patch-1.3.4 linux/include/asm-sparc/smpprim.h

• Lines: 54
• Date: Thu Jun 8 23:47:23 1995
• Orig file: v1.3.3/linux/include/asm-sparc/smpprim.h
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.3/linux/include/asm-sparc/smpprim.h linux/include/asm-sparc/smpprim.h
@@ -0,0 +1,53 @@
+/*  smpprim.h:  SMP locking primitives on the Sparc
+ *
+ *  God knows we won't be actually using this code for some time
+ *  but I thought I'd write it since I knew how.
+ *
+ *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#ifndef __SPARC_SMPPRIM_H
+#define __SPARC_SMPPRIM_H
+
+/* Test and set the unsigned byte at ADDR to 1.  Returns the previous
+ * value.  On the Sparc we use the ldstub instruction since it is
+ * atomic.
+ */
+
+extern inline volatile char test_and_set(void *addr)
+{
+	char state = 0;
+
+	__asm__ __volatile__("ldstub [%0], %1         ! test_and_set\n\t"
+			     "=r" (addr), "=r" (state) :
+			     "0" (addr), "1" (state) : "memory");
+
+	return state;
+}
+
+/* Initialize a spin-lock. */
+extern inline volatile smp_initlock(void *spinlock)
+{
+	/* Unset the lock. */
+	*((unsigned char *) spinlock) = 0;
+
+	return;
+}
+
+/* This routine spins until it acquires the lock at ADDR. */
+extern inline volatile smp_lock(void *addr)
+{
+	while(test_and_set(addr) == 0xff)
+		;
+
+	/* We now have the lock */
+	return;
+}
+
+/* This routine releases the lock at ADDR. */
+extern inline volatile smp_unlock(void *addr)
+{
+	*((unsigned char *) addr) = 0;
+}
+
+#endif /* !(__SPARC_SMPPRIM_H) */