[PATCH v2 1/3] Uboot RNG Driver using Data Co-processor
Kshitiz Varshney
kshitiz.varshney at nxp.com
Thu Dec 22 09:50:27 CET 2022
This commit introduces Random number generator to uboot. It uses DCP
driver for number generation.
RNG driver can be invoked by using below command on uboot prompt:-
rng <number of bytes>
Signed-off-by: Kshitiz Varshney <kshitiz.varshney at nxp.com>
Reviewed-by: Ye Li <ye.li at nxp.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---
drivers/crypto/fsl/Kconfig | 10 ++
drivers/crypto/fsl/Makefile | 1 +
drivers/crypto/fsl/dcp_rng.c | 182 +++++++++++++++++++++++++++++++++++
3 files changed, 193 insertions(+)
create mode 100644 drivers/crypto/fsl/dcp_rng.c
diff --git a/drivers/crypto/fsl/Kconfig b/drivers/crypto/fsl/Kconfig
index b04c70183d..91a51cc5fe 100644
--- a/drivers/crypto/fsl/Kconfig
+++ b/drivers/crypto/fsl/Kconfig
@@ -73,3 +73,13 @@ config FSL_CAAM_RNG
reseeded from the TRNG every time random data is generated.
endif
+
+config FSL_DCP_RNG
+ bool "Enable Random Number Generator support"
+ depends on DM_RNG
+ default n
+ help
+ Enable support for the hardware based random number generator
+ module of the DCP. It uses the True Random Number Generator (TRNG)
+ and a Pseudo-Random Number Generator (PRNG) to achieve a true
+ randomness and cryptographic strength.
diff --git a/drivers/crypto/fsl/Makefile b/drivers/crypto/fsl/Makefile
index f9c3ccecfc..7a2543e16c 100644
--- a/drivers/crypto/fsl/Makefile
+++ b/drivers/crypto/fsl/Makefile
@@ -7,4 +7,5 @@ obj-$(CONFIG_FSL_CAAM) += jr.o fsl_hash.o jobdesc.o error.o
obj-$(CONFIG_CMD_BLOB)$(CONFIG_IMX_CAAM_DEK_ENCAP) += fsl_blob.o
obj-$(CONFIG_RSA_FREESCALE_EXP) += fsl_rsa.o
obj-$(CONFIG_FSL_CAAM_RNG) += rng.o
+obj-$(CONFIG_FSL_DCP_RNG) += dcp_rng.o
obj-$(CONFIG_FSL_MFGPROT) += fsl_mfgprot.o
diff --git a/drivers/crypto/fsl/dcp_rng.c b/drivers/crypto/fsl/dcp_rng.c
new file mode 100644
index 0000000000..3170696015
--- /dev/null
+++ b/drivers/crypto/fsl/dcp_rng.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RNG driver for Freescale RNGC
+ *
+ * Copyright 2022 NXP
+ *
+ * Based on RNGC driver in drivers/char/hw_random/imx-rngc.c in Linux
+ */
+
+#include <common.h>
+#include <cpu_func.h>
+#include <dm.h>
+#include <rng.h>
+#include <asm/cache.h>
+#include <asm/io.h>
+#include <dm/root.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+
+#define DCP_RNG_MAX_FIFO_STORE_SIZE 4
+#define RNGC_VER_ID 0x0
+#define RNGC_COMMAND 0x4
+#define RNGC_CONTROL 0x8
+#define RNGC_STATUS 0xC
+#define RNGC_ERROR 0x10
+#define RNGC_FIFO 0x14
+
+/* the fields in the ver id register */
+#define RNGC_TYPE_SHIFT 28
+
+/* the rng_type field */
+#define RNGC_TYPE_RNGB 0x1
+#define RNGC_TYPE_RNGC 0x2
+
+#define RNGC_CMD_CLR_ERR 0x20
+#define RNGC_CMD_SEED 0x2
+
+#define RNGC_CTRL_AUTO_SEED 0x10
+
+#define RNGC_STATUS_ERROR 0x10000
+#define RNGC_STATUS_FIFO_LEVEL_MASK 0xf00
+#define RNGC_STATUS_FIFO_LEVEL_SHIFT 8
+#define RNGC_STATUS_SEED_DONE 0x20
+#define RNGC_STATUS_ST_DONE 0x10
+
+#define RNGC_ERROR_STATUS_STAT_ERR 0x8
+
+#define RNGC_TIMEOUT 3000000U /* 3 sec */
+
+struct imx_rngc_priv {
+ unsigned long base;
+};
+
+static int rngc_read(struct udevice *dev, void *data, size_t len)
+{
+ struct imx_rngc_priv *priv = dev_get_priv(dev);
+ u8 buffer[DCP_RNG_MAX_FIFO_STORE_SIZE];
+ u32 status, level;
+ size_t size;
+
+ while (len) {
+ status = readl(priv->base + RNGC_STATUS);
+
+ /* is there some error while reading this random number? */
+ if (status & RNGC_STATUS_ERROR)
+ break;
+ /* how many random numbers are in FIFO? [0-16] */
+ level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >>
+ RNGC_STATUS_FIFO_LEVEL_SHIFT;
+
+ if (level) {
+ /* retrieve a random number from FIFO */
+ *(u32 *)buffer = readl(priv->base + RNGC_FIFO);
+ size = min(len, sizeof(u32));
+ memcpy(data, buffer, size);
+ data += size;
+ len -= size;
+ }
+ }
+
+ return len ? -EIO : 0;
+}
+
+static int rngc_init(struct imx_rngc_priv *priv)
+{
+ u32 cmd, ctrl, status, err_reg = 0;
+ unsigned long long timeval = 0;
+ unsigned long long timeout = RNGC_TIMEOUT;
+
+ /* clear error */
+ cmd = readl(priv->base + RNGC_COMMAND);
+ writel(cmd | RNGC_CMD_CLR_ERR, priv->base + RNGC_COMMAND);
+
+ /* create seed, repeat while there is some statistical error */
+ do {
+ /* seed creation */
+ cmd = readl(priv->base + RNGC_COMMAND);
+ writel(cmd | RNGC_CMD_SEED, priv->base + RNGC_COMMAND);
+
+ udelay(1);
+ timeval += 1;
+
+ status = readl(priv->base + RNGC_STATUS);
+ err_reg = readl(priv->base + RNGC_ERROR);
+
+ if (status & (RNGC_STATUS_SEED_DONE | RNGC_STATUS_ST_DONE))
+ break;
+
+ if (timeval > timeout) {
+ debug("rngc timed out\n");
+ return -ETIMEDOUT;
+ }
+ } while (err_reg == RNGC_ERROR_STATUS_STAT_ERR);
+
+ if (err_reg)
+ return -EIO;
+
+ /*
+ * enable automatic seeding, the rngc creates a new seed automatically
+ * after serving 2^20 random 160-bit words
+ */
+ ctrl = readl(priv->base + RNGC_CONTROL);
+ ctrl |= RNGC_CTRL_AUTO_SEED;
+ writel(ctrl, priv->base + RNGC_CONTROL);
+ return 0;
+}
+
+static int rngc_probe(struct udevice *dev)
+{
+ struct imx_rngc_priv *priv = dev_get_priv(dev);
+ fdt_addr_t addr;
+ u32 ver_id;
+ u8 rng_type;
+ int ret;
+
+ addr = dev_read_addr(dev);
+ if (addr == FDT_ADDR_T_NONE) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ priv->base = addr;
+ ver_id = readl(priv->base + RNGC_VER_ID);
+ rng_type = ver_id >> RNGC_TYPE_SHIFT;
+ /*
+ * This driver supports only RNGC and RNGB. (There's a different
+ * driver for RNGA.)
+ */
+ if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB) {
+ ret = -ENODEV;
+ goto err;
+ }
+
+ ret = rngc_init(priv);
+ if (ret)
+ goto err;
+
+ return 0;
+
+err:
+ printf("%s error = %d\n", __func__, ret);
+ return ret;
+}
+
+static const struct dm_rng_ops rngc_ops = {
+ .read = rngc_read,
+};
+
+static const struct udevice_id rngc_dt_ids[] = {
+ { .compatible = "fsl,imx25-rngb" },
+ { }
+};
+
+U_BOOT_DRIVER(dcp_rng) = {
+ .name = "dcp_rng",
+ .id = UCLASS_RNG,
+ .of_match = rngc_dt_ids,
+ .ops = &rngc_ops,
+ .probe = rngc_probe,
+ .priv_auto = sizeof(struct imx_rngc_priv),
+ .flags = DM_FLAG_ALLOC_PRIV_DMA,
+};
--
2.25.1
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