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https://github.com/Telecominfraproject/OpenCellular.git
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06d3155c51
It turns out TRNG could turn idle under certain circumstances, and needs to be restarted in that case. This code adds a check for the idle state and necessary recovery. BRANCH=none BUG=b:27646393 TEST=none yet Change-Id: Ibd0a13f40f5ce081d4211b2c0f1026468967f826 Signed-off-by: Vadim Bendebury <vbendeb@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/332573 Reviewed-by: Bill Richardson <wfrichar@chromium.org>
51 lines
1.1 KiB
C
51 lines
1.1 KiB
C
/* Copyright 2015 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "registers.h"
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void init_trng(void)
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{
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GWRITE(TRNG, POWER_DOWN_B, 1);
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GWRITE(TRNG, GO_EVENT, 1);
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while (GREAD(TRNG, EMPTY))
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;
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GREAD(TRNG, READ_DATA);
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}
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uint32_t rand(void)
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{
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while (GREAD(TRNG, EMPTY)) {
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if (!GREAD_FIELD(TRNG, FSM_STATE, FSM_IDLE))
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continue;
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/* TRNG must have stopped, needs to be restarted. */
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GWRITE(TRNG, STOP_WORK, 1);
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init_trng();
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}
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return GREAD(TRNG, READ_DATA);
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}
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void rand_bytes(void *buffer, size_t len)
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{
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int random_togo = 0;
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int buffer_index = 0;
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uint32_t random_value;
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uint8_t *buf = (uint8_t *) buffer;
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/*
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* Retrieve random numbers in 4 byte quantities and pack as many bytes
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* as needed into 'buffer'. If len is not divisible by 4, the
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* remaining random bytes get dropped.
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*/
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while (buffer_index < len) {
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if (!random_togo) {
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random_value = rand();
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random_togo = sizeof(random_value);
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}
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buf[buffer_index++] = random_value >>
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((random_togo-- - 1) * 8);
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}
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}
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