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A RNG driver for Armada 3720 boards running the Turris Mox rWTM firmware from CZ.NIC in the secure processor. Signed-off-by: Max Resch <resch.max@gmail.com> Reviewed-by: Stefan Roese <sr@denx.de>
124 lines
2.7 KiB
C
124 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later OR BSD-3-Clause
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/*
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* Copyright (c) 2024, Max Resch
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*/
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#include <dm.h>
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#include <malloc.h>
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#include <rng.h>
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#include <asm/dma-mapping.h>
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#include <asm/types.h>
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#include <mach/mbox.h>
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/* size of entropy buffer */
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#define RNG_BUFFER_SIZE 128U
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struct turris_rwtm_rng_priv {
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phys_addr_t buffer;
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};
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static int turris_rwtm_rng_fill_entropy(phys_addr_t entropy, size_t size)
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{
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u32 args[3] = { 1, (u32)entropy, size };
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int ret;
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/* flush data cache */
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flush_dcache_range(entropy, entropy + size);
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/*
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* get entropy
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* args[0] = 1 copies BYTES array in args[1] of length args[2]
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*/
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ret = mbox_do_cmd(MBOX_CMD_GET_RANDOM, args, 3, NULL, 0);
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if (ret < 0)
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return ret;
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/* invalidate data cache */
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invalidate_dcache_range(entropy, entropy + size);
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return 0;
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}
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static int turris_rwtm_rng_random_read(struct udevice *dev, void *data, size_t count)
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{
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struct turris_rwtm_rng_priv *priv = dev_get_priv(dev);
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phys_addr_t phys;
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size_t size;
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int ret;
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phys = priv->buffer;
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while (count) {
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size = min_t(size_t, RNG_BUFFER_SIZE, count);
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ret = turris_rwtm_rng_fill_entropy(phys, size);
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if (ret < 0)
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return ret;
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memcpy(data, (void *)phys, size);
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count -= size;
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data = (u8 *)data + size;
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}
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return 0;
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}
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static int turris_rwtm_rng_probe(struct udevice *dev)
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{
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struct turris_rwtm_rng_priv *priv = dev_get_priv(dev);
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u32 args[] = { 0 };
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int ret;
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/*
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* check if the random command is supported
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* args[0] = 0 would copy 16 DWORDS entropy to out but we ignore them
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*/
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ret = mbox_do_cmd(MBOX_CMD_GET_RANDOM, args, ARRAY_SIZE(args), NULL, 0);
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if (ret < 0)
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return ret;
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/* entropy buffer */
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priv->buffer = 0;
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/* buffer address need to be aligned */
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dma_alloc_coherent(RNG_BUFFER_SIZE, (unsigned long *)&priv->buffer);
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if (!priv->buffer)
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return -ENOMEM;
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return 0;
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}
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static int turris_rwtm_rng_remove(struct udevice *dev)
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{
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struct turris_rwtm_rng_priv *priv = dev_get_priv(dev);
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phys_addr_t phys = priv->buffer;
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dma_free_coherent((void *)phys);
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return 0;
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}
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static const struct dm_rng_ops turris_rwtm_rng_ops = {
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.read = turris_rwtm_rng_random_read,
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};
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/*
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* only Turris MOX firmware has the RNG but allow all probable devices to be
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* probed the default firmware will just reject the probe
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*/
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static const struct udevice_id turris_rwtm_rng_match[] = {
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{ .compatible = "cznic,turris-mox-rwtm" },
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{ .compatible = "marvell,armada-3700-rwtm-firmware" },
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{},
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};
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U_BOOT_DRIVER(turris_rwtm_rng) = {
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.name = "turris-rwtm-rng",
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.id = UCLASS_RNG,
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.of_match = turris_rwtm_rng_match,
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.ops = &turris_rwtm_rng_ops,
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.probe = turris_rwtm_rng_probe,
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.remove = turris_rwtm_rng_remove,
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.priv_auto = sizeof(struct turris_rwtm_rng_priv),
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};
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