[PATCH 3/5] hpet: wire up entropy generation function
From: Jarod Wilson <hidden>
Date: 2011-06-13 22:07:39
Subsystem:
hpet: x86, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
HPET is high enough resolution that we can use its low-order byte to stir new data into the random number generator entropy pool. CC: Matt Mackall <redacted> CC: "Venkatesh Pallipadi (Venki)" <redacted> CC: Thomas Gleixner <redacted> CC: Ingo Molnar <redacted> CC: John Stultz <redacted> CC: Herbert Xu <herbert@gondor.apana.org.au> CC: "David S. Miller" <davem@davemloft.net> Signed-off-by: Jarod Wilson <redacted> --- arch/x86/kernel/hpet.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 6781765..cf23090 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c@@ -10,6 +10,7 @@ #include <linux/cpu.h> #include <linux/pm.h> #include <linux/io.h> +#include <linux/random.h> #include <asm/fixmap.h> #include <asm/i8253.h>
@@ -63,6 +64,22 @@ static inline void hpet_writel(unsigned int d, unsigned int a) writel(d, hpet_virt_address + a); } +static void hpet_add_entropy(void) +{ + static unsigned long last; + unsigned long counter; + int delta; + + counter = hpet_readl(HPET_COUNTER); + delta = (int)(counter - last); + last = counter; + + if (delta == counter) + return; + + add_clocksource_randomness(delta); +} + #ifdef CONFIG_X86_64 #include <asm/pgtable.h> #endif
@@ -752,6 +769,7 @@ static struct clocksource clocksource_hpet = { .mask = HPET_MASK, .flags = CLOCK_SOURCE_IS_CONTINUOUS, .resume = hpet_resume_counter, + .entropy = hpet_add_entropy, #ifdef CONFIG_X86_64 .vread = vread_hpet, #endif
--
1.7.1