93 lines
3.0 KiB
C
93 lines
3.0 KiB
C
/* $NetBSD: amdccp.c,v 1.2 2020/04/30 03:40:53 riastradh Exp $ */
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/*
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* Copyright (c) 2018 Jonathan A. Kollasch
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: amdccp.c,v 1.2 2020/04/30 03:40:53 riastradh Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/device.h>
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#include <sys/bus.h>
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#include <sys/rndsource.h>
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#include <dev/ic/amdccpvar.h>
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static uint32_t amdccp_rnd_read(struct amdccp_softc *);
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static void amdccp_rnd_callback(size_t, void *);
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void
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amdccp_common_attach(struct amdccp_softc *sc)
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{
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mutex_init(&sc->sc_rndlock, MUTEX_DEFAULT, IPL_VM);
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rndsource_setcb(&sc->sc_rndsource, amdccp_rnd_callback, sc);
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rnd_attach_source(&sc->sc_rndsource, device_xname(sc->sc_dev),
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RND_TYPE_RNG, RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
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}
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static uint32_t
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amdccp_rnd_read(struct amdccp_softc *sc)
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{
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size_t retries = 5;
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uint32_t bits;
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/* TRNG register reads 0x0 when bits aren't valid */
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while (retries--) {
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bits = bus_space_read_4(sc->sc_bst, sc->sc_bsh, CCP_TRNG_REG);
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if (bits != 0x0)
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break;
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}
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return bits;
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}
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static void
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amdccp_rnd_callback(size_t bytes_wanted, void *priv)
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{
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struct amdccp_softc * const sc = priv;
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uint32_t buf[128];
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size_t cnt;
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mutex_enter(&sc->sc_rndlock);
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while (bytes_wanted) {
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const size_t nbytes = MIN(bytes_wanted, sizeof(buf));
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const size_t nwords = howmany(nbytes, sizeof(buf[0]));
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for (cnt = 0; cnt < nwords; cnt++) {
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buf[cnt] = amdccp_rnd_read(sc);
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if (buf[cnt] == 0) {
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break;
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}
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}
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const size_t cntby = cnt * sizeof(buf[0]);
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rnd_add_data_sync(&sc->sc_rndsource, buf, cntby, cntby * NBBY);
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bytes_wanted -= MIN(bytes_wanted, cntby);
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}
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explicit_memset(buf, 0, sizeof(buf));
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mutex_exit(&sc->sc_rndlock);
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}
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