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authorHarald Welte <HaraldWelte@viatech.com>2009-05-15 10:00:32 +0400
committerHerbert Xu <herbert@gondor.apana.org.au>2009-06-02 08:04:53 +0400
commit858576bdc5d65edf1fffd2e65b2165ec1dc68486 (patch)
treefbece7a0b0ad73218ca24071ca8f0e17584e0963 /drivers/char/hw_random/via-rng.c
parent608d1cd5d375580a49d01b5ed1f9944f5141ae19 (diff)
downloadlinux-858576bdc5d65edf1fffd2e65b2165ec1dc68486.tar.xz
hwrng: via_rng - Support VIA Nano hardware RNG
The VIA Nano CPU supports the same XSTORE instruction based RNG, but it lacks the MSR present in earlier CPUs. Signed-off-by: Harald Welte <HaraldWelte@viatech.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/char/hw_random/via-rng.c')
-rw-r--r--drivers/char/hw_random/via-rng.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 02ee63906713..794aacb715c1 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -132,6 +132,19 @@ static int via_rng_init(struct hwrng *rng)
struct cpuinfo_x86 *c = &cpu_data(0);
u32 lo, hi, old_lo;
+ /* VIA Nano CPUs don't have the MSR_VIA_RNG anymore. The RNG
+ * is always enabled if CPUID rng_en is set. There is no
+ * RNG configuration like it used to be the case in this
+ * register */
+ if ((c->x86 == 6) && (c->x86_model >= 0x0f)) {
+ if (!cpu_has_xstore_enabled) {
+ printk(KERN_ERR PFX "can't enable hardware RNG "
+ "if XSTORE is not enabled\n");
+ return -ENODEV;
+ }
+ return 0;
+ }
+
/* 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