105 lines
3.2 KiB
C
105 lines
3.2 KiB
C
/*
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* Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of ARM nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <assert.h>
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#include <string.h>
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#include <bakery_lock.h>
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#define assert_bakery_entry_valid(entry, bakery) do { \
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assert(bakery); \
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assert(entry < BAKERY_LOCK_MAX_CPUS); \
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} while(0)
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void bakery_lock_init(bakery_lock * bakery)
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{
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assert(bakery);
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memset(bakery, 0, sizeof(*bakery));
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bakery->owner = NO_OWNER;
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}
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void bakery_lock_get(unsigned long mpidr, bakery_lock * bakery)
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{
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unsigned int i, max = 0, my_full_number, his_full_number, entry;
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entry = platform_get_core_pos(mpidr);
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assert_bakery_entry_valid(entry, bakery);
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// Catch recursive attempts to take the lock under the same entry:
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assert(bakery->owner != entry);
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// Get a ticket
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bakery->entering[entry] = 1;
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for (i = 0; i < BAKERY_LOCK_MAX_CPUS; ++i) {
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if (bakery->number[i] > max) {
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max = bakery->number[i];
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}
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}
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++max;
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bakery->number[entry] = max;
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bakery->entering[entry] = 0;
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// Wait for our turn
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my_full_number = (max << 8) + entry;
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for (i = 0; i < BAKERY_LOCK_MAX_CPUS; ++i) {
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while (bakery->entering[i]) ; /* Wait */
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do {
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his_full_number = bakery->number[i];
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if (his_full_number) {
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his_full_number = (his_full_number << 8) + i;
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}
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}
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while (his_full_number && (his_full_number < my_full_number));
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}
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bakery->owner = entry;
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}
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void bakery_lock_release(unsigned long mpidr, bakery_lock * bakery)
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{
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unsigned int entry = platform_get_core_pos(mpidr);
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assert_bakery_entry_valid(entry, bakery);
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assert(bakery_lock_held(entry, bakery));
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bakery->owner = NO_OWNER;
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bakery->number[entry] = 0;
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}
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int bakery_lock_held(unsigned long mpidr, const bakery_lock * bakery)
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{
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unsigned int entry = platform_get_core_pos(mpidr);
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assert_bakery_entry_valid(entry, bakery);
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return bakery->owner == entry;
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}
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