hwrng: timeriomem - New driver

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>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 8822eca58ffa..e86dd425a70f 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -20,6 +20,20 @@ config HW_RANDOM
 
           If unsure, say Y.
 
+config HW_RANDOM_TIMERIOMEM
+        tristate "Timer IOMEM HW Random Number Generator support"
+        depends on HW_RANDOM
+        ---help---
+          This driver provides kernel-side support for a generic Random
+          Number Generator used by reading a 'dumb' iomem address that
+          is to be read no faster than, for example, once a second;
+          the default FPGA bitstream on the TS-7800 has such functionality.
+
+          To compile this driver as a module, choose M here: the
+          module will be called timeriomem-rng.
+
+          If unsure, say Y.
+
 config HW_RANDOM_INTEL
         tristate "Intel HW Random Number Generator support"
         depends on HW_RANDOM && (X86 || IA64) && PCI