1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2019 HiSilicon Limited. */
 3
 4#include <linux/acpi.h>
 5#include <linux/err.h>
 6#include <linux/hw_random.h>
 7#include <linux/io.h>
 8#include <linux/iopoll.h>
 9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/platform_device.h>
12#include <linux/random.h>
13
14#define HISI_TRNG_REG		0x00F0
15#define HISI_TRNG_BYTES		4
16#define HISI_TRNG_QUALITY	512
17#define SLEEP_US		10
18#define TIMEOUT_US		10000
19
20struct hisi_trng {
21	void __iomem *base;
22	struct hwrng rng;
23};
24
25static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
26{
27	struct hisi_trng *trng;
28	int currsize = 0;
29	u32 val = 0;
30	u32 ret;
31
32	trng = container_of(rng, struct hisi_trng, rng);
33
34	do {
35		ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
36					 val, SLEEP_US, TIMEOUT_US);
37		if (ret)
38			return currsize;
39
40		if (max - currsize >= HISI_TRNG_BYTES) {
41			memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
42			currsize += HISI_TRNG_BYTES;
43			if (currsize == max)
44				return currsize;
45			continue;
46		}
47
48		/* copy remaining bytes */
49		memcpy(buf + currsize, &val, max - currsize);
50		currsize = max;
51	} while (currsize < max);
52
53	return currsize;
54}
55
56static int hisi_trng_probe(struct platform_device *pdev)
57{
58	struct hisi_trng *trng;
59	int ret;
60
61	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
62	if (!trng)
63		return -ENOMEM;
64
65	trng->base = devm_platform_ioremap_resource(pdev, 0);
66	if (IS_ERR(trng->base))
67		return PTR_ERR(trng->base);
68
69	trng->rng.name = pdev->name;
70	trng->rng.read = hisi_trng_read;
71	trng->rng.quality = HISI_TRNG_QUALITY;
72
73	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
74	if (ret)
75		dev_err(&pdev->dev, "failed to register hwrng!\n");
76
77	return ret;
78}
79
80static const struct acpi_device_id hisi_trng_acpi_match[] = {
81	{ "HISI02B3", 0 },
82	{ }
83};
84MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
85
86static struct platform_driver hisi_trng_driver = {
87	.probe		= hisi_trng_probe,
88	.driver		= {
89		.name	= "hisi-trng-v2",
90		.acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
91	},
92};
93
94module_platform_driver(hisi_trng_driver);
95
96MODULE_LICENSE("GPL v2");
97MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
98MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
99MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");