Root/drivers/char/hw_random/amd-rng.c

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    printk(KERN_INFO "AMD768 RNG detected\n");
146    err = hwrng_register(&amd_rng);
147    if (err) {
148        printk(KERN_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

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