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

1/*
2 * RNG driver for AMD Geode 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#define GEODE_RNG_DATA_REG 0x50
38#define GEODE_RNG_STATUS_REG 0x54
39
40/*
41 * Data for PCI driver interface
42 *
43 * This data only exists for exporting the supported
44 * PCI ids via MODULE_DEVICE_TABLE. We do not actually
45 * register a pci_driver, because someone else might one day
46 * want to register another driver on the same PCI id.
47 */
48static const struct pci_device_id pci_tbl[] = {
49    { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), 0, },
50    { 0, }, /* terminate list */
51};
52MODULE_DEVICE_TABLE(pci, pci_tbl);
53
54
55static int geode_rng_data_read(struct hwrng *rng, u32 *data)
56{
57    void __iomem *mem = (void __iomem *)rng->priv;
58
59    *data = readl(mem + GEODE_RNG_DATA_REG);
60
61    return 4;
62}
63
64static int geode_rng_data_present(struct hwrng *rng, int wait)
65{
66    void __iomem *mem = (void __iomem *)rng->priv;
67    int data, i;
68
69    for (i = 0; i < 20; i++) {
70        data = !!(readl(mem + GEODE_RNG_STATUS_REG));
71        if (data || !wait)
72            break;
73        udelay(10);
74    }
75    return data;
76}
77
78
79static struct hwrng geode_rng = {
80    .name = "geode",
81    .data_present = geode_rng_data_present,
82    .data_read = geode_rng_data_read,
83};
84
85
86static int __init mod_init(void)
87{
88    int err = -ENODEV;
89    struct pci_dev *pdev = NULL;
90    const struct pci_device_id *ent;
91    void __iomem *mem;
92    unsigned long rng_base;
93
94    for_each_pci_dev(pdev) {
95        ent = pci_match_id(pci_tbl, pdev);
96        if (ent)
97            goto found;
98    }
99    /* Device not found. */
100    goto out;
101
102found:
103    rng_base = pci_resource_start(pdev, 0);
104    if (rng_base == 0)
105        goto out;
106    err = -ENOMEM;
107    mem = ioremap(rng_base, 0x58);
108    if (!mem)
109        goto out;
110    geode_rng.priv = (unsigned long)mem;
111
112    printk(KERN_INFO "AMD Geode RNG detected\n");
113    err = hwrng_register(&geode_rng);
114    if (err) {
115        printk(KERN_ERR PFX "RNG registering failed (%d)\n",
116               err);
117        goto err_unmap;
118    }
119out:
120    return err;
121
122err_unmap:
123    iounmap(mem);
124    goto out;
125}
126
127static void __exit mod_exit(void)
128{
129    void __iomem *mem = (void __iomem *)geode_rng.priv;
130
131    hwrng_unregister(&geode_rng);
132    iounmap(mem);
133}
134
135module_init(mod_init);
136module_exit(mod_exit);
137
138MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
139MODULE_LICENSE("GPL");
140

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