/*
* RNG driver for Intel 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 <alan@redhat.com>
*
* 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 <asm/io.h>
#define PFX KBUILD_MODNAME ": "
/*
* RNG registers
*/
#define INTEL_RNG_HW_STATUS 0
#define INTEL_RNG_PRESENT 0x40
#define INTEL_RNG_ENABLED 0x01
#define INTEL_RNG_STATUS 1
#define INTEL_RNG_DATA_PRESENT 0x01
#define INTEL_RNG_DATA 2
/*
* Magic address at which Intel PCI bridges locate the RNG
*/
#define INTEL_RNG_ADDR 0xFFBC015F
#define INTEL_RNG_ADDR_LEN 3
/*
* 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[] = {
{ 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0x8086, 0x2430, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
{ 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, pci_tbl);
static inline u8 hwstatus_get(void __iomem *mem)
{
return readb(mem + INTEL_RNG_HW_STATUS);
}
static inline u8 hwstatus_set(void __iomem *mem,
u8 hw_status)
{
writeb(hw_status, mem + INTEL_RNG_HW_STATUS);
return hwstatus_get(mem);
}
static int intel_rng_data_present(struct hwrng *rng)
{
void __iomem *mem = (void __iomem *)rng->priv;
return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT);
}
static int intel_rng_data_read(struct hwrng *rng, u32 *data)
{
void __iomem *mem = (void __iomem *)rng->priv;
*data = readb(mem + INTEL_RNG_DATA);
return 1;
}
static int intel_rng_init(struct hwrng *rng)
{
void __iomem *mem = (void __iomem *)rng->priv;
u8 hw_status;
int err = -EIO;
hw_status = hwstatus_get(mem);
/* turn RNG h/w on, if it's off */
if ((hw_status & INTEL_RNG_ENABLED) == 0)
hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
if ((hw_status & INTEL_RNG_ENABLED) == 0) {
printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
goto out;
}
err = 0;
out:
return err;
}
static void intel_rng_cleanup(struct hwrng *rng)
{
void __iomem *mem = (void __iomem *)rng->priv;
u8 hw_status;
hw_status = hwstatus_get(mem);
if (hw_status & INTEL_RNG_ENABLED)
hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
else
printk(KERN_WARNING PFX "unusual: RNG already disabled\n");
}
static struct hwrng intel_rng = {
.name = "intel",
.init = intel_rng_init,
.cleanup = intel_rng_cleanup,
.data_present = intel_rng_data_present,
.data_read = intel_rng_data_read,
};
static int __init mod_init(void)
{
int err = -ENODEV;
void __iomem *mem;
u8 hw_status;
if (!pci_dev_present(pci_tbl))
goto out; /* Device not found. */
err = -ENOMEM;
mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
if (!mem)
goto out;
intel_rng.priv = (unsigned long)mem;
/* Check for Intel 82802 */
err = -ENODEV;
hw_status = hwstatus_get(mem);
if ((hw_status & INTEL_RNG_PRESENT) == 0)
goto err_unmap;
printk(KERN_INFO "Intel 82802 RNG detected\n");
err = hwrng_register(&intel_rng);
if (err) {
printk(KERN_ERR PFX "RNG registering failed (%d)\n",
err);
goto err_unmap;
}
out:
return err;
err_unmap:
iounmap(mem);
goto out;
}
static void __exit mod_exit(void)
{
void __iomem *mem = (void __iomem *)intel_rng.priv;
hwrng_unregister(&intel_rng);
iounmap(mem);
}
subsys_initcall(mod_init);
module_exit(mod_exit);
MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
MODULE_LICENSE("GPL");
