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      1 /*	$NetBSD: rng200.c,v 1.4 2022/03/19 11:55:03 riastradh Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2019 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Michael van Elst
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Driver for the Broadcom iProc RNG200
     34  */
     35 
     36 #include <sys/param.h>
     37 #include <sys/bus.h>
     38 #include <sys/mutex.h>
     39 #include <sys/rndsource.h>
     40 
     41 #include <dev/ic/rng200var.h>
     42 #include <dev/ic/rng200reg.h>
     43 
     44 #define READ4(sc, r) \
     45 	bus_space_read_4((sc)->sc_bst, (sc)->sc_bsh, (r))
     46 
     47 #define WRITE4(sc, r, v) \
     48 	bus_space_write_4((sc)->sc_bst, (sc)->sc_bsh, (r), (v))
     49 
     50 static void
     51 rng200_reset(struct rng200_softc *sc)
     52 {
     53 	uint32_t ctl, rng, rbg;
     54 
     55 	/* Disable RBG */
     56 	ctl = READ4(sc, RNG200_CONTROL);
     57 	ctl &= ~RNG200_RBG_MASK;
     58 	WRITE4(sc, RNG200_CONTROL, ctl);
     59 
     60 	/* Clear interrupts */
     61 	WRITE4(sc, RNG200_STATUS, 0xffffffff);
     62 
     63 	/* Reset RNG and RBG */
     64 	rbg = READ4(sc, RNG200_RBG_RESET);
     65 	rng = READ4(sc, RNG200_RNG_RESET);
     66 	WRITE4(sc, RNG200_RBG_RESET, rbg | RBG_RESET);
     67 	WRITE4(sc, RNG200_RNG_RESET, rng | RNG_RESET);
     68 	WRITE4(sc, RNG200_RNG_RESET, rng);
     69 	WRITE4(sc, RNG200_RBG_RESET, rbg);
     70 
     71 	/* Enable RBG */
     72 	WRITE4(sc, RNG200_CONTROL, ctl | RNG200_RBG_ENABLE);
     73 }
     74 
     75 static void
     76 rng200_get(size_t bytes_wanted, void *priv)
     77 {
     78 	struct rng200_softc * const sc = priv;
     79 	uint32_t w, data;
     80 	unsigned count;
     81 
     82 	while (bytes_wanted) {
     83 
     84 		w = READ4(sc, RNG200_STATUS);
     85 		if ((w & (RNG200_MASTER_FAIL | RNG200_NIST_FAIL)) != 0)
     86 			rng200_reset(sc);
     87 
     88 		w = READ4(sc, RNG200_COUNT);
     89 		count = __SHIFTOUT(w, RNG200_COUNT_MASK);
     90 
     91 		if (count == 0)
     92 			break;
     93 
     94 		data = READ4(sc, RNG200_DATA);
     95 		rnd_add_data_sync(&sc->sc_rndsource, &data,
     96 		    sizeof(data), sizeof(data) * NBBY);
     97 		bytes_wanted -= MIN(bytes_wanted, sizeof(data));
     98 	}
     99 	explicit_memset(&data, 0, sizeof(data));
    100 }
    101 
    102 void
    103 rng200_attach(struct rng200_softc *sc)
    104 {
    105 
    106 	rndsource_setcb(&sc->sc_rndsource, rng200_get, sc);
    107 	rnd_attach_source(&sc->sc_rndsource, sc->sc_name,
    108 		RND_TYPE_RNG, RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
    109 }
    110 
    111 void
    112 rng200_detach(struct rng200_softc *sc)
    113 {
    114 
    115 	rnd_detach_source(&sc->sc_rndsource);
    116 }
    117 
    118