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 ---

Changes in v5: - check return code turris_rwtm_rng_fill_entropy - remove empty line

Changes in v4: - wrongful/missing git rebase

Changes in v3: - More meaningful variable names in accordance with review

Changes in v2: - Removed ring buffer implementation

drivers/rng/Kconfig | 8 +++ drivers/rng/Makefile | 1 + drivers/rng/turris_rwtm_rng.c | 123 ++++++++++++++++++++++++++++++++++ 3 files changed, 132 insertions(+) create mode 100644 drivers/rng/turris_rwtm_rng.c

diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig index a89c899568..cd72852a47 100644 --- a/drivers/rng/Kconfig +++ b/drivers/rng/Kconfig @@ -105,4 +105,12 @@ config RNG_JH7110 help Enable True Random Number Generator in StarFive JH7110 SoCs.

+config RNG_TURRIS_RWTM + bool "Turris Mox TRNG in Secure Processor" + depends on DM_RNG && ARMADA_3700 + help + Use TRNG in Turris Mox Secure Processor Firmware. Can be used + on other Armada-3700 devices (like EspressoBin) if Secure + Firmware from CZ.NIC is used. + endif diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile index 7e64c4cdfc..ecae1a3da3 100644 --- a/drivers/rng/Makefile +++ b/drivers/rng/Makefile @@ -17,3 +17,4 @@ obj-$(CONFIG_RNG_SMCCC_TRNG) += smccc_trng.o obj-$(CONFIG_RNG_ARM_RNDR) += arm_rndr.o obj-$(CONFIG_TPM_RNG) += tpm_rng.o obj-$(CONFIG_RNG_JH7110) += jh7110_rng.o +obj-$(CONFIG_RNG_TURRIS_RWTM) += turris_rwtm_rng.o diff --git a/drivers/rng/turris_rwtm_rng.c b/drivers/rng/turris_rwtm_rng.c new file mode 100644 index 0000000000..ca808c4579 --- /dev/null +++ b/drivers/rng/turris_rwtm_rng.c @@ -0,0 +1,123 @@ +// 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), +};