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/*

 *  Description:

 *      HPPA fast spinlock semaphores based on LDCWX instruction.

 *      These semaphores are not known to RTEMS.

 *

 *  TODO:

 *      Put node number in high 16 bits of flag??

 *      XXX: Need h_s_deallocate

 *

 *  COPYRIGHT (c) 1994 by Division Incorporated

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: semaphore.c,v 1.1.1.1 2001-07-10 09:55:40 chris Exp $

 */

#include <rtems.h>

#include <hppa1.1/semaphore.h>

/*

 * Report fatal semaphore error

 */

#define SEM_FATAL_ERROR(sp)  rtems_fatal_error_occurred((rtems_unsigned32) sp)

#define SEM_CHECK(sp)   do { \

                              if (((sp) == 0) || (int) (sp) & 0xf) \

                              { \

                                  SEM_FATAL_ERROR(sp); \

                              } \

                         } while (0)

/*

 * Init a semaphore to be free

 */

#define SEM_FREE_INIT(sp) \

    do { \

        (sp)->lock = 1; \

        (sp)->flags = 0; \

        (sp)->owner_tcb  = 0; \

    } while (0)

/*

 * Grab a semaphore recording its owner.

 */

#define SEM_MARK_GRABBED(sp) \

    do { \

        (sp)->owner_tcb  = _Thread_Executing; \

    } while (0)

/*

 * Mark the semaphore busy

 */

#define SEM_MARK_BUSY(sp)    ((sp)->flags |= HPPA_SEM_IN_USE)

/*

 * Is a semaphore available?

 */

#define SEM_IS_AVAILABLE(sp)  ((sp)->owner_tcb == 0)

/*

 * The pool control semaphore is the first in the pool

 */

#define SEM_CONTROL  (&hppa_semaphore_pool[0])

#define SEM_FIRST    (&hppa_semaphore_pool[1])

#define SEM_PRIVATE(cookie)  rtems_interrupt_disable(cookie)

#define SEM_PUBLIC(cookie)   rtems_interrupt_enable(cookie)

/*

 * Control variables for the pool

 */

hppa_semaphore_t *hppa_semaphore_pool;        /* ptr to first */

int               hppa_semaphores;

int               hppa_semaphores_available;

void

hppa_semaphore_pool_initialize(void *pool_base,

                               int   pool_size)

{

    hppa_semaphore_t *sp;

    int align_factor;

    rtems_unsigned32 isr_level;

    /*

     * round pool_base up to be a multiple of SEM_ALIGN

     */

    align_factor = SEM_ALIGN - (((int) pool_base) & (SEM_ALIGN-1));

    if (align_factor != SEM_ALIGN)

    {

        pool_base += align_factor;

        pool_size -= align_factor;

    }

    /*

     * How many can the pool hold?

     * Assumes the semaphores are SEM_ALIGN bytes each

     */

    if (sizeof(hppa_semaphore_t) != SEM_ALIGN)

        rtems_fatal_error_occurred(RTEMS_INVALID_SIZE);

    pool_size &= ~(SEM_ALIGN - 1);

    SEM_PRIVATE(isr_level);

    hppa_semaphore_pool = pool_base;

    hppa_semaphores = pool_size / SEM_ALIGN;

    /*

     * If we are node0, then init all in the pool

     */

#if 0

    if (cpu_number == 0)

#else

    if (_Configuration_Table->User_multiprocessing_table->node == 1)

#endif

    {

        /*

         * Tell other cpus we are not done, jic

         */

        SEM_CONTROL->user = rtems_build_name('!', 'D', 'N', 'E');

        for (sp=SEM_FIRST; sp < &hppa_semaphore_pool[hppa_semaphores]; sp++)

            SEM_FREE_INIT(sp);

        SEM_FREE_INIT(SEM_CONTROL);

    }

    /*

     * Tell other cpus we are done, or wait for it to be done if on another cpu

     */

#if 0

    if (cpu_number == 0)

#else

    if (_Configuration_Table->User_multiprocessing_table->node == 1)

#endif

        SEM_CONTROL->user = rtems_build_name('D', 'O', 'N', 'E');

    else

        while (SEM_CONTROL->user != rtems_build_name('D', 'O', 'N', 'E'))

            ;

    hppa_semaphores_available = hppa_semaphores;

    SEM_PUBLIC(isr_level);

}

/*

 *  Function:   hppa_semaphore_acquire

 *  Created:    94/11/29

 *  RespEngr:   tony bennett

 *

 *  Description:

 *      Acquire a semaphore.   Will spin on the semaphore unless

 *      'flag' says not to.

 *

 *  Parameters:

 *

 *

 *  Returns:

 *      0        -- if did not acquire

 *      non-zero -- if acquired semaphore

 *                      (actually this is the spin count)

 *

 *  Notes:

 *      There is no requirement that the semaphore be within the pool

 *

 *  Deficiencies/ToDo:

 *

 */

rtems_unsigned32

hppa_semaphore_acquire(hppa_semaphore_t *sp,

                       int               flag)

{

    rtems_unsigned32 lock_value;

    rtems_unsigned32 spin_count = 1;

    SEM_CHECK(sp);

    for (;;)

    {

        HPPA_ASM_LDCWS(0, 0, sp, lock_value);

        if (lock_value)         /* we now own the lock */

        {

            SEM_MARK_GRABBED(sp);

            return spin_count ? spin_count : ~0;        /* jic */

        }

        if (flag & HPPA_SEM_NO_SPIN)

            return 0;

        spin_count++;

    }

}

void

hppa_semaphore_release(hppa_semaphore_t *sp)

{

    SEM_CHECK(sp);

    if (sp->owner_tcb != _Thread_Executing)

        SEM_FATAL_ERROR("owner mismatch");

    sp->lock = 1;

}

/*

 *  Function:   hppa_semaphore_allocate

 *  Created:    94/11/29

 *  RespEngr:   tony bennett

 *

 *  Description:

 *      Get a pointer to a semaphore.

 *

 *  Parameters:

 *      which -- if 0, then allocate a free semaphore from the pool

 *               if non-zero, then return pointer to that one, even

 *                  if it is already busy.

 *

 *  Returns:

 *      successful -- pointer to semaphore

 *                    NULL otherwise

 *

 *  Notes:

 *

 *

 *  Deficiencies/ToDo:

 *

 *

 */

hppa_semaphore_t *

hppa_semaphore_allocate(rtems_unsigned32 which,

                        int              flag)

{

    hppa_semaphore_t *sp = 0;

    /*

     * grab the control semaphore

     */

    if (hppa_semaphore_acquire(SEM_CONTROL, 0) == 0)

        SEM_FATAL_ERROR("could not grab control semaphore");

    /*

     * Find a free one and init it

     */

    if (which)

    {

        if (which >= hppa_semaphores)

            SEM_FATAL_ERROR("requested non-existent semaphore");

        sp = &hppa_semaphore_pool[which];

        /*

         * if it is "free", then mark it claimed now.

         * If it is not free then we are done.

         */

        if (SEM_IS_AVAILABLE(sp))

            goto allmine;

    }

    else for (sp = SEM_FIRST;

              sp < &hppa_semaphore_pool[hppa_semaphores];

              sp++)

    {

        if (SEM_IS_AVAILABLE(sp))

        {

allmine:    SEM_FREE_INIT(sp);

            SEM_MARK_BUSY(sp);

            if ( ! (flag & HPPA_SEM_INITIALLY_FREE))

                SEM_MARK_GRABBED(sp);

            break;

        }

    }

    /*

     * Free up the control semaphore

     */

    hppa_semaphore_release(SEM_CONTROL);

    return sp;

}