/*
        Hardware Random Number Generator

        Please read Documentation/admin-guide/hw_random.rst 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/completion.h>
#include <linux/kref.h>
#include <linux/types.h>
#include <linux/workqueue_types.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.  *OBSOLETE*
 * @data_read:          Read data from the RNG device.
 *                      Returns the number of lower random bytes in "data".
 *                      Must not be NULL.    *OBSOLETE*
 * @read:               New API. drivers can fill up to max bytes of data
 *                      into the buffer. The buffer is aligned for any type
 *                      and max is a multiple of 4 and >= 32 bytes.
 * @priv:               Private data, for use by the RNG driver.
 * @quality:            Estimation of true entropy in RNG's bitstream
 *                      (in bits of entropy per 1024 bits of input;
 *                      valid values: 1 to 1024, or 0 for maximum).
 */
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);
        int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
        unsigned long priv;
        unsigned short quality;

        /* internal. */
        struct list_head list;
        struct kref ref;
        struct work_struct cleanup_work;
        struct completion cleanup_done;
        struct completion dying;
};

struct device;

/** Register a new Hardware Random Number Generator driver. */
extern int hwrng_register(struct hwrng *rng);
extern int devm_hwrng_register(struct device *dev, struct hwrng *rng);
/** Unregister a Hardware Random Number Generator driver. */
extern void hwrng_unregister(struct hwrng *rng);
extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng);

extern long hwrng_msleep(struct hwrng *rng, unsigned int msecs);
extern long hwrng_yield(struct hwrng *rng);

#endif /* LINUX_HWRANDOM_H_ */