tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2015 Maxime Ripard <maxime.ripard@free-electrons.com>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/bitops.h>
10#include <linux/clk-provider.h>
11#include <linux/err.h>
12#include <linux/export.h>
13#include <linux/kernel.h>
14#include <linux/of.h>
15#include <linux/slab.h>
16
17static unsigned long __get_mult(struct clk_multiplier *mult,
18 unsigned long rate,
19 unsigned long parent_rate)
20{
21 if (mult->flags & CLK_MULTIPLIER_ROUND_CLOSEST)
22 return DIV_ROUND_CLOSEST(rate, parent_rate);
23
24 return rate / parent_rate;
25}
26
27static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw,
28 unsigned long parent_rate)
29{
30 struct clk_multiplier *mult = to_clk_multiplier(hw);
31 unsigned long val;
32
33 val = clk_readl(mult->reg) >> mult->shift;
34 val &= GENMASK(mult->width - 1, 0);
35
36 if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)
37 val = 1;
38
39 return parent_rate * val;
40}
41
42static bool __is_best_rate(unsigned long rate, unsigned long new,
43 unsigned long best, unsigned long flags)
44{
45 if (flags & CLK_MULTIPLIER_ROUND_CLOSEST)
46 return abs(rate - new) < abs(rate - best);
47
48 return new >= rate && new < best;
49}
50
51static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate,
52 unsigned long *best_parent_rate,
53 u8 width, unsigned long flags)
54{
55 struct clk_multiplier *mult = to_clk_multiplier(hw);
56 unsigned long orig_parent_rate = *best_parent_rate;
57 unsigned long parent_rate, current_rate, best_rate = ~0;
58 unsigned int i, bestmult = 0;
59 unsigned int maxmult = (1 << width) - 1;
60
61 if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
62 bestmult = rate / orig_parent_rate;
63
64 /* Make sure we don't end up with a 0 multiplier */
65 if ((bestmult == 0) &&
66 !(mult->flags & CLK_MULTIPLIER_ZERO_BYPASS))
67 bestmult = 1;
68
69 /* Make sure we don't overflow the multiplier */
70 if (bestmult > maxmult)
71 bestmult = maxmult;
72
73 return bestmult;
74 }
75
76 for (i = 1; i < maxmult; i++) {
77 if (rate == orig_parent_rate * i) {
78 /*
79 * This is the best case for us if we have a
80 * perfect match without changing the parent
81 * rate.
82 */
83 *best_parent_rate = orig_parent_rate;
84 return i;
85 }
86
87 parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
88 rate / i);
89 current_rate = parent_rate * i;
90
91 if (__is_best_rate(rate, current_rate, best_rate, flags)) {
92 bestmult = i;
93 best_rate = current_rate;
94 *best_parent_rate = parent_rate;
95 }
96 }
97
98 return bestmult;
99}
100
101static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate,
102 unsigned long *parent_rate)
103{
104 struct clk_multiplier *mult = to_clk_multiplier(hw);
105 unsigned long factor = __bestmult(hw, rate, parent_rate,
106 mult->width, mult->flags);
107
108 return *parent_rate * factor;
109}
110
111static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
112 unsigned long parent_rate)
113{
114 struct clk_multiplier *mult = to_clk_multiplier(hw);
115 unsigned long factor = __get_mult(mult, rate, parent_rate);
116 unsigned long flags = 0;
117 unsigned long val;
118
119 if (mult->lock)
120 spin_lock_irqsave(mult->lock, flags);
121 else
122 __acquire(mult->lock);
123
124 val = clk_readl(mult->reg);
125 val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift);
126 val |= factor << mult->shift;
127 clk_writel(val, mult->reg);
128
129 if (mult->lock)
130 spin_unlock_irqrestore(mult->lock, flags);
131 else
132 __release(mult->lock);
133
134 return 0;
135}
136
137const struct clk_ops clk_multiplier_ops = {
138 .recalc_rate = clk_multiplier_recalc_rate,
139 .round_rate = clk_multiplier_round_rate,
140 .set_rate = clk_multiplier_set_rate,
141};
142EXPORT_SYMBOL_GPL(clk_multiplier_ops);