hwrng: add sandbox driver interface to host /dev/random

Linux as well as other operating systems can provide /dev/random and
/dev/urandom device to service userspace need for randomness.
Add a driver to use /dev/random for blocking and /dev/urandom for
non-blocking barebox random numbers.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 32 insertions, 0 deletions

diff --git a/arch/sandbox/board/Makefile b/arch/sandbox/board/Makefile
index b6c271c858..26f6cb1922 100644
--- a/arch/sandbox/board/Makefile
+++ b/arch/sandbox/board/Makefile
@@ -5,5 +5,6 @@ obj-y += console.o
 obj-y += devices.o
 obj-y += dtb.o
 obj-y += poweroff.o
+obj-y += dev-random.o
 
 extra-y += barebox.lds
diff --git a/arch/sandbox/board/board.c b/arch/sandbox/board/board.c
index 1f6392d15e..ad2bc910c3 100644
--- a/arch/sandbox/board/board.c
+++ b/arch/sandbox/board/board.c
@@ -42,6 +42,11 @@ static struct device_d sdl_device = {
 	.platform_data = &mode,
 };
 
+static struct device_d devrandom_device = {
+	.id	  = DEVICE_ID_DYNAMIC,
+	.name     = "devrandom",
+};
+
 static int devices_init(void)
 {
 	platform_device_register(&tap_device);
@@ -54,6 +59,8 @@ static int devices_init(void)
 
 	platform_device_register(&sdl_device);
 
+	platform_device_register(&devrandom_device);
+
 	return 0;
 }
 
diff --git a/arch/sandbox/board/dev-random.c b/arch/sandbox/board/dev-random.c
new file mode 100644
index 0000000000..f65e5ef6e5
--- /dev/null
+++ b/arch/sandbox/board/dev-random.c
@@ -0,0 +1,24 @@
+#include <common.h>
+#include <mach/linux.h>
+
+devrandom_t *devrandom_init(void) {
+	devrandom_t *fds = xzalloc(sizeof(*fds));
+
+	fds->randomfd = linux_open("/dev/random", false);
+	if (fds->randomfd < 0)
+		return ERR_PTR(-EPERM);
+
+	fds->urandomfd = linux_open("/dev/urandom", false);
+	if (fds->urandomfd < 0)
+		return ERR_PTR(-EPERM);
+
+	return fds;
+}
+
+int devrandom_read(devrandom_t *devrandom, void *buf, size_t len, int wait)
+{
+	if (wait)
+		return linux_read(devrandom->randomfd, buf, len);
+
+	return linux_read(devrandom->urandomfd, buf, len);
+}