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 */
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
54struct amd_geode_priv {
55	struct pci_dev *pcidev;
56	void __iomem *membase;
57};
58
59static int geode_rng_data_read(struct hwrng *rng, u32 *data)
60{
61	struct amd_geode_priv *priv = (struct amd_geode_priv *)rng->priv;
62	void __iomem *mem = priv->membase;
63
64	*data = readl(mem + GEODE_RNG_DATA_REG);
65
66	return 4;
67}
68
69static int geode_rng_data_present(struct hwrng *rng, int wait)
70{
71	struct amd_geode_priv *priv = (struct amd_geode_priv *)rng->priv;
72	void __iomem *mem = priv->membase;
73	int data, i;
74
75	for (i = 0; i < 20; i++) {
76		data = !!(readl(mem + GEODE_RNG_STATUS_REG));
77		if (data || !wait)
78			break;
79		udelay(10);
80	}
81	return data;
82}
83
84
85static struct hwrng geode_rng = {
86	.name		= "geode",
87	.data_present	= geode_rng_data_present,
88	.data_read	= geode_rng_data_read,
89};
90
91
92static int __init geode_rng_init(void)
93{
94	int err = -ENODEV;
95	struct pci_dev *pdev = NULL;
96	const struct pci_device_id *ent;
97	void __iomem *mem;
98	unsigned long rng_base;
99	struct amd_geode_priv *priv;
100
101	for_each_pci_dev(pdev) {
102		ent = pci_match_id(pci_tbl, pdev);
103		if (ent)
104			goto found;
105	}
106	/* Device not found. */
107	return err;
108
109found:
110	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
111	if (!priv) {
112		err = -ENOMEM;
113		goto put_dev;
114	}
115
116	rng_base = pci_resource_start(pdev, 0);
117	if (rng_base == 0)
118		goto free_priv;
119	err = -ENOMEM;
120	mem = ioremap(rng_base, 0x58);
121	if (!mem)
122		goto free_priv;
123
124	geode_rng.priv = (unsigned long)priv;
125	priv->membase = mem;
126	priv->pcidev = pdev;
127
128	pr_info("AMD Geode RNG detected\n");
129	err = hwrng_register(&geode_rng);
130	if (err) {
131		pr_err(PFX "RNG registering failed (%d)\n",
132		       err);
133		goto err_unmap;
134	}
135	return err;
136
137err_unmap:
138	iounmap(mem);
139free_priv:
140	kfree(priv);
141put_dev:
142	pci_dev_put(pdev);
143	return err;
144}
145
146static void __exit geode_rng_exit(void)
147{
148	struct amd_geode_priv *priv;
149
150	priv = (struct amd_geode_priv *)geode_rng.priv;
151	hwrng_unregister(&geode_rng);
152	iounmap(priv->membase);
153	pci_dev_put(priv->pcidev);
154	kfree(priv);
155}
156
157module_init(geode_rng_init);
158module_exit(geode_rng_exit);
159
160MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
161MODULE_LICENSE("GPL");
162