1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /* Copyright (c) 2019 HiSilicon Limited. */
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun #include <linux/acpi.h>
5*4882a593Smuzhiyun #include <linux/err.h>
6*4882a593Smuzhiyun #include <linux/hw_random.h>
7*4882a593Smuzhiyun #include <linux/io.h>
8*4882a593Smuzhiyun #include <linux/iopoll.h>
9*4882a593Smuzhiyun #include <linux/kernel.h>
10*4882a593Smuzhiyun #include <linux/module.h>
11*4882a593Smuzhiyun #include <linux/platform_device.h>
12*4882a593Smuzhiyun #include <linux/random.h>
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #define HISI_TRNG_REG 0x00F0
15*4882a593Smuzhiyun #define HISI_TRNG_BYTES 4
16*4882a593Smuzhiyun #define HISI_TRNG_QUALITY 512
17*4882a593Smuzhiyun #define SLEEP_US 10
18*4882a593Smuzhiyun #define TIMEOUT_US 10000
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun struct hisi_trng {
21*4882a593Smuzhiyun void __iomem *base;
22*4882a593Smuzhiyun struct hwrng rng;
23*4882a593Smuzhiyun };
24*4882a593Smuzhiyun
hisi_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)25*4882a593Smuzhiyun static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun struct hisi_trng *trng;
28*4882a593Smuzhiyun int currsize = 0;
29*4882a593Smuzhiyun u32 val = 0;
30*4882a593Smuzhiyun u32 ret;
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun trng = container_of(rng, struct hisi_trng, rng);
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun do {
35*4882a593Smuzhiyun ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
36*4882a593Smuzhiyun val, SLEEP_US, TIMEOUT_US);
37*4882a593Smuzhiyun if (ret)
38*4882a593Smuzhiyun return currsize;
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun if (max - currsize >= HISI_TRNG_BYTES) {
41*4882a593Smuzhiyun memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
42*4882a593Smuzhiyun currsize += HISI_TRNG_BYTES;
43*4882a593Smuzhiyun if (currsize == max)
44*4882a593Smuzhiyun return currsize;
45*4882a593Smuzhiyun continue;
46*4882a593Smuzhiyun }
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun /* copy remaining bytes */
49*4882a593Smuzhiyun memcpy(buf + currsize, &val, max - currsize);
50*4882a593Smuzhiyun currsize = max;
51*4882a593Smuzhiyun } while (currsize < max);
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun return currsize;
54*4882a593Smuzhiyun }
55*4882a593Smuzhiyun
hisi_trng_probe(struct platform_device * pdev)56*4882a593Smuzhiyun static int hisi_trng_probe(struct platform_device *pdev)
57*4882a593Smuzhiyun {
58*4882a593Smuzhiyun struct hisi_trng *trng;
59*4882a593Smuzhiyun int ret;
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
62*4882a593Smuzhiyun if (!trng)
63*4882a593Smuzhiyun return -ENOMEM;
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun trng->base = devm_platform_ioremap_resource(pdev, 0);
66*4882a593Smuzhiyun if (IS_ERR(trng->base))
67*4882a593Smuzhiyun return PTR_ERR(trng->base);
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun trng->rng.name = pdev->name;
70*4882a593Smuzhiyun trng->rng.read = hisi_trng_read;
71*4882a593Smuzhiyun trng->rng.quality = HISI_TRNG_QUALITY;
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun ret = devm_hwrng_register(&pdev->dev, &trng->rng);
74*4882a593Smuzhiyun if (ret)
75*4882a593Smuzhiyun dev_err(&pdev->dev, "failed to register hwrng!\n");
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun return ret;
78*4882a593Smuzhiyun }
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun static const struct acpi_device_id hisi_trng_acpi_match[] = {
81*4882a593Smuzhiyun { "HISI02B3", 0 },
82*4882a593Smuzhiyun { }
83*4882a593Smuzhiyun };
84*4882a593Smuzhiyun MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun static struct platform_driver hisi_trng_driver = {
87*4882a593Smuzhiyun .probe = hisi_trng_probe,
88*4882a593Smuzhiyun .driver = {
89*4882a593Smuzhiyun .name = "hisi-trng-v2",
90*4882a593Smuzhiyun .acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
91*4882a593Smuzhiyun },
92*4882a593Smuzhiyun };
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun module_platform_driver(hisi_trng_driver);
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
97*4882a593Smuzhiyun MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
98*4882a593Smuzhiyun MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
99*4882a593Smuzhiyun MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");
100