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, 21 insertions, 0 deletions

diff --git a/include/linux/timeriomem-rng.h b/include/linux/timeriomem-rng.h
new file mode 100644
index 00000000000..dd253177f65
--- /dev/null
+++ b/include/linux/timeriomem-rng.h
@@ -0,0 +1,21 @@
+/*
+ * linux/include/linux/timeriomem-rng.h
+ *
+ * Copyright (c) 2009 Alexander Clouter <alex@digriz.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/completion.h>
+
+struct timeriomem_rng_data {
+        struct completion       completion;
+        unsigned int            present:1;
+
+        u32 __iomem             *address;
+
+        /* measures in usecs */
+        unsigned int            period;
+};