drivers/staging/fwserial/dma_fifo.c

   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  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/slab.h>
  23 #include <linux/list.h>
  24 #include <linux/bug.h>
  25
  26 #include "dma_fifo.h"
  27
  28 #ifdef DEBUG_TRACING
  29 #define df_trace(s, args...) pr_debug(s, ##args)
  30 #else
  31 #define df_trace(s, args...)
  32 #endif
  33
  34 #define FAIL(fifo, condition, format...) ({                             \
  35         fifo->corrupt = !!(condition);                                  \
  36         WARN(fifo->corrupt, format);                                    \
  37 })
  38
  39 /*
  40  * private helper fn to determine if check is in open interval (lo,hi)
  41  */
  42 static bool addr_check(unsigned check, unsigned lo, unsigned hi)
  43 {
  44         return check - (lo + 1) < (hi - 1) - lo;
  45 }
  46
  47 /**
  48  * dma_fifo_init: initialize the fifo to a valid but inoperative state
  49  * @fifo: address of in-place "struct dma_fifo" object
  50  */
  51 void dma_fifo_init(struct dma_fifo *fifo)
  52 {
  53         memset(fifo, 0, sizeof(*fifo));
  54         INIT_LIST_HEAD(&fifo->pending);
  55 }
  56
  57 /**
  58  * dma_fifo_alloc - initialize and allocate dma_fifo
  59  * @fifo: address of in-place "struct dma_fifo" object
  60  * @size: 'apparent' size, in bytes, of fifo
  61  * @align: dma alignment to maintain (should be at least cpu cache alignment),
  62  *         must be power of 2
  63  * @tx_limit: maximum # of bytes transmissable per dma (rounded down to
  64  *            multiple of alignment, but at least align size)
  65  * @open_limit: maximum # of outstanding dma transactions allowed
  66  * @gfp_mask: get_free_pages mask, passed to kmalloc()
  67  *
  68  * The 'apparent' size will be rounded up to next greater aligned size.
  69  * Returns 0 if no error, otherwise an error code
  70  */
  71 int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned align,
  72                    int tx_limit, int open_limit, gfp_t gfp_mask)
  73 {
  74         int capacity;
  75
  76         if (!is_power_of_2(align) || size < 0)
  77                 return -EINVAL;
  78
  79         size = round_up(size, align);
  80         capacity = size + align * open_limit + align * DMA_FIFO_GUARD;
  81         fifo->data = kmalloc(capacity, gfp_mask);
  82         if (!fifo->data)
  83                 return -ENOMEM;
  84
  85         fifo->in = 0;
  86         fifo->out = 0;
  87         fifo->done = 0;
  88         fifo->size = size;
  89         fifo->avail = size;
  90         fifo->align = align;
  91         fifo->tx_limit = max_t(int, round_down(tx_limit, align), align);
  92         fifo->open = 0;
  93         fifo->open_limit = open_limit;
  94         fifo->guard = size + align * open_limit;
  95         fifo->capacity = capacity;
  96         fifo->corrupt = 0;
  97
  98         return 0;
  99 }
 100
 101 /**
 102  * dma_fifo_free - frees the fifo
 103  * @fifo: address of in-place "struct dma_fifo" to free
 104  *
 105  * Also reinits the fifo to a valid but inoperative state. This
 106  * allows the fifo to be reused with a different target requiring
 107  * different fifo parameters.
 108  */
 109 void dma_fifo_free(struct dma_fifo *fifo)
 110 {
 111         struct dma_pending *pending, *next;
 112
 113         if (fifo->data == NULL)
 114                 return;
 115
 116         list_for_each_entry_safe(pending, next, &fifo->pending, link)
 117                 list_del_init(&pending->link);
 118         kfree(fifo->data);
 119         fifo->data = NULL;
 120 }
 121
 122 /**
 123  * dma_fifo_reset - dumps the fifo contents and reinits for reuse
 124  * @fifo: address of in-place "struct dma_fifo" to reset
 125  */
 126 void dma_fifo_reset(struct dma_fifo *fifo)
 127 {
 128         struct dma_pending *pending, *next;
 129
 130         if (fifo->data == NULL)
 131                 return;
 132
 133         list_for_each_entry_safe(pending, next, &fifo->pending, link)
 134                 list_del_init(&pending->link);
 135         fifo->in = 0;
 136         fifo->out = 0;
 137         fifo->done = 0;
 138         fifo->avail = fifo->size;
 139         fifo->open = 0;
 140         fifo->corrupt = 0;
 141 }
 142
 143 /**
 144  * dma_fifo_in - copies data into the fifo
 145  * @fifo: address of in-place "struct dma_fifo" to write to
 146  * @src: buffer to copy from
 147  * @n: # of bytes to copy
 148  *
 149  * Returns the # of bytes actually copied, which can be less than requested if
 150  * the fifo becomes full. If < 0, return is error code.
 151  */
 152 int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
 153 {
 154         int ofs, l;
 155
 156         if (fifo->data == NULL)
 157                 return -ENOENT;
 158         if (fifo->corrupt)
 159                 return -ENXIO;
 160
 161         if (n > fifo->avail)
 162                 n = fifo->avail;
 163         if (n <= 0)
 164                 return 0;
 165
 166         ofs = fifo->in % fifo->capacity;
 167         l = min(n, fifo->capacity - ofs);
 168         memcpy(fifo->data + ofs, src, l);
 169         memcpy(fifo->data, src + l, n - l);
 170
 171         if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) ||
 172                         fifo->avail < n,
 173                         "fifo corrupt: in:%u out:%u done:%u n:%d avail:%d",
 174                         fifo->in, fifo->out, fifo->done, n, fifo->avail))
 175                 return -ENXIO;
 176
 177         fifo->in += n;
 178         fifo->avail -= n;
 179
 180         df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out,
 181                  fifo->done, n, fifo->avail);
 182
 183         return n;
 184 }
 185
 186 /**
 187  * dma_fifo_out_pend - gets address/len of next avail read and marks as pended
 188  * @fifo: address of in-place "struct dma_fifo" to read from
 189  * @pended: address of structure to fill with read address/len
 190  *          The data/len fields will be NULL/0 if no dma is pended.
 191  *
 192  * Returns the # of used bytes remaining in fifo (ie, if > 0, more data
 193  * remains in the fifo that was not pended). If < 0, return is error code.
 194  */
 195 int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
 196 {
 197         unsigned len, n, ofs, l, limit;
 198
 199         if (fifo->data == NULL)
 200                 return -ENOENT;
 201         if (fifo->corrupt)
 202                 return -ENXIO;
 203
 204         pended->len = 0;
 205         pended->data = NULL;
 206         pended->out = fifo->out;
 207
 208         len = fifo->in - fifo->out;
 209         if (!len)
 210                 return -ENODATA;
 211         if (fifo->open == fifo->open_limit)
 212                 return -EAGAIN;
 213
 214         n = len;
 215         ofs = fifo->out % fifo->capacity;
 216         l = fifo->capacity - ofs;
 217         limit = min_t(unsigned, l, fifo->tx_limit);
 218         if (n > limit) {
 219                 n = limit;
 220                 fifo->out += limit;
 221         } else if (ofs + n > fifo->guard) {
 222                 fifo->out += l;
 223                 fifo->in = fifo->out;
 224         } else {
 225                 fifo->out += round_up(n, fifo->align);
 226                 fifo->in = fifo->out;
 227         }
 228
 229         df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in,
 230                  fifo->out, fifo->done, n, len, fifo->avail);
 231
 232         pended->len = n;
 233         pended->data = fifo->data + ofs;
 234         pended->next = fifo->out;
 235         list_add_tail(&pended->link, &fifo->pending);
 236         ++fifo->open;
 237
 238         if (FAIL(fifo, fifo->open > fifo->open_limit,
 239                         "past open limit:%d (limit:%d)",
 240                         fifo->open, fifo->open_limit))
 241                 return -ENXIO;
 242         if (FAIL(fifo, fifo->out & (fifo->align - 1),
 243                         "fifo out unaligned:%u (align:%u)",
 244                         fifo->out, fifo->align))
 245                 return -ENXIO;
 246
 247         return len - n;
 248 }
 249
 250 /**
 251  * dma_fifo_out_complete - marks pended dma as completed
 252  * @fifo: address of in-place "struct dma_fifo" which was read from
 253  * @complete: address of structure for previously pended dma to mark completed
 254  */
 255 int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
 256 {
 257         struct dma_pending *pending, *next, *tmp;
 258
 259         if (fifo->data == NULL)
 260                 return -ENOENT;
 261         if (fifo->corrupt)
 262                 return -ENXIO;
 263         if (list_empty(&fifo->pending) && fifo->open == 0)
 264                 return -EINVAL;
 265
 266         if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0),
 267                         "pending list disagrees with open count:%d",
 268                         fifo->open))
 269                 return -ENXIO;
 270
 271         tmp = complete->data;
 272         *tmp = *complete;
 273         list_replace(&complete->link, &tmp->link);
 274         dp_mark_completed(tmp);
 275
 276         /* Only update the fifo in the original pended order */
 277         list_for_each_entry_safe(pending, next, &fifo->pending, link) {
 278                 if (!dp_is_completed(pending)) {
 279                         df_trace("still pending: saved out: %u len: %d",
 280                                  pending->out, pending->len);
 281                         break;
 282                 }
 283
 284                 if (FAIL(fifo, pending->out != fifo->done ||
 285                                 addr_check(fifo->in, fifo->done, pending->next),
 286                                 "in:%u out:%u done:%u saved:%u next:%u",
 287                                 fifo->in, fifo->out, fifo->done, pending->out,
 288                                 pending->next))
 289                         return -ENXIO;
 290
 291                 list_del_init(&pending->link);
 292                 fifo->done = pending->next;
 293                 fifo->avail += pending->len;
 294                 --fifo->open;
 295
 296                 df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in,
 297                          fifo->out, fifo->done, pending->len, fifo->avail);
 298         }
 299
 300         if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open))
 301                 return -ENXIO;
 302         if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d",
 303                         fifo->avail, fifo->size))
 304                 return -ENXIO;
 305
 306         return 0;
 307 }