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linux/drivers/char/hw_random/intel-rng.c
Jan Beulich c24c95a085 [PATCH] fix Intel RNG detection 
Previously, since determination whether there was an Intel random number
generator was based on a single bit, on systems with a matching bridge
device but without a firmware hub, there was a 50% chance that the code
would incorrectly decide that the system had an RNG.  This patch adds
detection of the firmware hub to better qualify the existence of an RNG.

There is one issue with the patch: I was unable to determine the LPC
equivalent for the PCI bridge 8086:2430 (since the old code didn't care
about which of the many devices provided by the ICH/ESB it was chose to use
the PCI bridge device, but the FWH settings live in the LPC device, so the
device list needed to be changed).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:09 -07:00

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/*
* 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
/*
* LPC bridge PCI config space registers
*/
#define FWH_DEC_EN1_REG_OLD 0xe3
#define FWH_DEC_EN1_REG_NEW 0xd9 /* high byte of 16-bit register */
#define FWH_F8_EN_MASK 0x80
#define BIOS_CNTL_REG_OLD 0x4e
#define BIOS_CNTL_REG_NEW 0xdc
#define BIOS_CNTL_WRITE_ENABLE_MASK 0x01
#define BIOS_CNTL_LOCK_ENABLE_MASK 0x02
/*
* Magic address at which Intel Firmware Hubs get accessed
*/
#define INTEL_FWH_ADDR 0xffff0000
#define INTEL_FWH_ADDR_LEN 2
/*
* Intel Firmware Hub command codes (write to any address inside the device)
*/
#define INTEL_FWH_RESET_CMD 0xff /* aka READ_ARRAY */
#define INTEL_FWH_READ_ID_CMD 0x90
/*
* Intel Firmware Hub Read ID command result addresses
*/
#define INTEL_FWH_MANUFACTURER_CODE_ADDRESS 0x000000
#define INTEL_FWH_DEVICE_CODE_ADDRESS 0x000001
/*
* Intel Firmware Hub Read ID command result values
*/
#define INTEL_FWH_MANUFACTURER_CODE 0x89
#define INTEL_FWH_DEVICE_CODE_8M 0xac
#define INTEL_FWH_DEVICE_CODE_4M 0xad
/*
* 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[] = {
/* AA
{ 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
{ 0x8086, 0x2410, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* AA */
/* AB
{ 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
{ 0x8086, 0x2420, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* AB */
/* ??
{ 0x8086, 0x2430, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
/* BAM, CAM, DBM, FBM, GxM
{ 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
{ 0x8086, 0x244c, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* BAM */
{ 0x8086, 0x248c, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* CAM */
{ 0x8086, 0x24cc, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* DBM */
{ 0x8086, 0x2641, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* FBM */
{ 0x8086, 0x27b9, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* GxM */
{ 0x8086, 0x27bd, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* GxM DH */
/* BA, CA, DB, Ex, 6300, Fx, 631x/632x, Gx
{ 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
{ 0x8086, 0x2440, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* BA */
{ 0x8086, 0x2480, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* CA */
{ 0x8086, 0x24c0, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* DB */
{ 0x8086, 0x24d0, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* Ex */
{ 0x8086, 0x25a1, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 6300 */
{ 0x8086, 0x2640, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* Fx */
{ 0x8086, 0x2670, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2671, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2672, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2673, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2674, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2675, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2676, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2677, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2678, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x2679, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267a, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267c, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267d, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x267f, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* 631x/632x */
{ 0x8086, 0x27b8, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* Gx */
/* E
{ 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, */
{ 0x8086, 0x2450, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, }, /* E */
{ 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,
};
#ifdef CONFIG_SMP
static char __initdata waitflag;
static void __init intel_init_wait(void *unused)
{
while (waitflag)
cpu_relax();
}
#endif
static int __init mod_init(void)
{
int err = -ENODEV;
unsigned i;
struct pci_dev *dev = NULL;
void __iomem *mem;
unsigned long flags;
u8 bios_cntl_off, fwh_dec_en1_off;
u8 bios_cntl_val = 0xff, fwh_dec_en1_val = 0xff;
u8 hw_status, mfc, dvc;
for (i = 0; !dev && pci_tbl[i].vendor; ++i)
dev = pci_get_device(pci_tbl[i].vendor, pci_tbl[i].device, NULL);
if (!dev)
goto out; /* Device not found. */
/* Check for Intel 82802 */
if (dev->device < 0x2640) {
fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
bios_cntl_off = BIOS_CNTL_REG_OLD;
} else {
fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
bios_cntl_off = BIOS_CNTL_REG_NEW;
}
pci_read_config_byte(dev, fwh_dec_en1_off, &fwh_dec_en1_val);
pci_read_config_byte(dev, bios_cntl_off, &bios_cntl_val);
mem = ioremap_nocache(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
if (mem == NULL) {
pci_dev_put(dev);
err = -EBUSY;
goto out;
}
/*
* Since the BIOS code/data is going to disappear from its normal
* location with the Read ID command, all activity on the system
* must be stopped until the state is back to normal.
*/
#ifdef CONFIG_SMP
set_mb(waitflag, 1);
if (smp_call_function(intel_init_wait, NULL, 1, 0) != 0) {
set_mb(waitflag, 0);
pci_dev_put(dev);
printk(KERN_ERR PFX "cannot run on all processors\n");
err = -EAGAIN;
goto err_unmap;
}
#endif
local_irq_save(flags);
if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(dev,
fwh_dec_en1_off,
fwh_dec_en1_val | FWH_F8_EN_MASK);
if (!(bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
pci_write_config_byte(dev,
bios_cntl_off,
bios_cntl_val | BIOS_CNTL_WRITE_ENABLE_MASK);
writeb(INTEL_FWH_RESET_CMD, mem);
writeb(INTEL_FWH_READ_ID_CMD, mem);
mfc = readb(mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
dvc = readb(mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
writeb(INTEL_FWH_RESET_CMD, mem);
if (!(bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
pci_write_config_byte(dev, bios_cntl_off, bios_cntl_val);
if (!(fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(dev, fwh_dec_en1_off, fwh_dec_en1_val);
local_irq_restore(flags);
#ifdef CONFIG_SMP
/* Tell other CPUs to resume. */
set_mb(waitflag, 0);
#endif
iounmap(mem);
pci_dev_put(dev);
if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
(dvc != INTEL_FWH_DEVICE_CODE_8M &&
dvc != INTEL_FWH_DEVICE_CODE_4M)) {
printk(KERN_ERR PFX "FWH not detected\n");
err = -ENODEV;
goto out;
}
err = -ENOMEM;
mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
if (!mem)
goto out;
intel_rng.priv = (unsigned long)mem;
/* Check for Random Number Generator */
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");
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