x86 RNG driver. This is basically the existing driver with
the user space interface bits ripped out.
Signed-off-by: Deepak Saxena <[email protected]>
Index: linux-2.6-rng/drivers/char/rng/x86-rng.c
===================================================================
--- /dev/null
+++ linux-2.6-rng/drivers/char/rng/x86-rng.c
@@ -0,0 +1,528 @@
+/*
+ * drivers/char/rng/x86.c
+ *
+ * RNG driver for Intel/AMD/VIA 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 <[email protected]>
+ *
+ * derived from
+ *
+ * Hardware driver for the AMD 768 Random Number Generator (RNG)
+ * (c) Copyright 2001 Red Hat Inc <[email protected]>
+ *
+ * derived from
+ *
+ * Hardware driver for Intel i810 Random Number Generator (RNG)
+ * Copyright 2000,2001 Jeff Garzik <[email protected]>
+ * Copyright 2000,2001 Philipp Rumpf <[email protected]>
+ *
+ * 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/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>
+
+#include <asm/msr.h>
+#include <asm/cpufeature.h>
+
+#include <asm/io.h>
+
+#include "rng.h"
+
+/*
+ * debugging macros
+ */
+
+/* pr_debug() collapses to a no-op if DEBUG is not defined */
+#define DPRINTK(fmt, args...) pr_debug(PFX "%s: " fmt, __FUNCTION__ , ## args)
+
+#define RNG_VERSION "1.1.0"
+#define RNG_MODULE_NAME "x86-rng"
+#define RNG_DRIVER_NAME RNG_MODULE_NAME " hardware driver " RNG_VERSION
+#define PFX RNG_MODULE_NAME ": "
+
+#undef RNG_NDEBUG /* define to enable lightweight runtime checks */
+#ifdef RNG_NDEBUG
+#define assert(expr) \
+ if(!(expr)) { \
+ printk(KERN_DEBUG PFX "Assertion failed! %s,%s,%s," \
+ "line=%d\n", #expr, __FILE__, __FUNCTION__, __LINE__); \
+ }
+#else
+#define assert(expr)
+#endif
+
+
+struct x86_rng_operations {
+ int (*init) (struct pci_dev *dev);
+ void (*cleanup) (void);
+ struct rng_operations rng_ops;
+};
+
+static struct x86_rng_operations *x86_rng_ops;
+
+static int __init intel_init (struct pci_dev *dev);
+static void intel_cleanup(void);
+static int intel_data_present (void);
+static int intel_data_read (u32 *data);
+
+static int __init amd_init (struct pci_dev *dev);
+static void amd_cleanup(void);
+static int amd_data_present (void);
+static int amd_data_read (u32 *data);
+
+#ifdef __i386__
+static int __init via_init(struct pci_dev *dev);
+static void via_cleanup(void);
+static int via_data_present (void);
+static int via_data_read (u32 *date);
+#endif
+
+enum {
+ rng_hw_none,
+ rng_hw_intel,
+ rng_hw_amd,
+ rng_hw_via,
+};
+
+static struct x86_rng_operations rng_vendor_ops[] = {
+ /* rng_hw_none */
+ { },
+
+ /* rng_hw_intel */
+ {
+ .init = intel_init,
+ .cleanup = intel_cleanup,
+ .rng_ops.data_present = intel_data_present,
+ .rng_ops.data_read = intel_data_read
+ },
+
+ /* rng_hw_amd */
+ {
+ .init = amd_init,
+ .cleanup = amd_cleanup,
+ .rng_ops.data_present = amd_data_present,
+ .rng_ops.data_read = amd_data_read
+ },
+
+#ifdef __i386__
+ /* rng_hw_via */
+ {
+ .init = via_init,
+ .cleanup = via_cleanup,
+ .rng_ops.data_present = via_data_present,
+ .rng_ops.data_read = via_data_read
+ }
+#endif
+};
+
+/*
+ * 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[] = {
+ { 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 __iomem *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 int intel_data_present(void)
+{
+ assert (rng_mem != NULL);
+
+ return (readb (rng_mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT) ?
+ 1 : 0;
+}
+
+static int intel_data_read(u32 *data)
+{
+ assert (rng_mem != NULL);
+
+ *data = readb (rng_mem + INTEL_RNG_DATA);
+
+ return 1;
+}
+
+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 int amd_data_present (void)
+{
+ return inl(pmbase + 0xF4) & 1;
+}
+
+
+static int amd_data_read (u32 *data)
+{
+ *data = inl(pmbase + 0xF0);
+
+ return 4;
+}
+
+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);
+
+ pr_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? */
+}
+
+#ifdef __i386__
+/***********************************************************************
+ *
+ * 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,
+};
+
+static 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 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 int via_data_read(u32 *data)
+{
+ *data = via_rng_datum;
+
+ return 1;
+}
+
+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)
+{
+ /* do nothing */
+}
+#endif
+
+
+/*
+ * rng_init - initialize RNG module
+ */
+static int __init x86_rng_init(void)
+{
+ int rc;
+ struct pci_dev *pdev = NULL;
+ const struct pci_device_id *ent;
+
+ DPRINTK ("ENTER\n");
+
+ /* Probe for Intel, AMD RNGs */
+ for_each_pci_dev(pdev) {
+ ent = pci_match_id(rng_pci_tbl, pdev);
+ if (ent) {
+ x86_rng_ops = &rng_vendor_ops[ent->driver_data];
+ goto match;
+ }
+ }
+
+ /* Probe for VIA RNG */
+ if (cpu_has_xstore) {
+ x86_rng_ops = &rng_vendor_ops[rng_hw_via];
+ pdev = NULL;
+ goto match;
+ }
+
+ DPRINTK ("EXIT, returning -ENODEV\n");
+ return -ENODEV;
+
+match:
+ rc = x86_rng_ops->init(pdev);
+ if (rc)
+ return rc;
+
+ rc = register_rng(&x86_rng_ops->rng_ops);
+ if (rc) {
+ x86_rng_ops->cleanup();
+ return rc;
+ }
+
+ pr_info( RNG_DRIVER_NAME " loaded\n");
+
+ DPRINTK ("EXIT, returning 0\n");
+ return 0;
+}
+
+/*
+ * rng_init - shutdown RNG module
+ */
+static void __exit x86_rng_exit (void)
+{
+ DPRINTK ("ENTER\n");
+
+ unregister_rng(&x86_rng_ops->rng_ops);
+
+ if (x86_rng_ops->cleanup)
+ x86_rng_ops->cleanup();
+
+ DPRINTK ("EXIT\n");
+}
+
+subsys_initcall(x86_rng_init);
+module_exit(x86_rng_exit);
+
+MODULE_AUTHOR("The Linux Kernel team");
+MODULE_DESCRIPTION("H/W RNG driver for Intel/AMD/VIA chipsets");
+MODULE_LICENSE("GPL");
--
Deepak Saxena - [email protected] - http://www.plexity.net
Even a stopped clock gives the right time twice a day.
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