1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * sun8i-ss-prng.c - hardware cryptographic offloader for
4 * Allwinner A80/A83T SoC
5 *
6 * Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
7 *
8 * This file handle the PRNG found in the SS
9 *
10 * You could find a link for the datasheet in Documentation/arm/sunxi.rst
11 */
12 #include "sun8i-ss.h"
13 #include <linux/dma-mapping.h>
14 #include <linux/pm_runtime.h>
15 #include <crypto/internal/rng.h>
16
sun8i_ss_prng_seed(struct crypto_rng * tfm,const u8 * seed,unsigned int slen)17 int sun8i_ss_prng_seed(struct crypto_rng *tfm, const u8 *seed,
18 unsigned int slen)
19 {
20 struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
21
22 if (ctx->seed && ctx->slen != slen) {
23 kfree_sensitive(ctx->seed);
24 ctx->slen = 0;
25 ctx->seed = NULL;
26 }
27 if (!ctx->seed)
28 ctx->seed = kmalloc(slen, GFP_KERNEL | GFP_DMA);
29 if (!ctx->seed)
30 return -ENOMEM;
31
32 memcpy(ctx->seed, seed, slen);
33 ctx->slen = slen;
34
35 return 0;
36 }
37
sun8i_ss_prng_init(struct crypto_tfm * tfm)38 int sun8i_ss_prng_init(struct crypto_tfm *tfm)
39 {
40 struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
41
42 memset(ctx, 0, sizeof(struct sun8i_ss_rng_tfm_ctx));
43 return 0;
44 }
45
sun8i_ss_prng_exit(struct crypto_tfm * tfm)46 void sun8i_ss_prng_exit(struct crypto_tfm *tfm)
47 {
48 struct sun8i_ss_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
49
50 kfree_sensitive(ctx->seed);
51 ctx->seed = NULL;
52 ctx->slen = 0;
53 }
54
sun8i_ss_prng_generate(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int dlen)55 int sun8i_ss_prng_generate(struct crypto_rng *tfm, const u8 *src,
56 unsigned int slen, u8 *dst, unsigned int dlen)
57 {
58 struct sun8i_ss_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
59 struct rng_alg *alg = crypto_rng_alg(tfm);
60 struct sun8i_ss_alg_template *algt;
61 struct sun8i_ss_dev *ss;
62 dma_addr_t dma_iv, dma_dst;
63 unsigned int todo;
64 int err = 0;
65 int flow;
66 void *d;
67 u32 v;
68
69 algt = container_of(alg, struct sun8i_ss_alg_template, alg.rng);
70 ss = algt->ss;
71
72 if (ctx->slen == 0) {
73 dev_err(ss->dev, "The PRNG is not seeded\n");
74 return -EINVAL;
75 }
76
77 /* The SS does not give an updated seed, so we need to get a new one.
78 * So we will ask for an extra PRNG_SEED_SIZE data.
79 * We want dlen + seedsize rounded up to a multiple of PRNG_DATA_SIZE
80 */
81 todo = dlen + PRNG_SEED_SIZE + PRNG_DATA_SIZE;
82 todo -= todo % PRNG_DATA_SIZE;
83
84 d = kzalloc(todo, GFP_KERNEL | GFP_DMA);
85 if (!d)
86 return -ENOMEM;
87
88 flow = sun8i_ss_get_engine_number(ss);
89
90 #ifdef CONFIG_CRYPTO_DEV_SUN8I_SS_DEBUG
91 algt->stat_req++;
92 algt->stat_bytes += todo;
93 #endif
94
95 v = SS_ALG_PRNG | SS_PRNG_CONTINUE | SS_START;
96 if (flow)
97 v |= SS_FLOW1;
98 else
99 v |= SS_FLOW0;
100
101 dma_iv = dma_map_single(ss->dev, ctx->seed, ctx->slen, DMA_TO_DEVICE);
102 if (dma_mapping_error(ss->dev, dma_iv)) {
103 dev_err(ss->dev, "Cannot DMA MAP IV\n");
104 err = -EFAULT;
105 goto err_free;
106 }
107
108 dma_dst = dma_map_single(ss->dev, d, todo, DMA_FROM_DEVICE);
109 if (dma_mapping_error(ss->dev, dma_dst)) {
110 dev_err(ss->dev, "Cannot DMA MAP DST\n");
111 err = -EFAULT;
112 goto err_iv;
113 }
114
115 err = pm_runtime_resume_and_get(ss->dev);
116 if (err < 0)
117 goto err_pm;
118 err = 0;
119
120 mutex_lock(&ss->mlock);
121 writel(dma_iv, ss->base + SS_IV_ADR_REG);
122 /* the PRNG act badly (failing rngtest) without SS_KEY_ADR_REG set */
123 writel(dma_iv, ss->base + SS_KEY_ADR_REG);
124 writel(dma_dst, ss->base + SS_DST_ADR_REG);
125 writel(todo / 4, ss->base + SS_LEN_ADR_REG);
126
127 reinit_completion(&ss->flows[flow].complete);
128 ss->flows[flow].status = 0;
129 /* Be sure all data is written before enabling the task */
130 wmb();
131
132 writel(v, ss->base + SS_CTL_REG);
133
134 wait_for_completion_interruptible_timeout(&ss->flows[flow].complete,
135 msecs_to_jiffies(todo));
136 if (ss->flows[flow].status == 0) {
137 dev_err(ss->dev, "DMA timeout for PRNG (size=%u)\n", todo);
138 err = -EFAULT;
139 }
140 /* Since cipher and hash use the linux/cryptoengine and that we have
141 * a cryptoengine per flow, we are sure that they will issue only one
142 * request per flow.
143 * Since the cryptoengine wait for completion before submitting a new
144 * one, the mlock could be left just after the final writel.
145 * But cryptoengine cannot handle crypto_rng, so we need to be sure
146 * nothing will use our flow.
147 * The easiest way is to grab mlock until the hardware end our requests.
148 * We could have used a per flow lock, but this would increase
149 * complexity.
150 * The drawback is that no request could be handled for the other flow.
151 */
152 mutex_unlock(&ss->mlock);
153
154 pm_runtime_put(ss->dev);
155
156 err_pm:
157 dma_unmap_single(ss->dev, dma_dst, todo, DMA_FROM_DEVICE);
158 err_iv:
159 dma_unmap_single(ss->dev, dma_iv, ctx->slen, DMA_TO_DEVICE);
160
161 if (!err) {
162 memcpy(dst, d, dlen);
163 /* Update seed */
164 memcpy(ctx->seed, d + dlen, ctx->slen);
165 }
166 err_free:
167 kfree_sensitive(d);
168
169 return err;
170 }
171