sh: add J2 atomics using the cas.l instruction

Signed-off-by: Rich Felker <dalias@libc.org>

arch/sh/include/asm/atomic.h

@@ -1,6 +1,12 @@
 #ifndef __ASM_SH_ATOMIC_H
 #define __ASM_SH_ATOMIC_H
 
+#if defined(CONFIG_CPU_J2)
+
+#include <asm-generic/atomic.h>
+
+#else
+
 /*
  * Atomic operations that C can't guarantee us.  Useful for
  * resource counting etc..
@@ -63,4 +69,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 	return c;
 }
 
+#endif /* CONFIG_CPU_J2 */
+
 #endif /* __ASM_SH_ATOMIC_H */

arch/sh/include/asm/barrier.h

@@ -29,6 +29,11 @@
 #define wmb()		mb()
 #define ctrl_barrier()	__icbi(PAGE_OFFSET)
 #else
+#if defined(CONFIG_CPU_J2) && defined(CONFIG_SMP)
+#define __smp_mb()	do { int tmp = 0; __asm__ __volatile__ ("cas.l %0,%0,@%1" : "+r"(tmp) : "z"(&tmp) : "memory", "t"); } while(0)
+#define __smp_rmb()	__smp_mb()
+#define __smp_wmb()	__smp_mb()
+#endif
 #define ctrl_barrier()	__asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop")
 #endif
 

arch/sh/include/asm/bitops-cas.h

@@ -0,0 +1,93 @@
+#ifndef __ASM_SH_BITOPS_CAS_H
+#define __ASM_SH_BITOPS_CAS_H
+
+static inline unsigned __bo_cas(volatile unsigned *p, unsigned old, unsigned new)
+{
+	__asm__ __volatile__("cas.l %1,%0,@r0"
+		: "+r"(new)
+		: "r"(old), "z"(p)
+		: "t", "memory" );
+	return new;
+}
+
+static inline void set_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old|mask) != old);
+}
+
+static inline void clear_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old&~mask) != old);
+}
+
+static inline void change_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old^mask) != old);
+}
+
+static inline int test_and_set_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old|mask) != old);
+
+	return !!(old & mask);
+}
+
+static inline int test_and_clear_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old&~mask) != old);
+
+	return !!(old & mask);
+}
+
+static inline int test_and_change_bit(int nr, volatile void *addr)
+{
+	unsigned mask, old;
+	volatile unsigned *a = addr;
+
+	a += nr >> 5;
+	mask = 1U << (nr & 0x1f);
+
+	do old = *a;
+	while (__bo_cas(a, old, old^mask) != old);
+
+	return !!(old & mask);
+}
+
+#include <asm-generic/bitops/non-atomic.h>
+
+#endif /* __ASM_SH_BITOPS_CAS_H */

arch/sh/include/asm/bitops.h

@@ -18,6 +18,8 @@
 #include <asm/bitops-op32.h>
 #elif defined(CONFIG_CPU_SH4A)
 #include <asm/bitops-llsc.h>
+#elif defined(CONFIG_CPU_J2) && defined(CONFIG_SMP)
+#include <asm/bitops-cas.h>
 #else
 #include <asm-generic/bitops/atomic.h>
 #include <asm-generic/bitops/non-atomic.h>

arch/sh/include/asm/cmpxchg-cas.h

@@ -0,0 +1,24 @@
+#ifndef __ASM_SH_CMPXCHG_CAS_H
+#define __ASM_SH_CMPXCHG_CAS_H
+
+static inline unsigned long
+__cmpxchg_u32(volatile u32 *m, unsigned long old, unsigned long new)
+{
+	__asm__ __volatile__("cas.l %1,%0,@r0"
+		: "+r"(new)
+		: "r"(old), "z"(m)
+		: "t", "memory" );
+	return new;
+}
+
+static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
+{
+	unsigned long old;
+	do old = *m;
+	while (__cmpxchg_u32(m, old, val) != old);
+	return old;
+}
+
+#include <asm/cmpxchg-xchg.h>
+
+#endif /* __ASM_SH_CMPXCHG_CAS_H */

arch/sh/include/asm/cmpxchg.h

@@ -13,6 +13,8 @@
 #include <asm/cmpxchg-grb.h>
 #elif defined(CONFIG_CPU_SH4A)
 #include <asm/cmpxchg-llsc.h>
+#elif defined(CONFIG_CPU_J2) && defined(CONFIG_SMP)
+#include <asm/cmpxchg-cas.h>
 #else
 #include <asm/cmpxchg-irq.h>
 #endif

arch/sh/include/asm/spinlock-cas.h

@@ -0,0 +1,117 @@
+/*
+ * include/asm-sh/spinlock-cas.h
+ *
+ * Copyright (C) 2015 SEI
+ *
+ * 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
+ * for more details.
+ */
+#ifndef __ASM_SH_SPINLOCK_CAS_H
+#define __ASM_SH_SPINLOCK_CAS_H
+
+#include <asm/barrier.h>
+#include <asm/processor.h>
+
+static inline unsigned __sl_cas(volatile unsigned *p, unsigned old, unsigned new)
+{
+	__asm__ __volatile__("cas.l %1,%0,@r0"
+		: "+r"(new)
+		: "r"(old), "z"(p)
+		: "t", "memory" );
+	return new;
+}
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ */
+
+#define arch_spin_is_locked(x)		((x)->lock <= 0)
+#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
+
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+	smp_cond_load_acquire(&lock->lock, VAL > 0);
+}
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+	while (!__sl_cas(&lock->lock, 1, 0));
+}
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+	__sl_cas(&lock->lock, 0, 1);
+}
+
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+	return __sl_cas(&lock->lock, 1, 0);
+}
+
+/*
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ *
+ * NOTE! it is quite common to have readers in interrupts but no interrupt
+ * writers. For those circumstances we can "mix" irq-safe locks - any writer
+ * needs to get a irq-safe write-lock, but readers can get non-irqsafe
+ * read-locks.
+ */
+
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define arch_read_can_lock(x)	((x)->lock > 0)
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define arch_write_can_lock(x)	((x)->lock == RW_LOCK_BIAS)
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+	unsigned old;
+	do old = rw->lock;
+	while (!old || __sl_cas(&rw->lock, old, old-1) != old);
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+	unsigned old;
+	do old = rw->lock;
+	while (__sl_cas(&rw->lock, old, old+1) != old);
+}
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+	while (__sl_cas(&rw->lock, RW_LOCK_BIAS, 0) != RW_LOCK_BIAS);
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+	__sl_cas(&rw->lock, 0, RW_LOCK_BIAS);
+}
+
+static inline int arch_read_trylock(arch_rwlock_t *rw)
+{
+	unsigned old;
+	do old = rw->lock;
+	while (old && __sl_cas(&rw->lock, old, old-1) != old);
+	return !!old;
+}
+
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+	return __sl_cas(&rw->lock, RW_LOCK_BIAS, 0) == RW_LOCK_BIAS;
+}
+
+#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
+#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
+
+#define arch_spin_relax(lock)	cpu_relax()
+#define arch_read_relax(lock)	cpu_relax()
+#define arch_write_relax(lock)	cpu_relax()
+
+#endif /* __ASM_SH_SPINLOCK_CAS_H */