1// SPDX-License-Identifier: GPL-2.0
2/*
3 * sun8i-ce-trng.c - hardware cryptographic offloader for
4 * Allwinner H3/A64/H5/H2+/H6/R40 SoC
5 *
6 * Copyright (C) 2015-2020 Corentin Labbe <clabbe@baylibre.com>
7 *
8 * This file handle the TRNG
9 *
10 * You could find a link for the datasheet in Documentation/arch/arm/sunxi.rst
11 */
12#include "sun8i-ce.h"
13#include <linux/dma-mapping.h>
14#include <linux/pm_runtime.h>
15#include <linux/hw_random.h>
16/*
17 * Note that according to the algorithm ID, 2 versions of the TRNG exists,
18 * The first present in H3/H5/R40/A64 and the second present in H6.
19 * This file adds support for both, but only the second is working
20 * reliabily according to rngtest.
21 **/
22
23static int sun8i_ce_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)
24{
25	struct sun8i_ce_dev *ce;
26	dma_addr_t dma_dst;
27	int err = 0;
28	int flow = 3;
29	unsigned int todo;
30	struct sun8i_ce_flow *chan;
31	struct ce_task *cet;
32	u32 common;
33	void *d;
34
35	ce = container_of(rng, struct sun8i_ce_dev, trng);
36
37	/* round the data length to a multiple of 32*/
38	todo = max + 32;
39	todo -= todo % 32;
40
41	d = kzalloc(todo, GFP_KERNEL | GFP_DMA);
42	if (!d)
43		return -ENOMEM;
44
45#ifdef CONFIG_CRYPTO_DEV_SUN8I_CE_DEBUG
46	ce->hwrng_stat_req++;
47	ce->hwrng_stat_bytes += todo;
48#endif
49
50	dma_dst = dma_map_single(ce->dev, d, todo, DMA_FROM_DEVICE);
51	if (dma_mapping_error(ce->dev, dma_dst)) {
52		dev_err(ce->dev, "Cannot DMA MAP DST\n");
53		err = -EFAULT;
54		goto err_dst;
55	}
56
57	err = pm_runtime_resume_and_get(ce->dev);
58	if (err < 0)
59		goto err_pm;
60
61	mutex_lock(&ce->rnglock);
62	chan = &ce->chanlist[flow];
63
64	cet = &chan->tl[0];
65	memset(cet, 0, sizeof(struct ce_task));
66
67	cet->t_id = cpu_to_le32(flow);
68	common = ce->variant->trng | CE_COMM_INT;
69	cet->t_common_ctl = cpu_to_le32(common);
70
71	/* recent CE (H6) need length in bytes, in word otherwise */
72	if (ce->variant->trng_t_dlen_in_bytes)
73		cet->t_dlen = cpu_to_le32(todo);
74	else
75		cet->t_dlen = cpu_to_le32(todo / 4);
76
77	cet->t_sym_ctl = 0;
78	cet->t_asym_ctl = 0;
79
80	cet->t_dst[0].addr = cpu_to_le32(dma_dst);
81	cet->t_dst[0].len = cpu_to_le32(todo / 4);
82	ce->chanlist[flow].timeout = todo;
83
84	err = sun8i_ce_run_task(ce, 3, "TRNG");
85	mutex_unlock(&ce->rnglock);
86
87	pm_runtime_put(ce->dev);
88
89err_pm:
90	dma_unmap_single(ce->dev, dma_dst, todo, DMA_FROM_DEVICE);
91
92	if (!err) {
93		memcpy(data, d, max);
94		err = max;
95	}
96err_dst:
97	kfree_sensitive(d);
98	return err;
99}
100
101int sun8i_ce_hwrng_register(struct sun8i_ce_dev *ce)
102{
103	int ret;
104
105	if (ce->variant->trng == CE_ID_NOTSUPP) {
106		dev_info(ce->dev, "TRNG not supported\n");
107		return 0;
108	}
109	ce->trng.name = "sun8i Crypto Engine TRNG";
110	ce->trng.read = sun8i_ce_trng_read;
111
112	ret = hwrng_register(&ce->trng);
113	if (ret)
114		dev_err(ce->dev, "Fail to register the TRNG\n");
115	return ret;
116}
117
118void sun8i_ce_hwrng_unregister(struct sun8i_ce_dev *ce)
119{
120	if (ce->variant->trng == CE_ID_NOTSUPP)
121		return;
122	hwrng_unregister(&ce->trng);
123}
124