diff options
Diffstat (limited to 'drivers/char/hw_random/via-rng.c')
| -rw-r--r-- | drivers/char/hw_random/via-rng.c | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c index ec435cb25c4f..f7feae4ebb5e 100644 --- a/drivers/char/hw_random/via-rng.c +++ b/drivers/char/hw_random/via-rng.c @@ -27,6 +27,7 @@ #include <linux/module.h> #include <linux/kernel.h> #include <linux/hw_random.h> +#include <linux/delay.h> #include <asm/io.h> #include <asm/msr.h> #include <asm/cpufeature.h> @@ -41,6 +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 */ @@ -77,10 +80,11 @@ static inline u32 xstore(u32 *addr, u32 edx_in) return eax_out; } -static int via_rng_data_present(struct hwrng *rng) +static int via_rng_data_present(struct hwrng *rng, int wait) { u32 bytes_out; u32 *via_rng_datum = (u32 *)(&rng->priv); + int i; /* We choose the recommended 1-byte-per-instruction RNG rate, * for greater randomness at the expense of speed. Larger @@ -95,12 +99,15 @@ static int via_rng_data_present(struct hwrng *rng) * 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; + for (i = 0; i < 20; i++) { + *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 || !wait) + break; + udelay(10); + } + return bytes_out ? 1 : 0; } static int via_rng_data_read(struct hwrng *rng, u32 *data) @@ -114,6 +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 @@ -129,6 +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); |