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- /*
- * 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 transmissible 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;
- }
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