[PATCH] ARM: omap2: throw the die id into the entropy pool

[PATCH] ARM: omap2: throw the die id into the entropy pool

[Linus Walleij]

Atleast eight bytes of this number are totally unique for the device
it seems, so this is a perfect candidate for feeding the entropy
pool. One byte more or less of constants does not matter so feed in
the entire OID struct.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/arm/mach-omap2/id.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/mach-omap2/id.c b/arch/arm/mach-omap2/id.c
index 2dc62a2..fc03cc6 100644
--- a/arch/arm/mach-omap2/id.c
+++ b/arch/arm/mach-omap2/id.c
@@ -18,6 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/random.h>
 #include <linux/slab.h>
 
 #ifdef CONFIG_SOC_BUS
@@ -130,6 +131,17 @@ void omap_get_die_id(struct omap_die_id *odi)
 	odi->id_3 = read_tap_reg(OMAP_TAP_DIE_ID_3);
 }
 
+static int __init omap_feed_randpool(void)
+{
+	struct omap_die_id odi;
+
+	/* Throw the die ID into the entropy pool at boot */
+	omap_get_die_id(&odi);
+	add_device_randomness(&odi, sizeof(odi));
+	return 0;
+}
+device_initcall(omap_feed_randpool);
+
 void __init omap2xxx_check_revision(void)
 {
 	int i, j;
-- 
1.8.1.4

[PATCH] ARM: omap2: throw the die id into the entropy pool

[Kevin Hilman]

Linus Walleij <linus.walleij@linaro.org> writes:

> Atleast eight bytes of this number are totally unique for the device
> it seems, so this is a perfect candidate for feeding the entropy
> pool. One byte more or less of constants does not matter so feed in
> the entire OID struct.
>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Paul Walmsley <paul@pwsan.com>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  arch/arm/mach-omap2/id.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/arch/arm/mach-omap2/id.c b/arch/arm/mach-omap2/id.c
> index 2dc62a2..fc03cc6 100644
> --- a/arch/arm/mach-omap2/id.c
> +++ b/arch/arm/mach-omap2/id.c
> @@ -18,6 +18,7 @@
>  #include <linux/kernel.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> +#include <linux/random.h>
>  #include <linux/slab.h>
>  
>  #ifdef CONFIG_SOC_BUS
> @@ -130,6 +131,17 @@ void omap_get_die_id(struct omap_die_id *odi)
>  	odi->id_3 = read_tap_reg(OMAP_TAP_DIE_ID_3);
>  }
>  
> +static int __init omap_feed_randpool(void)
> +{
> +	struct omap_die_id odi;
> +
> +	/* Throw the die ID into the entropy pool at boot */
> +	omap_get_die_id(&odi);
> +	add_device_randomness(&odi, sizeof(odi));
> +	return 0;
> +}
> +device_initcall(omap_feed_randpool);

Needs to be omap_device_initcall() so it doesn't get called on non-OMAPs
in a multi-platform kernel.

Otherwise looks good.

Reviewed-by: Kevin Hilman <khilman@linaro.org>

Kevin