linux-toradex.git/include/linux/hw_random.h, branch v4.19-rc5

hwrng: Make explicit that max >= 32 always

2016-11-21T14:50:45+00:00

As hw_random core calls ->read with max > 32 or more, make it explicit.
Also remove checks involving 'max' being less than 8.

Signed-off-by: PrasannaKumar Muralidharan 
Signed-off-by: Herbert Xu

hwrng: core - Improve description of the ->read() interface

2016-08-24T13:04:48+00:00

Currently, very few RNG drivers support single byte reads using the
->read() interface. Of the 14 drivers in drivers/char/hw_random that
support this interface only three of these actually support max == 1.
The other behaviours vary between return 0, return 2, return 4 and return
-EIO).

This is not a problem in practice because the core hw_random code never
performs a read shorter than 16 bytes. The documentation for this function
already contrains the alignment of the buffer pointer, so let's also
guarantee that the buffer is at least as large as its alignment.

This constraint is intended to be the weakest guarantee neccessary to
allow driver writers to safely simplify their code.

Signed-off-by: Daniel Thompson 
Signed-off-by: Herbert Xu

hwrng: add devm_* interfaces

2015-03-16T10:45:54+00:00

This change adds devm_hwrng_register and devm_hwrng_unregister which
use can simplify error unwinding and unbinding code paths in device
drivers.

Signed-off-by: Dmitry Torokhov 
Signed-off-by: Herbert Xu

hwrng: core - Use struct completion for cleanup_done

2014-12-25T21:33:34+00:00

There is no point in doing a manual completion for cleanup_done
when struct completion fits in perfectly.

Signed-off-by: Herbert Xu

hwrng: fix unregister race.

2014-12-22T12:02:40+00:00

The previous patch added one potential problem: we can still be
reading from a hwrng when it's unregistered.  Add a wait for zero
in the hwrng_unregister path.

Signed-off-by: Rusty Russell 
Signed-off-by: Amos Kong 
Signed-off-by: Herbert Xu

hwrng: use reference counts on each struct hwrng.

2014-12-22T12:02:39+00:00

current_rng holds one reference, and we bump it every time we want
to do a read from it.

This means we only hold the rng_mutex to grab or drop a reference,
so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't
block on read of /dev/hwrng.

Using a kref is overkill (we're always under the rng_mutex), but
a standard pattern.

This also solves the problem that the hwrng_fillfn thread was
accessing current_rng without a lock, which could change (eg. to NULL)
underneath it.

Signed-off-by: Rusty Russell 
Signed-off-by: Amos Kong 
Signed-off-by: Herbert Xu

hwrng: add per-device entropy derating

2014-07-15T08:49:40+00:00

This patch introduces a derating factor to struct hwrng for
the random bits going into the kernel input pool, and a common
default derating for drivers which do not specify one.

Signed-off-by: Torsten Duwe 
Signed-off-by: Theodore Ts'o 
Acked-by: H. Peter Anvin

random: add_hwgenerator_randomness() for feeding entropy from devices

2014-07-15T08:49:40+00:00

This patch adds an interface to the random pool for feeding entropy
in-kernel.

Signed-off-by: Torsten Duwe 
Signed-off-by: Theodore Ts'o 
Acked-by: H. Peter Anvin

hwrng: fix spelling mistake in header comment

2011-05-25T12:15:12+00:00

Cc: Herbert Xu 
Cc: Matt Mackall 
Signed-off-by: Sasha Levin 
Signed-off-by: Jiri Kosina

hwrng: core - Replace u32 in driver API with byte array

2009-12-01T06:47:32+00:00

This patch implements a new method by which hw_random hardware drivers
can pass data to the core more efficiently, using a shared buffer.

The old methods have been retained as a compatability layer until all the
drivers have been updated.

Signed-off-by: Ian Molton 
Acked-by: Matt Mackall 
Acked-by: Rusty Russell 
Signed-off-by: Herbert Xu