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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/delay.h>
#include <linux/hw_random.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#define DRV_NAME "AMD768-HWRNG"
#define RNGDATA 0x00
#define RNGDONE 0x04
#define PMBASE_OFFSET 0xF0
#define PMBASE_SIZE 8
/*
* 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);
struct amd768_priv {
void __iomem *iobase;
struct pci_dev *pcidev;
};
static int amd_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
u32 *data = buf;
struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
size_t read = 0;
/* We will wait at maximum one time per read */
int timeout = max / 4 + 1;
/*
* RNG data is available when RNGDONE is set to 1
* New random numbers are generated approximately 128 microseconds
* after RNGDATA is read
*/
while (read < max) {
if (ioread32(priv->iobase + RNGDONE) == 0) {
if (wait) {
/* Delay given by datasheet */
usleep_range(128, 196);
if (timeout-- == 0)
return read;
} else {
return 0;
}
} else {
*data = ioread32(priv->iobase + RNGDATA);
data++;
read += 4;
}
}
return read;
}
static int amd_rng_init(struct hwrng *rng)
{
struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
u8 rnen;
pci_read_config_byte(priv->pcidev, 0x40, &rnen);
rnen |= BIT(7); /* RNG on */
pci_write_config_byte(priv->pcidev, 0x40, rnen);
pci_read_config_byte(priv->pcidev, 0x41, &rnen);
rnen |= BIT(7); /* PMIO enable */
pci_write_config_byte(priv->pcidev, 0x41, rnen);
return 0;
}
static void amd_rng_cleanup(struct hwrng *rng)
{
struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
u8 rnen;
pci_read_config_byte(priv->pcidev, 0x40, &rnen);
rnen &= ~BIT(7); /* RNG off */
pci_write_config_byte(priv->pcidev, 0x40, rnen);
}
static struct hwrng amd_rng = {
.name = "amd",
.init = amd_rng_init,
.cleanup = amd_rng_cleanup,
.read = amd_rng_read,
};
static int __init mod_init(void)
{
int err = -ENODEV;
struct pci_dev *pdev = NULL;
const struct pci_device_id *ent;
u32 pmbase;
struct amd768_priv *priv;
for_each_pci_dev(pdev) {
ent = pci_match_id(pci_tbl, pdev);
if (ent)
goto found;
}
/* Device not found. */
return -ENODEV;
found:
err = pci_read_config_dword(pdev, 0x58, &pmbase);
if (err)
return err;
pmbase &= 0x0000FF00;
if (pmbase == 0)
return -EIO;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
if (!devm_request_region(&pdev->dev, pmbase + PMBASE_OFFSET,
PMBASE_SIZE, DRV_NAME)) {
dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
pmbase + 0xF0);
return -EBUSY;
}
priv->iobase = devm_ioport_map(&pdev->dev, pmbase + PMBASE_OFFSET,
PMBASE_SIZE);
if (!priv->iobase) {
pr_err(DRV_NAME "Cannot map ioport\n");
return -ENOMEM;
}
amd_rng.priv = (unsigned long)priv;
priv->pcidev = pdev;
pr_info(DRV_NAME " detected\n");
return devm_hwrng_register(&pdev->dev, &amd_rng);
}
static void __exit mod_exit(void)
{
}
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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