cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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geode-rng.c (3057B)

      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
     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 geode_rng_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 geode_rng_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(geode_rng_init);
    136module_exit(geode_rng_exit);
    137
    138MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs");
    139MODULE_LICENSE("GPL");