() - attr func to set number of datums in the buffer
 177  **/
 178 ssize_t iio_write_ring_length(struct device *dev,
 179                               struct device_attribute *attr,
 180                               const char *buf,
 181                               size_t len);
 182 /**
 183  * iio_read_ring_bytes_per_datum() - attr for number of bytes in whole datum
 184  **/
 185 ssize_t iio_read_ring_bytes_per_datum(struct device *dev,
 186                           struct device_attribute *attr,
 187                           char *buf);
 188 /**
 189  * iio_store_ring_enable() - attr to turn the buffer on
 190  **/
 191 ssize_t iio_store_ring_enable(struct device *dev,
 192                               struct device_attribute *attr,
 193                               const char *buf,
 194                               size_t len);
 195 /**
 196  * iio_show_ring_enable() - attr to see if the buffer is on
 197  **/
 198 ssize_t iio_show_ring_enable(struct device *dev,
 199                              struct device_attribute *attr,
 200                              char *buf);
 201 #define IIO_RING_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,     \
 202                                          iio_read_ring_length,          \
 203                                          iio_write_ring_length)
 204 #define IIO_RING_BYTES_PER_DATUM_ATTR DEVICE_ATTR(bytes_per_datum, S_IRUGO | S_IWUSR,   \
 205                                       iio_read_ring_bytes_per_datum, NULL)
 206 #define IIO_RING_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \
 207                                          iio_show_ring_enable,          \
 208                                          iio_store_ring_enable)
 209
 210 int iio_sw_ring_preenable(struct iio_dev *indio_dev);
 211
 212 #else /* CONFIG_IIO_BUFFER */
 213
 214 static inline int iio_ring_buffer_register(struct iio_dev *indio_dev,
 215                                            struct iio_chan_spec *channels,
 216                                            int num_channels)
 217 {
 218         return 0;
 219 }
 220
 221 static inline void iio_ring_buffer_unregister(struct iio_dev *indio_dev)
 222 {};
 223
 224 #endif /* CONFIG_IIO_BUFFER */
 225
 226 #endif /* _IIO_RING_GENERIC_H_ */