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path: root/drivers/char/hw_random/via-rng.c
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Diffstat (limited to 'drivers/char/hw_random/via-rng.c')
-rw-r--r--drivers/char/hw_random/via-rng.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 868e39fd42e4..f7feae4ebb5e 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -42,6 +42,8 @@ enum {
VIA_STRFILT_ENABLE = (1 << 14),
VIA_RAWBITS_ENABLE = (1 << 13),
VIA_RNG_ENABLE = (1 << 6),
+ VIA_NOISESRC1 = (1 << 8),
+ VIA_NOISESRC2 = (1 << 9),
VIA_XSTORE_CNT_MASK = 0x0F,
VIA_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */
@@ -119,6 +121,7 @@ static int via_rng_data_read(struct hwrng *rng, u32 *data)
static int via_rng_init(struct hwrng *rng)
{
+ struct cpuinfo_x86 *c = &cpu_data(0);
u32 lo, hi, old_lo;
/* Control the RNG via MSR. Tread lightly and pay very close
@@ -134,6 +137,17 @@ static int via_rng_init(struct hwrng *rng)
lo &= ~VIA_XSTORE_CNT_MASK;
lo &= ~(VIA_STRFILT_ENABLE | VIA_STRFILT_FAIL | VIA_RAWBITS_ENABLE);
lo |= VIA_RNG_ENABLE;
+ lo |= VIA_NOISESRC1;
+
+ /* Enable secondary noise source on CPUs where it is present. */
+
+ /* Nehemiah stepping 8 and higher */
+ if ((c->x86_model == 9) && (c->x86_mask > 7))
+ lo |= VIA_NOISESRC2;
+
+ /* Esther */
+ if (c->x86_model >= 10)
+ lo |= VIA_NOISESRC2;
if (lo != old_lo)
wrmsr(MSR_VIA_RNG, lo, hi);