1 files changed, 296 insertions, 0 deletions
diff --git a/target/linux/ubicom32/files/arch/ubicom32/include/asm/spinlock.h b/target/linux/ubicom32/files/arch/ubicom32/include/asm/spinlock.h
new file mode 100644
index 000000000..40080584c
--- /dev/null
+++ b/target/linux/ubicom32/files/arch/ubicom32/include/asm/spinlock.h
@@ -0,0 +1,296 @@
+/*
+ * arch/ubicom32/include/asm/spinlock.h
+ *   Spinlock related definitions for Ubicom32 architecture.
+ *
+ * (C) Copyright 2009, Ubicom, Inc.
+ *
+ * This file is part of the Ubicom32 Linux Kernel Port.
+ *
+ * The Ubicom32 Linux Kernel Port is free software: you can redistribute
+ * it and/or modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * The Ubicom32 Linux Kernel Port is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with the Ubicom32 Linux Kernel Port.  If not,
+ * see <http://www.gnu.org/licenses/>.
+ *
+ * Ubicom32 implementation derived from (with many thanks):
+ *   arch/m68knommu
+ *   arch/blackfin
+ *   arch/parisc
+ */
+#ifndef _ASM_UBICOM32_SPINLOCK_H
+#define _ASM_UBICOM32_SPINLOCK_H
+
+#include <asm/system.h>
+#include <asm/processor.h>
+#include <asm/spinlock_types.h>
+
+/*
+ * __raw_spin_lock()
+ *	Lock the lock.
+ */
+static inline void __raw_spin_lock(raw_spinlock_t *x)
+{
+	asm volatile (
+	"1:	bset	%0, %0, #0	\n\t"
+	"	jmpne.f	1b		\n\t"
+		: "+U4" (x->lock)
+		:
+		: "memory", "cc"
+	);
+}
+
+/*
+ * __raw_spin_unlock()
+ *	Unlock the lock.
+ */
+static inline void __raw_spin_unlock(raw_spinlock_t *x)
+{
+	asm volatile (
+	"	bclr	%0, %0, #0	\n\t"
+		: "+U4" (x->lock)
+		:
+		: "memory", "cc"
+	);
+}
+
+/*
+ * __raw_spin_is_locked()
+ *	Test if the lock is locked.
+ */
+static inline int __raw_spin_is_locked(raw_spinlock_t *x)
+{
+	return x->lock;
+}
+
+/*
+ * __raw_spin_unlock_wait()
+ *	Wait for the lock to be unlocked.
+ *
+ * Note: the caller has not guarantee that the lock will not
+ * be acquired before they get to it.
+ */
+static inline void __raw_spin_unlock_wait(raw_spinlock_t *x)
+{
+	do {
+		cpu_relax();
+	} while (__raw_spin_is_locked(x));
+}
+
+/*
+ * __raw_spin_trylock()
+ *	Try the lock, return 0 on failure, 1 on success.
+ */
+static inline int __raw_spin_trylock(raw_spinlock_t *x)
+{
+	int ret = 0;
+
+	asm volatile (
+	"	bset	%1, %1, #0	\n\t"
+	"	jmpne.f	1f		\n\t"
+	"	move.4	%0, #1		\n\t"
+	"1:				\n\t"
+		: "+r" (ret), "+U4" (x->lock)
+		:
+		: "memory", "cc"
+	);
+
+	return ret;
+}
+
+/*
+ * __raw_spin_lock_flags()
+ *	Spin waiting for the lock (enabling IRQ(s))
+ */
+static inline void __raw_spin_lock_flags(raw_spinlock_t *x, unsigned long flags)
+{
+	mb();
+	while (!__raw_spin_trylock(x)) {
+		/*
+		 * If the flags from the IRQ are set, interrupts are disabled and we
+		 * need to re-enable them.
+		 */
+		if (!flags) {
+			cpu_relax();
+		} else {
+			raw_local_irq_enable();
+			cpu_relax();
+			raw_local_irq_disable();
+		}
+	}
+	mb();
+}
+
+/*
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ * Linux rwlocks are unfair to writers; they can be starved for an indefinite
+ * time by readers.  With care, they can also be taken in interrupt context.
+ *
+ * In Ubicom32 architecture implementation, we have a spinlock and a counter.
+ * Readers use the lock to serialise their access to the counter (which
+ * records how many readers currently hold the lock).
+ * Writers hold the spinlock, preventing any readers or other writers from
+ * grabbing the rwlock.
+ */
+
+/*
+ * __raw_read_lock()
+ *	Increment the counter in the rwlock.
+ *
+ * Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock
+ */
+static inline void __raw_read_lock(raw_rwlock_t *rw)
+{
+	unsigned long flags;
+	raw_local_irq_save(flags);
+	__raw_spin_lock_flags(&rw->lock, flags);
+	rw->counter++;
+	__raw_spin_unlock(&rw->lock);
+	raw_local_irq_restore(flags);
+}
+
+/*
+ * __raw_read_unlock()
+ *	Decrement the counter.
+ *
+ * Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock
+ */
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
+{
+	unsigned long flags;
+	raw_local_irq_save(flags);
+	__raw_spin_lock_flags(&rw->lock, flags);
+	rw->counter--;
+	__raw_spin_unlock(&rw->lock);
+	raw_local_irq_restore(flags);
+}
+
+/*
+ * __raw_read_trylock()
+ *	Increment the counter if we can.
+ *
+ * Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock
+ */
+static inline int __raw_read_trylock(raw_rwlock_t *rw)
+{
+	unsigned long flags;
+ retry:
+	raw_local_irq_save(flags);
+	if (__raw_spin_trylock(&rw->lock)) {
+		rw->counter++;
+		__raw_spin_unlock(&rw->lock);
+		raw_local_irq_restore(flags);
+		return 1;
+	}
+
+	raw_local_irq_restore(flags);
+
+	/*
+	 * If write-locked, we fail to acquire the lock
+	 */
+	if (rw->counter < 0) {
+		return 0;
+	}
+
+	/*
+	 * Wait until we have a realistic chance at the lock
+	 */
+	while (__raw_spin_is_locked(&rw->lock) && rw->counter >= 0) {
+		cpu_relax();
+	}
+
+	goto retry;
+}
+
+/*
+ * __raw_write_lock()
+ *
+ * Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to read_trylock() this lock
+ */
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+	unsigned long flags;
+retry:
+	raw_local_irq_save(flags);
+	__raw_spin_lock_flags(&rw->lock, flags);
+
+	if (rw->counter != 0) {
+		__raw_spin_unlock(&rw->lock);
+		raw_local_irq_restore(flags);
+
+		while (rw->counter != 0)
+			cpu_relax();
+
+		goto retry;
+	}
+
+	rw->counter = -1; /* mark as write-locked */
+	mb();
+	raw_local_irq_restore(flags);
+}
+
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
+{
+	rw->counter = 0;
+	__raw_spin_unlock(&rw->lock);
+}
+
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to read_trylock() this lock */
+static inline int __raw_write_trylock(raw_rwlock_t *rw)
+{
+	unsigned long flags;
+	int result = 0;
+
+	raw_local_irq_save(flags);
+	if (__raw_spin_trylock(&rw->lock)) {
+		if (rw->counter == 0) {
+			rw->counter = -1;
+			result = 1;
+		} else {
+			/* Read-locked.  Oh well. */
+			__raw_spin_unlock(&rw->lock);
+		}
+	}
+	raw_local_irq_restore(flags);
+
+	return result;
+}
+
+/*
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int __raw_read_can_lock(raw_rwlock_t *rw)
+{
+	return rw->counter >= 0;
+}
+
+/*
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int __raw_write_can_lock(raw_rwlock_t *rw)
+{
+	return !rw->counter;
+}
+
+#define __raw_read_lock_flags(lock, flags) __raw_read_lock(lock)
+#define __raw_write_lock_flags(lock, flags) __raw_write_lock(lock)
+
+#define _raw_spin_relax(lock)	cpu_relax()
+#define _raw_read_relax(lock)	cpu_relax()
+#define _raw_write_relax(lock)	cpu_relax()
+
+#endif /* _ASM_UBICOM32_SPINLOCK_H */