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// SPDX-License-Identifier: GPL-2.0
/*
* sun8i-ss-prng.c - hardware cryptographic offloader for
* Allwinner A80/A83T SoC
*
* Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
*
* This file handle the PRNG found in the SS
*
* You could find a link for the datasheet in Documentation/arm/sunxi.rst
*/
#include "sun8i-ss.h"
#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pm_runtime.h>
#include <crypto/internal/rng.h>
int sun8i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed,
unsigned int slen)
{
struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
if (ctx->seed && ctx->slen != slen) {
kfree_sensitive(ctx->seed);
ctx->slen = 0;
ctx->seed = NULL;
}
if (!ctx->seed)
ctx->seed = kmalloc(slen, GFP_KERNEL);
if (!ctx->seed)
return -ENOMEM;
memcpy(ctx->seed, seed, slen);
ctx->slen = slen;
return 0;
}
int sun8i_ss_prng_init(struct crypto_tfm *tfm)
{
struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
memset(ctx, 0, sizeof(struct sun8i_ss_rng_tfm_ctx));
return 0;
}
void sun8i_ss_prng_exit(struct crypto_tfm *tfm)
{
struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
kfree_sensitive(ctx->seed);
ctx->seed = NULL;
ctx->slen = 0;
}
int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int dlen)
{
struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
struct rng_alg *alg = crypto_rng_alg(tfm);
struct sun8i_ss_alg_template *algt;
unsigned int todo_with_padding;
struct sun8i_ss_dev *ss;
dma_addr_t dma_iv, dma_dst;
unsigned int todo;
int err = 0;
int flow;
void *d;
u32 v;
algt = container_of(alg, struct sun8i_ss_alg_template, alg.rng);
ss = algt->ss;
if (ctx->slen == 0) {
dev_err(ss->dev, "The PRNG is not seeded\n");
return -EINVAL;
}
/* The SS does not give an updated seed, so we need to get a new one.
* So we will ask for an extra PRNG_SEED_SIZE data.
* We want dlen + seedsize rounded up to a multiple of PRNG_DATA_SIZE
*/
todo = dlen + PRNG_SEED_SIZE + PRNG_DATA_SIZE;
todo -= todo % PRNG_DATA_SIZE;
todo_with_padding = ALIGN(todo, dma_get_cache_alignment());
if (todo_with_padding < todo || todo < dlen)
return -EOVERFLOW;
d = kzalloc(todo_with_padding, GFP_KERNEL);
if (!d)
return -ENOMEM;
flow = sun8i_ss_get_engine_number(ss);
#ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_DEBUG
algt->stat_req++;
algt->stat_bytes += todo;
#endif
v = SS_ALG_PRNG | SS_PRNG_CONTINUE | SS_START;
if (flow)
v |= SS_FLOW1;
else
v |= SS_FLOW0;
dma_iv = dma_map_single(ss->dev, ctx->seed, ctx->slen, DMA_TO_DEVICE);
if (dma_mapping_error(ss->dev, dma_iv)) {
dev_err(ss->dev, "Cannot DMA MAP IV\n");
err = -EFAULT;
goto err_free;
}
dma_dst = dma_map_single(ss->dev, d, todo, DMA_FROM_DEVICE);
if (dma_mapping_error(ss->dev, dma_dst)) {
dev_err(ss->dev, "Cannot DMA MAP DST\n");
err = -EFAULT;
goto err_iv;
}
err = pm_runtime_resume_and_get(ss->dev);
if (err < 0)
goto err_pm;
err = 0;
mutex_lock(&ss->mlock);
writel(dma_iv, ss->base + SS_IV_ADR_REG);
/* the PRNG act badly (failing rngtest) without SS_KEY_ADR_REG set */
writel(dma_iv, ss->base + SS_KEY_ADR_REG);
writel(dma_dst, ss->base + SS_DST_ADR_REG);
writel(todo / 4, ss->base + SS_LEN_ADR_REG);
reinit_completion(&ss->flows[flow].complete);
ss->flows[flow].status = 0;
/* Be sure all data is written before enabling the task */
wmb();
writel(v, ss->base + SS_CTL_REG);
wait_for_completion_interruptible_timeout(&ss->flows[flow].complete,
msecs_to_jiffies(todo));
if (ss->flows[flow].status == 0) {
dev_err(ss->dev, "DMA timeout for PRNG (size=%u)\n", todo);
err = -EFAULT;
}
/* Since cipher and hash use the linux/cryptoengine and that we have
* a cryptoengine per flow, we are sure that they will issue only one
* request per flow.
* Since the cryptoengine wait for completion before submitting a new
* one, the mlock could be left just after the final writel.
* But cryptoengine cannot handle crypto_rng, so we need to be sure
* nothing will use our flow.
* The easiest way is to grab mlock until the hardware end our requests.
* We could have used a per flow lock, but this would increase
* complexity.
* The drawback is that no request could be handled for the other flow.
*/
mutex_unlock(&ss->mlock);
pm_runtime_put(ss->dev);
err_pm:
dma_unmap_single(ss->dev, dma_dst, todo, DMA_FROM_DEVICE);
err_iv:
dma_unmap_single(ss->dev, dma_iv, ctx->slen, DMA_TO_DEVICE);
if (!err) {
memcpy(dst, d, dlen);
/* Update seed */
memcpy(ctx->seed, d + dlen, ctx->slen);
}
err_free:
kfree_sensitive(d);
return err;
}
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