[U-Boot] [PATCH 10/20] x86: Add atomic operations

[Bin Meng]

On Tue, Apr 28, 2015 at 6:48 AM, Simon Glass <sjg at chromium.org> wrote:
> Add a subset of this header file from Linux 4.0 to support atomic operations
> in U-Boot.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  arch/x86/include/asm/atomic.h | 115 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 115 insertions(+)
>  create mode 100644 arch/x86/include/asm/atomic.h
>
> diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
> new file mode 100644
> index 0000000..806f787
> --- /dev/null
> +++ b/arch/x86/include/asm/atomic.h
> @@ -0,0 +1,115 @@
> +#ifndef _ASM_X86_ATOMIC_H
> +#define _ASM_X86_ATOMIC_H
> +
> +#include <linux/compiler.h>
> +#include <linux/types.h>
> +#include <asm/processor.h>
> +
> +typedef struct { volatile int counter; } atomic_t;
> +
> +/*
> + * Atomic operations that C can't guarantee us.  Useful for
> + * resource counting etc..
> + */
> +
> +#define ATOMIC_INIT(i) { (i) }
> +
> +/**
> + * atomic_read - read atomic variable
> + * @v: pointer of type atomic_t
> + *
> + * Atomically reads the value of @v.
> + */
> +static inline int atomic_read(const atomic_t *v)
> +{
> +       return ACCESS_ONCE((v)->counter);
> +}
> +
> +/**
> + * atomic_set - set atomic variable
> + * @v: pointer of type atomic_t
> + * @i: required value
> + *
> + * Atomically sets the value of @v to @i.
> + */
> +static inline void atomic_set(atomic_t *v, int i)
> +{
> +       v->counter = i;
> +}
> +
> +/**
> + * atomic_add - add integer to atomic variable
> + * @i: integer value to add
> + * @v: pointer of type atomic_t
> + *
> + * Atomically adds @i to @v.
> + */
> +static inline void atomic_add(int i, atomic_t *v)
> +{
> +       asm volatile(LOCK_PREFIX "addl %1,%0"
> +                    : "+m" (v->counter)
> +                    : "ir" (i));
> +}
> +
> +/**
> + * atomic_sub - subtract integer from atomic variable
> + * @i: integer value to subtract
> + * @v: pointer of type atomic_t
> + *
> + * Atomically subtracts @i from @v.
> + */
> +static inline void atomic_sub(int i, atomic_t *v)
> +{
> +       asm volatile(LOCK_PREFIX "subl %1,%0"
> +                    : "+m" (v->counter)
> +                    : "ir" (i));
> +}
> +
> +/**
> + * atomic_inc - increment atomic variable
> + * @v: pointer of type atomic_t
> + *
> + * Atomically increments @v by 1.
> + */
> +static inline void atomic_inc(atomic_t *v)
> +{
> +       asm volatile(LOCK_PREFIX "incl %0"
> +                    : "+m" (v->counter));
> +}
> +
> +/**
> + * atomic_dec - decrement atomic variable
> + * @v: pointer of type atomic_t
> + *
> + * Atomically decrements @v by 1.
> + */
> +static inline void atomic_dec(atomic_t *v)
> +{
> +       asm volatile(LOCK_PREFIX "decl %0"
> +                    : "+m" (v->counter));
> +}
> +
> +/**
> + * atomic_inc_short - increment of a short integer
> + * @v: pointer to type int
> + *
> + * Atomically adds 1 to @v
> + * Returns the new value of @u
> + */
> +static inline short int atomic_inc_short(short int *v)
> +{
> +       asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
> +       return *v;
> +}
> +
> +/* These are x86-specific, used by some header files */
> +#define atomic_clear_mask(mask, addr)                          \
> +       asm volatile(LOCK_PREFIX "andl %0,%1"                   \
> +                    : : "r" (~(mask)), "m" (*(addr)) : "memory")
> +
> +#define atomic_set_mask(mask, addr)                            \
> +       asm volatile(LOCK_PREFIX "orl %0,%1"                    \
> +                    : : "r" ((unsigned)(mask)), "m" (*(addr))  \
> +                    : "memory")
> +
> +#endif /* _ASM_X86_ATOMIC_H */
> --

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>