1 /*
2 	Hardware Random Number Generator
3 
4 	Please read Documentation/admin-guide/hw_random.rst for details on use.
5 
6 	----------------------------------------------------------
7 	This software may be used and distributed according to the terms
8         of the GNU General Public License, incorporated herein by reference.
9 
10  */
11 
12 #ifndef LINUX_HWRANDOM_H_
13 #define LINUX_HWRANDOM_H_
14 
15 #include <linux/completion.h>
16 #include <linux/kref.h>
17 #include <linux/types.h>
18 
19 /**
20  * struct hwrng - Hardware Random Number Generator driver
21  * @name:		Unique RNG name.
22  * @init:		Initialization callback (can be NULL).
23  * @cleanup:		Cleanup callback (can be NULL).
24  * @data_present:	Callback to determine if data is available
25  *			on the RNG. If NULL, it is assumed that
26  *			there is always data available.  *OBSOLETE*
27  * @data_read:		Read data from the RNG device.
28  *			Returns the number of lower random bytes in "data".
29  *			Must not be NULL.    *OBSOLETE*
30  * @read:		New API. drivers can fill up to max bytes of data
31  *			into the buffer. The buffer is aligned for any type
32  *			and max is a multiple of 4 and >= 32 bytes.
33  * @priv:		Private data, for use by the RNG driver.
34  * @quality:		Estimation of true entropy in RNG's bitstream
35  *			(in bits of entropy per 1024 bits of input;
36  *			valid values: 1 to 1024, or 0 for maximum).
37  */
38 struct hwrng {
39 	const char *name;
40 	int (*init)(struct hwrng *rng);
41 	void (*cleanup)(struct hwrng *rng);
42 	int (*data_present)(struct hwrng *rng, int wait);
43 	int (*data_read)(struct hwrng *rng, u32 *data);
44 	int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
45 	unsigned long priv;
46 	unsigned short quality;
47 
48 	/* internal. */
49 	struct list_head list;
50 	struct kref ref;
51 	struct completion cleanup_done;
52 	struct completion dying;
53 };
54 
55 struct device;
56 
57 /** Register a new Hardware Random Number Generator driver. */
58 extern int hwrng_register(struct hwrng *rng);
59 extern int devm_hwrng_register(struct device *dev, struct hwrng *rng);
60 /** Unregister a Hardware Random Number Generator driver. */
61 extern void hwrng_unregister(struct hwrng *rng);
62 extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng);
63 
64 extern long hwrng_msleep(struct hwrng *rng, unsigned int msecs);
65 extern long hwrng_yield(struct hwrng *rng);
66 
67 #endif /* LINUX_HWRANDOM_H_ */
68