1/*-
2 * Copyright 2014 John Wehle <john@feith.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27/*
28 * Amlogic aml8726 random number generator driver.
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD$");
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/conf.h>
37#include <sys/bus.h>
38#include <sys/kernel.h>
39#include <sys/module.h>
40#include <sys/lock.h>
41#include <sys/mutex.h>
42#include <sys/resource.h>
43#include <sys/rman.h>
44#include <sys/random.h>
45
46#include <machine/bus.h>
47
48#include <dev/fdt/fdt_common.h>
49#include <dev/ofw/ofw_bus.h>
50#include <dev/ofw/ofw_bus_subr.h>
51
52
53struct aml8726_rng_softc {
54	device_t		dev;
55	struct resource		*res[1];
56	struct callout		co;
57	int			ticks;
58};
59
60static struct resource_spec aml8726_rng_spec[] = {
61	{ SYS_RES_MEMORY,	0,	RF_ACTIVE },
62	{ -1, 0 }
63};
64
65#define	AML_RNG_0_REG			0
66#define	AML_RNG_1_REG			4
67
68#define	CSR_READ_4(sc, reg)		bus_read_4((sc)->res[0], reg)
69
70static void
71aml8726_rng_harvest(void *arg)
72{
73	struct aml8726_rng_softc *sc = arg;
74	uint32_t rn[2];
75
76	rn[0] = CSR_READ_4(sc, AML_RNG_0_REG);
77	rn[1] = CSR_READ_4(sc, AML_RNG_1_REG);
78
79	random_harvest(rn, sizeof(rn), sizeof(rn) * NBBY / 2,
80	    RANDOM_PURE_AML8726);
81
82	callout_reset(&sc->co, sc->ticks, aml8726_rng_harvest, sc);
83}
84
85static int
86aml8726_rng_probe(device_t dev)
87{
88
89	if (!ofw_bus_status_okay(dev))
90		return (ENXIO);
91
92	if (!ofw_bus_is_compatible(dev, "amlogic,aml8726-rng"))
93		return (ENXIO);
94
95	device_set_desc(dev, "Amlogic aml8726 RNG");
96
97	return (BUS_PROBE_DEFAULT);
98}
99
100static int
101aml8726_rng_attach(device_t dev)
102{
103	struct aml8726_rng_softc *sc = device_get_softc(dev);
104
105	sc->dev = dev;
106
107	if (bus_alloc_resources(dev, aml8726_rng_spec, sc->res)) {
108		device_printf(dev, "can not allocate resources for device\n");
109		return (ENXIO);
110	}
111
112	/* Install a periodic collector for the RNG */
113	if (hz > 100)
114		sc->ticks = hz / 100;
115	else
116		sc->ticks = 1;
117
118	callout_init(&sc->co, 1);
119	callout_reset(&sc->co, sc->ticks, aml8726_rng_harvest, sc);
120
121	return (0);
122}
123
124static int
125aml8726_rng_detach(device_t dev)
126{
127	struct aml8726_rng_softc *sc = device_get_softc(dev);
128
129	callout_drain(&sc->co);
130
131	bus_release_resources(dev, aml8726_rng_spec, sc->res);
132
133	return (0);
134}
135
136static device_method_t aml8726_rng_methods[] = {
137	/* Device interface */
138	DEVMETHOD(device_probe,		aml8726_rng_probe),
139	DEVMETHOD(device_attach,	aml8726_rng_attach),
140	DEVMETHOD(device_detach,	aml8726_rng_detach),
141
142	DEVMETHOD_END
143};
144
145static driver_t aml8726_rng_driver = {
146	"rng",
147	aml8726_rng_methods,
148	sizeof(struct aml8726_rng_softc),
149};
150
151static devclass_t aml8726_rng_devclass;
152
153DRIVER_MODULE(aml8726_rng, simplebus, aml8726_rng_driver,
154    aml8726_rng_devclass, 0, 0);
155MODULE_DEPEND(aml8726_rng, random, 1, 1, 1);
156