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linux/drivers/char/hw_random/intel-rng.c

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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
*
* 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/hw_random.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/stop_machine.h>
#include <linux/delay.h>
#include <linux/slab.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
{ PCI_DEVICE(0x8086, 0x2418) }, */
{ PCI_DEVICE(0x8086, 0x2410) }, /* AA */
/* AB
{ PCI_DEVICE(0x8086, 0x2428) }, */
{ PCI_DEVICE(0x8086, 0x2420) }, /* AB */
/* ??
{ PCI_DEVICE(0x8086, 0x2430) }, */
/* BAM, CAM, DBM, FBM, GxM
{ PCI_DEVICE(0x8086, 0x2448) }, */
{ PCI_DEVICE(0x8086, 0x244c) }, /* BAM */
{ PCI_DEVICE(0x8086, 0x248c) }, /* CAM */
{ PCI_DEVICE(0x8086, 0x24cc) }, /* DBM */
{ PCI_DEVICE(0x8086, 0x2641) }, /* FBM */
{ PCI_DEVICE(0x8086, 0x27b9) }, /* GxM */
{ PCI_DEVICE(0x8086, 0x27bd) }, /* GxM DH */
/* BA, CA, DB, Ex, 6300, Fx, 631x/632x, Gx
{ PCI_DEVICE(0x8086, 0x244e) }, */
{ PCI_DEVICE(0x8086, 0x2440) }, /* BA */
{ PCI_DEVICE(0x8086, 0x2480) }, /* CA */
{ PCI_DEVICE(0x8086, 0x24c0) }, /* DB */
{ PCI_DEVICE(0x8086, 0x24d0) }, /* Ex */
{ PCI_DEVICE(0x8086, 0x25a1) }, /* 6300 */
{ PCI_DEVICE(0x8086, 0x2640) }, /* Fx */
{ PCI_DEVICE(0x8086, 0x2670) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2671) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2672) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2673) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2674) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2675) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2676) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2677) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2678) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x2679) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267a) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267b) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267c) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267d) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267e) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x267f) }, /* 631x/632x */
{ PCI_DEVICE(0x8086, 0x27b8) }, /* Gx */
/* E
{ PCI_DEVICE(0x8086, 0x245e) }, */
{ PCI_DEVICE(0x8086, 0x2450) }, /* E */
{ 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, pci_tbl);
static __initdata int no_fwh_detect;
module_param(no_fwh_detect, int, 0);
MODULE_PARM_DESC(no_fwh_detect, "Skip FWH detection:\n"
" positive value - skip if FWH space locked read-only\n"
" negative value - skip always");
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, int wait)
{
void __iomem *mem = (void __iomem *)rng->priv;
int data, i;
for (i = 0; i < 20; i++) {
data = !!(readb(mem + INTEL_RNG_STATUS) &
INTEL_RNG_DATA_PRESENT);
if (data || !wait)
break;
udelay(10);
}
return data;
}
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) {
pr_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
pr_warn(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,
};
struct intel_rng_hw {
struct pci_dev *dev;
void __iomem *mem;
u8 bios_cntl_off;
u8 bios_cntl_val;
u8 fwh_dec_en1_off;
u8 fwh_dec_en1_val;
};
static int __init intel_rng_hw_init(void *_intel_rng_hw)
{
struct intel_rng_hw *intel_rng_hw = _intel_rng_hw;
u8 mfc, dvc;
/* interrupts disabled in stop_machine call */
if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->fwh_dec_en1_off,
intel_rng_hw->fwh_dec_en1_val |
FWH_F8_EN_MASK);
if (!(intel_rng_hw->bios_cntl_val & BIOS_CNTL_WRITE_ENABLE_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->bios_cntl_off,
intel_rng_hw->bios_cntl_val |
BIOS_CNTL_WRITE_ENABLE_MASK);
writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
writeb(INTEL_FWH_READ_ID_CMD, intel_rng_hw->mem);
mfc = readb(intel_rng_hw->mem + INTEL_FWH_MANUFACTURER_CODE_ADDRESS);
dvc = readb(intel_rng_hw->mem + INTEL_FWH_DEVICE_CODE_ADDRESS);
writeb(INTEL_FWH_RESET_CMD, intel_rng_hw->mem);
if (!(intel_rng_hw->bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK)))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->bios_cntl_off,
intel_rng_hw->bios_cntl_val);
if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(intel_rng_hw->dev,
intel_rng_hw->fwh_dec_en1_off,
intel_rng_hw->fwh_dec_en1_val);
if (mfc != INTEL_FWH_MANUFACTURER_CODE ||
(dvc != INTEL_FWH_DEVICE_CODE_8M &&
dvc != INTEL_FWH_DEVICE_CODE_4M)) {
pr_notice(PFX "FWH not detected\n");
return -ENODEV;
}
return 0;
}
static int __init intel_init_hw_struct(struct intel_rng_hw *intel_rng_hw,
struct pci_dev *dev)
{
intel_rng_hw->bios_cntl_val = 0xff;
intel_rng_hw->fwh_dec_en1_val = 0xff;
intel_rng_hw->dev = dev;
/* Check for Intel 82802 */
if (dev->device < 0x2640) {
intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_OLD;
intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_OLD;
} else {
intel_rng_hw->fwh_dec_en1_off = FWH_DEC_EN1_REG_NEW;
intel_rng_hw->bios_cntl_off = BIOS_CNTL_REG_NEW;
}
pci_read_config_byte(dev, intel_rng_hw->fwh_dec_en1_off,
&intel_rng_hw->fwh_dec_en1_val);
pci_read_config_byte(dev, intel_rng_hw->bios_cntl_off,
&intel_rng_hw->bios_cntl_val);
if ((intel_rng_hw->bios_cntl_val &
(BIOS_CNTL_LOCK_ENABLE_MASK|BIOS_CNTL_WRITE_ENABLE_MASK))
== BIOS_CNTL_LOCK_ENABLE_MASK) {
static __initdata /*const*/ char warning[] =
PFX "Firmware space is locked read-only. If you can't or\n"
PFX "don't want to disable this in firmware setup, and if\n"
PFX "you are certain that your system has a functional\n"
PFX "RNG, try using the 'no_fwh_detect' option.\n";
if (no_fwh_detect)
return -ENODEV;
pr_warn("%s", warning);
return -EBUSY;
}
intel_rng_hw->mem = ioremap_nocache(INTEL_FWH_ADDR, INTEL_FWH_ADDR_LEN);
if (intel_rng_hw->mem == NULL)
return -EBUSY;
return 0;
}
static int __init mod_init(void)
{
int err = -ENODEV;
int i;
struct pci_dev *dev = NULL;
void __iomem *mem = mem;
u8 hw_status;
struct intel_rng_hw *intel_rng_hw;
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. */
if (no_fwh_detect < 0) {
pci_dev_put(dev);
goto fwh_done;
}
intel_rng_hw = kmalloc(sizeof(*intel_rng_hw), GFP_KERNEL);
if (!intel_rng_hw) {
pci_dev_put(dev);
goto out;
}
err = intel_init_hw_struct(intel_rng_hw, dev);
if (err) {
pci_dev_put(dev);
kfree(intel_rng_hw);
if (err == -ENODEV)
goto fwh_done;
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.
*
* Use stop_machine because IPIs can be blocked by disabling
* interrupts.
*/
err = stop_machine(intel_rng_hw_init, intel_rng_hw, NULL);
pci_dev_put(dev);
iounmap(intel_rng_hw->mem);
kfree(intel_rng_hw);
if (err)
goto out;
fwh_done:
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) {
iounmap(mem);
goto out;
}
pr_info("Intel 82802 RNG detected\n");
err = hwrng_register(&intel_rng);
if (err) {
pr_err(PFX "RNG registering failed (%d)\n",
err);
iounmap(mem);
}
out:
return err;
}
static void __exit mod_exit(void)
{
void __iomem *mem = (void __iomem *)intel_rng.priv;
hwrng_unregister(&intel_rng);
iounmap(mem);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
MODULE_LICENSE("GPL");
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