tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2010 Michael Neuling IBM Corporation
3 *
4 * Driver for the pseries hardware RNG for POWER7+ and above
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/hw_random.h>
25#include <asm/vio.h>
26
27
28static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
29{
30 u64 buffer[PLPAR_HCALL_BUFSIZE];
31 int rc;
32
33 rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
34 if (rc != H_SUCCESS) {
35 pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
36 return -EIO;
37 }
38 memcpy(data, buffer, 8);
39
40 /* The hypervisor interface returns 64 bits */
41 return 8;
42}
43
44/**
45 * pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
46 *
47 * This is a required function for a driver to operate in a CMO environment
48 * but this device does not make use of DMA allocations, return 0.
49 *
50 * Return value:
51 * Number of bytes of IO data the driver will need to perform well -> 0
52 */
53static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
54{
55 return 0;
56};
57
58static struct hwrng pseries_rng = {
59 .name = KBUILD_MODNAME,
60 .read = pseries_rng_read,
61};
62
63static int pseries_rng_probe(struct vio_dev *dev,
64 const struct vio_device_id *id)
65{
66 return hwrng_register(&pseries_rng);
67}
68
69static int pseries_rng_remove(struct vio_dev *dev)
70{
71 hwrng_unregister(&pseries_rng);
72 return 0;
73}
74
75static const struct vio_device_id pseries_rng_driver_ids[] = {
76 { "ibm,random-v1", "ibm,random"},
77 { "", "" }
78};
79MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
80
81static struct vio_driver pseries_rng_driver = {
82 .name = KBUILD_MODNAME,
83 .probe = pseries_rng_probe,
84 .remove = pseries_rng_remove,
85 .get_desired_dma = pseries_rng_get_desired_dma,
86 .id_table = pseries_rng_driver_ids
87};
88
89static int __init rng_init(void)
90{
91 pr_info("Registering IBM pSeries RNG driver\n");
92 return vio_register_driver(&pseries_rng_driver);
93}
94
95module_init(rng_init);
96
97static void __exit rng_exit(void)
98{
99 vio_unregister_driver(&pseries_rng_driver);
100}
101module_exit(rng_exit);
102
103MODULE_LICENSE("GPL");
104MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
105MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");