1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2017 BayLibre, SAS
4 * Author: Neil Armstrong <narmstrong@baylibre.com>
5 * Author: Jerome Brunet <jbrunet@baylibre.com>
6 */
7
8 /*
9 * The AO Domain embeds a dual/divider to generate a more precise
10 * 32,768KHz clock for low-power suspend mode and CEC.
11 * ______ ______
12 * | | | |
13 * | Div1 |-| Cnt1 |
14 * /|______| |______|\
15 * -| ______ ______ X--> Out
16 * \| | | |/
17 * | Div2 |-| Cnt2 |
18 * |______| |______|
19 *
20 * The dividing can be switched to single or dual, with a counter
21 * for each divider to set when the switching is done.
22 */
23
24 #include <linux/clk-provider.h>
25 #include <linux/module.h>
26
27 #include "clk-regmap.h"
28 #include "clk-dualdiv.h"
29
30 static inline struct meson_clk_dualdiv_data *
meson_clk_dualdiv_data(struct clk_regmap * clk)31 meson_clk_dualdiv_data(struct clk_regmap *clk)
32 {
33 return (struct meson_clk_dualdiv_data *)clk->data;
34 }
35
36 static unsigned long
__dualdiv_param_to_rate(unsigned long parent_rate,const struct meson_clk_dualdiv_param * p)37 __dualdiv_param_to_rate(unsigned long parent_rate,
38 const struct meson_clk_dualdiv_param *p)
39 {
40 if (!p->dual)
41 return DIV_ROUND_CLOSEST(parent_rate, p->n1);
42
43 return DIV_ROUND_CLOSEST(parent_rate * (p->m1 + p->m2),
44 p->n1 * p->m1 + p->n2 * p->m2);
45 }
46
meson_clk_dualdiv_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)47 static unsigned long meson_clk_dualdiv_recalc_rate(struct clk_hw *hw,
48 unsigned long parent_rate)
49 {
50 struct clk_regmap *clk = to_clk_regmap(hw);
51 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk);
52 struct meson_clk_dualdiv_param setting;
53
54 setting.dual = meson_parm_read(clk->map, &dualdiv->dual);
55 setting.n1 = meson_parm_read(clk->map, &dualdiv->n1) + 1;
56 setting.m1 = meson_parm_read(clk->map, &dualdiv->m1) + 1;
57 setting.n2 = meson_parm_read(clk->map, &dualdiv->n2) + 1;
58 setting.m2 = meson_parm_read(clk->map, &dualdiv->m2) + 1;
59
60 return __dualdiv_param_to_rate(parent_rate, &setting);
61 }
62
63 static const struct meson_clk_dualdiv_param *
__dualdiv_get_setting(unsigned long rate,unsigned long parent_rate,struct meson_clk_dualdiv_data * dualdiv)64 __dualdiv_get_setting(unsigned long rate, unsigned long parent_rate,
65 struct meson_clk_dualdiv_data *dualdiv)
66 {
67 const struct meson_clk_dualdiv_param *table = dualdiv->table;
68 unsigned long best = 0, now = 0;
69 unsigned int i, best_i = 0;
70
71 if (!table)
72 return NULL;
73
74 for (i = 0; table[i].n1; i++) {
75 now = __dualdiv_param_to_rate(parent_rate, &table[i]);
76
77 /* If we get an exact match, don't bother any further */
78 if (now == rate) {
79 return &table[i];
80 } else if (abs(now - rate) < abs(best - rate)) {
81 best = now;
82 best_i = i;
83 }
84 }
85
86 return (struct meson_clk_dualdiv_param *)&table[best_i];
87 }
88
meson_clk_dualdiv_determine_rate(struct clk_hw * hw,struct clk_rate_request * req)89 static int meson_clk_dualdiv_determine_rate(struct clk_hw *hw,
90 struct clk_rate_request *req)
91 {
92 struct clk_regmap *clk = to_clk_regmap(hw);
93 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk);
94 const struct meson_clk_dualdiv_param *setting;
95
96 setting = __dualdiv_get_setting(req->rate, req->best_parent_rate,
97 dualdiv);
98 if (setting)
99 req->rate = __dualdiv_param_to_rate(req->best_parent_rate,
100 setting);
101 else
102 req->rate = meson_clk_dualdiv_recalc_rate(hw,
103 req->best_parent_rate);
104
105 return 0;
106 }
107
meson_clk_dualdiv_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)108 static int meson_clk_dualdiv_set_rate(struct clk_hw *hw, unsigned long rate,
109 unsigned long parent_rate)
110 {
111 struct clk_regmap *clk = to_clk_regmap(hw);
112 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk);
113 const struct meson_clk_dualdiv_param *setting =
114 __dualdiv_get_setting(rate, parent_rate, dualdiv);
115
116 if (!setting)
117 return -EINVAL;
118
119 meson_parm_write(clk->map, &dualdiv->dual, setting->dual);
120 meson_parm_write(clk->map, &dualdiv->n1, setting->n1 - 1);
121 meson_parm_write(clk->map, &dualdiv->m1, setting->m1 - 1);
122 meson_parm_write(clk->map, &dualdiv->n2, setting->n2 - 1);
123 meson_parm_write(clk->map, &dualdiv->m2, setting->m2 - 1);
124
125 return 0;
126 }
127
128 const struct clk_ops meson_clk_dualdiv_ops = {
129 .recalc_rate = meson_clk_dualdiv_recalc_rate,
130 .determine_rate = meson_clk_dualdiv_determine_rate,
131 .set_rate = meson_clk_dualdiv_set_rate,
132 };
133 EXPORT_SYMBOL_NS_GPL(meson_clk_dualdiv_ops, CLK_MESON);
134
135 const struct clk_ops meson_clk_dualdiv_ro_ops = {
136 .recalc_rate = meson_clk_dualdiv_recalc_rate,
137 };
138 EXPORT_SYMBOL_NS_GPL(meson_clk_dualdiv_ro_ops, CLK_MESON);
139
140 MODULE_DESCRIPTION("Amlogic dual divider driver");
141 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
142 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
143 MODULE_LICENSE("GPL");
144 MODULE_IMPORT_NS(CLK_MESON);
145