Subversion Repositories c0or1k

/*

 * Copyright (C) 2009 B Labs Ltd.

 */

#include <l4/macros.h>

#include <l4/lib/printk.h>

#include <l4/lib/mutex.h>

#include INC_SUBARCH(mmu_ops.h)

#define MUTEX_UNLOCKED  0

#define MUTEX_LOCKED    1

/* Notes on ldrex/strex:

 * ldrex rD, [rN, #imm] : loads rD with contents of at address (rN + imm)

 * strex rD, rS, [rN, #imm]: pushes contents of rS to memory location (rN + imm)

 *              rD is 0 if operation is successful, 1 otherwise

 */

void __spin_lock(unsigned int *s)

{

        unsigned int tmp;

        __asm__ __volatile__ (

                "1:\n"

                "ldrex    %0, [%2]\n"

                "teq      %0, #0\n"

                "strexeq  %0, %1, [%2]\n"

                "teq      %0, #0\n"

#ifdef CONFIG_SMP

                "wfene\n"

#endif

                "bne      1b\n"

                : "=&r" (tmp)

                : "r"(1), "r"(s)

                : "cc", "memory"

        );

        dsb();

}

void __spin_unlock(unsigned int *s)

{

        __asm__ __volatile__ (

                "str    %0, [%1]\n"

                :

                : "r"(0), "r"(s)

                : "memory"

        );

#ifdef CONFIG_SMP

        dsb();

        __asm__ __volatile__ ("sev\n");

#endif

}

/*

 * Current implementation uses __mutex_(un)lock within a protected

 * spinlock, needs to be revisited in the future

 */

unsigned int __mutex_lock(unsigned int *m)

{

        unsigned int tmp, res;

        __asm__ __volatile__ (

                "1:\n"

                "ldrex  %0, [%3]\n"

                "tst    %0, #0\n"

                "strexeq %1, %2, [%3]\n"

                "tsteq  %1, #0\n"

                "bne 1b\n"

                : "=&r" (tmp), "=&r"(res)

                : "r"(1), "r"(m)

                : "cc", "memory"

        );

        if ((tmp | res) != 0)

                return 0;

        return 1;

}

void __mutex_unlock(unsigned int *m)

{

        __asm__ __volatile__ (

                "str  %0, [%1] \n"

                :

                : "r"(0), "r"(m)

                : "memory"

                );

}