Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 858576bd authored by Harald Welte's avatar Harald Welte Committed by Herbert Xu
Browse files

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: default avatarHarald Welte <HaraldWelte@viatech.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 608d1cd5

drivers/char/hw_random/via-rng.c

+13 −0
Original line number Diff line number Diff line
@@ -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