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/delay.h>
28 #include <linux/hw_random.h>
29 #include <linux/io.h>
30 #include <linux/kernel.h>
31 #include <linux/module.h>
32 #include <linux/pci.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 */
48 static const struct pci_device_id pci_tbl[] = {
49 { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), 0, },
50 { 0, }, /* terminate list */
51 };
52 MODULE_DEVICE_TABLE(pci, pci_tbl);
53
54
geode_rng_data_read(struct hwrng * rng,u32 * data)55 static 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
geode_rng_data_present(struct hwrng * rng,int wait)64 static 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
79 static struct hwrng geode_rng = {
80 .name = "geode",
81 .data_present = geode_rng_data_present,
82 .data_read = geode_rng_data_read,
83 };
84
85
mod_init(void)86 static 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
102 found:
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 pr_info("AMD Geode RNG detected\n");
113 err = hwrng_register(&geode_rng);
114 if (err) {
115 pr_err(PFX "RNG registering failed (%d)\n",
116 err);
117 goto err_unmap;
118 }
119 out:
120 return err;
121
122 err_unmap:
123 iounmap(mem);
124 goto out;
125 }
126
mod_exit(void)127 static 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
135 module_init(mod_init);
136 module_exit(mod_exit);
137
138 MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
139 MODULE_LICENSE("GPL");
140
