drivers: add simple hw_random implementation

Add a simple hw_random implementation based on code from
Linux v4.5-rc5.

All the entropypool initialization stuff is left out and
the obsolete data_read/data_present calls are omitted.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 47 insertions, 0 deletions

diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
new file mode 100644
index 0000000000..bae442166c
--- /dev/null
+++ b/include/linux/hw_random.h
@@ -0,0 +1,47 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef LINUX_HWRANDOM_H_
+#define LINUX_HWRANDOM_H_
+
+#include <linux/list.h>
+
+/**
+ * struct hwrng - Hardware Random Number Generator driver
+ * @name:		Unique RNG name.
+ * @init:		Initialization callback (can be NULL).
+ * @read:		New API. drivers can fill up to max bytes of data
+ *			into the buffer. The buffer is aligned for any type.
+ */
+struct hwrng {
+	const char *name;
+	int (*init)(struct hwrng *rng);
+	int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
+
+	struct list_head list;
+
+	struct cdev cdev;
+	struct device_d *dev;
+	void *buf;
+};
+
+/* Register a new Hardware Random Number Generator driver. */
+int hwrng_register(struct device_d *dev, struct hwrng *rng);
+int hwrng_get_data(struct hwrng *rng, void *buffer, size_t size, int wait);
+
+#ifdef CONFIG_HWRNG
+struct hwrng *hwrng_get_first(void);
+#else
+static inline struct hwrng *hwrng_get_first(void) { return ERR_PTR(-ENODEV); };
+#endif
+
+#endif /* LINUX_HWRANDOM_H_ */