ARC: Atomic/bitops/cmpxchg/barriers

This covers the UP / SMP (with no hardware assist for atomic r-m-w) as
well as ARC700 LLOCK/SCOND insns based.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

1 files changed, 232 insertions, 0 deletions

diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
new file mode 100644
index 000000000000..83f03ca6caf6
--- /dev/null
+++ b/arch/arc/include/asm/atomic.h
@@ -0,0 +1,232 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * 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.
+ */
+
+#ifndef _ASM_ARC_ATOMIC_H
+#define _ASM_ARC_ATOMIC_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <asm/cmpxchg.h>
+#include <asm/barrier.h>
+#include <asm/smp.h>
+
+#define atomic_read(v)  ((v)->counter)
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define atomic_set(v, i) (((v)->counter) = (i))
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+        unsigned int temp;
+
+        __asm__ __volatile__(
+        "1:     llock   %0, [%1]        \n"
+        "       add     %0, %0, %2      \n"
+        "       scond   %0, [%1]        \n"
+        "       bnz     1b              \n"
+        : "=&r"(temp)   /* Early clobber, to prevent reg reuse */
+        : "r"(&v->counter), "ir"(i)
+        : "cc");
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+        unsigned int temp;
+
+        __asm__ __volatile__(
+        "1:     llock   %0, [%1]        \n"
+        "       sub     %0, %0, %2      \n"
+        "       scond   %0, [%1]        \n"
+        "       bnz     1b              \n"
+        : "=&r"(temp)
+        : "r"(&v->counter), "ir"(i)
+        : "cc");
+}
+
+/* add and also return the new value */
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+        unsigned int temp;
+
+        __asm__ __volatile__(
+        "1:     llock   %0, [%1]        \n"
+        "       add     %0, %0, %2      \n"
+        "       scond   %0, [%1]        \n"
+        "       bnz     1b              \n"
+        : "=&r"(temp)
+        : "r"(&v->counter), "ir"(i)
+        : "cc");
+
+        return temp;
+}
+
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+        unsigned int temp;
+
+        __asm__ __volatile__(
+        "1:     llock   %0, [%1]        \n"
+        "       sub     %0, %0, %2      \n"
+        "       scond   %0, [%1]        \n"
+        "       bnz     1b              \n"
+        : "=&r"(temp)
+        : "r"(&v->counter), "ir"(i)
+        : "cc");
+
+        return temp;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+        unsigned int temp;
+
+        __asm__ __volatile__(
+        "1:     llock   %0, [%1]        \n"
+        "       bic     %0, %0, %2      \n"
+        "       scond   %0, [%1]        \n"
+        "       bnz     1b              \n"
+        : "=&r"(temp)
+        : "r"(addr), "ir"(mask)
+        : "cc");
+}
+
+#else   /* !CONFIG_ARC_HAS_LLSC */
+
+#ifndef CONFIG_SMP
+
+ /* violating atomic_xxx API locking protocol in UP for optimization sake */
+#define atomic_set(v, i) (((v)->counter) = (i))
+
+#else
+
+static inline void atomic_set(atomic_t *v, int i)
+{
+        /*
+         * Independent of hardware support, all of the atomic_xxx() APIs need
+         * to follow the same locking rules to make sure that a "hardware"
+         * atomic insn (e.g. LD) doesn't clobber an "emulated" atomic insn
+         * sequence
+         *
+         * Thus atomic_set() despite being 1 insn (and seemingly atomic)
+         * requires the locking.
+         */
+        unsigned long flags;
+
+        atomic_ops_lock(flags);
+        v->counter = i;
+        atomic_ops_unlock(flags);
+}
+#endif
+
+/*
+ * Non hardware assisted Atomic-R-M-W
+ * Locking would change to irq-disabling only (UP) and spinlocks (SMP)
+ */
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+        unsigned long flags;
+
+        atomic_ops_lock(flags);
+        v->counter += i;
+        atomic_ops_unlock(flags);
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+        unsigned long flags;
+
+        atomic_ops_lock(flags);
+        v->counter -= i;
+        atomic_ops_unlock(flags);
+}
+
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+        unsigned long flags;
+        unsigned long temp;
+
+        atomic_ops_lock(flags);
+        temp = v->counter;
+        temp += i;
+        v->counter = temp;
+        atomic_ops_unlock(flags);
+
+        return temp;
+}
+
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+        unsigned long flags;
+        unsigned long temp;
+
+        atomic_ops_lock(flags);
+        temp = v->counter;
+        temp -= i;
+        v->counter = temp;
+        atomic_ops_unlock(flags);
+
+        return temp;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+        unsigned long flags;
+
+        atomic_ops_lock(flags);
+        *addr &= ~mask;
+        atomic_ops_unlock(flags);
+}
+
+#endif /* !CONFIG_ARC_HAS_LLSC */
+
+/**
+ * __atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns the old value of @v
+ */
+#define __atomic_add_unless(v, a, u)                                    \
+({                                                                      \
+        int c, old;                                                     \
+        c = atomic_read(v);                                             \
+        while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
+                c = old;                                                \
+        c;                                                              \
+})
+
+#define atomic_inc_not_zero(v)          atomic_add_unless((v), 1, 0)
+
+#define atomic_inc(v)                   atomic_add(1, v)
+#define atomic_dec(v)                   atomic_sub(1, v)
+
+#define atomic_inc_and_test(v)          (atomic_add_return(1, v) == 0)
+#define atomic_dec_and_test(v)          (atomic_sub_return(1, v) == 0)
+#define atomic_inc_return(v)            atomic_add_return(1, (v))
+#define atomic_dec_return(v)            atomic_sub_return(1, (v))
+#define atomic_sub_and_test(i, v)       (atomic_sub_return(i, v) == 0)
+
+#define atomic_add_negative(i, v)       (atomic_add_return(i, v) < 0)
+
+#define ATOMIC_INIT(i)                  { (i) }
+
+#include <asm-generic/atomic64.h>
+
+#endif
+
+#endif
+
+#endif