--- /dev/null
+/*
+ * DMA-able FIFO implementation
+ *
+ * Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/bug.h>
+
+#include "dma_fifo.h"
+
+#ifdef DEBUG_TRACING
+#define df_trace(s, args...) pr_debug(s, ##args)
+#else
+#define df_trace(s, args...)
+#endif
+
+#define FAIL(fifo, condition, format...) ({ \
+ fifo->corrupt = !!(condition); \
+ WARN(fifo->corrupt, format); \
+})
+
+/*
+ * private helper fn to determine if check is in open interval (lo,hi)
+ */
+static bool addr_check(unsigned check, unsigned lo, unsigned hi)
+{
+ return check - (lo + 1) < (hi - 1) - lo;
+}
+
+/**
+ * dma_fifo_init: initialize the fifo to a valid but inoperative state
+ * @fifo: address of in-place "struct dma_fifo" object
+ */
+void dma_fifo_init(struct dma_fifo *fifo)
+{
+ memset(fifo, 0, sizeof(*fifo));
+ INIT_LIST_HEAD(&fifo->pending);
+}
+
+/**
+ * dma_fifo_alloc - initialize and allocate dma_fifo
+ * @fifo: address of in-place "struct dma_fifo" object
+ * @size: 'apparent' size, in bytes, of fifo
+ * @align: dma alignment to maintain (should be at least cpu cache alignment),
+ * must be power of 2
+ * @tx_limit: maximum # of bytes transmissable per dma (rounded down to
+ * multiple of alignment, but at least align size)
+ * @open_limit: maximum # of outstanding dma transactions allowed
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ *
+ * The 'apparent' size will be rounded up to next greater aligned size.
+ * Returns 0 if no error, otherwise an error code
+ */
+int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned align,
+ int tx_limit, int open_limit, gfp_t gfp_mask)
+{
+ int capacity;
+
+ if (!is_power_of_2(align) || size < 0)
+ return -EINVAL;
+
+ size = round_up(size, align);
+ capacity = size + align * open_limit + align * DMA_FIFO_GUARD;
+ fifo->data = kmalloc(capacity, gfp_mask);
+ if (!fifo->data)
+ return -ENOMEM;
+
+ fifo->in = 0;
+ fifo->out = 0;
+ fifo->done = 0;
+ fifo->size = size;
+ fifo->avail = size;
+ fifo->align = align;
+ fifo->tx_limit = max_t(int, round_down(tx_limit, align), align);
+ fifo->open = 0;
+ fifo->open_limit = open_limit;
+ fifo->guard = size + align * open_limit;
+ fifo->capacity = capacity;
+ fifo->corrupt = 0;
+
+ return 0;
+}
+
+/**
+ * dma_fifo_free - frees the fifo
+ * @fifo: address of in-place "struct dma_fifo" to free
+ *
+ * Also reinits the fifo to a valid but inoperative state. This
+ * allows the fifo to be reused with a different target requiring
+ * different fifo parameters.
+ */
+void dma_fifo_free(struct dma_fifo *fifo)
+{
+ struct dma_pending *pending, *next;
+
+ if (fifo->data == NULL)
+ return;
+
+ list_for_each_entry_safe(pending, next, &fifo->pending, link)
+ list_del_init(&pending->link);
+ kfree(fifo->data);
+ fifo->data = NULL;
+}
+
+/**
+ * dma_fifo_reset - dumps the fifo contents and reinits for reuse
+ * @fifo: address of in-place "struct dma_fifo" to reset
+ */
+void dma_fifo_reset(struct dma_fifo *fifo)
+{
+ struct dma_pending *pending, *next;
+
+ if (fifo->data == NULL)
+ return;
+
+ list_for_each_entry_safe(pending, next, &fifo->pending, link)
+ list_del_init(&pending->link);
+ fifo->in = 0;
+ fifo->out = 0;
+ fifo->done = 0;
+ fifo->avail = fifo->size;
+ fifo->open = 0;
+ fifo->corrupt = 0;
+}
+
+/**
+ * dma_fifo_in - copies data into the fifo
+ * @fifo: address of in-place "struct dma_fifo" to write to
+ * @src: buffer to copy from
+ * @n: # of bytes to copy
+ *
+ * Returns the # of bytes actually copied, which can be less than requested if
+ * the fifo becomes full. If < 0, return is error code.
+ */
+int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
+{
+ int ofs, l;
+
+ if (fifo->data == NULL)
+ return -ENOENT;
+ if (fifo->corrupt)
+ return -ENXIO;
+
+ if (n > fifo->avail)
+ n = fifo->avail;
+ if (n <= 0)
+ return 0;
+
+ ofs = fifo->in % fifo->capacity;
+ l = min(n, fifo->capacity - ofs);
+ memcpy(fifo->data + ofs, src, l);
+ memcpy(fifo->data, src + l, n - l);
+
+ if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) ||
+ fifo->avail < n,
+ "fifo corrupt: in:%u out:%u done:%u n:%d avail:%d",
+ fifo->in, fifo->out, fifo->done, n, fifo->avail))
+ return -ENXIO;
+
+ fifo->in += n;
+ fifo->avail -= n;
+
+ df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out,
+ fifo->done, n, fifo->avail);
+
+ return n;
+}
+
+/**
+ * dma_fifo_out_pend - gets address/len of next avail read and marks as pended
+ * @fifo: address of in-place "struct dma_fifo" to read from
+ * @pended: address of structure to fill with read address/len
+ * The data/len fields will be NULL/0 if no dma is pended.
+ *
+ * Returns the # of used bytes remaining in fifo (ie, if > 0, more data
+ * remains in the fifo that was not pended). If < 0, return is error code.
+ */
+int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
+{
+ unsigned len, n, ofs, l, limit;
+
+ if (fifo->data == NULL)
+ return -ENOENT;
+ if (fifo->corrupt)
+ return -ENXIO;
+
+ pended->len = 0;
+ pended->data = NULL;
+ pended->out = fifo->out;
+
+ len = fifo->in - fifo->out;
+ if (!len)
+ return -ENODATA;
+ if (fifo->open == fifo->open_limit)
+ return -EAGAIN;
+
+ n = len;
+ ofs = fifo->out % fifo->capacity;
+ l = fifo->capacity - ofs;
+ limit = min_t(unsigned, l, fifo->tx_limit);
+ if (n > limit) {
+ n = limit;
+ fifo->out += limit;
+ } else if (ofs + n > fifo->guard) {
+ fifo->out += l;
+ fifo->in = fifo->out;
+ } else {
+ fifo->out += round_up(n, fifo->align);
+ fifo->in = fifo->out;
+ }
+
+ df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in,
+ fifo->out, fifo->done, n, len, fifo->avail);
+
+ pended->len = n;
+ pended->data = fifo->data + ofs;
+ pended->next = fifo->out;
+ list_add_tail(&pended->link, &fifo->pending);
+ ++fifo->open;
+
+ if (FAIL(fifo, fifo->open > fifo->open_limit,
+ "past open limit:%d (limit:%d)",
+ fifo->open, fifo->open_limit))
+ return -ENXIO;
+ if (FAIL(fifo, fifo->out & (fifo->align - 1),
+ "fifo out unaligned:%u (align:%u)",
+ fifo->out, fifo->align))
+ return -ENXIO;
+
+ return len - n;
+}
+
+/**
+ * dma_fifo_out_complete - marks pended dma as completed
+ * @fifo: address of in-place "struct dma_fifo" which was read from
+ * @complete: address of structure for previously pended dma to mark completed
+ */
+int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
+{
+ struct dma_pending *pending, *next, *tmp;
+
+ if (fifo->data == NULL)
+ return -ENOENT;
+ if (fifo->corrupt)
+ return -ENXIO;
+ if (list_empty(&fifo->pending) && fifo->open == 0)
+ return -EINVAL;
+
+ if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0),
+ "pending list disagrees with open count:%d",
+ fifo->open))
+ return -ENXIO;
+
+ tmp = complete->data;
+ *tmp = *complete;
+ list_replace(&complete->link, &tmp->link);
+ dp_mark_completed(tmp);
+
+ /* Only update the fifo in the original pended order */
+ list_for_each_entry_safe(pending, next, &fifo->pending, link) {
+ if (!dp_is_completed(pending)) {
+ df_trace("still pending: saved out: %u len: %d",
+ pending->out, pending->len);
+ break;
+ }
+
+ if (FAIL(fifo, pending->out != fifo->done ||
+ addr_check(fifo->in, fifo->done, pending->next),
+ "in:%u out:%u done:%u saved:%u next:%u",
+ fifo->in, fifo->out, fifo->done, pending->out,
+ pending->next))
+ return -ENXIO;
+
+ list_del_init(&pending->link);
+ fifo->done = pending->next;
+ fifo->avail += pending->len;
+ --fifo->open;
+
+ df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in,
+ fifo->out, fifo->done, pending->len, fifo->avail);
+ }
+
+ if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open))
+ return -ENXIO;
+ if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d",
+ fifo->avail, fifo->size))
+ return -ENXIO;
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff