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