tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/delay.h>
28#include <linux/hw_random.h>
29#include <linux/kernel.h>
30#include <linux/module.h>
31#include <linux/pci.h>
32
33#define DRV_NAME "AMD768-HWRNG"
34
35#define RNGDATA 0x00
36#define RNGDONE 0x04
37#define PMBASE_OFFSET 0xF0
38#define PMBASE_SIZE 8
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, 0x7443), 0, },
50 { PCI_VDEVICE(AMD, 0x746b), 0, },
51 { 0, }, /* terminate list */
52};
53MODULE_DEVICE_TABLE(pci, pci_tbl);
54
55struct amd768_priv {
56 void __iomem *iobase;
57 struct pci_dev *pcidev;
58};
59
60static int amd_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
61{
62 u32 *data = buf;
63 struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
64 size_t read = 0;
65 /* We will wait at maximum one time per read */
66 int timeout = max / 4 + 1;
67
68 /*
69 * RNG data is available when RNGDONE is set to 1
70 * New random numbers are generated approximately 128 microseconds
71 * after RNGDATA is read
72 */
73 while (read < max) {
74 if (ioread32(priv->iobase + RNGDONE) == 0) {
75 if (wait) {
76 /* Delay given by datasheet */
77 usleep_range(128, 196);
78 if (timeout-- == 0)
79 return read;
80 } else {
81 return 0;
82 }
83 } else {
84 *data = ioread32(priv->iobase + RNGDATA);
85 data++;
86 read += 4;
87 }
88 }
89
90 return read;
91}
92
93static int amd_rng_init(struct hwrng *rng)
94{
95 struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
96 u8 rnen;
97
98 pci_read_config_byte(priv->pcidev, 0x40, &rnen);
99 rnen |= BIT(7); /* RNG on */
100 pci_write_config_byte(priv->pcidev, 0x40, rnen);
101
102 pci_read_config_byte(priv->pcidev, 0x41, &rnen);
103 rnen |= BIT(7); /* PMIO enable */
104 pci_write_config_byte(priv->pcidev, 0x41, rnen);
105
106 return 0;
107}
108
109static void amd_rng_cleanup(struct hwrng *rng)
110{
111 struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
112 u8 rnen;
113
114 pci_read_config_byte(priv->pcidev, 0x40, &rnen);
115 rnen &= ~BIT(7); /* RNG off */
116 pci_write_config_byte(priv->pcidev, 0x40, rnen);
117}
118
119static struct hwrng amd_rng = {
120 .name = "amd",
121 .init = amd_rng_init,
122 .cleanup = amd_rng_cleanup,
123 .read = amd_rng_read,
124};
125
126static int __init mod_init(void)
127{
128 int err = -ENODEV;
129 struct pci_dev *pdev = NULL;
130 const struct pci_device_id *ent;
131 u32 pmbase;
132 struct amd768_priv *priv;
133
134 for_each_pci_dev(pdev) {
135 ent = pci_match_id(pci_tbl, pdev);
136 if (ent)
137 goto found;
138 }
139 /* Device not found. */
140 return -ENODEV;
141
142found:
143 err = pci_read_config_dword(pdev, 0x58, &pmbase);
144 if (err)
145 return err;
146
147 pmbase &= 0x0000FF00;
148 if (pmbase == 0)
149 return -EIO;
150
151 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
152 if (!priv)
153 return -ENOMEM;
154
155 if (!devm_request_region(&pdev->dev, pmbase + PMBASE_OFFSET,
156 PMBASE_SIZE, DRV_NAME)) {
157 dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
158 pmbase + 0xF0);
159 return -EBUSY;
160 }
161
162 priv->iobase = devm_ioport_map(&pdev->dev, pmbase + PMBASE_OFFSET,
163 PMBASE_SIZE);
164 if (!priv->iobase) {
165 pr_err(DRV_NAME "Cannot map ioport\n");
166 return -ENOMEM;
167 }
168
169 amd_rng.priv = (unsigned long)priv;
170 priv->pcidev = pdev;
171
172 pr_info(DRV_NAME " detected\n");
173 return devm_hwrng_register(&pdev->dev, &amd_rng);
174}
175
176static void __exit mod_exit(void)
177{
178}
179
180module_init(mod_init);
181module_exit(mod_exit);
182
183MODULE_AUTHOR("The Linux Kernel team");
184MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
185MODULE_LICENSE("GPL");