random: add_hwgenerator_randomness() for feeding entropy from devices

#include <linux/interrupt.h>

#include <linux/mm.h>

#include <linux/spinlock.h>

#include <linux/kthread.h>

#include <linux/percpu.h>

#include <linux/cryptohash.h>

#include <linux/fips.h>

		return 0;

	return PAGE_ALIGN(get_random_int() % range + start);

}

/* Interface for in-kernel drivers of true hardware RNGs.

 * Those devices may produce endless random bits and will be throttled

 * when our pool is full.

 */

void add_hwgenerator_randomness(const char *buffer, size_t count,

				size_t entropy)

{

	struct entropy_store *poolp = &input_pool;

	/* Suspend writing if we're above the trickle threshold.

	 * We'll be woken up again once below random_write_wakeup_thresh,

	 * or when the calling thread is about to terminate.

	 */

	wait_event_interruptible(random_write_wait, kthread_should_stop() ||

			ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);

	mix_pool_bytes(poolp, buffer, count);

	credit_entropy_bits(poolp, entropy);

}

EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);

extern int hwrng_register(struct hwrng *rng);

/** Unregister a Hardware Random Number Generator driver. */

extern void hwrng_unregister(struct hwrng *rng);

/** Feed random bits into the pool. */

extern void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy);

#endif /* LINUX_HWRANDOM_H_ */