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	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	}
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