rng: Add Turris Mox rTWM RNG driver

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>

diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index a89c8995682655ee49347b941eafc2e27feecd4a..cd72852a479e2f09e2df3f357615bb5363a08688 100644 (file)
--- 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 7e64c4cdfc30e0a3cdc43493ce995a9a8013f91f..ecae1a3da33be95838be6b471b22f40002ea66cc 100644 (file)
--- 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 (file)
index 0000000..ca808c4
--- /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),
+};