95 lines
2.0 KiB
C
95 lines
2.0 KiB
C
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/*
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* arch/arm/common/fiq_debugger_ringbuf.c
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*
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* simple lockless ringbuffer
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*
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* Copyright (C) 2010 Google, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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struct fiq_debugger_ringbuf {
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int len;
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int head;
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int tail;
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u8 buf[];
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};
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static inline struct fiq_debugger_ringbuf *fiq_debugger_ringbuf_alloc(int len)
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{
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struct fiq_debugger_ringbuf *rbuf;
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rbuf = kzalloc(sizeof(*rbuf) + len, GFP_KERNEL);
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if (rbuf == NULL)
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return NULL;
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rbuf->len = len;
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rbuf->head = 0;
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rbuf->tail = 0;
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smp_mb();
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return rbuf;
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}
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static inline void fiq_debugger_ringbuf_free(struct fiq_debugger_ringbuf *rbuf)
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{
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kfree(rbuf);
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}
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static inline int fiq_debugger_ringbuf_level(struct fiq_debugger_ringbuf *rbuf)
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{
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int level = rbuf->head - rbuf->tail;
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if (level < 0)
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level = rbuf->len + level;
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return level;
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}
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static inline int fiq_debugger_ringbuf_room(struct fiq_debugger_ringbuf *rbuf)
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{
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return rbuf->len - fiq_debugger_ringbuf_level(rbuf) - 1;
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}
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static inline u8
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fiq_debugger_ringbuf_peek(struct fiq_debugger_ringbuf *rbuf, int i)
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{
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return rbuf->buf[(rbuf->tail + i) % rbuf->len];
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}
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static inline int
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fiq_debugger_ringbuf_consume(struct fiq_debugger_ringbuf *rbuf, int count)
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{
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count = min(count, fiq_debugger_ringbuf_level(rbuf));
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rbuf->tail = (rbuf->tail + count) % rbuf->len;
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smp_mb();
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return count;
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}
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static inline int
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fiq_debugger_ringbuf_push(struct fiq_debugger_ringbuf *rbuf, u8 datum)
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{
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if (fiq_debugger_ringbuf_room(rbuf) == 0)
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return 0;
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rbuf->buf[rbuf->head] = datum;
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smp_mb();
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rbuf->head = (rbuf->head + 1) % rbuf->len;
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smp_mb();
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return 1;
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}
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