[patch 2.4 2/2] add hw_random RNG driver

Jeff Garzik
2003-08-08T02:56:31Z

#
# drivers/char/Config.in 1.48 -> 1.49
# Documentation/Configure.help 1.176 -> 1.177
# drivers/char/Makefile 1.34 -> 1.35
# (new) -> 1.1 drivers/char/hw_random.c
# (new) -> 1.2 Documentation/hw_random.txt
#
# --------------------------------------------
# 03/08/07 jgarzik@redhat.com 1.1067
# [hw_random] add combined Intel+AMD+VIA h/w RNG driver
# --------------------------------------------
#
diff -Nru a/Documentation/Configure.help b/Documentation/Configure.help
--- a/Documentation/Configure.help Thu Aug 7 22:51:42 2003
+++ b/Documentation/Configure.help Thu Aug 7 22:51:43 2003
@@ -18797,6 +18797,21 @@

If unsure, say N.

+Intel/AMD/VIA HW Random Number Generator support
+CONFIG_HW_RANDOM
+ This driver provides kernel-side support for the
+ Random Number Generator hardware found on Intel i8xx-based motherboards,
+ AMD 76x-based motherboards, and Via Nehemiah CPUs.
+
+ Provides a character driver, used to read() entropy data.
+
+ To compile this driver as a module ( = code which can be inserted in
+ and removed from the running kernel whenever you want), say M here
+ and read <file:Documentation/modules.txt>. The module will be called
+ hw_random.
+
+ If unsure, say N.
+
Power Management support
CONFIG_PM
"Power Management" means that parts of your computer are shut
diff -Nru a/Documentation/hw_random.txt b/Documentation/hw_random.txt
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/Documentation/hw_random.txt Thu Aug 7 22:51:43 2003
@@ -0,0 +1,138 @@
+ Hardware driver for Intel/AMD/VIA Random Number Generators (RNG)
+ Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
+ Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
+
+Introduction:
+
+ The hw_random device driver is software that makes use of a
+ special hardware feature on your CPU or motherboard,
+ a Random Number Generator (RNG).
+
+ In order to make effective use of this device driver, you
+ should download the support software as well. Download the
+ latest version of the "rng-tools" package from the
+ hw_random driver's official Web site:
+
+ http://sourceforge.net/projects/gkernel/
+
+About the Intel RNG hardware, from the firmware hub datasheet:
+
+ The Firmware Hub integrates a Random Number Generator (RNG)
+ using thermal noise generated from inherently random quantum
+ mechanical properties of silicon. When not generating new random
+ bits the RNG circuitry will enter a low power state. Intel will
+ provide a binary software driver to give third party software
+ access to our RNG for use as a security feature. At this time,
+ the RNG is only to be used with a system in an OS-present state.
+
+Theory of operation:
+
+ Character driver. Using the standard open()
+ and read() system calls, you can read random data from
+ the hardware RNG device. This data is NOT CHECKED by any
+ fitness tests, and could potentially be bogus (if the
+ hardware is faulty or has been tampered with). Data is only
+ output if the hardware "has-data" flag is set, but nevertheless
+ a security-conscious person would run fitness tests on the
+ data before assuming it is truly random.
+
+ /dev/hwrandom is char device major 10, minor 183.
+
+Driver notes:
+
+ * FIXME: support poll(2)
+
+ NOTE: request_mem_region was removed, for two reasons:
+ 1) Only one RNG is supported by this driver, 2) The location
+ used by the RNG is a fixed location in MMIO-addressable memory,
+ 3) users with properly working BIOS e820 handling will always
+ have the region in which the RNG is located reserved, so
+ request_mem_region calls always fail for proper setups.
+ However, for people who use mem=XX, BIOS e820 information is
+ -not- in /proc/iomem, and request_mem_region(RNG_ADDR) can
+ succeed.
+
+Driver details:
+
+ Based on:
+ Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet
+ May 1999 Order Number: 290658-002 R
+
+ Intel 82802 Firmware Hub: Random Number Generator
+ Programmer's Reference Manual
+ December 1999 Order Number: 298029-001 R
+
+ Intel 82802 Firmware HUB Random Number Generator Driver
+ Copyright (c) 2000 Matt Sottek <msottek@quiknet.com>
+
+ Special thanks to Matt Sottek. I did the "guts", he
+ did the "brains" and all the testing.
+
+Change history:
+
+ Version 1.0.0:
+ * Merge Intel, AMD, VIA RNG drivers into one.
+ Further changelog in BitKeeper.
+
+ Version 0.9.8:
+ * Support other i8xx chipsets by adding 82801E detection
+ * 82801DB detection is the same as for 82801CA.
+
+ Version 0.9.7:
+ * Support other i8xx chipsets too (by adding 82801BA(M) and
+ 82801CA(M) detection)
+
+ Version 0.9.6:
+ * Internal driver cleanups, prep for 1.0.0 release.
+
+ Version 0.9.5:
+ * Rip out entropy injection via timer. It never ever worked,
+ and a better solution (rngd) is now available.
+
+ Version 0.9.4:
+ * Fix: Remove request_mem_region
+ * Fix: Horrible bugs in FIPS calculation and test execution
+
+ Version 0.9.3:
+ * Clean up rng_read a bit.
+ * Update i810_rng driver Web site URL.
+ * Increase default timer interval to 4 samples per second.
+ * Abort if mem region is not available.
+ * BSS zero-initialization cleanup.
+ * Call misc_register() from rng_init_one.
+ * Fix O_NONBLOCK to occur before we schedule.
+
+ Version 0.9.2:
+ * Simplify open blocking logic
+
+ Version 0.9.1:
+ * Support i815 chipsets too (Matt Sottek)
+ * Fix reference counting when statically compiled (prumpf)
+ * Rewrite rng_dev_read (prumpf)
+ * Make module races less likely (prumpf)
+ * Small miscellaneous bug fixes (prumpf)
+ * Use pci table for PCI id list
+
+ Version 0.9.0:
+ * Don't register a pci_driver, because we are really
+ using PCI bridge vendor/device ids, and someone
+ may want to register a driver for the bridge. (bug fix)
+ * Don't let the usage count go negative (bug fix)
+ * Clean up spinlocks (bug fix)
+ * Enable PCI device, if necessary (bug fix)
+ * iounmap on module unload (bug fix)
+ * If RNG chrdev is already in use when open(2) is called,
+ sleep until it is available.
+ * Remove redundant globals rng_allocated, rng_use_count
+ * Convert numeric globals to unsigned
+ * Module unload cleanup
+
+ Version 0.6.2:
+ * Clean up spinlocks. Since we don't have any interrupts
+ to worry about, but we do have a timer to worry about,
+ we use spin_lock_bh everywhere except the timer function
+ itself.
+ * Fix module load/unload.
+ * Fix timer function and h/w enable/disable logic
+ * New timer interval sysctl
+ * Clean up sysctl names
diff -Nru a/drivers/char/Config.in b/drivers/char/Config.in
--- a/drivers/char/Config.in Thu Aug 7 22:51:42 2003
+++ b/drivers/char/Config.in Thu Aug 7 22:51:42 2003
@@ -267,6 +267,10 @@
if [ "$CONFIG_X86" = "y" -o "$CONFIG_IA64" = "y" ]; then
dep_tristate 'Intel i8x0 Random Number Generator support' CONFIG_INTEL_RNG $CONFIG_PCI
fi
+if [ "$CONFIG_X86" = "y" -o "$CONFIG_IA64" = "y" -o \
+ "$CONFIG_X86_64" = "y" ]; then
+ dep_tristate 'Intel/AMD/VIA HW Random Number Generator support' CONFIG_HW_RANDOM $CONFIG_PCI
+fi
dep_tristate 'AMD 76x native power management (Experimental)' CONFIG_AMD_PM768 $CONFIG_PCI
tristate '/dev/nvram support' CONFIG_NVRAM
tristate 'Enhanced Real Time Clock Support' CONFIG_RTC
diff -Nru a/drivers/char/Makefile b/drivers/char/Makefile
--- a/drivers/char/Makefile Thu Aug 7 22:51:43 2003
+++ b/drivers/char/Makefile Thu Aug 7 22:51:43 2003
@@ -247,6 +247,7 @@
obj-$(CONFIG_DS1620) += ds1620.o
obj-$(CONFIG_INTEL_RNG) += i810_rng.o
obj-$(CONFIG_AMD_RNG) += amd768_rng.o
+obj-$(CONFIG_HW_RANDOM) += hw_random.o
obj-$(CONFIG_AMD_PM768) += amd76x_pm.o
obj-$(CONFIG_BRIQ_PANEL) += briq_panel.o

diff -Nru a/drivers/char/hw_random.c b/drivers/char/hw_random.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/drivers/char/hw_random.c Thu Aug 7 22:51:43 2003
@@ -0,0 +1,631 @@
+/*
+ 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>
+
+ Please read Documentation/hw_random.txt for details on use.
+
+ ----------------------------------------------------------
+ This software may be used and distributed according to the terms
+ of the GNU General Public License, incorporated herein by reference.
+
+ */
+
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/random.h>
+#include <linux/miscdevice.h>
+#include <linux/smp_lock.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+
+#ifdef __i386__
+#include <asm/msr.h>
+#include <asm/cpufeature.h>
+#endif
+
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+
+/*
+ * core module and version information
+ */
+#define RNG_VERSION "1.0.0"
+#define RNG_MODULE_NAME "hw_random"
+#define RNG_DRIVER_NAME RNG_MODULE_NAME " hardware driver " RNG_VERSION
+#define PFX RNG_MODULE_NAME ": "
+
+
+/*
+ * debugging macros
+ */
+#undef RNG_DEBUG /* define to enable copious debugging info */
+
+#ifdef RNG_DEBUG
+/* note: prints function name for you */
+#define DPRINTK(fmt, args...) printk(KERN_DEBUG "%s: " fmt, __FUNCTION__ , ## args)
+#else
+#define DPRINTK(fmt, args...)
+#endif
+
+#define RNG_NDEBUG /* define to disable lightweight runtime checks */
+#ifdef RNG_NDEBUG
+#define assert(expr)
+#else
+#define assert(expr) \
+ if(!(expr)) { \
+ printk( "Assertion failed! %s,%s,%s,line=%d\n", \
+ #expr,__FILE__,__FUNCTION__,__LINE__); \
+ }
+#endif
+
+#define RNG_MISCDEV_MINOR 183 /* official */
+
+static int rng_dev_open (struct inode *inode, struct file *filp);
+static ssize_t rng_dev_read (struct file *filp, char *buf, size_t size,
+ loff_t * offp);
+
+static int __init intel_init (struct pci_dev *dev);
+static void intel_cleanup(void);
+static unsigned int intel_data_present (void);
+static u32 intel_data_read (void);
+
+static int __init amd_init (struct pci_dev *dev);
+static void amd_cleanup(void);
+static unsigned int amd_data_present (void);
+static u32 amd_data_read (void);
+
+static int __init via_init(struct pci_dev *dev);
+static void via_cleanup(void);
+static unsigned int via_data_present (void);
+static u32 via_data_read (void);
+
+struct rng_operations {
+ int (*init) (struct pci_dev *dev);
+ void (*cleanup) (void);
+ unsigned int (*data_present) (void);
+ u32 (*data_read) (void);
+ unsigned int n_bytes; /* number of bytes per ->data_read */
+};
+static struct rng_operations *rng_ops;
+
+static struct file_operations rng_chrdev_ops = {
+ .owner = THIS_MODULE,
+ .open = rng_dev_open,
+ .read = rng_dev_read,
+};
+
+
+static struct miscdevice rng_miscdev = {
+ RNG_MISCDEV_MINOR,
+ RNG_MODULE_NAME,
+ &rng_chrdev_ops,
+};
+
+enum {
+ rng_hw_none,
+ rng_hw_intel,
+ rng_hw_amd,
+ rng_hw_via,
+};
+
+static struct rng_operations rng_vendor_ops[] = {
+ /* rng_hw_none */
+ { },
+
+ /* rng_hw_intel */
+ { intel_init, intel_cleanup, intel_data_present,
+ intel_data_read, 1 },
+
+ /* rng_hw_amd */
+ { amd_init, amd_cleanup, amd_data_present, amd_data_read, 4 },
+
+ /* rng_hw_via */
+ { via_init, via_cleanup, via_data_present, via_data_read, 1 },
+};
+
+/*
+ * 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 struct pci_device_id rng_pci_tbl[] __initdata = {
+ { 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_amd },
+ { 0x1022, 0x746b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_amd },
+
+ { 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel },
+ { 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel },
+ { 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel },
+ { 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel },
+ { 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel },
+
+ { 0, }, /* terminate list */
+};
+MODULE_DEVICE_TABLE (pci, rng_pci_tbl);
+
+
+/***********************************************************************
+ *
+ * Intel RNG operations
+ *
+ */
+
+/*
+ * RNG registers (offsets from rng_mem)
+ */
+#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
+
+/* token to our ioremap'd RNG register area */
+static void *rng_mem;
+
+static inline u8 intel_hwstatus (void)
+{
+ assert (rng_mem != NULL);
+ return readb (rng_mem + INTEL_RNG_HW_STATUS);
+}
+
+static inline u8 intel_hwstatus_set (u8 hw_status)
+{
+ assert (rng_mem != NULL);
+ writeb (hw_status, rng_mem + INTEL_RNG_HW_STATUS);
+ return intel_hwstatus ();
+}
+
+static unsigned int intel_data_present(void)
+{
+ assert (rng_mem != NULL);
+
+ return (readb (rng_mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT) ?
+ 1 : 0;
+}
+
+static u32 intel_data_read(void)
+{
+ assert (rng_mem != NULL);
+
+ return readb (rng_mem + INTEL_RNG_DATA);
+}
+
+static int __init intel_init (struct pci_dev *dev)
+{
+ int rc;
+ u8 hw_status;
+
+ DPRINTK ("ENTER\n");
+
+ rng_mem = ioremap (INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
+ if (rng_mem == NULL) {
+ printk (KERN_ERR PFX "cannot ioremap RNG Memory\n");
+ rc = -EBUSY;
+ goto err_out;
+ }
+
+ /* Check for Intel 82802 */
+ hw_status = intel_hwstatus ();
+ if ((hw_status & INTEL_RNG_PRESENT) == 0) {
+ printk (KERN_ERR PFX "RNG not detected\n");
+ rc = -ENODEV;
+ goto err_out_free_map;
+ }
+
+ /* turn RNG h/w on, if it's off */
+ if ((hw_status & INTEL_RNG_ENABLED) == 0)
+ hw_status = intel_hwstatus_set (hw_status | INTEL_RNG_ENABLED);
+ if ((hw_status & INTEL_RNG_ENABLED) == 0) {
+ printk (KERN_ERR PFX "cannot enable RNG, aborting\n");
+ rc = -EIO;
+ goto err_out_free_map;
+ }
+
+ DPRINTK ("EXIT, returning 0\n");
+ return 0;
+
+err_out_free_map:
+ iounmap (rng_mem);
+ rng_mem = NULL;
+err_out:
+ DPRINTK ("EXIT, returning %d\n", rc);
+ return rc;
+}
+
+static void intel_cleanup(void)
+{
+ u8 hw_status;
+
+ hw_status = intel_hwstatus ();
+ if (hw_status & INTEL_RNG_ENABLED)
+ intel_hwstatus_set (hw_status & ~INTEL_RNG_ENABLED);
+ else
+ printk(KERN_WARNING PFX "unusual: RNG already disabled\n");
+ iounmap(rng_mem);
+ rng_mem = NULL;
+}
+
+/***********************************************************************
+ *
+ * AMD RNG operations
+ *
+ */
+
+static u32 pmbase; /* PMxx I/O base */
+static struct pci_dev *amd_dev;
+
+static unsigned int amd_data_present (void)
+{
+ return inl(pmbase + 0xF4) & 1;
+}
+
+
+static u32 amd_data_read (void)
+{
+ return inl(pmbase + 0xF0);
+}
+
+static int __init amd_init (struct pci_dev *dev)
+{
+ int rc;
+ u8 rnen;
+
+ DPRINTK ("ENTER\n");
+
+ pci_read_config_dword(dev, 0x58, &pmbase);
+
+ pmbase &= 0x0000FF00;
+
+ if (pmbase == 0)
+ {
+ printk (KERN_ERR PFX "power management base not set\n");
+ rc = -EIO;
+ goto err_out;
+ }
+
+ pci_read_config_byte(dev, 0x40, &rnen);
+ rnen |= (1 << 7); /* RNG on */
+ pci_write_config_byte(dev, 0x40, rnen);
+
+ pci_read_config_byte(dev, 0x41, &rnen);
+ rnen |= (1 << 7); /* PMIO enable */
+ pci_write_config_byte(dev, 0x41, rnen);
+
+ printk(KERN_INFO PFX "AMD768 system management I/O registers at 0x%X.\n", pmbase);
+
+ amd_dev = dev;
+
+ DPRINTK ("EXIT, returning 0\n");
+ return 0;
+
+err_out:
+ DPRINTK ("EXIT, returning %d\n", rc);
+ return rc;
+}
+
+static void amd_cleanup(void)
+{
+ u8 rnen;
+
+ pci_read_config_byte(amd_dev, 0x40, &rnen);
+ rnen &= ~(1 << 7); /* RNG off */
+ pci_write_config_byte(amd_dev, 0x40, rnen);
+
+ /* FIXME: twiddle pmio, also? */
+}
+
+/***********************************************************************
+ *
+ * VIA RNG operations
+ *
+ */
+
+enum {
+ VIA_STRFILT_CNT_SHIFT = 16,
+ VIA_STRFILT_FAIL = (1 << 15),
+ VIA_STRFILT_ENABLE = (1 << 14),
+ VIA_RAWBITS_ENABLE = (1 << 13),
+ VIA_RNG_ENABLE = (1 << 6),
+ VIA_XSTORE_CNT_MASK = 0x0F,
+
+ VIA_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */
+ VIA_RNG_CHUNK_4 = 0x01, /* 32 rand bits, 32 stored bits */
+ VIA_RNG_CHUNK_4_MASK = 0xFFFFFFFF,
+ VIA_RNG_CHUNK_2 = 0x02, /* 16 rand bits, 32 stored bits */
+ VIA_RNG_CHUNK_2_MASK = 0xFFFF,
+ VIA_RNG_CHUNK_1 = 0x03, /* 8 rand bits, 32 stored bits */
+ VIA_RNG_CHUNK_1_MASK = 0xFF,
+};
+
+u32 via_rng_datum;
+
+/*
+ * Investigate using the 'rep' prefix to obtain 32 bits of random data
+ * in one insn. The upside is potentially better performance. The
+ * downside is that the instruction becomes no longer atomic. Due to
+ * this, just like familiar issues with /dev/random itself, the worst
+ * case of a 'rep xstore' could potentially pause a cpu for an
+ * unreasonably long time. In practice, this condition would likely
+ * only occur when the hardware is failing. (or so we hope :))
+ *
+ * Another possible performance boost may come from simply buffering
+ * until we have 4 bytes, thus returning a u32 at a time,
+ * instead of the current u8-at-a-time.
+ */
+
+static inline u32 xstore(u32 *addr, u32 edx_in)
+{
+ u32 eax_out;
+
+ asm(".byte 0x0F,0xA7,0xC0 /* xstore %%edi (addr=%0) */"
+ :"=m"(*addr), "=a"(eax_out)
+ :"D"(addr), "d"(edx_in));
+
+ return eax_out;
+}
+
+static unsigned int via_data_present(void)
+{
+ u32 bytes_out;
+
+ /* We choose the recommended 1-byte-per-instruction RNG rate,
+ * for greater randomness at the expense of speed. Larger
+ * values 2, 4, or 8 bytes-per-instruction yield greater
+ * speed at lesser randomness.
+ *
+ * If you change this to another VIA_CHUNK_n, you must also
+ * change the ->n_bytes values in rng_vendor_ops[] tables.
+ * VIA_CHUNK_8 requires further code changes.
+ *
+ * A copy of MSR_VIA_RNG is placed in eax_out when xstore
+ * completes.
+ */
+ via_rng_datum = 0; /* paranoia, not really necessary */
+ bytes_out = xstore(&via_rng_datum, VIA_RNG_CHUNK_1) & VIA_XSTORE_CNT_MASK;
+ if (bytes_out == 0)
+ return 0;
+
+ return 1;
+}
+
+static u32 via_data_read(void)
+{
+ return via_rng_datum;
+}
+
+static int __init via_init(struct pci_dev *dev)
+{
+ u32 lo, hi, old_lo;
+
+ /* Control the RNG via MSR. Tread lightly and pay very close
+ * close attention to values written, as the reserved fields
+ * are documented to be "undefined and unpredictable"; but it
+ * does not say to write them as zero, so I make a guess that
+ * we restore the values we find in the register.
+ */
+ rdmsr(MSR_VIA_RNG, lo, hi);
+
+ old_lo = lo;
+ lo &= ~(0x7f << VIA_STRFILT_CNT_SHIFT);
+ lo &= ~VIA_XSTORE_CNT_MASK;
+ lo &= ~(VIA_STRFILT_ENABLE | VIA_STRFILT_FAIL | VIA_RAWBITS_ENABLE);
+ lo |= VIA_RNG_ENABLE;
+
+ if (lo != old_lo)
+ wrmsr(MSR_VIA_RNG, lo, hi);
+
+ /* perhaps-unnecessary sanity check; remove after testing if
+ unneeded */
+ rdmsr(MSR_VIA_RNG, lo, hi);
+ if ((lo & VIA_RNG_ENABLE) == 0) {
+ printk(KERN_ERR PFX "cannot enable VIA C3 RNG, aborting\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static void via_cleanup(void)
+{
+ u32 lo, hi;
+
+ rdmsr(MSR_VIA_RNG, lo, hi);
+ lo &= ~VIA_RNG_ENABLE;
+ wrmsr(MSR_VIA_RNG, lo, hi);
+}
+
+
+/***********************************************************************
+ *
+ * /dev/hwrandom character device handling (major 10, minor 183)
+ *
+ */
+
+static int rng_dev_open (struct inode *inode, struct file *filp)
+{
+ /* enforce read-only access to this chrdev */
+ if ((filp->f_mode & FMODE_READ) == 0)
+ return -EINVAL;
+ if (filp->f_mode & FMODE_WRITE)
+ return -EINVAL;
+
+ return 0;
+}
+
+
+static ssize_t rng_dev_read (struct file *filp, char *buf, size_t size,
+ loff_t * offp)
+{
+ static spinlock_t rng_lock = SPIN_LOCK_UNLOCKED;
+ unsigned int have_data;
+ u32 data = 0;
+ ssize_t ret = 0;
+
+ while (size) {
+ spin_lock(&rng_lock);
+
+ have_data = 0;
+ if (rng_ops->data_present()) {
+ data = rng_ops->data_read();
+ have_data = rng_ops->n_bytes;
+ }
+
+ spin_unlock (&rng_lock);
+
+ while (have_data && size) {
+ if (put_user((u8)data, buf++)) {
+ ret = ret ? : -EFAULT;
+ break;
+ }
+ size--;
+ ret++;
+ have_data--;
+ data>>=8;
+ }
+
+ if (filp->f_flags & O_NONBLOCK)
+ return ret ? : -EAGAIN;
+
+ if(need_resched())
+ {
+ current->state = TASK_INTERRUPTIBLE;
+ schedule_timeout(1);
+ }
+ else
+ udelay(200); /* FIXME: We could poll for 250uS ?? */
+
+ if (signal_pending (current))
+ return ret ? : -ERESTARTSYS;
+ }
+ return ret;
+}
+
+
+
+/*
+ * rng_init_one - look for and attempt to init a single RNG
+ */
+static int __init rng_init_one (struct pci_dev *dev)
+{
+ int rc;
+
+ DPRINTK ("ENTER\n");
+
+ assert(rng_ops != NULL);
+
+ rc = rng_ops->init(dev);
+ if (rc)
+ goto err_out;
+
+ rc = misc_register (&rng_miscdev);
+ if (rc) {
+ printk (KERN_ERR PFX "misc device register failed\n");
+ goto err_out_cleanup_hw;
+ }
+
+ DPRINTK ("EXIT, returning 0\n");
+ return 0;
+
+err_out_cleanup_hw:
+ rng_ops->cleanup();
+err_out:
+ DPRINTK ("EXIT, returning %d\n", rc);
+ return rc;
+}
+
+
+
+MODULE_AUTHOR("The Linux Kernel team");
+MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL");
+
+
+/*
+ * rng_init - initialize RNG module
+ */
+static int __init rng_init (void)
+{
+ int rc;
+ struct pci_dev *pdev = NULL;
+ const struct pci_device_id *ent;
+
+ DPRINTK ("ENTER\n");
+
+ /* Probe for Intel, AMD RNGs */
+ while ((pdev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, pdev)) != NULL) {
+ ent = pci_match_device (rng_pci_tbl, pdev);
+ if (ent) {
+ rng_ops = &rng_vendor_ops[ent->driver_data];
+ goto match;
+ }
+ }
+
+#ifdef __i386__
+ /* Probe for VIA RNG */
+ if (cpu_has_xstore) {
+ rng_ops = &rng_vendor_ops[rng_hw_via];
+ pdev = NULL;
+ goto match;
+ }
+#endif
+
+ DPRINTK ("EXIT, returning -ENODEV\n");
+ return -ENODEV;
+
+match:
+ rc = rng_init_one (pdev);
+ if (rc)
+ return rc;
+
+ printk (KERN_INFO RNG_DRIVER_NAME " loaded\n");
+
+ DPRINTK ("EXIT, returning 0\n");
+ return 0;
+}
+
+
+/*
+ * rng_init - shutdown RNG module
+ */
+static void __exit rng_cleanup (void)
+{
+ DPRINTK ("ENTER\n");
+
+ misc_deregister (&rng_miscdev);
+
+ if (rng_ops->cleanup)
+ rng_ops->cleanup();
+
+ DPRINTK ("EXIT\n");
+}
+
+
+module_init (rng_init);
+module_exit (rng_cleanup);