linux/drivers/staging/fwserial/dma_fifo.c
<<
>>
Prefs
   1/*
   2 * DMA-able FIFO implementation
   3 *
   4 * Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 */
  16
  17#include <linux/kernel.h>
  18#include <linux/slab.h>
  19#include <linux/list.h>
  20#include <linux/bug.h>
  21
  22#include "dma_fifo.h"
  23
  24#ifdef DEBUG_TRACING
  25#define df_trace(s, args...) pr_debug(s, ##args)
  26#else
  27#define df_trace(s, args...)
  28#endif
  29
  30#define FAIL(fifo, condition, format...) ({                             \
  31        fifo->corrupt = !!(condition);                                  \
  32        WARN(fifo->corrupt, format);                                    \
  33})
  34
  35/*
  36 * private helper fn to determine if check is in open interval (lo,hi)
  37 */
  38static bool addr_check(unsigned check, unsigned lo, unsigned hi)
  39{
  40        return check - (lo + 1) < (hi - 1) - lo;
  41}
  42
  43/**
  44 * dma_fifo_init: initialize the fifo to a valid but inoperative state
  45 * @fifo: address of in-place "struct dma_fifo" object
  46 */
  47void dma_fifo_init(struct dma_fifo *fifo)
  48{
  49        memset(fifo, 0, sizeof(*fifo));
  50        INIT_LIST_HEAD(&fifo->pending);
  51}
  52
  53/**
  54 * dma_fifo_alloc - initialize and allocate dma_fifo
  55 * @fifo: address of in-place "struct dma_fifo" object
  56 * @size: 'apparent' size, in bytes, of fifo
  57 * @align: dma alignment to maintain (should be at least cpu cache alignment),
  58 *         must be power of 2
  59 * @tx_limit: maximum # of bytes transmissable per dma (rounded down to
  60 *            multiple of alignment, but at least align size)
  61 * @open_limit: maximum # of outstanding dma transactions allowed
  62 * @gfp_mask: get_free_pages mask, passed to kmalloc()
  63 *
  64 * The 'apparent' size will be rounded up to next greater aligned size.
  65 * Returns 0 if no error, otherwise an error code
  66 */
  67int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned align,
  68                   int tx_limit, int open_limit, gfp_t gfp_mask)
  69{
  70        int capacity;
  71
  72        if (!is_power_of_2(align) || size < 0)
  73                return -EINVAL;
  74
  75        size = round_up(size, align);
  76        capacity = size + align * open_limit + align * DMA_FIFO_GUARD;
  77        fifo->data = kmalloc(capacity, gfp_mask);
  78        if (!fifo->data)
  79                return -ENOMEM;
  80
  81        fifo->in = 0;
  82        fifo->out = 0;
  83        fifo->done = 0;
  84        fifo->size = size;
  85        fifo->avail = size;
  86        fifo->align = align;
  87        fifo->tx_limit = max_t(int, round_down(tx_limit, align), align);
  88        fifo->open = 0;
  89        fifo->open_limit = open_limit;
  90        fifo->guard = size + align * open_limit;
  91        fifo->capacity = capacity;
  92        fifo->corrupt = 0;
  93
  94        return 0;
  95}
  96
  97/**
  98 * dma_fifo_free - frees the fifo
  99 * @fifo: address of in-place "struct dma_fifo" to free
 100 *
 101 * Also reinits the fifo to a valid but inoperative state. This
 102 * allows the fifo to be reused with a different target requiring
 103 * different fifo parameters.
 104 */
 105void dma_fifo_free(struct dma_fifo *fifo)
 106{
 107        struct dma_pending *pending, *next;
 108
 109        if (fifo->data == NULL)
 110                return;
 111
 112        list_for_each_entry_safe(pending, next, &fifo->pending, link)
 113                list_del_init(&pending->link);
 114        kfree(fifo->data);
 115        fifo->data = NULL;
 116}
 117
 118/**
 119 * dma_fifo_reset - dumps the fifo contents and reinits for reuse
 120 * @fifo: address of in-place "struct dma_fifo" to reset
 121 */
 122void dma_fifo_reset(struct dma_fifo *fifo)
 123{
 124        struct dma_pending *pending, *next;
 125
 126        if (fifo->data == NULL)
 127                return;
 128
 129        list_for_each_entry_safe(pending, next, &fifo->pending, link)
 130                list_del_init(&pending->link);
 131        fifo->in = 0;
 132        fifo->out = 0;
 133        fifo->done = 0;
 134        fifo->avail = fifo->size;
 135        fifo->open = 0;
 136        fifo->corrupt = 0;
 137}
 138
 139/**
 140 * dma_fifo_in - copies data into the fifo
 141 * @fifo: address of in-place "struct dma_fifo" to write to
 142 * @src: buffer to copy from
 143 * @n: # of bytes to copy
 144 *
 145 * Returns the # of bytes actually copied, which can be less than requested if
 146 * the fifo becomes full. If < 0, return is error code.
 147 */
 148int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
 149{
 150        int ofs, l;
 151
 152        if (fifo->data == NULL)
 153                return -ENOENT;
 154        if (fifo->corrupt)
 155                return -ENXIO;
 156
 157        if (n > fifo->avail)
 158                n = fifo->avail;
 159        if (n <= 0)
 160                return 0;
 161
 162        ofs = fifo->in % fifo->capacity;
 163        l = min(n, fifo->capacity - ofs);
 164        memcpy(fifo->data + ofs, src, l);
 165        memcpy(fifo->data, src + l, n - l);
 166
 167        if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) ||
 168                 fifo->avail < n,
 169                 "fifo corrupt: in:%u out:%u done:%u n:%d avail:%d",
 170                 fifo->in, fifo->out, fifo->done, n, fifo->avail))
 171                return -ENXIO;
 172
 173        fifo->in += n;
 174        fifo->avail -= n;
 175
 176        df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out,
 177                 fifo->done, n, fifo->avail);
 178
 179        return n;
 180}
 181
 182/**
 183 * dma_fifo_out_pend - gets address/len of next avail read and marks as pended
 184 * @fifo: address of in-place "struct dma_fifo" to read from
 185 * @pended: address of structure to fill with read address/len
 186 *          The data/len fields will be NULL/0 if no dma is pended.
 187 *
 188 * Returns the # of used bytes remaining in fifo (ie, if > 0, more data
 189 * remains in the fifo that was not pended). If < 0, return is error code.
 190 */
 191int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
 192{
 193        unsigned len, n, ofs, l, limit;
 194
 195        if (fifo->data == NULL)
 196                return -ENOENT;
 197        if (fifo->corrupt)
 198                return -ENXIO;
 199
 200        pended->len = 0;
 201        pended->data = NULL;
 202        pended->out = fifo->out;
 203
 204        len = fifo->in - fifo->out;
 205        if (!len)
 206                return -ENODATA;
 207        if (fifo->open == fifo->open_limit)
 208                return -EAGAIN;
 209
 210        n = len;
 211        ofs = fifo->out % fifo->capacity;
 212        l = fifo->capacity - ofs;
 213        limit = min_t(unsigned, l, fifo->tx_limit);
 214        if (n > limit) {
 215                n = limit;
 216                fifo->out += limit;
 217        } else if (ofs + n > fifo->guard) {
 218                fifo->out += l;
 219                fifo->in = fifo->out;
 220        } else {
 221                fifo->out += round_up(n, fifo->align);
 222                fifo->in = fifo->out;
 223        }
 224
 225        df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in,
 226                 fifo->out, fifo->done, n, len, fifo->avail);
 227
 228        pended->len = n;
 229        pended->data = fifo->data + ofs;
 230        pended->next = fifo->out;
 231        list_add_tail(&pended->link, &fifo->pending);
 232        ++fifo->open;
 233
 234        if (FAIL(fifo, fifo->open > fifo->open_limit,
 235                 "past open limit:%d (limit:%d)",
 236                 fifo->open, fifo->open_limit))
 237                return -ENXIO;
 238        if (FAIL(fifo, fifo->out & (fifo->align - 1),
 239                 "fifo out unaligned:%u (align:%u)",
 240                 fifo->out, fifo->align))
 241                return -ENXIO;
 242
 243        return len - n;
 244}
 245
 246/**
 247 * dma_fifo_out_complete - marks pended dma as completed
 248 * @fifo: address of in-place "struct dma_fifo" which was read from
 249 * @complete: address of structure for previously pended dma to mark completed
 250 */
 251int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
 252{
 253        struct dma_pending *pending, *next, *tmp;
 254
 255        if (fifo->data == NULL)
 256                return -ENOENT;
 257        if (fifo->corrupt)
 258                return -ENXIO;
 259        if (list_empty(&fifo->pending) && fifo->open == 0)
 260                return -EINVAL;
 261
 262        if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0),
 263                 "pending list disagrees with open count:%d",
 264                 fifo->open))
 265                return -ENXIO;
 266
 267        tmp = complete->data;
 268        *tmp = *complete;
 269        list_replace(&complete->link, &tmp->link);
 270        dp_mark_completed(tmp);
 271
 272        /* Only update the fifo in the original pended order */
 273        list_for_each_entry_safe(pending, next, &fifo->pending, link) {
 274                if (!dp_is_completed(pending)) {
 275                        df_trace("still pending: saved out: %u len: %d",
 276                                 pending->out, pending->len);
 277                        break;
 278                }
 279
 280                if (FAIL(fifo, pending->out != fifo->done ||
 281                         addr_check(fifo->in, fifo->done, pending->next),
 282                         "in:%u out:%u done:%u saved:%u next:%u",
 283                         fifo->in, fifo->out, fifo->done, pending->out,
 284                         pending->next))
 285                        return -ENXIO;
 286
 287                list_del_init(&pending->link);
 288                fifo->done = pending->next;
 289                fifo->avail += pending->len;
 290                --fifo->open;
 291
 292                df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in,
 293                         fifo->out, fifo->done, pending->len, fifo->avail);
 294        }
 295
 296        if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open))
 297                return -ENXIO;
 298        if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d",
 299                 fifo->avail, fifo->size))
 300                return -ENXIO;
 301
 302        return 0;
 303}
 304