1 files changed, 148 insertions, 0 deletions
diff --git a/arch/avr32/kernel/semaphore.c b/arch/avr32/kernel/semaphore.c
new file mode 100644
index 000000000000..1e2705a05016
--- /dev/null
+++ b/arch/avr32/kernel/semaphore.c
@@ -0,0 +1,148 @@
+/*
+ * AVR32 sempahore implementation.
+ *
+ * Copyright (C) 2004-2006 Atmel Corporation
+ *
+ * Based on linux/arch/i386/kernel/semaphore.c
+ *  Copyright (C) 1999 Linus Torvalds
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <asm/semaphore.h>
+#include <asm/atomic.h>
+/*
+ * Semaphores are implemented using a two-way counter:
+ * The "count" variable is decremented for each process
+ * that tries to acquire the semaphore, while the "sleeping"
+ * variable is a count of such acquires.
+ *
+ * Notably, the inline "up()" and "down()" functions can
+ * efficiently test if they need to do any extra work (up
+ * needs to do something only if count was negative before
+ * the increment operation.
+ *
+ * "sleeping" and the contention routine ordering is protected
+ * by the spinlock in the semaphore's waitqueue head.
+ *
+ * Note that these functions are only called when there is
+ * contention on the lock, and as such all this is the
+ * "non-critical" part of the whole semaphore business. The
+ * critical part is the inline stuff in <asm/semaphore.h>
+ * where we want to avoid any extra jumps and calls.
+ */
+/*
+ * Logic:
+ *  - only on a boundary condition do we need to care. When we go
+ *    from a negative count to a non-negative, we wake people up.
+ *  - when we go from a non-negative count to a negative do we
+ *    (a) synchronize with the "sleeper" count and (b) make sure
+ *    that we're on the wakeup list before we synchronize so that
+ *    we cannot lose wakeup events.
+ */
+void __up(struct semaphore *sem)
+{
+        wake_up(&sem->wait);
+}
+EXPORT_SYMBOL(__up);
+void __sched __down(struct semaphore *sem)
+{
+        struct task_struct *tsk = current;
+        DECLARE_WAITQUEUE(wait, tsk);
+        unsigned long flags;
+        tsk->state = TASK_UNINTERRUPTIBLE;
+        spin_lock_irqsave(&sem->wait.lock, flags);
+        add_wait_queue_exclusive_locked(&sem->wait, &wait);
+        sem->sleepers++;
+        for (;;) {
+                int sleepers = sem->sleepers;
+                /*
+                 * Add "everybody else" into it. They aren't
+                 * playing, because we own the spinlock in
+                 * the wait_queue_head.
+                 */
+                if (atomic_add_return(sleepers - 1, &sem->count) >= 0) {
+                        sem->sleepers = 0;
+                        break;
+                }
+                sem->sleepers = 1;      /* us - see -1 above */
+                spin_unlock_irqrestore(&sem->wait.lock, flags);
+                schedule();
+                spin_lock_irqsave(&sem->wait.lock, flags);
+                tsk->state = TASK_UNINTERRUPTIBLE;
+        }
+        remove_wait_queue_locked(&sem->wait, &wait);
+        wake_up_locked(&sem->wait);
+        spin_unlock_irqrestore(&sem->wait.lock, flags);
+        tsk->state = TASK_RUNNING;
+}
+EXPORT_SYMBOL(__down);
+int __sched __down_interruptible(struct semaphore *sem)
+{
+        int retval = 0;
+        struct task_struct *tsk = current;
+        DECLARE_WAITQUEUE(wait, tsk);
+        unsigned long flags;
+        tsk->state = TASK_INTERRUPTIBLE;
+        spin_lock_irqsave(&sem->wait.lock, flags);
+        add_wait_queue_exclusive_locked(&sem->wait, &wait);
+        sem->sleepers++;
+        for (;;) {
+                int sleepers = sem->sleepers;
+                /*
+                 * With signals pending, this turns into the trylock
+                 * failure case - we won't be sleeping, and we can't
+                 * get the lock as it has contention. Just correct the
+                 * count and exit.
+                 */
+                if (signal_pending(current)) {
+                        retval = -EINTR;
+                        sem->sleepers = 0;
+                        atomic_add(sleepers, &sem->count);
+                        break;
+                }
+                /*
+                 * Add "everybody else" into it. They aren't
+                 * playing, because we own the spinlock in
+                 * the wait_queue_head.
+                 */
+                if (atomic_add_return(sleepers - 1, &sem->count) >= 0) {
+                        sem->sleepers = 0;
+                        break;
+                }
+                sem->sleepers = 1;      /* us - see -1 above */
+                spin_unlock_irqrestore(&sem->wait.lock, flags);
+                schedule();
+                spin_lock_irqsave(&sem->wait.lock, flags);
+                tsk->state = TASK_INTERRUPTIBLE;
+        }
+        remove_wait_queue_locked(&sem->wait, &wait);
+        wake_up_locked(&sem->wait);
+        spin_unlock_irqrestore(&sem->wait.lock, flags);
+        tsk->state = TASK_RUNNING;
+        return retval;
+}
+EXPORT_SYMBOL(__down_interruptible);

diff --git a/arch/avr32/kernel/semaphore.c b/arch/avr32/kernel/semaphore.c new file mode 100644 index 000000000000..1e2705a05016 --- /dev/null +++ b/arch/avr32/kernel/semaphore.c
@@ -0,0 +1,148 @@
	1	/*
	2	* AVR32 sempahore implementation.
	3	*
	4	* Copyright (C) 2004-2006 Atmel Corporation
	5	*
	6	* Based on linux/arch/i386/kernel/semaphore.c
	7	* Copyright (C) 1999 Linus Torvalds
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*/
	13
	14	#include <linux/sched.h>
	15	#include <linux/errno.h>
	16	#include <linux/module.h>
	17
	18	#include <asm/semaphore.h>
	19	#include <asm/atomic.h>
	20
	21	/*
	22	* Semaphores are implemented using a two-way counter:
	23	* The "count" variable is decremented for each process
	24	* that tries to acquire the semaphore, while the "sleeping"
	25	* variable is a count of such acquires.
	26	*
	27	* Notably, the inline "up()" and "down()" functions can
	28	* efficiently test if they need to do any extra work (up
	29	* needs to do something only if count was negative before
	30	* the increment operation.
	31	*
	32	* "sleeping" and the contention routine ordering is protected
	33	* by the spinlock in the semaphore's waitqueue head.
	34	*
	35	* Note that these functions are only called when there is
	36	* contention on the lock, and as such all this is the
	37	* "non-critical" part of the whole semaphore business. The
	38	* critical part is the inline stuff in <asm/semaphore.h>
	39	* where we want to avoid any extra jumps and calls.
	40	*/
	41
	42	/*
	43	* Logic:
	44	* - only on a boundary condition do we need to care. When we go
	45	* from a negative count to a non-negative, we wake people up.
	46	* - when we go from a non-negative count to a negative do we
	47	* (a) synchronize with the "sleeper" count and (b) make sure
	48	* that we're on the wakeup list before we synchronize so that
	49	* we cannot lose wakeup events.
	50	*/
	51
	52	void __up(struct semaphore *sem)
	53	{
	54	wake_up(&sem->wait);
	55	}
	56	EXPORT_SYMBOL(__up);
	57
	58	void __sched __down(struct semaphore *sem)
	59	{
	60	struct task_struct *tsk = current;
	61	DECLARE_WAITQUEUE(wait, tsk);
	62	unsigned long flags;
	63
	64	tsk->state = TASK_UNINTERRUPTIBLE;
	65	spin_lock_irqsave(&sem->wait.lock, flags);
	66	add_wait_queue_exclusive_locked(&sem->wait, &wait);
	67
	68	sem->sleepers++;
	69	for (;;) {
	70	int sleepers = sem->sleepers;
	71
	72	/*
	73	* Add "everybody else" into it. They aren't
	74	* playing, because we own the spinlock in
	75	* the wait_queue_head.
	76	*/
	77	if (atomic_add_return(sleepers - 1, &sem->count) >= 0) {
	78	sem->sleepers = 0;
	79	break;
	80	}
	81	sem->sleepers = 1; /* us - see -1 above */
	82	spin_unlock_irqrestore(&sem->wait.lock, flags);
	83
	84	schedule();
	85
	86	spin_lock_irqsave(&sem->wait.lock, flags);
	87	tsk->state = TASK_UNINTERRUPTIBLE;
	88	}
	89	remove_wait_queue_locked(&sem->wait, &wait);
	90	wake_up_locked(&sem->wait);
	91	spin_unlock_irqrestore(&sem->wait.lock, flags);
	92	tsk->state = TASK_RUNNING;
	93	}
	94	EXPORT_SYMBOL(__down);
	95
	96	int __sched __down_interruptible(struct semaphore *sem)
	97	{
	98	int retval = 0;
	99	struct task_struct *tsk = current;
	100	DECLARE_WAITQUEUE(wait, tsk);
	101	unsigned long flags;
	102
	103	tsk->state = TASK_INTERRUPTIBLE;
	104	spin_lock_irqsave(&sem->wait.lock, flags);
	105	add_wait_queue_exclusive_locked(&sem->wait, &wait);
	106
	107	sem->sleepers++;
	108	for (;;) {
	109	int sleepers = sem->sleepers;
	110
	111	/*
	112	* With signals pending, this turns into the trylock
	113	* failure case - we won't be sleeping, and we can't
	114	* get the lock as it has contention. Just correct the
	115	* count and exit.
	116	*/
	117	if (signal_pending(current)) {
	118	retval = -EINTR;
	119	sem->sleepers = 0;
	120	atomic_add(sleepers, &sem->count);
	121	break;
	122	}
	123
	124	/*
	125	* Add "everybody else" into it. They aren't
	126	* playing, because we own the spinlock in
	127	* the wait_queue_head.
	128	*/
	129	if (atomic_add_return(sleepers - 1, &sem->count) >= 0) {
	130	sem->sleepers = 0;
	131	break;
	132	}
	133	sem->sleepers = 1; /* us - see -1 above */
	134	spin_unlock_irqrestore(&sem->wait.lock, flags);
	135
	136	schedule();
	137
	138	spin_lock_irqsave(&sem->wait.lock, flags);
	139	tsk->state = TASK_INTERRUPTIBLE;
	140	}
	141	remove_wait_queue_locked(&sem->wait, &wait);
	142	wake_up_locked(&sem->wait);
	143	spin_unlock_irqrestore(&sem->wait.lock, flags);
	144
	145	tsk->state = TASK_RUNNING;
	146	return retval;
	147	}
	148	EXPORT_SYMBOL(__down_interruptible);