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 struct amd_geode_priv {
55 struct pci_dev *pcidev;
56 void __iomem *membase;
57 };
58
geode_rng_data_read(struct hwrng * rng,u32 * data)59 static int geode_rng_data_read(struct hwrng *rng, u32 *data)
60 {
61 void __iomem *mem = (void __iomem *)rng->priv;
62
63 *data = readl(mem + GEODE_RNG_DATA_REG);
64
65 return 4;
66 }
67
geode_rng_data_present(struct hwrng * rng,int wait)68 static int geode_rng_data_present(struct hwrng *rng, int wait)
69 {
70 void __iomem *mem = (void __iomem *)rng->priv;
71 int data, i;
72
73 for (i = 0; i < 20; i++) {
74 data = !!(readl(mem + GEODE_RNG_STATUS_REG));
75 if (data || !wait)
76 break;
77 udelay(10);
78 }
79 return data;
80 }
81
82
83 static struct hwrng geode_rng = {
84 .name = "geode",
85 .data_present = geode_rng_data_present,
86 .data_read = geode_rng_data_read,
87 };
88
89
geode_rng_init(void)90 static int __init geode_rng_init(void)
91 {
92 int err = -ENODEV;
93 struct pci_dev *pdev = NULL;
94 const struct pci_device_id *ent;
95 void __iomem *mem;
96 unsigned long rng_base;
97 struct amd_geode_priv *priv;
98
99 for_each_pci_dev(pdev) {
100 ent = pci_match_id(pci_tbl, pdev);
101 if (ent)
102 goto found;
103 }
104 /* Device not found. */
105 return err;
106
107 found:
108 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
109 if (!priv) {
110 err = -ENOMEM;
111 goto put_dev;
112 }
113
114 rng_base = pci_resource_start(pdev, 0);
115 if (rng_base == 0)
116 goto free_priv;
117 err = -ENOMEM;
118 mem = ioremap(rng_base, 0x58);
119 if (!mem)
120 goto free_priv;
121
122 geode_rng.priv = (unsigned long)priv;
123 priv->membase = mem;
124 priv->pcidev = pdev;
125
126 pr_info("AMD Geode RNG detected\n");
127 err = hwrng_register(&geode_rng);
128 if (err) {
129 pr_err(PFX "RNG registering failed (%d)\n",
130 err);
131 goto err_unmap;
132 }
133 return err;
134
135 err_unmap:
136 iounmap(mem);
137 free_priv:
138 kfree(priv);
139 put_dev:
140 pci_dev_put(pdev);
141 return err;
142 }
143
geode_rng_exit(void)144 static void __exit geode_rng_exit(void)
145 {
146 struct amd_geode_priv *priv;
147
148 priv = (struct amd_geode_priv *)geode_rng.priv;
149 hwrng_unregister(&geode_rng);
150 iounmap(priv->membase);
151 pci_dev_put(priv->pcidev);
152 kfree(priv);
153 }
154
155 module_init(geode_rng_init);
156 module_exit(geode_rng_exit);
157
158 MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
159 MODULE_LICENSE("GPL");
160
