Signed-off-by: Michael Buesch <[EMAIL PROTECTED]>
Index: hwrng/drivers/char/hw_random/Kconfig
===================================================================
--- hwrng.orig/drivers/char/hw_random/Kconfig 2006-05-08 00:12:08.000000000
+0200
+++ hwrng/drivers/char/hw_random/Kconfig 2006-05-08 00:12:20.000000000
+0200
@@ -48,3 +48,16 @@
module will be called geode-rng.
If unsure, say Y.
+
+config HW_RANDOM_VIA
+ tristate "VIA HW Random Number Generator support"
+ depends on HW_RANDOM && X86
+ default y
+ ---help---
+ This driver provides kernel-side support for the Random Number
+ Generator hardware found on VIA based motherboards.
+
+ To compile this driver as a module, choose M here: the
+ module will be called via-rng.
+
+ If unsure, say Y.
Index: hwrng/drivers/char/hw_random/Makefile
===================================================================
--- hwrng.orig/drivers/char/hw_random/Makefile 2006-05-08 00:12:03.000000000
+0200
+++ hwrng/drivers/char/hw_random/Makefile 2006-05-08 00:12:12.000000000
+0200
@@ -6,3 +6,4 @@
obj-$(CONFIG_HW_RANDOM_INTEL) += intel-rng.o
obj-$(CONFIG_HW_RANDOM_AMD) += amd-rng.o
obj-$(CONFIG_HW_RANDOM_GEODE) += geode-rng.o
+obj-$(CONFIG_HW_RANDOM_VIA) += via-rng.o
Index: hwrng/drivers/char/hw_random/via-rng.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ hwrng/drivers/char/hw_random/via-rng.c 2006-05-08 00:12:12.000000000
+0200
@@ -0,0 +1,184 @@
+/*
+ * RNG driver for 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/pci.h>
+#include <linux/hw_random.h>
+#include <asm/io.h>
+#include <asm/msr.h>
+#include <asm/cpufeature.h>
+
+
+#define PFX KBUILD_MODNAME ": "
+
+
+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,
+};
+
+/*
+ * 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_rng_data_present(struct hwrng *rng)
+{
+ u32 bytes_out;
+ u32 *via_rng_datum = (u32 *)(&rng->priv);
+
+ /* 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);
+ bytes_out &= VIA_XSTORE_CNT_MASK;
+ if (bytes_out == 0)
+ return 0;
+ return 1;
+}
+
+static int via_rng_data_read(struct hwrng *rng, u32 *data)
+{
+ u32 via_rng_datum = (u32)rng->priv;
+
+ *data = via_rng_datum;
+
+ return 1;
+}
+
+static int via_rng_init(struct hwrng *rng)
+{
+ 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 struct hwrng via_rng = {
+ .name = "via",
+ .init = via_rng_init,
+ .data_present = via_rng_data_present,
+ .data_read = via_rng_data_read,
+};
+
+
+static int __init mod_init(void)
+{
+ int err;
+
+ if (!cpu_has_xstore)
+ return -ENODEV;
+ printk(KERN_INFO "VIA RNG detected\n");
+ err = hwrng_register(&via_rng);
+ if (err) {
+ printk(KERN_ERR PFX "RNG registering failed (%d)\n",
+ err);
+ goto out;
+ }
+out:
+ return err;
+}
+
+static void __exit mod_exit(void)
+{
+ hwrng_unregister(&via_rng);
+}
+
+subsys_initcall(mod_init);
+module_exit(mod_exit);
+
+MODULE_AUTHOR("The Linux Kernel team");
+MODULE_DESCRIPTION("H/W RNG driver for VIA chipsets");
+MODULE_LICENSE("GPL");
--
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