sound/drivers/pcm-indirect2.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Helper functions for indirect PCM data transfer to a simple FIFO in
   4  * hardware (small, no possibility to read "hardware io position",
   5  * updating position done by interrupt, ...)
   6  *
   7  *  Copyright (c) by 2007  Joachim Foerster <JOFT@gmx.de>
   8  *
   9  *  Based on "pcm-indirect.h" (alsa-driver-1.0.13) by
  10  *
  11  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
  12  *                   Jaroslav Kysela <perex@suse.cz>
  13  */
  14
  15 #ifndef __SOUND_PCM_INDIRECT2_H
  16 #define __SOUND_PCM_INDIRECT2_H
  17
  18 /* struct snd_pcm_substream, struct snd_pcm_runtime, snd_pcm_uframes_t */
  19 #include <sound/pcm.h>
  20
  21 /* Debug options for code which may be removed completely in a final version */
  22 #ifdef CONFIG_SND_DEBUG
  23 #define SND_PCM_INDIRECT2_STAT    /* turn on some "statistics" about the
  24                                    * process of copying bytes from the
  25                                    * intermediate buffer to the hardware
  26                                    * fifo and the other way round
  27                                    */
  28 #endif
  29
  30 struct snd_pcm_indirect2 {
  31         unsigned int hw_buffer_size;  /* Byte size of hardware buffer */
  32         int hw_ready;                 /* playback: 1 = hw fifo has room left,
  33                                        * 0 = hw fifo is full
  34                                        */
  35         unsigned int min_multiple;
  36         int min_periods;              /* counts number of min. periods until
  37                                        * min_multiple is reached
  38                                        */
  39         int min_period_count;         /* counts bytes to count number of
  40                                        * min. periods
  41                                        */
  42
  43         unsigned int sw_buffer_size;  /* Byte size of software buffer */
  44
  45         /* sw_data: position in intermediate buffer, where we will read (or
  46          *          write) from/to next time (to transfer data to/from HW)
  47          */
  48         unsigned int sw_data;         /* Offset to next dst (or src) in sw
  49                                        * ring buffer
  50                                        */
  51         /* easiest case (playback):
  52          * sw_data is nearly the same as ~ runtime->control->appl_ptr, with the
  53          * exception that sw_data is "behind" by the number if bytes ALSA wrote
  54          * to the intermediate buffer last time.
  55          * A call to ack() callback synchronizes both indirectly.
  56          */
  57
  58         /* We have no real sw_io pointer here. Usually sw_io is pointing to the
  59          * current playback/capture position _inside_ the hardware. Devices
  60          * with plain FIFOs often have no possibility to publish this position.
  61          * So we say: if sw_data is updated, that means bytes were copied to
  62          * the hardware, we increase sw_io by that amount, because there have
  63          * to be as much bytes which were played. So sw_io will stay behind
  64          * sw_data all the time and has to converge to sw_data at the end of
  65          * playback.
  66          */
  67         unsigned int sw_io;           /* Current software pointer in bytes */
  68
  69         /* sw_ready: number of bytes ALSA copied to the intermediate buffer, so
  70          * it represents the number of bytes which wait for transfer to the HW
  71          */
  72         int sw_ready;             /* Bytes ready to be transferred to/from hw */
  73
  74         /* appl_ptr: last known position of ALSA (where ALSA is going to write
  75          * next time into the intermediate buffer
  76          */
  77         snd_pcm_uframes_t appl_ptr;   /* Last seen appl_ptr */
  78
  79         unsigned int bytes2hw;
  80         int check_alignment;
  81
  82 #ifdef SND_PCM_INDIRECT2_STAT
  83         unsigned int zeros2hw;
  84         unsigned int mul_elapsed;
  85         unsigned int mul_elapsed_real;
  86         unsigned long firstbytetime;
  87         unsigned long lastbytetime;
  88         unsigned long firstzerotime;
  89         unsigned int byte_sizes[64];
  90         unsigned int zero_sizes[64];
  91         unsigned int min_adds[8];
  92         unsigned int mul_adds[8];
  93         unsigned int zero_times[3750];  /* = 15s */
  94         unsigned int zero_times_saved;
  95         unsigned int zero_times_notsaved;
  96         unsigned int irq_occured;
  97         unsigned int pointer_calls;
  98         unsigned int lastdifftime;
  99 #endif
 100 };
 101
 102 typedef size_t (*snd_pcm_indirect2_copy_t) (struct snd_pcm_substream *substream,
 103                                            struct snd_pcm_indirect2 *rec,
 104                                            size_t bytes);
 105 typedef size_t (*snd_pcm_indirect2_zero_t) (struct snd_pcm_substream *substream,
 106                                            struct snd_pcm_indirect2 *rec);
 107
 108 #ifdef SND_PCM_INDIRECT2_STAT
 109 void snd_pcm_indirect2_stat(struct snd_pcm_substream *substream,
 110                                    struct snd_pcm_indirect2 *rec);
 111 #endif
 112
 113 snd_pcm_uframes_t
 114 snd_pcm_indirect2_pointer(struct snd_pcm_substream *substream,
 115                           struct snd_pcm_indirect2 *rec);
 116 void
 117 snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
 118                                      struct snd_pcm_indirect2 *rec,
 119                                      snd_pcm_indirect2_copy_t copy,
 120                                      snd_pcm_indirect2_zero_t zero);
 121 void
 122 snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
 123                                     struct snd_pcm_indirect2 *rec,
 124                                     snd_pcm_indirect2_copy_t copy,
 125                                     snd_pcm_indirect2_zero_t null);
 126
 127 #endif /* __SOUND_PCM_INDIRECT2_H */