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/*
* RNG driver for AMD RNGs
*
* Copyright 2005 (c) MontaVista Software, Inc.
*
* with the majority of the code coming from:
*
* Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
* (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
*
* derived from
*
* Hardware driver for the AMD 768 Random Number Generator (RNG)
* (c) Copyright 2001 Red Hat Inc
*
* derived from
*
* Hardware driver for Intel i810 Random Number Generator (RNG)
* Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
* Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/hw_random.h>
#include <linux/delay.h>
#include <asm/io.h>
#define DRV_NAME "AMD768-HWRNG"
/*
* Data for PCI driver interface
*
* This data only exists for exporting the supported
* PCI ids via MODULE_DEVICE_TABLE. We do not actually
* register a pci_driver, because someone else might one day
* want to register another driver on the same PCI id.
*/
static const struct pci_device_id pci_tbl[] = {
{ PCI_VDEVICE(AMD, 0x7443), 0, },
{ PCI_VDEVICE(AMD, 0x746b), 0, },
{ 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, pci_tbl);
static struct pci_dev *amd_pdev;
static int amd_rng_data_present(struct hwrng *rng, int wait)
{
u32 pmbase = (u32)rng->priv;
int data, i;
for (i = 0; i < 20; i++) {
data = !!(inl(pmbase + 0xF4) & 1);
if (data || !wait)
break;
udelay(10);
}
return data;
}
static int amd_rng_data_read(struct hwrng *rng, u32 *data)
{
u32 pmbase = (u32)rng->priv;
*data = inl(pmbase + 0xF0);
return 4;
}
static int amd_rng_init(struct hwrng *rng)
{
u8 rnen;
pci_read_config_byte(amd_pdev, 0x40, &rnen);
rnen |= BIT(7); /* RNG on */
pci_write_config_byte(amd_pdev, 0x40, rnen);
pci_read_config_byte(amd_pdev, 0x41, &rnen);
rnen |= BIT(7); /* PMIO enable */
pci_write_config_byte(amd_pdev, 0x41, rnen);
return 0;
}
static void amd_rng_cleanup(struct hwrng *rng)
{
u8 rnen;
pci_read_config_byte(amd_pdev, 0x40, &rnen);
rnen &= ~BIT(7); /* RNG off */
pci_write_config_byte(amd_pdev, 0x40, rnen);
}
static struct hwrng amd_rng = {
.name = "amd",
.init = amd_rng_init,
.cleanup = amd_rng_cleanup,
.data_present = amd_rng_data_present,
.data_read = amd_rng_data_read,
};
static int __init mod_init(void)
{
int err = -ENODEV;
struct pci_dev *pdev = NULL;
const struct pci_device_id *ent;
u32 pmbase;
for_each_pci_dev(pdev) {
ent = pci_match_id(pci_tbl, pdev);
if (ent)
goto found;
}
/* Device not found. */
goto out;
found:
err = pci_read_config_dword(pdev, 0x58, &pmbase);
if (err)
goto out;
err = -EIO;
pmbase &= 0x0000FF00;
if (pmbase == 0)
goto out;
if (!request_region(pmbase + 0xF0, 8, DRV_NAME)) {
dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
pmbase + 0xF0);
err = -EBUSY;
goto out;
}
amd_rng.priv = (unsigned long)pmbase;
amd_pdev = pdev;
pr_info(DRV_NAME " detected\n");
err = hwrng_register(&amd_rng);
if (err) {
pr_err(DRV_NAME " registering failed (%d)\n", err);
release_region(pmbase + 0xF0, 8);
goto out;
}
out:
return err;
}
static void __exit mod_exit(void)
{
u32 pmbase = (unsigned long)amd_rng.priv;
release_region(pmbase + 0xF0, 8);
hwrng_unregister(&amd_rng);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("The Linux Kernel team");
MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
MODULE_LICENSE("GPL");
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