1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/module.h>
9*4882a593Smuzhiyun #include <linux/mod_devicetable.h>
10*4882a593Smuzhiyun #include <linux/kernel.h>
11*4882a593Smuzhiyun #include <linux/platform_device.h>
12*4882a593Smuzhiyun #include <linux/random.h>
13*4882a593Smuzhiyun #include <linux/hw_random.h>
14*4882a593Smuzhiyun
powernv_rng_read(struct hwrng * rng,void * data,size_t max,bool wait)15*4882a593Smuzhiyun static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
16*4882a593Smuzhiyun {
17*4882a593Smuzhiyun unsigned long *buf;
18*4882a593Smuzhiyun int i, len;
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */
21*4882a593Smuzhiyun len = max / sizeof(unsigned long);
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun buf = (unsigned long *)data;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun for (i = 0; i < len; i++)
26*4882a593Smuzhiyun powernv_get_random_long(buf++);
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun return len * sizeof(unsigned long);
29*4882a593Smuzhiyun }
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun static struct hwrng powernv_hwrng = {
32*4882a593Smuzhiyun .name = "powernv-rng",
33*4882a593Smuzhiyun .read = powernv_rng_read,
34*4882a593Smuzhiyun };
35*4882a593Smuzhiyun
powernv_rng_probe(struct platform_device * pdev)36*4882a593Smuzhiyun static int powernv_rng_probe(struct platform_device *pdev)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun int rc;
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun rc = devm_hwrng_register(&pdev->dev, &powernv_hwrng);
41*4882a593Smuzhiyun if (rc) {
42*4882a593Smuzhiyun /* We only register one device, ignore any others */
43*4882a593Smuzhiyun if (rc == -EEXIST)
44*4882a593Smuzhiyun rc = -ENODEV;
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun return rc;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun pr_info("Registered powernv hwrng.\n");
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun return 0;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun static const struct of_device_id powernv_rng_match[] = {
55*4882a593Smuzhiyun { .compatible = "ibm,power-rng",},
56*4882a593Smuzhiyun {},
57*4882a593Smuzhiyun };
58*4882a593Smuzhiyun MODULE_DEVICE_TABLE(of, powernv_rng_match);
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun static struct platform_driver powernv_rng_driver = {
61*4882a593Smuzhiyun .driver = {
62*4882a593Smuzhiyun .name = "powernv_rng",
63*4882a593Smuzhiyun .of_match_table = powernv_rng_match,
64*4882a593Smuzhiyun },
65*4882a593Smuzhiyun .probe = powernv_rng_probe,
66*4882a593Smuzhiyun };
67*4882a593Smuzhiyun module_platform_driver(powernv_rng_driver);
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun MODULE_LICENSE("GPL");
70*4882a593Smuzhiyun MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");
71