1 files changed, 96 insertions, 0 deletions
diff --git a/acsr/c_helpers.c b/acsr/c_helpers.c
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+/*
+  Copyright (c) 2009-11, ARM Limited. All rights reserved.
+  
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+   * Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+   * Neither the name of ARM nor the names of its contributors may be used to
+     endorse or promote products derived from this software without specific
+     prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+   POSSIBILITY OF SUCH DAMAGE.
+*/
+ 
+ 
+/**
+ * Lamport's Bakery algorithm for spinlock handling
+ *
+ * Note that the algorithm requires the stack and the bakery struct
+ * to be in Strongly-Ordered memory.
+ */
+
+#include "appf_types.h"
+#include "appf_internals.h"
+#include "appf_helpers.h"
+
+/**
+ * Initialize a bakery - only required if the bakery_t is
+ * on the stack or heap, as static data is zeroed anyway.
+ */
+void initialize_spinlock(bakery_t *bakery)
+{
+    appf_memset(bakery, 0, sizeof(bakery_t));
+}
+
+/**
+ * Claim a bakery lock. Function does not return until
+ * lock has been obtained.
+ */
+void get_spinlock(unsigned cpuid, bakery_t *bakery)
+{
+    unsigned i, max=0, my_full_number, his_full_number;
+
+    /* Get a ticket */
+    bakery->entering[cpuid] = TRUE;
+    for (i=0; i<MAX_CPUS; ++i)
+    {
+        if (bakery->number[i] > max)
+        {
+            max = bakery->number[i];
+        }
+    }
+    ++max;
+    bakery->number[cpuid] = max;
+    bakery->entering[cpuid] = FALSE;
+
+    /* Wait for our turn */
+    my_full_number = (max << 8) + cpuid;
+    for (i=0; i<MAX_CPUS; ++i)
+    {
+        while(bakery->entering[i]);  /* Wait */
+        do
+        {
+            his_full_number = bakery->number[i];
+            if (his_full_number)
+            {
+                his_full_number = (his_full_number << 8) + i;
+            }
+        }
+        while(his_full_number && (his_full_number < my_full_number));
+    }
+    dmb();
+}
+
+/**
+ * Release a bakery lock.
+ */
+void release_spinlock(unsigned cpuid, bakery_t *bakery)
+{
+    dmb();
+    bakery->number[cpuid] = 0;
+}