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
20 struct hisi_trng {
21 void __iomem *base;
22 struct hwrng rng;
23 };
24
hisi_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)25 static 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
hisi_trng_probe(struct platform_device * pdev)56 static 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
80 static const struct acpi_device_id hisi_trng_acpi_match[] = {
81 { "HISI02B3", 0 },
82 { }
83 };
84 MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
85
86 static 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
94 module_platform_driver(hisi_trng_driver);
95
96 MODULE_LICENSE("GPL v2");
97 MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
98 MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
99 MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");
100