fixedclock.c revision 1.1 
1/* $NetBSD: fixedclock.c,v 1.1 2017/04/16 12:29:20 jmcneill Exp $ */
2
3/*-
4 * Copyright (c) 2017 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: fixedclock.c,v 1.1 2017/04/16 12:29:20 jmcneill Exp $");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/device.h>
35#include <sys/kmem.h>
36#include <sys/bus.h>
37
38#include <dev/clk/clk_backend.h>
39
40#include <dev/fdt/fdtvar.h>
41
42static int	fixedclock_match(device_t, cfdata_t, void *);
43static void	fixedclock_attach(device_t, device_t, void *);
44
45static struct clk *fixedclock_decode(device_t, const void *, size_t);
46
47static const struct fdtbus_clock_controller_func fixedclock_fdt_funcs = {
48	.decode = fixedclock_decode
49};
50
51static struct clk *fixedclock_get(void *, const char *);
52static void	fixedclock_put(void *, struct clk *);
53static u_int	fixedclock_get_rate(void *, struct clk *);
54
55static const struct clk_funcs fixedclock_clk_funcs = {
56	.get = fixedclock_get,
57	.put = fixedclock_put,
58	.get_rate = fixedclock_get_rate,
59};
60
61struct fixedclock_clk {
62	struct clk	base;
63	u_int		rate;
64};
65
66struct fixedclock_softc {
67	device_t	sc_dev;
68	int		sc_phandle;
69
70	struct clk_domain sc_clkdom;
71	struct fixedclock_clk sc_clk;
72};
73
74CFATTACH_DECL_NEW(fclock, sizeof(struct fixedclock_softc),
75    fixedclock_match, fixedclock_attach, NULL, NULL);
76
77static int
78fixedclock_match(device_t parent, cfdata_t cf, void *aux)
79{
80	const char * const compatible[] = { "fixed-clock", NULL };
81	const struct fdt_attach_args *faa = aux;
82
83	return of_match_compatible(faa->faa_phandle, compatible);
84}
85
86static void
87fixedclock_attach(device_t parent, device_t self, void *aux)
88{
89	struct fixedclock_softc * const sc = device_private(self);
90	const struct fdt_attach_args *faa = aux;
91	const int phandle = faa->faa_phandle;
92
93	sc->sc_dev = self;
94	sc->sc_phandle = phandle;
95	sc->sc_clkdom.funcs = &fixedclock_clk_funcs;
96	sc->sc_clkdom.priv = sc;
97	if (of_getprop_uint32(phandle, "clock-frequency",
98	    &sc->sc_clk.rate) != 0) {
99		aprint_error(": couldn't determine frequency\n");
100		return;
101	}
102	sc->sc_clk.base.domain = &sc->sc_clkdom;
103	sc->sc_clk.base.name = kmem_asprintf("%s", faa->faa_name);
104
105	aprint_naive(": %u Hz fixed clock (%s)\n", sc->sc_clk.rate,
106	    sc->sc_clk.base.name);
107
108	fdtbus_register_clock_controller(self, phandle, &fixedclock_fdt_funcs);
109}
110
111static struct clk *
112fixedclock_decode(device_t dev, const void *data, size_t len)
113{
114	struct fixedclock_softc * const sc = device_private(dev);
115
116	/* #clock-cells for a fixed clock is always 0 */
117	if (len != 0)
118		return NULL;
119
120	return &sc->sc_clk.base;
121}
122
123static struct clk *
124fixedclock_get(void *priv, const char *name)
125{
126	struct fixedclock_softc * const sc = priv;
127
128	if (strcmp(name, sc->sc_clk.base.name) != 0)
129		return NULL;
130
131	return &sc->sc_clk.base;
132}
133
134static void
135fixedclock_put(void *priv, struct clk *clk)
136{
137}
138
139static u_int
140fixedclock_get_rate(void *priv, struct clk *clk)
141{
142	struct fixedclock_clk *fclk = (struct fixedclock_clk *)clk;
143
144	return fclk->rate;
145}
146