Some hardware RNGs provide a single register for obtaining random data.
Instead of signaling when new data is available, the reader must wait a
fixed amount of time between reads for new data to be generated.
timeriomem_rng implements this scheme with the period specified in
platform data or device tree. While the period is specified in
microseconds, the implementation used a standard timer which has a
minimum delay of 1 jiffie and caused a significant bottleneck for
devices that can update at 1us. By switching to an hrtimer, 1us periods
now only delay at most 2us per read.
Signed-off-by: Rick Altherr <raltherr@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Preserves the existing behavior of only returning 32-bits per call.
Signed-off-by: Rick Altherr <raltherr@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The site-specific OOM messages are unnecessary, because they
duplicate the MM subsystem generic OOM message.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use devm_*() functions to make cleanup paths simpler.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use this new function to make code more comprehensible, since we are
reinitialzing the completion, not initializing.
[akpm@linux-foundation.org: linux-next resyncs]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org> (personally at LCE13)
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d06310
(device-core: Ensure drvdata = NULL when no driver is bound).
Thus, it is not needed to manually clear the device driver data to NULL.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch allows timeriomem_rng to be used via devicetree.
Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
timeriomem_rng only supports a single device instance. This patch
enables multiple timeriomem_rng devices to coexist as well as adds
some additional error checking.
Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
CONFIG_HOTPLUG is going away as an option. As a result, the __dev*
markings need to be removed.
This change removes the use of __devinit, __devexit_p, __devinitdata,
__devinitconst, and __devexit from these drivers.
Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: David Airlie <airlied@linux.ie>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch converts the drivers in drivers/char/hw_random/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.
Cc: David S. Miller <davem@davemloft.net>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Alexander Clouter <alex@digriz.org.uk>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fixed oops when calling device_unregister followed by device_register
(changing __init to __devinit) and removed request_mem_region() as
platform_device_register already does this which can result in EBUSY
Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
There is no ioremap'ing or anything in timeriomem-rng.c as I foolishly
used already remapped virtual addresses instead of passing the physical
address to be polled.
This patch fixes this flaw and lets developers do the Right Thing(tm).
Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Some hardware platforms, the TS-7800[1] is one for example, can
supply the kernel with an entropy source, albeit a slow one for
TS-7800 users, by just reading a particular IO address. This
source must not be read above a certain rate otherwise the quality
suffers.
The driver is then hooked into by calling
platform_device_(register|add|del) passing a structure similar to:
------
static struct timeriomem_rng_data ts78xx_ts_rng_data = {
.address = (u32 *__iomem) TS_RNG,
.period = 1000000, /* one second */
};
static struct platform_device ts78xx_ts_rng_device = {
.name = "timeriomem_rng",
.id = -1,
.dev = {
.platform_data = &ts78xx_ts_rng_data,
},
.num_resources = 0,
};
------
[1] http://www.embeddedarm.com/products/board-detail.php?product=TS-7800
Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Rick Altherr