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
39 u_int
meson_clk_div_get_rate(struct meson_clk_softc * sc,struct meson_clk_clk * clk)40 meson_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
79 int
meson_clk_div_set_rate(struct meson_clk_softc * sc,struct meson_clk_clk * clk,u_int new_rate)80 meson_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
133 done:
134 CLK_UNLOCK(sc);
135
136 return error;
137 }
138
139 const char *
meson_clk_div_get_parent(struct meson_clk_softc * sc,struct meson_clk_clk * clk)140 meson_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