1/*
2 * RNG driver for AMD RNGs
3 *
4 * Copyright 2005 (c) MontaVista Software, Inc.
5 *
6 * with the majority of the code coming from:
7 *
8 * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
9 * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
10 *
11 * derived from
12 *
13 * Hardware driver for the AMD 768 Random Number Generator (RNG)
14 * (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
15 *
16 * derived from
17 *
18 * Hardware driver for Intel i810 Random Number Generator (RNG)
19 * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
20 * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
21 *
22 * This file is licensed under  the terms of the GNU General Public
23 * License version 2. This program is licensed "as is" without any
24 * warranty of any kind, whether express or implied.
25 */
26
27#include <linux/module.h>
28#include <linux/kernel.h>
29#include <linux/pci.h>
30#include <linux/hw_random.h>
31#include <asm/io.h>
32
33
34#define PFX	KBUILD_MODNAME ": "
35
36
37/*
38 * Data for PCI driver interface
39 *
40 * This data only exists for exporting the supported
41 * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
42 * register a pci_driver, because someone else might one day
43 * want to register another driver on the same PCI id.
44 */
45static const struct pci_device_id pci_tbl[] = {
46	{ 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
47	{ 0x1022, 0x746b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
48	{ 0, },	/* terminate list */
49};
50MODULE_DEVICE_TABLE(pci, pci_tbl);
51
52static struct pci_dev *amd_pdev;
53
54
55static int amd_rng_data_present(struct hwrng *rng)
56{
57	u32 pmbase = (u32)rng->priv;
58
59      	return !!(inl(pmbase + 0xF4) & 1);
60}
61
62static int amd_rng_data_read(struct hwrng *rng, u32 *data)
63{
64	u32 pmbase = (u32)rng->priv;
65
66	*data = inl(pmbase + 0xF0);
67
68	return 4;
69}
70
71static int amd_rng_init(struct hwrng *rng)
72{
73	u8 rnen;
74
75	pci_read_config_byte(amd_pdev, 0x40, &rnen);
76	rnen |= (1 << 7);	/* RNG on */
77	pci_write_config_byte(amd_pdev, 0x40, rnen);
78
79	pci_read_config_byte(amd_pdev, 0x41, &rnen);
80	rnen |= (1 << 7);	/* PMIO enable */
81	pci_write_config_byte(amd_pdev, 0x41, rnen);
82
83	return 0;
84}
85
86static void amd_rng_cleanup(struct hwrng *rng)
87{
88	u8 rnen;
89
90	pci_read_config_byte(amd_pdev, 0x40, &rnen);
91	rnen &= ~(1 << 7);	/* RNG off */
92	pci_write_config_byte(amd_pdev, 0x40, rnen);
93}
94
95
96static struct hwrng amd_rng = {
97	.name		= "amd",
98	.init		= amd_rng_init,
99	.cleanup	= amd_rng_cleanup,
100	.data_present	= amd_rng_data_present,
101	.data_read	= amd_rng_data_read,
102};
103
104
105static int __init mod_init(void)
106{
107	int err = -ENODEV;
108	struct pci_dev *pdev = NULL;
109	const struct pci_device_id *ent;
110	u32 pmbase;
111
112	for_each_pci_dev(pdev) {
113		ent = pci_match_id(pci_tbl, pdev);
114		if (ent)
115			goto found;
116	}
117	/* Device not found. */
118	goto out;
119
120found:
121	err = pci_read_config_dword(pdev, 0x58, &pmbase);
122	if (err)
123		goto out;
124	err = -EIO;
125	pmbase &= 0x0000FF00;
126	if (pmbase == 0)
127		goto out;
128	amd_rng.priv = (unsigned long)pmbase;
129	amd_pdev = pdev;
130
131	printk(KERN_INFO "AMD768 RNG detected\n");
132	err = hwrng_register(&amd_rng);
133	if (err) {
134		printk(KERN_ERR PFX "RNG registering failed (%d)\n",
135		       err);
136		goto out;
137	}
138out:
139	return err;
140}
141
142static void __exit mod_exit(void)
143{
144	hwrng_unregister(&amd_rng);
145}
146
147module_init(mod_init);
148module_exit(mod_exit);
149
150MODULE_AUTHOR("The Linux Kernel team");
151MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
152MODULE_LICENSE("GPL");
153