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
  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  */
  38 static 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  */
  47 void 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 transmissible 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  */
  67 int 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  */
 105 void 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  */
 122 void 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  */
 148 int 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  */
 191 int 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  */
 251 int 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 }