1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2010 Michael Neuling IBM Corporation
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Driver for the pseries hardware RNG for POWER7+ and above
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/kernel.h>
11*4882a593Smuzhiyun #include <linux/module.h>
12*4882a593Smuzhiyun #include <linux/hw_random.h>
13*4882a593Smuzhiyun #include <asm/vio.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun
pseries_rng_read(struct hwrng * rng,void * data,size_t max,bool wait)16*4882a593Smuzhiyun static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
17*4882a593Smuzhiyun {
18*4882a593Smuzhiyun u64 buffer[PLPAR_HCALL_BUFSIZE];
19*4882a593Smuzhiyun int rc;
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
22*4882a593Smuzhiyun if (rc != H_SUCCESS) {
23*4882a593Smuzhiyun pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
24*4882a593Smuzhiyun return -EIO;
25*4882a593Smuzhiyun }
26*4882a593Smuzhiyun memcpy(data, buffer, 8);
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun /* The hypervisor interface returns 64 bits */
29*4882a593Smuzhiyun return 8;
30*4882a593Smuzhiyun }
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun /**
33*4882a593Smuzhiyun * pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
34*4882a593Smuzhiyun *
35*4882a593Smuzhiyun * This is a required function for a driver to operate in a CMO environment
36*4882a593Smuzhiyun * but this device does not make use of DMA allocations, return 0.
37*4882a593Smuzhiyun *
38*4882a593Smuzhiyun * Return value:
39*4882a593Smuzhiyun * Number of bytes of IO data the driver will need to perform well -> 0
40*4882a593Smuzhiyun */
pseries_rng_get_desired_dma(struct vio_dev * vdev)41*4882a593Smuzhiyun static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
42*4882a593Smuzhiyun {
43*4882a593Smuzhiyun return 0;
44*4882a593Smuzhiyun };
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun static struct hwrng pseries_rng = {
47*4882a593Smuzhiyun .name = KBUILD_MODNAME,
48*4882a593Smuzhiyun .read = pseries_rng_read,
49*4882a593Smuzhiyun };
50*4882a593Smuzhiyun
pseries_rng_probe(struct vio_dev * dev,const struct vio_device_id * id)51*4882a593Smuzhiyun static int pseries_rng_probe(struct vio_dev *dev,
52*4882a593Smuzhiyun const struct vio_device_id *id)
53*4882a593Smuzhiyun {
54*4882a593Smuzhiyun return hwrng_register(&pseries_rng);
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
pseries_rng_remove(struct vio_dev * dev)57*4882a593Smuzhiyun static int pseries_rng_remove(struct vio_dev *dev)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun hwrng_unregister(&pseries_rng);
60*4882a593Smuzhiyun return 0;
61*4882a593Smuzhiyun }
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun static const struct vio_device_id pseries_rng_driver_ids[] = {
64*4882a593Smuzhiyun { "ibm,random-v1", "ibm,random"},
65*4882a593Smuzhiyun { "", "" }
66*4882a593Smuzhiyun };
67*4882a593Smuzhiyun MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun static struct vio_driver pseries_rng_driver = {
70*4882a593Smuzhiyun .name = KBUILD_MODNAME,
71*4882a593Smuzhiyun .probe = pseries_rng_probe,
72*4882a593Smuzhiyun .remove = pseries_rng_remove,
73*4882a593Smuzhiyun .get_desired_dma = pseries_rng_get_desired_dma,
74*4882a593Smuzhiyun .id_table = pseries_rng_driver_ids
75*4882a593Smuzhiyun };
76*4882a593Smuzhiyun
rng_init(void)77*4882a593Smuzhiyun static int __init rng_init(void)
78*4882a593Smuzhiyun {
79*4882a593Smuzhiyun pr_info("Registering IBM pSeries RNG driver\n");
80*4882a593Smuzhiyun return vio_register_driver(&pseries_rng_driver);
81*4882a593Smuzhiyun }
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun module_init(rng_init);
84*4882a593Smuzhiyun
rng_exit(void)85*4882a593Smuzhiyun static void __exit rng_exit(void)
86*4882a593Smuzhiyun {
87*4882a593Smuzhiyun vio_unregister_driver(&pseries_rng_driver);
88*4882a593Smuzhiyun }
89*4882a593Smuzhiyun module_exit(rng_exit);
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun MODULE_LICENSE("GPL");
92*4882a593Smuzhiyun MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
93*4882a593Smuzhiyun MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");
94