// file: include/linux/hw_random.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 unknown).
*/
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 completion cleanup_done;
};
// file: include/linux/hw_random.h
/** 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);
/** Feed random bits into the pool. */
extern void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy);
