crypto/fsl: add RNG support

Register the random number generator with the rng subsystem in u-boot.
This way it can be used by EFI as well as for the 'rng' command.

Signed-off-by: Michael Walle <michael@walle.cc>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

drivers/crypto/fsl/Kconfig

@@ -45,3 +45,17 @@ config SYS_FSL_SEC_COMPAT
 
 config SYS_FSL_SEC_LE
 	bool "Little-endian access to Freescale Secure Boot"
+
+if FSL_CAAM
+
+config FSL_CAAM_RNG
+	bool "Enable Random Number Generator support"
+	depends on DM_RNG
+	default y
+	help
+	  Enable support for the hardware based random number generator
+	  module of the CAAM. The random data is fetched from the DRGB
+	  using the prediction resistance flag which means the DRGB is
+	  reseeded from the TRNG every time random data is generated.
+
+endif

drivers/crypto/fsl/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_FSL_CAAM) += jr.o fsl_hash.o jobdesc.o error.o
 obj-$(CONFIG_CMD_BLOB) += fsl_blob.o
 obj-$(CONFIG_CMD_DEKBLOB) += fsl_blob.o
 obj-$(CONFIG_RSA_FREESCALE_EXP) += fsl_rsa.o
+obj-$(CONFIG_FSL_CAAM_RNG) += rng.o

drivers/crypto/fsl/jobdesc.c

@@ -296,6 +296,16 @@ void inline_cnstr_jobdesc_rng_deinstantiation(u32 *desc, int handle)
 			 (handle << OP_ALG_AAI_SHIFT) | OP_ALG_AS_INITFINAL);
 }
 
+void inline_cnstr_jobdesc_rng(u32 *desc, void *data_out, u32 size)
+{
+	dma_addr_t dma_data_out = virt_to_phys(data_out);
+
+	init_job_desc(desc, 0);
+	append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG |
+			 OP_ALG_PR_ON);
+	append_fifo_store(desc, dma_data_out, size, FIFOST_TYPE_RNGSTORE);
+}
+
 /* Change key size to bytes form bits in calling function*/
 void inline_cnstr_jobdesc_pkha_rsaexp(uint32_t *desc,
 				      struct pk_in_params *pkin, uint8_t *out,

drivers/crypto/fsl/jobdesc.h

@@ -43,7 +43,10 @@ void inline_cnstr_jobdesc_rng_instantiation(u32 *desc, int handle, int do_sk);
 
 void inline_cnstr_jobdesc_rng_deinstantiation(u32 *desc, int handle);
 
+void inline_cnstr_jobdesc_rng(u32 *desc, void *data_out, u32 size);
+
 void inline_cnstr_jobdesc_pkha_rsaexp(uint32_t *desc,
 				      struct pk_in_params *pkin, uint8_t *out,
 				      uint32_t out_siz);
+
 #endif

drivers/crypto/fsl/jr.c

@@ -20,6 +20,7 @@
 #include <asm/cache.h>
 #include <asm/fsl_pamu.h>
 #endif
+#include <dm/lists.h>
 
 #define CIRC_CNT(head, tail, size)	(((head) - (tail)) & (size - 1))
 #define CIRC_SPACE(head, tail, size)	CIRC_CNT((tail), (head) + 1, (size))
@@ -721,6 +722,14 @@ int sec_init_idx(uint8_t sec_idx)
 			printf("SEC%u:  RNG instantiation failed\n", sec_idx);
 			return -1;
 		}
+
+		if (IS_ENABLED(CONFIG_DM_RNG)) {
+			ret = device_bind_driver(NULL, "caam-rng", "caam-rng",
+						 NULL);
+			if (ret)
+				printf("Couldn't bind rng driver (%d)\n", ret);
+		}
+
 		printf("SEC%u:  RNG instantiated\n", sec_idx);
 	}
 #endif

drivers/crypto/fsl/rng.c

@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020 Michael Walle <michael@walle.cc>
+ *
+ * Driver for Freescale Cryptographic Accelerator and Assurance
+ * Module (CAAM) hardware random number generator.
+ */
+
+#include <asm/cache.h>
+#include <common.h>
+#include <cpu_func.h>
+#include <dm.h>
+#include <rng.h>
+#include <linux/kernel.h>
+#include "desc_constr.h"
+#include "jobdesc.h"
+#include "jr.h"
+
+#define CAAM_RNG_MAX_FIFO_STORE_SIZE 16
+#define CAAM_RNG_DESC_LEN (3 * CAAM_CMD_SZ + CAAM_PTR_SZ)
+
+struct caam_rng_priv {
+	u32 desc[CAAM_RNG_DESC_LEN / 4];
+	u8 data[CAAM_RNG_MAX_FIFO_STORE_SIZE] __aligned(ARCH_DMA_MINALIGN);
+};
+
+static int caam_rng_read_one(struct caam_rng_priv *priv)
+{
+	int size = ALIGN(CAAM_RNG_MAX_FIFO_STORE_SIZE, ARCH_DMA_MINALIGN);
+	int ret;
+
+	ret = run_descriptor_jr(priv->desc);
+	if (ret < 0)
+		return -EIO;
+
+	invalidate_dcache_range((unsigned long)priv->data,
+				(unsigned long)priv->data + size);
+
+	return 0;
+}
+
+static int caam_rng_read(struct udevice *dev, void *data, size_t len)
+{
+	struct caam_rng_priv *priv = dev_get_priv(dev);
+	u8 *buffer = data;
+	size_t size;
+	int ret;
+
+	while (len) {
+		ret = caam_rng_read_one(priv);
+		if (ret)
+			return ret;
+
+		size = min(len, (size_t)CAAM_RNG_MAX_FIFO_STORE_SIZE);
+
+		memcpy(buffer, priv->data, size);
+		buffer += size;
+		len -= size;
+	}
+
+	return 0;
+}
+
+static int caam_rng_probe(struct udevice *dev)
+{
+	struct caam_rng_priv *priv = dev_get_priv(dev);
+	ulong size = ALIGN(CAAM_RNG_DESC_LEN, ARCH_DMA_MINALIGN);
+
+	inline_cnstr_jobdesc_rng(priv->desc, priv->data,
+				 CAAM_RNG_MAX_FIFO_STORE_SIZE);
+	flush_dcache_range((unsigned long)priv->desc,
+			   (unsigned long)priv->desc + size);
+
+	return 0;
+}
+
+static const struct dm_rng_ops caam_rng_ops = {
+	.read = caam_rng_read,
+};
+
+U_BOOT_DRIVER(caam_rng) = {
+	.name = "caam-rng",
+	.id = UCLASS_RNG,
+	.ops = &caam_rng_ops,
+	.probe = caam_rng_probe,
+	.priv_auto_alloc_size = sizeof(struct caam_rng_priv),
+	.flags = DM_FLAG_ALLOC_PRIV_DMA,
+};