xref: /openbmc/qemu/include/sysemu/rng.h (revision c122bca9)
1 /*
2  * QEMU Random Number Generator Backend
3  *
4  * Copyright IBM, Corp. 2012
5  *
6  * Authors:
7  *  Anthony Liguori   <aliguori@us.ibm.com>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
10  * See the COPYING file in the top-level directory.
11  */
12 
13 #ifndef QEMU_RNG_H
14 #define QEMU_RNG_H
15 
16 #include "qemu/queue.h"
17 #include "qom/object.h"
18 
19 #define TYPE_RNG_BACKEND "rng-backend"
20 OBJECT_DECLARE_TYPE(RngBackend, RngBackendClass,
21                     RNG_BACKEND)
22 
23 #define TYPE_RNG_BUILTIN "rng-builtin"
24 
25 typedef struct RngRequest RngRequest;
26 
27 typedef void (EntropyReceiveFunc)(void *opaque,
28                                   const void *data,
29                                   size_t size);
30 
31 struct RngRequest
32 {
33     EntropyReceiveFunc *receive_entropy;
34     uint8_t *data;
35     void *opaque;
36     size_t offset;
37     size_t size;
38     QSIMPLEQ_ENTRY(RngRequest) next;
39 };
40 
41 struct RngBackendClass
42 {
43     ObjectClass parent_class;
44 
45     void (*request_entropy)(RngBackend *s, RngRequest *req);
46 
47     void (*opened)(RngBackend *s, Error **errp);
48 };
49 
50 struct RngBackend
51 {
52     Object parent;
53 
54     /*< protected >*/
55     bool opened;
56     QSIMPLEQ_HEAD(, RngRequest) requests;
57 };
58 
59 
60 /**
61  * rng_backend_request_entropy:
62  * @s: the backend to request entropy from
63  * @size: the number of bytes of data to request
64  * @receive_entropy: a function to be invoked when entropy is available
65  * @opaque: data that should be passed to @receive_entropy
66  *
67  * This function is used by the front-end to request entropy from an entropy
68  * source.  This function can be called multiple times before @receive_entropy
69  * is invoked with different values of @receive_entropy and @opaque.  The
70  * backend will queue each request and handle appropriately.
71  *
72  * The backend does not need to pass the full amount of data to @receive_entropy
73  * but will pass a value greater than 0.
74  */
75 void rng_backend_request_entropy(RngBackend *s, size_t size,
76                                  EntropyReceiveFunc *receive_entropy,
77                                  void *opaque);
78 
79 /**
80  * rng_backend_free_request:
81  * @s: the backend that created the request
82  * @req: the request to finalize
83  *
84  * Used by child rng backend classes to finalize requests once they've been
85  * processed. The request is removed from the list of active requests and
86  * deleted.
87  */
88 void rng_backend_finalize_request(RngBackend *s, RngRequest *req);
89 #endif
90