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
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 <linux/delay.h>
32#include <asm/io.h>
33
34
35#define PFX	KBUILD_MODNAME ": "
36
37
38/*
39 * Data for PCI driver interface
40 *
41 * This data only exists for exporting the supported
42 * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
43 * register a pci_driver, because someone else might one day
44 * want to register another driver on the same PCI id.
45 */
46static const struct pci_device_id pci_tbl[] = {
47	{ PCI_VDEVICE(AMD, 0x7443), 0, },
48	{ PCI_VDEVICE(AMD, 0x746b), 0, },
49	{ 0, },	/* terminate list */
50};
51MODULE_DEVICE_TABLE(pci, pci_tbl);
52
53static struct pci_dev *amd_pdev;
54
55
56static int amd_rng_data_present(struct hwrng *rng, int wait)
57{
58	u32 pmbase = (u32)rng->priv;
59	int data, i;
60
61	for (i = 0; i < 20; i++) {
62		data = !!(inl(pmbase + 0xF4) & 1);
63		if (data || !wait)
64			break;
65		udelay(10);
66	}
67	return data;
68}
69
70static int amd_rng_data_read(struct hwrng *rng, u32 *data)
71{
72	u32 pmbase = (u32)rng->priv;
73
74	*data = inl(pmbase + 0xF0);
75
76	return 4;
77}
78
79static int amd_rng_init(struct hwrng *rng)
80{
81	u8 rnen;
82
83	pci_read_config_byte(amd_pdev, 0x40, &rnen);
84	rnen |= (1 << 7);	/* RNG on */
85	pci_write_config_byte(amd_pdev, 0x40, rnen);
86
87	pci_read_config_byte(amd_pdev, 0x41, &rnen);
88	rnen |= (1 << 7);	/* PMIO enable */
89	pci_write_config_byte(amd_pdev, 0x41, rnen);
90
91	return 0;
92}
93
94static void amd_rng_cleanup(struct hwrng *rng)
95{
96	u8 rnen;
97
98	pci_read_config_byte(amd_pdev, 0x40, &rnen);
99	rnen &= ~(1 << 7);	/* RNG off */
100	pci_write_config_byte(amd_pdev, 0x40, rnen);
101}
102
103
104static struct hwrng amd_rng = {
105	.name		= "amd",
106	.init		= amd_rng_init,
107	.cleanup	= amd_rng_cleanup,
108	.data_present	= amd_rng_data_present,
109	.data_read	= amd_rng_data_read,
110};
111
112
113static int __init mod_init(void)
114{
115	int err = -ENODEV;
116	struct pci_dev *pdev = NULL;
117	const struct pci_device_id *ent;
118	u32 pmbase;
119
120	for_each_pci_dev(pdev) {
121		ent = pci_match_id(pci_tbl, pdev);
122		if (ent)
123			goto found;
124	}
125	/* Device not found. */
126	goto out;
127
128found:
129	err = pci_read_config_dword(pdev, 0x58, &pmbase);
130	if (err)
131		goto out;
132	err = -EIO;
133	pmbase &= 0x0000FF00;
134	if (pmbase == 0)
135		goto out;
136	if (!request_region(pmbase + 0xF0, 8, "AMD HWRNG")) {
137		dev_err(&pdev->dev, "AMD HWRNG region 0x%x already in use!\n",
138			pmbase + 0xF0);
139		err = -EBUSY;
140		goto out;
141	}
142	amd_rng.priv = (unsigned long)pmbase;
143	amd_pdev = pdev;
144
145	pr_info("AMD768 RNG detected\n");
146	err = hwrng_register(&amd_rng);
147	if (err) {
148		pr_err(PFX "RNG registering failed (%d)\n",
149		       err);
150		release_region(pmbase + 0xF0, 8);
151		goto out;
152	}
153out:
154	return err;
155}
156
157static void __exit mod_exit(void)
158{
159	u32 pmbase = (unsigned long)amd_rng.priv;
160	release_region(pmbase + 0xF0, 8);
161	hwrng_unregister(&amd_rng);
162}
163
164module_init(mod_init);
165module_exit(mod_exit);
166
167MODULE_AUTHOR("The Linux Kernel team");
168MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
169MODULE_LICENSE("GPL");
170