1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2020 Michael Walle <michael@walle.cc>
4 *
5 * Driver for Freescale Cryptographic Accelerator and Assurance
6 * Module (CAAM) hardware random number generator.
7 */
8
9 #include <asm/cache.h>
10 #include <common.h>
11 #include <cpu_func.h>
12 #include <dm.h>
13 #include <rng.h>
14 #include <linux/kernel.h>
15 #include "desc_constr.h"
16 #include "jobdesc.h"
17 #include "jr.h"
18
19 #define CAAM_RNG_MAX_FIFO_STORE_SIZE 16
20 #define CAAM_RNG_DESC_LEN (3 * CAAM_CMD_SZ + CAAM_PTR_SZ)
21
22 struct caam_rng_priv {
23 u32 desc[CAAM_RNG_DESC_LEN / 4];
24 u8 data[CAAM_RNG_MAX_FIFO_STORE_SIZE] __aligned(ARCH_DMA_MINALIGN);
25 };
26
caam_rng_read_one(struct caam_rng_priv * priv)27 static int caam_rng_read_one(struct caam_rng_priv *priv)
28 {
29 int size = ALIGN(CAAM_RNG_MAX_FIFO_STORE_SIZE, ARCH_DMA_MINALIGN);
30 int ret;
31
32 ret = run_descriptor_jr(priv->desc);
33 if (ret < 0)
34 return -EIO;
35
36 invalidate_dcache_range((unsigned long)priv->data,
37 (unsigned long)priv->data + size);
38
39 return 0;
40 }
41
caam_rng_read(struct udevice * dev,void * data,size_t len)42 static int caam_rng_read(struct udevice *dev, void *data, size_t len)
43 {
44 struct caam_rng_priv *priv = dev_get_priv(dev);
45 u8 *buffer = data;
46 size_t size;
47 int ret;
48
49 while (len) {
50 ret = caam_rng_read_one(priv);
51 if (ret)
52 return ret;
53
54 size = min(len, (size_t)CAAM_RNG_MAX_FIFO_STORE_SIZE);
55
56 memcpy(buffer, priv->data, size);
57 buffer += size;
58 len -= size;
59 }
60
61 return 0;
62 }
63
caam_rng_probe(struct udevice * dev)64 static int caam_rng_probe(struct udevice *dev)
65 {
66 struct caam_rng_priv *priv = dev_get_priv(dev);
67 ulong size = ALIGN(CAAM_RNG_DESC_LEN, ARCH_DMA_MINALIGN);
68
69 inline_cnstr_jobdesc_rng(priv->desc, priv->data,
70 CAAM_RNG_MAX_FIFO_STORE_SIZE);
71 flush_dcache_range((unsigned long)priv->desc,
72 (unsigned long)priv->desc + size);
73
74 return 0;
75 }
76
77 static const struct dm_rng_ops caam_rng_ops = {
78 .read = caam_rng_read,
79 };
80
81 U_BOOT_DRIVER(caam_rng) = {
82 .name = "caam-rng",
83 .id = UCLASS_RNG,
84 .ops = &caam_rng_ops,
85 .probe = caam_rng_probe,
86 .priv_auto = sizeof(struct caam_rng_priv),
87 .flags = DM_FLAG_ALLOC_PRIV_DMA,
88 };
89