1 /* $NetBSD: meson_rng.c,v 1.5 2022/03/19 11:36:43 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2015-2019 Jared D. McNeill <jmcneill@invisible.ca>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: meson_rng.c,v 1.5 2022/03/19 11:36:43 riastradh Exp $");
31
32 #include <sys/param.h>
33 #include <sys/bus.h>
34 #include <sys/device.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/mutex.h>
38 #include <sys/rndsource.h>
39
40 #include <dev/fdt/fdtvar.h>
41
42 static int meson_rng_match(device_t, cfdata_t, void *);
43 static void meson_rng_attach(device_t, device_t, void *);
44
45 static void meson_rng_get(size_t, void *);
46
47 struct meson_rng_softc {
48 device_t sc_dev;
49 bus_space_tag_t sc_bst;
50 bus_space_handle_t sc_bsh;
51
52 krndsource_t sc_rndsource;
53 };
54
55 static const struct device_compatible_entry compat_data[] = {
56 { .compat = "amlogic,meson-rng" },
57 DEVICE_COMPAT_EOL
58 };
59
60 CFATTACH_DECL_NEW(meson_rng, sizeof(struct meson_rng_softc),
61 meson_rng_match, meson_rng_attach, NULL, NULL);
62
63 static int
meson_rng_match(device_t parent,cfdata_t cf,void * aux)64 meson_rng_match(device_t parent, cfdata_t cf, void *aux)
65 {
66 struct fdt_attach_args * const faa = aux;
67
68 return of_compatible_match(faa->faa_phandle, compat_data);
69 }
70
71 static void
meson_rng_attach(device_t parent,device_t self,void * aux)72 meson_rng_attach(device_t parent, device_t self, void *aux)
73 {
74 struct meson_rng_softc * const sc = device_private(self);
75 struct fdt_attach_args * const faa = aux;
76 const int phandle = faa->faa_phandle;
77 struct clk *clk;
78 bus_addr_t addr;
79 bus_size_t size;
80
81 if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
82 aprint_error(": couldn't get registers\n");
83 return;
84 }
85
86 sc->sc_dev = self;
87 sc->sc_bst = faa->faa_bst;
88 if (bus_space_map(sc->sc_bst, addr, size, 0, &sc->sc_bsh) != 0) {
89 aprint_error(": couldn't map registers\n");
90 return;
91 }
92
93 /* Core clock is optional */
94 clk = fdtbus_clock_get(phandle, "core");
95 if (clk != NULL && clk_enable(clk) != 0) {
96 aprint_error(": couldn't enable core clock\n");
97 return;
98 }
99
100 aprint_naive("\n");
101 aprint_normal(": Hardware RNG\n");
102
103 rndsource_setcb(&sc->sc_rndsource, meson_rng_get, sc);
104 rnd_attach_source(&sc->sc_rndsource, device_xname(self), RND_TYPE_RNG,
105 RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
106 }
107
108 static void
meson_rng_get(size_t bytes_wanted,void * priv)109 meson_rng_get(size_t bytes_wanted, void *priv)
110 {
111 struct meson_rng_softc * const sc = priv;
112 uint32_t data;
113
114 while (bytes_wanted) {
115 data = bus_space_read_4(sc->sc_bst, sc->sc_bsh, 0);
116 rnd_add_data_sync(&sc->sc_rndsource, &data, sizeof(data),
117 sizeof(data) * NBBY);
118 bytes_wanted -= MIN(bytes_wanted, sizeof(data));
119 }
120 explicit_memset(&data, 0, sizeof(data));
121 }
122