root/include/linux/hw_random.h

/*
        Hardware Random Number Generator

        Please read Documentation/hw_random.txt for details on use.

        ----------------------------------------------------------
        This software may be used and distributed according to the terms
        of the GNU General Public License, incorporated herein by reference.

 */

#ifndef LINUX_HWRANDOM_H_
#define LINUX_HWRANDOM_H_

#include <linux/types.h>
#include <linux/list.h>

/**
 * struct hwrng - Hardware Random Number Generator driver
 * @name:               Unique RNG name.
 * @init:               Initialization callback (can be NULL).
 * @cleanup:            Cleanup callback (can be NULL).
 * @data_present:       Callback to determine if data is available
 *                      on the RNG. If NULL, it is assumed that
 *                      there is always data available.
 * @data_read:          Read data from the RNG device.
 *                      Returns the number of lower random bytes in "data".
 *                      Must not be NULL.
 * @priv:               Private data, for use by the RNG driver.
 */
struct hwrng {
        const char *name;
        int (*init)(struct hwrng *rng);
        void (*cleanup)(struct hwrng *rng);
        int (*data_present)(struct hwrng *rng, int wait);
        int (*data_read)(struct hwrng *rng, u32 *data);
        unsigned long priv;

        /* internal. */
        struct list_head list;
};

/** Register a new Hardware Random Number Generator driver. */
extern int hwrng_register(struct hwrng *rng);
/** Unregister a Hardware Random Number Generator driver. */
extern void hwrng_unregister(struct hwrng *rng);

#endif /* LINUX_HWRANDOM_H_ */