On Mi, 2019-11-20 at 08:53 -0800, Andrey Smirnov wrote:
> In order to give CAAM-generated random data highest quarlity
> raiting (999), replace current code that uses DRNG with code that
> fetches data straight out of TRNG used to seed aforementioned DRNG.
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
I don't know how others feel about this, but I think it's the right
thing to do.
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Cc: Chris Healy <cphealy@xxxxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Cc: Horia Geantă <horia.geanta@xxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Iuliana Prodan <iuliana.prodan@xxxxxxx>
> Cc: linux-imx@xxxxxxx
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
> drivers/crypto/caam/Kconfig | 17 +-
> drivers/crypto/caam/Makefile | 2 +-
> drivers/crypto/caam/caamrng.c | 351 --------------------------------
> --
> drivers/crypto/caam/ctrl.c | 6 +
> drivers/crypto/caam/intern.h | 9 +-
> drivers/crypto/caam/jr.c | 2 -
> drivers/crypto/caam/regs.h | 7 +-
> drivers/crypto/caam/trng.c | 89 +++++++++
> 8 files changed, 111 insertions(+), 372 deletions(-)
> delete mode 100644 drivers/crypto/caam/caamrng.c
> create mode 100644 drivers/crypto/caam/trng.c
>
> diff --git a/drivers/crypto/caam/Kconfig
> b/drivers/crypto/caam/Kconfig
> index 137ed3df0c74..22116a8e2ff3 100644
> --- a/drivers/crypto/caam/Kconfig
> +++ b/drivers/crypto/caam/Kconfig
> @@ -31,6 +31,14 @@ config CRYPTO_DEV_FSL_CAAM_DEBUG
> Selecting this will enable printing of various debug
> information in the CAAM driver.
>
> +config CRYPTO_DEV_FSL_CAAM_RNG_API
> + bool "Register caam device for hwrng API"
> + default y
> + select HW_RANDOM
> + help
> + Selecting this will register the hardware TRNG to
> + the hw_random API for suppying the kernel entropy pool.
> +
> menuconfig CRYPTO_DEV_FSL_CAAM_JR
> tristate "Freescale CAAM Job Ring driver backend"
> default y
> @@ -138,15 +146,6 @@ config CRYPTO_DEV_FSL_CAAM_PKC_API
> Supported cryptographic primitives: encryption,
> decryption,
> signature and verification.
>
> -config CRYPTO_DEV_FSL_CAAM_RNG_API
> - bool "Register caam device for hwrng API"
> - default y
> - select CRYPTO_RNG
> - select HW_RANDOM
> - help
> - Selecting this will register the SEC4 hardware rng to
> - the hw_random API for suppying the kernel entropy pool.
> -
> endif # CRYPTO_DEV_FSL_CAAM_JR
>
> endif # CRYPTO_DEV_FSL_CAAM
> diff --git a/drivers/crypto/caam/Makefile
> b/drivers/crypto/caam/Makefile
> index 68d5cc0f28e2..04884fc087f9 100644
> --- a/drivers/crypto/caam/Makefile
> +++ b/drivers/crypto/caam/Makefile
> @@ -15,11 +15,11 @@ obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_DESC)
> += caamalg_desc.o
> obj-$(CONFIG_CRYPTO_DEV_FSL_CAAM_AHASH_API_DESC) += caamhash_desc.o
>
> caam-y := ctrl.o
> +caam-$(CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API) += trng.o
> caam_jr-y := jr.o key_gen.o
> caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API) += caamalg.o
> caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI) += caamalg_qi.o
> caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_AHASH_API) += caamhash.o
> -caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API) += caamrng.o
> caam_jr-$(CONFIG_CRYPTO_DEV_FSL_CAAM_PKC_API) += caampkc.o
> pkc_desc.o
>
> caam-$(CONFIG_CRYPTO_DEV_FSL_CAAM_CRYPTO_API_QI) += qi.o
> diff --git a/drivers/crypto/caam/caamrng.c
> b/drivers/crypto/caam/caamrng.c
> deleted file mode 100644
> index 70ddfbf90ac7..000000000000
> --- a/drivers/crypto/caam/caamrng.c
> +++ /dev/null
> @@ -1,351 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0+
> -/*
> - * caam - Freescale FSL CAAM support for hw_random
> - *
> - * Copyright 2011 Freescale Semiconductor, Inc.
> - * Copyright 2018-2019 NXP
> - *
> - * Based on caamalg.c crypto API driver.
> - *
> - * relationship between job descriptors to shared descriptors:
> - *
> - * --------------- --------------
> - * | JobDesc #0 |-------------------->| ShareDesc |
> - * | *(buffer 0) | |------------->| (generate) |
> - * --------------- | | (move) |
> - * | | (store) |
> - * --------------- | --------------
> - * | JobDesc #1 |------|
> - * | *(buffer 1) |
> - * ---------------
> - *
> - * A job desc looks like this:
> - *
> - * ---------------------
> - * | Header |
> - * | ShareDesc Pointer |
> - * | SEQ_OUT_PTR |
> - * | (output buffer) |
> - * ---------------------
> - *
> - * The SharedDesc never changes, and each job descriptor points to
> one of two
> - * buffers for each device, from which the data will be copied into
> the
> - * requested destination
> - */
> -
> -#include <linux/hw_random.h>
> -#include <linux/completion.h>
> -#include <linux/atomic.h>
> -
> -#include "compat.h"
> -
> -#include "regs.h"
> -#include "intern.h"
> -#include "desc_constr.h"
> -#include "jr.h"
> -#include "error.h"
> -
> -/*
> - * Maximum buffer size: maximum number of random, cache-aligned
> bytes that
> - * will be generated and moved to seq out ptr (extlen not allowed)
> - */
> -#define RN_BUF_SIZE (0xffff / L1_CACHE_BYTES * \
> - L1_CACHE_BYTES)
> -
> -/* length of descriptors */
> -#define DESC_JOB_O_LEN (CAAM_CMD_SZ * 2 +
> CAAM_PTR_SZ_MAX * 2)
> -#define DESC_RNG_LEN (3 * CAAM_CMD_SZ)
> -
> -/* Buffer, its dma address and lock */
> -struct buf_data {
> - u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
> - dma_addr_t addr;
> - struct completion filled;
> - u32 hw_desc[DESC_JOB_O_LEN];
> -#define BUF_NOT_EMPTY 0
> -#define BUF_EMPTY 1
> -#define BUF_PENDING 2 /* Empty, but with job pending --don't submit
> another */
> - atomic_t empty;
> -};
> -
> -/* rng per-device context */
> -struct caam_rng_ctx {
> - struct device *jrdev;
> - dma_addr_t sh_desc_dma;
> - u32 sh_desc[DESC_RNG_LEN];
> - unsigned int cur_buf_idx;
> - int current_buf;
> - struct buf_data bufs[2];
> -};
> -
> -static struct caam_rng_ctx *rng_ctx;
> -
> -/*
> - * Variable used to avoid double free of resources in case
> - * algorithm registration was unsuccessful
> - */
> -static bool init_done;
> -
> -static inline void rng_unmap_buf(struct device *jrdev, struct
> buf_data *bd)
> -{
> - if (bd->addr)
> - dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
> - DMA_FROM_DEVICE);
> -}
> -
> -static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
> -{
> - struct device *jrdev = ctx->jrdev;
> -
> - if (ctx->sh_desc_dma)
> - dma_unmap_single(jrdev, ctx->sh_desc_dma,
> - desc_bytes(ctx->sh_desc),
> DMA_TO_DEVICE);
> - rng_unmap_buf(jrdev, &ctx->bufs[0]);
> - rng_unmap_buf(jrdev, &ctx->bufs[1]);
> -}
> -
> -static void rng_done(struct device *jrdev, u32 *desc, u32 err, void
> *context)
> -{
> - struct buf_data *bd;
> -
> - bd = container_of(desc, struct buf_data, hw_desc[0]);
> -
> - if (err)
> - caam_jr_strstatus(jrdev, err);
> -
> - atomic_set(&bd->empty, BUF_NOT_EMPTY);
> - complete(&bd->filled);
> -
> - /* Buffer refilled, invalidate cache */
> - dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE,
> DMA_FROM_DEVICE);
> -
> - print_hex_dump_debug("rng refreshed buf@: ",
> DUMP_PREFIX_ADDRESS, 16, 4,
> - bd->buf, RN_BUF_SIZE, 1);
> -}
> -
> -static inline int submit_job(struct caam_rng_ctx *ctx, int
> to_current)
> -{
> - struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx-
> >current_buf)];
> - struct device *jrdev = ctx->jrdev;
> - u32 *desc = bd->hw_desc;
> - int err;
> -
> - dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx-
> >current_buf));
> - init_completion(&bd->filled);
> - err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
> - if (err)
> - complete(&bd->filled); /* don't wait on failed job*/
> - else
> - atomic_inc(&bd->empty); /* note if pending */
> -
> - return err;
> -}
> -
> -static int caam_read(struct hwrng *rng, void *data, size_t max, bool
> wait)
> -{
> - struct caam_rng_ctx *ctx = rng_ctx;
> - struct buf_data *bd = &ctx->bufs[ctx->current_buf];
> - int next_buf_idx, copied_idx;
> - int err;
> -
> - if (atomic_read(&bd->empty)) {
> - /* try to submit job if there wasn't one */
> - if (atomic_read(&bd->empty) == BUF_EMPTY) {
> - err = submit_job(ctx, 1);
> - /* if can't submit job, can't even wait */
> - if (err)
> - return 0;
> - }
> - /* no immediate data, so exit if not waiting */
> - if (!wait)
> - return 0;
> -
> - /* waiting for pending job */
> - if (atomic_read(&bd->empty))
> - wait_for_completion(&bd->filled);
> - }
> -
> - next_buf_idx = ctx->cur_buf_idx + max;
> - dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
> - __func__, ctx->current_buf, ctx->cur_buf_idx);
> -
> - /* if enough data in current buffer */
> - if (next_buf_idx < RN_BUF_SIZE) {
> - memcpy(data, bd->buf + ctx->cur_buf_idx, max);
> - ctx->cur_buf_idx = next_buf_idx;
> - return max;
> - }
> -
> - /* else, copy what's left... */
> - copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
> - memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
> - ctx->cur_buf_idx = 0;
> - atomic_set(&bd->empty, BUF_EMPTY);
> -
> - /* ...refill... */
> - submit_job(ctx, 1);
> -
> - /* and use next buffer */
> - ctx->current_buf = !ctx->current_buf;
> - dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx-
> >current_buf);
> -
> - /* since there already is some data read, don't wait */
> - return copied_idx + caam_read(rng, data + copied_idx,
> - max - copied_idx, false);
> -}
> -
> -static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
> -{
> - struct device *jrdev = ctx->jrdev;
> - u32 *desc = ctx->sh_desc;
> -
> - init_sh_desc(desc, HDR_SHARE_SERIAL);
> -
> - /* Generate random bytes */
> - append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG |
> - OP_ALG_PR_ON);
> -
> - /* Store bytes */
> - append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
> -
> - ctx->sh_desc_dma = dma_map_single(jrdev, desc,
> desc_bytes(desc),
> - DMA_TO_DEVICE);
> - if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
> - dev_err(jrdev, "unable to map shared descriptor\n");
> - return -ENOMEM;
> - }
> -
> - print_hex_dump_debug("rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16,
> 4,
> - desc, desc_bytes(desc), 1);
> -
> - return 0;
> -}
> -
> -static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int
> buf_id)
> -{
> - struct device *jrdev = ctx->jrdev;
> - struct buf_data *bd = &ctx->bufs[buf_id];
> - u32 *desc = bd->hw_desc;
> - int sh_len = desc_len(ctx->sh_desc);
> -
> - init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len,
> HDR_SHARE_DEFER |
> - HDR_REVERSE);
> -
> - bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE,
> DMA_FROM_DEVICE);
> - if (dma_mapping_error(jrdev, bd->addr)) {
> - dev_err(jrdev, "unable to map dst\n");
> - return -ENOMEM;
> - }
> -
> - append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
> -
> - print_hex_dump_debug("rng job desc@: ", DUMP_PREFIX_ADDRESS,
> 16, 4,
> - desc, desc_bytes(desc), 1);
> -
> - return 0;
> -}
> -
> -static void caam_cleanup(struct hwrng *rng)
> -{
> - int i;
> - struct buf_data *bd;
> -
> - for (i = 0; i < 2; i++) {
> - bd = &rng_ctx->bufs[i];
> - if (atomic_read(&bd->empty) == BUF_PENDING)
> - wait_for_completion(&bd->filled);
> - }
> -
> - rng_unmap_ctx(rng_ctx);
> -}
> -
> -static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
> -{
> - struct buf_data *bd = &ctx->bufs[buf_id];
> - int err;
> -
> - err = rng_create_job_desc(ctx, buf_id);
> - if (err)
> - return err;
> -
> - atomic_set(&bd->empty, BUF_EMPTY);
> - submit_job(ctx, buf_id == ctx->current_buf);
> - wait_for_completion(&bd->filled);
> -
> - return 0;
> -}
> -
> -static int caam_init_rng(struct caam_rng_ctx *ctx, struct device
> *jrdev)
> -{
> - int err;
> -
> - ctx->jrdev = jrdev;
> -
> - err = rng_create_sh_desc(ctx);
> - if (err)
> - return err;
> -
> - ctx->current_buf = 0;
> - ctx->cur_buf_idx = 0;
> -
> - err = caam_init_buf(ctx, 0);
> - if (err)
> - return err;
> -
> - return caam_init_buf(ctx, 1);
> -}
> -
> -static struct hwrng caam_rng = {
> - .name = "rng-caam",
> - .cleanup = caam_cleanup,
> - .read = caam_read,
> -};
> -
> -void caam_rng_exit(void)
> -{
> - if (!init_done)
> - return;
> -
> - caam_jr_free(rng_ctx->jrdev);
> - hwrng_unregister(&caam_rng);
> - kfree(rng_ctx);
> -}
> -
> -int caam_rng_init(struct device *ctrldev)
> -{
> - struct device *dev;
> - struct caam_drv_private *priv = dev_get_drvdata(ctrldev);
> - int err;
> - init_done = false;
> -
> - if (!caam_has_rng(priv))
> - return 0;
> -
> - dev = caam_jr_alloc();
> - if (IS_ERR(dev)) {
> - pr_err("Job Ring Device allocation for transform
> failed\n");
> - return PTR_ERR(dev);
> - }
> - rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
> - if (!rng_ctx) {
> - err = -ENOMEM;
> - goto free_caam_alloc;
> - }
> - err = caam_init_rng(rng_ctx, dev);
> - if (err)
> - goto free_rng_ctx;
> -
> - dev_info(dev, "registering rng-caam\n");
> -
> - err = hwrng_register(&caam_rng);
> - if (!err) {
> - init_done = true;
> - return err;
> - }
> -
> -free_rng_ctx:
> - kfree(rng_ctx);
> -free_caam_alloc:
> - caam_jr_free(dev);
> - return err;
> -}
> diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
> index 8054ec29d35a..adbdef06bcf9 100644
> --- a/drivers/crypto/caam/ctrl.c
> +++ b/drivers/crypto/caam/ctrl.c
> @@ -907,6 +907,12 @@ static int caam_probe(struct platform_device
> *pdev)
> &ctrlpriv->ctl_tdsk_wrap);
> #endif
>
> + ret = caam_trng_register(dev);
> + if (ret) {
> + dev_err(dev, "Failed to register HWRNG interface\n");
> + return ret;
> + }
> +
> ret = devm_of_platform_populate(dev);
> if (ret)
> dev_err(dev, "JR platform devices creation error\n");
> diff --git a/drivers/crypto/caam/intern.h
> b/drivers/crypto/caam/intern.h
> index f815e1ad4608..54bb04aa86bd 100644
> --- a/drivers/crypto/caam/intern.h
> +++ b/drivers/crypto/caam/intern.h
> @@ -174,20 +174,15 @@ static inline void caam_pkc_exit(void)
>
> #ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API
>
> -int caam_rng_init(struct device *dev);
> -void caam_rng_exit(void);
> +int caam_trng_register(struct device *dev);
>
> #else
>
> -static inline int caam_rng_init(struct device *dev)
> +static inline int caam_trng_register(struct device *dev)
> {
> return 0;
> }
>
> -static inline void caam_rng_exit(void)
> -{
> -}
> -
> #endif /* CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_API */
>
> #ifdef CONFIG_CAAM_QI
> diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
> index fc97cde27059..c745b7044fe6 100644
> --- a/drivers/crypto/caam/jr.c
> +++ b/drivers/crypto/caam/jr.c
> @@ -37,7 +37,6 @@ static void register_algs(struct device *dev)
> caam_algapi_init(dev);
> caam_algapi_hash_init(dev);
> caam_pkc_init(dev);
> - caam_rng_init(dev);
> caam_qi_algapi_init(dev);
>
> algs_unlock:
> @@ -53,7 +52,6 @@ static void unregister_algs(void)
>
> caam_qi_algapi_exit();
>
> - caam_rng_exit();
> caam_pkc_exit();
> caam_algapi_hash_exit();
> caam_algapi_exit();
> diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
> index fe1f8c1409fd..262399387e27 100644
> --- a/drivers/crypto/caam/regs.h
> +++ b/drivers/crypto/caam/regs.h
> @@ -488,6 +488,7 @@ struct rngtst {
> /* RNG4 TRNG test registers */
> struct rng4tst {
> #define RTMCTL_ACC BIT(5) /* TRNG access mode */
> +#define RTMCTL_ENT_VAL BIT(10)
> #define RTMCTL_PRGM BIT(16) /* 1 -> program mode, 0 -> run mode */
> #define RTMCTL_SAMP_MODE_VON_NEUMANN_ES_SC 0 /* use von Neumann
> data in
> both entropy
> shifter and
> @@ -521,7 +522,9 @@ struct rng4tst {
> u32 rtfrqmax; /* PRGM=1: freq. count max. limit
> register */
> u32 rtfrqcnt; /* PRGM=0: freq. count register */
> };
> - u32 rsvd1[40];
> + u32 rsvd1[8];
> + u32 rtent[16]; /* RTENT0 - RTENT15 */
> + u32 rsvd2[16]; /* RTPKRCNTn */
> #define RDSTA_SKVT 0x80000000
> #define RDSTA_SKVN 0x40000000
> #define RDSTA_PR0 BIT(4)
> @@ -530,7 +533,7 @@ struct rng4tst {
> #define RDSTA_IF1 0x00000002
> #define RDSTA_IFMASK (RDSTA_PR1 | RDSTA_PR0 | RDSTA_IF1 | RDSTA_IF0)
> u32 rdsta;
> - u32 rsvd2[15];
> + u32 rsvd3[15];
> };
>
> /*
> diff --git a/drivers/crypto/caam/trng.c b/drivers/crypto/caam/trng.c
> new file mode 100644
> index 000000000000..881fe588a229
> --- /dev/null
> +++ b/drivers/crypto/caam/trng.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * hw_random interface for TRNG generator in CAAM RNG block
> + *
> + * Copyright 2019 Zodiac Inflight Innovations
> + *
> + */
> +
> +#include <linux/hw_random.h>
> +
> +#include "compat.h"
> +#include "regs.h"
> +#include "intern.h"
> +
> +struct caam_trng_ctx {
> + struct rng4tst __iomem *r4tst;
> + struct hwrng rng;
> +};
> +
> +static bool caam_trng_busy(struct caam_trng_ctx *ctx)
> +{
> + return !(rd_reg32(&ctx->r4tst->rtmctl) & RTMCTL_ENT_VAL);
> +}
> +
> +static int caam_trng_read(struct hwrng *rng, void *data, size_t max,
> bool wait)
> +{
> + struct caam_trng_ctx *ctx = (void *)rng->priv;
> + u32 rtent[ARRAY_SIZE(ctx->r4tst->rtent)];
> + size_t residue = max;
> +
> + if (!wait)
> + return 0;
> +
> + clrsetbits_32(&ctx->r4tst->rtmctl, 0, RTMCTL_ACC);
> +
> + do {
> + const size_t chunk = min(residue, sizeof(rtent));
> + unsigned int i;
> +
> + do {
> + /*
> + * It takes about 70 ms to finish on i.MX6 and
> + * i.MX8MQ
> + */
> + msleep(70);
> + } while (caam_trng_busy(ctx));
> +
> + for (i = 0; i < DIV_ROUND_UP(chunk, sizeof(u32)); i++)
> + rtent[i] = rd_reg32(&ctx->r4tst->rtent[i]);
> +
> + memcpy(data, rtent, chunk);
> +
> + residue -= chunk;
> + data += chunk;
> + } while (residue);
> +
> + clrsetbits_32(&ctx->r4tst->rtmctl, RTMCTL_ACC, 0);
> +
> + return max;
> +}
> +
> +int caam_trng_register(struct device *ctrldev)
> +{
> + struct caam_drv_private *priv = dev_get_drvdata(ctrldev);
> +
> + if (caam_has_rng(priv)) {
> + struct caam_trng_ctx *ctx;
> + int err;
> +
> + ctx = devm_kzalloc(ctrldev, sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return -ENOMEM;
> +
> + ctx->r4tst = &priv->ctrl->r4tst[0];
> +
> + ctx->rng.name = "trng-caam";
> + ctx->rng.read = caam_trng_read;
> + ctx->rng.priv = (unsigned long)ctx;
> + ctx->rng.quality = 999;
> +
> + dev_info(ctrldev, "registering %s\n", ctx->rng.name);
> +
> + err = devm_hwrng_register(ctrldev, &ctx->rng);
> + if (err)
> + return err;
> + }
> +
> + return 0;
> +}
