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Annotation of coherent/d/286_KERNEL/USRSRC/ldrv/dmalock.c, revision 1.1

1.1     ! root        1: /* $Header: /usr/src/sys/ldrv/RCS/dmalock.c,v 1.1 89/06/30 16:29:52 src Exp $
        !             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        !            12:  *     An unpublished work by INETCO Systems, Ltd.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: src $
        !            19:  *
        !            20:  * $Creation: June 29, 1989 $
        !            21:  *
        !            22:  * $Log:       /usr/src/sys/ldrv/RCS/dmalock.c,v $
        !            23:  * Revision 1.1        89/06/30  16:29:52      src
        !            24:  * Initial revision
        !            25:  * 
        !            26:  */
        !            27: 
        !            28: #include <sys/coherent.h>
        !            29: 
        !            30: typedef void (* vfp_t)();              /* Void function pointer type.       */
        !            31: 
        !            32: /*
        !            33:  * External functions.
        !            34:  */
        !            35: extern void Kdmalock();
        !            36: extern void Kdmaunlock();
        !            37: extern void Kldtimcall();
        !            38: extern saddr_t getcs();
        !            39: 
        !            40: /*
        !            41:  * int
        !            42:  * dmalock( tp, fun, arg )
        !            43:  * TIM * tp;
        !            44:  * vfp_t fun;
        !            45:  * int  arg;
        !            46:  *
        !            47:  *     Inputs: tp  = Deferred function structure pointer.
        !            48:  *             fun = Function to call if request is deferred.
        !            49:  *             arg = Argument to pass to function.
        !            50:  *
        !            51:  *     Action: Calls kernel dmalock() routine.
        !            52:  *
        !            53:  *     Return: 0 = Lock granted or -1 = Lock deferred.
        !            54:  *
        !            55:  *     Notes:  DMA controller locking was introduced to cure a bug on the
        !            56:  *             NCR DMA controller, where overlapped DMA caused problems.
        !            57:  *             No action is taken if DMA locking is disabled.
        !            58:  */
        !            59: 
        !            60: int
        !            61: dmalock( tp, fun, arg )
        !            62: register TIM  * tp;
        !            63: vfp_t          fun;
        !            64: int            arg;
        !            65: {
        !            66:        /*
        !            67:         * Define loadable driver interface.
        !            68:         * Kldtimcall will be invoked when a deferred function is executed.
        !            69:         * It will in turn invoke FP_SEL(tp->t_ldrv):4 (the calling drivers
        !            70:         * function call entry point), passing FP_OFF(tp->t_ldrv) (the function
        !            71:         * to call) in AX.
        !            72:         */
        !            73:        FP_SEL(tp->t_ldrv) = getcs();
        !            74:        FP_OFF(tp->t_ldrv) = fun;
        !            75:        return( kcall( Kdmalock, tp, Kldtimcall, arg ) );
        !            76: }
        !            77: 
        !            78: /*
        !            79:  * void
        !            80:  * dmaunlock( tp )
        !            81:  * TIM * tp;
        !            82:  *
        !            83:  *     Inputs: tp = Deferred function structure pointer.
        !            84:  *
        !            85:  *     Action: Calls the kernel dmaunlock().
        !            86:  */
        !            87: 
        !            88: void
        !            89: dmaunlock( tp )
        !            90: register TIM * tp;
        !            91: {
        !            92:        kcall( Kdmaunlock, tp );
        !            93: }
        !            94: 

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