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Annotation of coherent/b/kernel/ldrv/dmalock.c, revision 1.1

1.1     ! root        1: /* $Header: /kernel/kersrc/ldrv/RCS/dmalock.c,v 1.1 92/07/17 15:27:50 bin Exp Locker: bin $
        !             2:  *
        !             3:  *     The  information  contained herein  is a trade secret  of INETCO
        !             4:  *     Systems, Ltd, and is  confidential information.   It is provided
        !             5:  *     under a license agreement,  and may be copied or disclosed  only
        !             6:  *     under  the  terms  of  that  agreement.    Any  reproduction  or
        !             7:  *     disclosure  of  this   material   without  the  express  written
        !             8:  *     authorization of INETCO Systems, Ltd. or persuant to the license
        !             9:  *     agreement is unlawful.
        !            10:  *
        !            11:  *     Copyright (c) 1989
        !            12:  *     An unpublished work by INETCO Systems, Ltd.
        !            13:  *     All rights reserved.
        !            14:  *
        !            15:  * $Description: $
        !            16:  *     Routines to lock/unlock the DMA controller chip from a loadable driver.
        !            17:  *
        !            18:  * $Author: bin $
        !            19:  *
        !            20:  * $Creation: June 29, 1989 $
        !            21:  *
        !            22:  * $Log:       dmalock.c,v $
        !            23:  * Revision 1.1  92/07/17  15:27:50  bin
        !            24:  * Initial revision
        !            25:  * 
        !            26:  * Revision 1.1        89/06/30  16:29:52      src
        !            27:  * Initial revision
        !            28:  * 
        !            29:  */
        !            30: 
        !            31: #include <sys/coherent.h>
        !            32: 
        !            33: typedef void (* vfp_t)();              /* Void function pointer type.       */
        !            34: 
        !            35: /*
        !            36:  * External functions.
        !            37:  */
        !            38: extern void Kdmalock();
        !            39: extern void Kdmaunlock();
        !            40: extern void Kldtimcall();
        !            41: extern saddr_t getcs();
        !            42: 
        !            43: /*
        !            44:  * int
        !            45:  * dmalock( tp, fun, arg )
        !            46:  * TIM * tp;
        !            47:  * vfp_t fun;
        !            48:  * int  arg;
        !            49:  *
        !            50:  *     Inputs: tp  = Deferred function structure pointer.
        !            51:  *             fun = Function to call if request is deferred.
        !            52:  *             arg = Argument to pass to function.
        !            53:  *
        !            54:  *     Action: Calls kernel dmalock() routine.
        !            55:  *
        !            56:  *     Return: 0 = Lock granted or -1 = Lock deferred.
        !            57:  *
        !            58:  *     Notes:  DMA controller locking was introduced to cure a bug on the
        !            59:  *             NCR DMA controller, where overlapped DMA caused problems.
        !            60:  *             No action is taken if DMA locking is disabled.
        !            61:  */
        !            62: 
        !            63: int
        !            64: dmalock( tp, fun, arg )
        !            65: register TIM  * tp;
        !            66: vfp_t          fun;
        !            67: int            arg;
        !            68: {
        !            69:        /*
        !            70:         * Define loadable driver interface.
        !            71:         * Kldtimcall will be invoked when a deferred function is executed.
        !            72:         * It will in turn invoke FP_SEL(tp->t_ldrv):4 (the calling drivers
        !            73:         * function call entry point), passing FP_OFF(tp->t_ldrv) (the function
        !            74:         * to call) in AX.
        !            75:         */
        !            76:        FP_SEL(tp->t_ldrv) = getcs();
        !            77:        FP_OFF(tp->t_ldrv) = fun;
        !            78:        return( kcall( Kdmalock, tp, Kldtimcall, arg ) );
        !            79: }
        !            80: 
        !            81: /*
        !            82:  * void
        !            83:  * dmaunlock( tp )
        !            84:  * TIM * tp;
        !            85:  *
        !            86:  *     Inputs: tp = Deferred function structure pointer.
        !            87:  *
        !            88:  *     Action: Calls the kernel dmaunlock().
        !            89:  */
        !            90: 
        !            91: void
        !            92: dmaunlock( tp )
        !            93: register TIM * tp;
        !            94: {
        !            95:        kcall( Kdmaunlock, tp );
        !            96: }
        !            97: 

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