// SPDX-License-Identifier: GPL-2.0+
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/*
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* DMA-able FIFO implementation
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*
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* Copyright (C) 2012 Peter Hurley <peter@hurleysoftware.com>
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/list.h>
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#include <linux/bug.h>
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#include "dma_fifo.h"
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#ifdef DEBUG_TRACING
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#define df_trace(s, args...) pr_debug(s, ##args)
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#else
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#define df_trace(s, args...)
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#endif
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#define FAIL(fifo, condition, format...) ({ \
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fifo->corrupt = !!(condition); \
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WARN(fifo->corrupt, format); \
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})
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/*
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* private helper fn to determine if check is in open interval (lo,hi)
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*/
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static bool addr_check(unsigned int check, unsigned int lo, unsigned int hi)
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{
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return check - (lo + 1) < (hi - 1) - lo;
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}
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/**
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* dma_fifo_init: initialize the fifo to a valid but inoperative state
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* @fifo: address of in-place "struct dma_fifo" object
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*/
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void dma_fifo_init(struct dma_fifo *fifo)
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{
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memset(fifo, 0, sizeof(*fifo));
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INIT_LIST_HEAD(&fifo->pending);
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}
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/**
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* dma_fifo_alloc - initialize and allocate dma_fifo
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* @fifo: address of in-place "struct dma_fifo" object
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* @size: 'apparent' size, in bytes, of fifo
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* @align: dma alignment to maintain (should be at least cpu cache alignment),
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* must be power of 2
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* @tx_limit: maximum # of bytes transmissible per dma (rounded down to
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* multiple of alignment, but at least align size)
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* @open_limit: maximum # of outstanding dma transactions allowed
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* @gfp_mask: get_free_pages mask, passed to kmalloc()
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*
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* The 'apparent' size will be rounded up to next greater aligned size.
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* Returns 0 if no error, otherwise an error code
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*/
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int dma_fifo_alloc(struct dma_fifo *fifo, int size, unsigned int align,
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int tx_limit, int open_limit, gfp_t gfp_mask)
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{
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int capacity;
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if (!is_power_of_2(align) || size < 0)
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return -EINVAL;
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size = round_up(size, align);
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capacity = size + align * open_limit + align * DMA_FIFO_GUARD;
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fifo->data = kmalloc(capacity, gfp_mask);
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if (!fifo->data)
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return -ENOMEM;
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fifo->in = 0;
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fifo->out = 0;
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fifo->done = 0;
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fifo->size = size;
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fifo->avail = size;
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fifo->align = align;
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fifo->tx_limit = max_t(int, round_down(tx_limit, align), align);
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fifo->open = 0;
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fifo->open_limit = open_limit;
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fifo->guard = size + align * open_limit;
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fifo->capacity = capacity;
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fifo->corrupt = 0;
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return 0;
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}
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/**
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* dma_fifo_free - frees the fifo
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* @fifo: address of in-place "struct dma_fifo" to free
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*
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* Also reinits the fifo to a valid but inoperative state. This
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* allows the fifo to be reused with a different target requiring
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* different fifo parameters.
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*/
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void dma_fifo_free(struct dma_fifo *fifo)
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{
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struct dma_pending *pending, *next;
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if (!fifo->data)
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return;
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list_for_each_entry_safe(pending, next, &fifo->pending, link)
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list_del_init(&pending->link);
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kfree(fifo->data);
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fifo->data = NULL;
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}
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/**
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* dma_fifo_reset - dumps the fifo contents and reinits for reuse
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* @fifo: address of in-place "struct dma_fifo" to reset
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*/
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void dma_fifo_reset(struct dma_fifo *fifo)
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{
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struct dma_pending *pending, *next;
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if (!fifo->data)
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return;
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list_for_each_entry_safe(pending, next, &fifo->pending, link)
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list_del_init(&pending->link);
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fifo->in = 0;
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fifo->out = 0;
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fifo->done = 0;
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fifo->avail = fifo->size;
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fifo->open = 0;
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fifo->corrupt = 0;
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}
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/**
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* dma_fifo_in - copies data into the fifo
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* @fifo: address of in-place "struct dma_fifo" to write to
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* @src: buffer to copy from
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* @n: # of bytes to copy
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*
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* Returns the # of bytes actually copied, which can be less than requested if
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* the fifo becomes full. If < 0, return is error code.
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*/
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int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
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{
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int ofs, l;
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if (!fifo->data)
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return -ENOENT;
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if (fifo->corrupt)
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return -ENXIO;
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if (n > fifo->avail)
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n = fifo->avail;
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if (n <= 0)
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return 0;
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ofs = fifo->in % fifo->capacity;
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l = min(n, fifo->capacity - ofs);
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memcpy(fifo->data + ofs, src, l);
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memcpy(fifo->data, src + l, n - l);
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if (FAIL(fifo, addr_check(fifo->done, fifo->in, fifo->in + n) ||
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fifo->avail < n,
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"fifo corrupt: in:%u out:%u done:%u n:%d avail:%d",
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fifo->in, fifo->out, fifo->done, n, fifo->avail))
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return -ENXIO;
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fifo->in += n;
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fifo->avail -= n;
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df_trace("in:%u out:%u done:%u n:%d avail:%d", fifo->in, fifo->out,
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fifo->done, n, fifo->avail);
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return n;
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}
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/**
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* dma_fifo_out_pend - gets address/len of next avail read and marks as pended
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* @fifo: address of in-place "struct dma_fifo" to read from
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* @pended: address of structure to fill with read address/len
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* The data/len fields will be NULL/0 if no dma is pended.
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*
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* Returns the # of used bytes remaining in fifo (ie, if > 0, more data
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* remains in the fifo that was not pended). If < 0, return is error code.
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*/
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int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
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{
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unsigned int len, n, ofs, l, limit;
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if (!fifo->data)
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return -ENOENT;
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if (fifo->corrupt)
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return -ENXIO;
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pended->len = 0;
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pended->data = NULL;
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pended->out = fifo->out;
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len = fifo->in - fifo->out;
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if (!len)
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return -ENODATA;
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if (fifo->open == fifo->open_limit)
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return -EAGAIN;
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n = len;
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ofs = fifo->out % fifo->capacity;
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l = fifo->capacity - ofs;
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limit = min_t(unsigned int, l, fifo->tx_limit);
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if (n > limit) {
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n = limit;
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fifo->out += limit;
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} else if (ofs + n > fifo->guard) {
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fifo->out += l;
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fifo->in = fifo->out;
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} else {
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fifo->out += round_up(n, fifo->align);
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fifo->in = fifo->out;
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}
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df_trace("in: %u out: %u done: %u n: %d len: %u avail: %d", fifo->in,
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fifo->out, fifo->done, n, len, fifo->avail);
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pended->len = n;
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pended->data = fifo->data + ofs;
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pended->next = fifo->out;
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list_add_tail(&pended->link, &fifo->pending);
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++fifo->open;
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if (FAIL(fifo, fifo->open > fifo->open_limit,
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"past open limit:%d (limit:%d)",
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fifo->open, fifo->open_limit))
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return -ENXIO;
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if (FAIL(fifo, fifo->out & (fifo->align - 1),
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"fifo out unaligned:%u (align:%u)",
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fifo->out, fifo->align))
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return -ENXIO;
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return len - n;
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}
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/**
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* dma_fifo_out_complete - marks pended dma as completed
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* @fifo: address of in-place "struct dma_fifo" which was read from
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* @complete: address of structure for previously pended dma to mark completed
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*/
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int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
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{
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struct dma_pending *pending, *next, *tmp;
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if (!fifo->data)
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return -ENOENT;
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if (fifo->corrupt)
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return -ENXIO;
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if (list_empty(&fifo->pending) && fifo->open == 0)
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return -EINVAL;
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if (FAIL(fifo, list_empty(&fifo->pending) != (fifo->open == 0),
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"pending list disagrees with open count:%d",
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fifo->open))
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return -ENXIO;
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tmp = complete->data;
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*tmp = *complete;
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list_replace(&complete->link, &tmp->link);
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dp_mark_completed(tmp);
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/* Only update the fifo in the original pended order */
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list_for_each_entry_safe(pending, next, &fifo->pending, link) {
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if (!dp_is_completed(pending)) {
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df_trace("still pending: saved out: %u len: %d",
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pending->out, pending->len);
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break;
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}
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if (FAIL(fifo, pending->out != fifo->done ||
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addr_check(fifo->in, fifo->done, pending->next),
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"in:%u out:%u done:%u saved:%u next:%u",
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fifo->in, fifo->out, fifo->done, pending->out,
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pending->next))
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return -ENXIO;
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list_del_init(&pending->link);
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fifo->done = pending->next;
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fifo->avail += pending->len;
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--fifo->open;
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df_trace("in: %u out: %u done: %u len: %u avail: %d", fifo->in,
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fifo->out, fifo->done, pending->len, fifo->avail);
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}
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if (FAIL(fifo, fifo->open < 0, "open dma:%d < 0", fifo->open))
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return -ENXIO;
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if (FAIL(fifo, fifo->avail > fifo->size, "fifo avail:%d > size:%d",
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fifo->avail, fifo->size))
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return -ENXIO;
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return 0;
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}
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