sh: Overhaul spinlocks and rwlocks for SH-4A SMP.
This rips out some of the old spinlock and rwlock behaviour that the SH-2
parts were using and reworks them for LL/SC semantics on the SH-4A.
This is primarily only useful for SH-X3 multi-cores, but can also be used
for building CONFIG_SMP=y testing kernels on SH-4A UP.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/spinlock.h b/include/asm-sh/spinlock.h
index 92f6e20..e793181 100644
--- a/include/asm-sh/spinlock.h
+++ b/include/asm-sh/spinlock.h
@@ -2,6 +2,7 @@
* include/asm-sh/spinlock.h
*
* Copyright (C) 2002, 2003 Paul Mundt
+ * Copyright (C) 2006, 2007 Akio Idehara
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
@@ -10,17 +11,22 @@
#ifndef __ASM_SH_SPINLOCK_H
#define __ASM_SH_SPINLOCK_H
-#include <asm/atomic.h>
-#include <asm/spinlock_types.h>
+/*
+ * The only locking implemented here uses SH-4A opcodes. For others,
+ * split this out as per atomic-*.h.
+ */
+#ifndef CONFIG_CPU_SH4A
+#error "Need movli.l/movco.l for spinlocks"
+#endif
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*/
-#define __raw_spin_is_locked(x) ((x)->lock != 0)
+#define __raw_spin_is_locked(x) ((x)->lock <= 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(x) \
- do { cpu_relax(); } while (__raw_spin_is_locked(x))
+ do { cpu_relax(); } while ((x)->lock)
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
@@ -30,12 +36,19 @@
*/
static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
+ unsigned long tmp;
+ unsigned long oldval;
+
__asm__ __volatile__ (
- "1:\n\t"
- "tas.b @%0\n\t"
- "bf/s 1b\n\t"
- "nop\n\t"
- : "=r" (lock->lock)
+ "1: \n\t"
+ "movli.l @%2, %0 ! __raw_spin_lock \n\t"
+ "mov %0, %1 \n\t"
+ "mov #0, %0 \n\t"
+ "movco.l %0, @%2 \n\t"
+ "bf 1b \n\t"
+ "cmp/pl %1 \n\t"
+ "bf 1b \n\t"
+ : "=&z" (tmp), "=&r" (oldval)
: "r" (&lock->lock)
: "t", "memory"
);
@@ -43,12 +56,36 @@
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
- //assert_spin_locked(lock);
+ unsigned long tmp;
- lock->lock = 0;
+ __asm__ __volatile__ (
+ "mov #1, %0 ! __raw_spin_unlock \n\t"
+ "mov.l %0, @%1 \n\t"
+ : "=&z" (tmp)
+ : "r" (&lock->lock)
+ : "t", "memory"
+ );
}
-#define __raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+ unsigned long tmp, oldval;
+
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%2, %0 ! __raw_spin_trylock \n\t"
+ "mov %0, %1 \n\t"
+ "mov #0, %0 \n\t"
+ "movco.l %0, @%2 \n\t"
+ "bf 1b \n\t"
+ "synco \n\t"
+ : "=&z" (tmp), "=&r" (oldval)
+ : "r" (&lock->lock)
+ : "t", "memory"
+ );
+
+ return oldval;
+}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
@@ -59,58 +96,124 @@
* read-locks.
*/
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define __raw_read_can_lock(x) ((x)->lock > 0)
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
+
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
- __raw_spin_lock(&rw->lock);
+ unsigned long tmp;
- atomic_inc(&rw->counter);
-
- __raw_spin_unlock(&rw->lock);
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%1, %0 ! __raw_read_lock \n\t"
+ "cmp/pl %0 \n\t"
+ "bf 1b \n\t"
+ "add #-1, %0 \n\t"
+ "movco.l %0, @%1 \n\t"
+ "bf 1b \n\t"
+ : "=&z" (tmp)
+ : "r" (&rw->lock)
+ : "t", "memory"
+ );
}
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
- __raw_spin_lock(&rw->lock);
+ unsigned long tmp;
- atomic_dec(&rw->counter);
-
- __raw_spin_unlock(&rw->lock);
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%1, %0 ! __raw_read_unlock \n\t"
+ "add #1, %0 \n\t"
+ "movco.l %0, @%1 \n\t"
+ "bf 1b \n\t"
+ : "=&z" (tmp)
+ : "r" (&rw->lock)
+ : "t", "memory"
+ );
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
- __raw_spin_lock(&rw->lock);
- atomic_set(&rw->counter, -1);
+ unsigned long tmp;
+
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%1, %0 ! __raw_write_lock \n\t"
+ "cmp/hs %2, %0 \n\t"
+ "bf 1b \n\t"
+ "sub %2, %0 \n\t"
+ "movco.l %0, @%1 \n\t"
+ "bf 1b \n\t"
+ : "=&z" (tmp)
+ : "r" (&rw->lock), "r" (RW_LOCK_BIAS)
+ : "t", "memory"
+ );
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
- atomic_set(&rw->counter, 0);
- __raw_spin_unlock(&rw->lock);
+ __asm__ __volatile__ (
+ "mov.l %1, @%0 ! __raw_write_unlock \n\t"
+ :
+ : "r" (&rw->lock), "r" (RW_LOCK_BIAS)
+ : "t", "memory"
+ );
}
-static inline int __raw_write_can_lock(raw_rwlock_t *rw)
+static inline int __raw_read_trylock(raw_rwlock_t *rw)
{
- return (atomic_read(&rw->counter) == RW_LOCK_BIAS);
-}
+ unsigned long tmp, oldval;
-static inline int __raw_read_trylock(raw_rwlock_t *lock)
-{
- atomic_t *count = (atomic_t*)lock;
- if (atomic_dec_return(count) >= 0)
- return 1;
- atomic_inc(count);
- return 0;
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%2, %0 ! __raw_read_trylock \n\t"
+ "mov %0, %1 \n\t"
+ "cmp/pl %0 \n\t"
+ "bf 2f \n\t"
+ "add #-1, %0 \n\t"
+ "movco.l %0, @%2 \n\t"
+ "bf 1b \n\t"
+ "2: \n\t"
+ "synco \n\t"
+ : "=&z" (tmp), "=&r" (oldval)
+ : "r" (&rw->lock)
+ : "t", "memory"
+ );
+
+ return (oldval > 0);
}
static inline int __raw_write_trylock(raw_rwlock_t *rw)
{
- if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
- return 1;
-
- atomic_add(RW_LOCK_BIAS, &rw->counter);
+ unsigned long tmp, oldval;
- return 0;
+ __asm__ __volatile__ (
+ "1: \n\t"
+ "movli.l @%2, %0 ! __raw_write_trylock \n\t"
+ "mov %0, %1 \n\t"
+ "cmp/hs %3, %0 \n\t"
+ "bf 2f \n\t"
+ "sub %3, %0 \n\t"
+ "2: \n\t"
+ "movco.l %0, @%2 \n\t"
+ "bf 1b \n\t"
+ "synco \n\t"
+ : "=&z" (tmp), "=&r" (oldval)
+ : "r" (&rw->lock), "r" (RW_LOCK_BIAS)
+ : "t", "memory"
+ );
+
+ return (oldval > (RW_LOCK_BIAS - 1));
}
#define _raw_spin_relax(lock) cpu_relax()