tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/module.h>
13#include <linux/mod_devicetable.h>
14#include <linux/kernel.h>
15#include <linux/platform_device.h>
16#include <linux/random.h>
17#include <linux/hw_random.h>
18
19static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
20{
21 unsigned long *buf;
22 int i, len;
23
24 /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */
25 len = max / sizeof(unsigned long);
26
27 buf = (unsigned long *)data;
28
29 for (i = 0; i < len; i++)
30 powernv_get_random_long(buf++);
31
32 return len * sizeof(unsigned long);
33}
34
35static struct hwrng powernv_hwrng = {
36 .name = "powernv-rng",
37 .read = powernv_rng_read,
38};
39
40static int powernv_rng_remove(struct platform_device *pdev)
41{
42 hwrng_unregister(&powernv_hwrng);
43
44 return 0;
45}
46
47static int powernv_rng_probe(struct platform_device *pdev)
48{
49 int rc;
50
51 rc = hwrng_register(&powernv_hwrng);
52 if (rc) {
53 /* We only register one device, ignore any others */
54 if (rc == -EEXIST)
55 rc = -ENODEV;
56
57 return rc;
58 }
59
60 pr_info("Registered powernv hwrng.\n");
61
62 return 0;
63}
64
65static const struct of_device_id powernv_rng_match[] = {
66 { .compatible = "ibm,power-rng",},
67 {},
68};
69MODULE_DEVICE_TABLE(of, powernv_rng_match);
70
71static struct platform_driver powernv_rng_driver = {
72 .driver = {
73 .name = "powernv_rng",
74 .of_match_table = powernv_rng_match,
75 },
76 .probe = powernv_rng_probe,
77 .remove = powernv_rng_remove,
78};
79module_platform_driver(powernv_rng_driver);
80
81MODULE_LICENSE("GPL");
82MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");