1 files changed, 251 insertions, 0 deletions
diff --git a/arch/sparc64/kernel/semaphore.c b/arch/sparc64/kernel/semaphore.c
new file mode 100644
index 000000000000..63496c43fe17
--- /dev/null
+++ b/arch/sparc64/kernel/semaphore.c
@@ -0,0 +1,251 @@
+/* $Id: semaphore.c,v 1.9 2001/11/18 00:12:56 davem Exp $
+ * semaphore.c: Sparc64 semaphore implementation.
+ *
+ * This is basically the PPC semaphore scheme ported to use
+ * the sparc64 atomic instructions, so see the PPC code for
+ * credits.
+ */
+
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+
+/*
+ * Atomically update sem->count.
+ * This does the equivalent of the following:
+ *
+ *	old_count = sem->count;
+ *	tmp = MAX(old_count, 0) + incr;
+ *	sem->count = tmp;
+ *	return old_count;
+ */
+static __inline__ int __sem_update_count(struct semaphore *sem, int incr)
+{
+	int old_count, tmp;
+
+	__asm__ __volatile__("\n"
+"	! __sem_update_count old_count(%0) tmp(%1) incr(%4) &sem->count(%3)\n"
+"1:	ldsw	[%3], %0\n"
+"	mov	%0, %1\n"
+"	cmp	%0, 0\n"
+"	movl	%%icc, 0, %1\n"
+"	add	%1, %4, %1\n"
+"	cas	[%3], %0, %1\n"
+"	cmp	%0, %1\n"
+"	bne,pn	%%icc, 1b\n"
+"	 membar #StoreLoad | #StoreStore\n"
+	: "=&r" (old_count), "=&r" (tmp), "=m" (sem->count)
+	: "r" (&sem->count), "r" (incr), "m" (sem->count)
+	: "cc");
+
+	return old_count;
+}
+
+static void __up(struct semaphore *sem)
+{
+	__sem_update_count(sem, 1);
+	wake_up(&sem->wait);
+}
+
+void up(struct semaphore *sem)
+{
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count + 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 0)
+	 *		__up(sem);
+	 *
+	 * The (old_val < 0) test is equivalent to
+	 * the more straightforward (new_val <= 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! up sem(%0)\n"
+"	membar	#StoreLoad | #LoadLoad\n"
+"1:	lduw	[%0], %%g1\n"
+"	add	%%g1, 1, %%g7\n"
+"	cas	[%0], %%g1, %%g7\n"
+"	cmp	%%g1, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 addcc	%%g7, 1, %%g0\n"
+"	ble,pn	%%icc, 3f\n"
+"	 membar	#StoreLoad | #StoreStore\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%0, %%g1\n"
+"	save	%%sp, -160, %%sp\n"
+"	call	%1\n"
+"	 mov	%%g1, %%o0\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore\n"
+"	.previous\n"
+	: : "r" (sem), "i" (__up)
+	: "g1", "g2", "g3", "g7", "memory", "cc");
+}
+
+static void __sched __down(struct semaphore * sem)
+{
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+
+	tsk->state = TASK_UNINTERRUPTIBLE;
+	add_wait_queue_exclusive(&sem->wait, &wait);
+
+	while (__sem_update_count(sem, -1) <= 0) {
+		schedule();
+		tsk->state = TASK_UNINTERRUPTIBLE;
+	}
+	remove_wait_queue(&sem->wait, &wait);
+	tsk->state = TASK_RUNNING;
+
+	wake_up(&sem->wait);
+}
+
+void __sched down(struct semaphore *sem)
+{
+	might_sleep();
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 1)
+	 *		__down(sem);
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down sem(%0)\n"
+"1:	lduw	[%0], %%g1\n"
+"	sub	%%g1, 1, %%g7\n"
+"	cas	[%0], %%g1, %%g7\n"
+"	cmp	%%g1, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 cmp	%%g7, 1\n"
+"	bl,pn	%%icc, 3f\n"
+"	 membar	#StoreLoad | #StoreStore\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%0, %%g1\n"
+"	save	%%sp, -160, %%sp\n"
+"	call	%1\n"
+"	 mov	%%g1, %%o0\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore\n"
+"	.previous\n"
+	: : "r" (sem), "i" (__down)
+	: "g1", "g2", "g3", "g7", "memory", "cc");
+}
+
+int down_trylock(struct semaphore *sem)
+{
+	int ret;
+
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	if (old_val < 1) {
+	 *		ret = 1;
+	 *	} else {
+	 *		sem->count = new_val;
+	 *		ret = 0;
+	 *	}
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down_trylock sem(%1) ret(%0)\n"
+"1:	lduw	[%1], %%g1\n"
+"	sub	%%g1, 1, %%g7\n"
+"	cmp	%%g1, 1\n"
+"	bl,pn	%%icc, 2f\n"
+"	 mov	1, %0\n"
+"	cas	[%1], %%g1, %%g7\n"
+"	cmp	%%g1, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 mov	0, %0\n"
+"	membar	#StoreLoad | #StoreStore\n"
+"2:\n"
+	: "=&r" (ret)
+	: "r" (sem)
+	: "g1", "g7", "memory", "cc");
+
+	return ret;
+}
+
+static int __sched __down_interruptible(struct semaphore * sem)
+{
+	int retval = 0;
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+
+	tsk->state = TASK_INTERRUPTIBLE;
+	add_wait_queue_exclusive(&sem->wait, &wait);
+
+	while (__sem_update_count(sem, -1) <= 0) {
+		if (signal_pending(current)) {
+			__sem_update_count(sem, 0);
+			retval = -EINTR;
+			break;
+		}
+		schedule();
+		tsk->state = TASK_INTERRUPTIBLE;
+	}
+	tsk->state = TASK_RUNNING;
+	remove_wait_queue(&sem->wait, &wait);
+	wake_up(&sem->wait);
+	return retval;
+}
+
+int __sched down_interruptible(struct semaphore *sem)
+{
+	int ret = 0;
+	
+	might_sleep();
+	/* This atomically does:
+	 * 	old_val = sem->count;
+	 *	new_val = sem->count - 1;
+	 *	sem->count = new_val;
+	 *	if (old_val < 1)
+	 *		ret = __down_interruptible(sem);
+	 *
+	 * The (old_val < 1) test is equivalent to
+	 * the more straightforward (new_val < 0),
+	 * but it is easier to test the former because
+	 * of how the CAS instruction works.
+	 */
+
+	__asm__ __volatile__("\n"
+"	! down_interruptible sem(%2) ret(%0)\n"
+"1:	lduw	[%2], %%g1\n"
+"	sub	%%g1, 1, %%g7\n"
+"	cas	[%2], %%g1, %%g7\n"
+"	cmp	%%g1, %%g7\n"
+"	bne,pn	%%icc, 1b\n"
+"	 cmp	%%g7, 1\n"
+"	bl,pn	%%icc, 3f\n"
+"	 membar	#StoreLoad | #StoreStore\n"
+"2:\n"
+"	.subsection 2\n"
+"3:	mov	%2, %%g1\n"
+"	save	%%sp, -160, %%sp\n"
+"	call	%3\n"
+"	 mov	%%g1, %%o0\n"
+"	ba,pt	%%xcc, 2b\n"
+"	 restore\n"
+"	.previous\n"
+	: "=r" (ret)
+	: "0" (ret), "r" (sem), "i" (__down_interruptible)
+	: "g1", "g2", "g3", "g7", "memory", "cc");
+	return ret;
+}