1/* $NetBSD: meson_clk_div.c,v 1.3 2019/02/25 19:30:17 jmcneill Exp $ */
2
3/*-
4 * Copyright (c) 2017-2019 Jared 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_clk_div.c,v 1.3 2019/02/25 19:30:17 jmcneill Exp $");
31
32#include <sys/param.h>
33#include <sys/bus.h>
34
35#include <dev/clk/clk_backend.h>
36
37#include <arm/amlogic/meson_clk.h>
38
39u_int
40meson_clk_div_get_rate(struct meson_clk_softc *sc,
41    struct meson_clk_clk *clk)
42{
43	struct meson_clk_div *div = &clk->u.div;
44	struct clk *clkp, *clkp_parent;
45	u_int rate, ratio;
46	uint32_t val;
47
48	KASSERT(clk->type == MESON_CLK_DIV);
49
50	clkp = &clk->base;
51	clkp_parent = clk_get_parent(clkp);
52	if (clkp_parent == NULL)
53		return 0;
54
55	rate = clk_get_rate(clkp_parent);
56	if (rate == 0)
57		return 0;
58
59	CLK_LOCK(sc);
60	val = CLK_READ(sc, div->reg);
61	CLK_UNLOCK(sc);
62
63	if (div->div)
64		ratio = __SHIFTOUT(val, div->div);
65	else
66		ratio = 0;
67
68	if (div->flags & MESON_CLK_DIV_POWER_OF_TWO) {
69		return rate >> ratio;
70	} else if (div->flags & MESON_CLK_DIV_CPU_SCALE_TABLE) {
71		if (ratio < 1 || ratio > 8)
72			return 0;
73		return rate / ((ratio + 1) * 2);
74	} else {
75		return rate / (ratio + 1);
76	}
77}
78
79int
80meson_clk_div_set_rate(struct meson_clk_softc *sc,
81    struct meson_clk_clk *clk, u_int new_rate)
82{
83	struct meson_clk_div *div = &clk->u.div;
84	struct clk *clkp, *clkp_parent;
85	int parent_rate;
86	uint32_t val, raw_div;
87	int ratio, error;
88
89	KASSERT(clk->type == MESON_CLK_DIV);
90
91	clkp = &clk->base;
92	clkp_parent = clk_get_parent(clkp);
93	if (clkp_parent == NULL)
94		return ENXIO;
95
96	if ((div->flags & MESON_CLK_DIV_SET_RATE_PARENT) != 0)
97		return clk_set_rate(clkp_parent, new_rate);
98
99	if (div->div == 0)
100		return ENXIO;
101
102	CLK_LOCK(sc);
103
104	val = CLK_READ(sc, div->reg);
105
106	parent_rate = clk_get_rate(clkp_parent);
107	if (parent_rate == 0) {
108		error = (new_rate == 0) ? 0 : ERANGE;
109		goto done;
110	}
111
112	ratio = howmany(parent_rate, new_rate);
113	if ((div->flags & MESON_CLK_DIV_POWER_OF_TWO) != 0) {
114		error = EINVAL;
115		goto done;
116	} else if ((div->flags & MESON_CLK_DIV_CPU_SCALE_TABLE) != 0) {
117		error = EINVAL;
118		goto done;
119	} else {
120		raw_div = (ratio > 0) ? ratio - 1 : 0;
121	}
122	if (raw_div > __SHIFTOUT_MASK(div->div)) {
123		error = ERANGE;
124		goto done;
125	}
126
127	val &= ~div->div;
128	val |= __SHIFTIN(raw_div, div->div);
129	CLK_WRITE(sc, div->reg, val);
130
131	error = 0;
132
133done:
134	CLK_UNLOCK(sc);
135
136	return error;
137}
138
139const char *
140meson_clk_div_get_parent(struct meson_clk_softc *sc,
141    struct meson_clk_clk *clk)
142{
143	struct meson_clk_div *div = &clk->u.div;
144
145	KASSERT(clk->type == MESON_CLK_DIV);
146
147	return div->parent;
148}
149